solar box cookers in zimbabwe:

the introduction of a radical innovation in cooking


patrice m. rodgers

b.s. (the university of connecticut) 1979


submitted in partial satisfaction

of the requirements for the degree of

master of science


international agricultural development

in the

graduate division

of the

university of california






committee in charge



"none of the principal foodcrops of the tropics is palatable unless it has been cooked first. lack of fuel can be as much a cause of malnutrition as the lack of food."

gunnar poulsen

man and trees in tropical africa

"it costs as much to heat a pot as to fill it"

old african proverb

(quoted in smil and knowland, 1980)

"cooking is one of the most culture-bound of human activities. food preparation, serving time and place, food flavor and cooking participants often are established by long tradition and, therefore, are resistant to change. social and religious customs may ...eliminate certain technology options even if energy output is good."

ashworth and neuendorffer

matching renewable energy systems to

village-level energy needs

this thesis is for my former students in bohicon and savalou, benin, whose pointed and often unanswerable questions pushed me towards my own inquiries into radical alternatives, with sincere thanks to all those who contributed their time, talents, finances, and sweat to this project, especially

solar cookers international of sacramento, the international agricultural development graduate group at uc davis, and the uc davis women's resources and research center, without whose financial sponsorship this research would not have been possible;

bob metcalf and bev blum of solar cookers international,

the plan mutare staff, especially stanley mashumba and j. kofa, the cd workers, and interviewers agnes chidende, patience chitobvu, joyleen kabaza, ruth mafaune, and spelile mauro;

thesis cohorts robin kozloff and barbara naess, and bea calo, for their steady encouragement and well-timed jokes; and last but by no means least

jim grieshop, barbara goldman and keith barton for their patience, support and discriminating judgment in guiding me through the process of writing this thesis.

patrice mary rodgers

december 1994

applied behavioral sciences:

international agricultural development

solar cookers in zimbabwe:

the introduction of a radical innovation in cooking


this study evaluated a zimbabwean/american promotion project to introduce a new technology, the solar box cooker (sbc), as part of a community development effort in the mutare district of zimbabwe. the study attempted to evaluate the degree of sbc use among the project participants, to determine whether or not and to what degree the technology had been adopted, and if it had diffused to other households.

the evaluation study took place in the mutare district of zimbabwe where a total of 171 people had attended sbc workshops in 1989 and 1990, during which they had built their own sbc. in 1992, as part of the evaluation, five interviewers spent 3 weeks interviewing workshop participants. in all, 155 of the original 171 participants were located and interviewed, a 91% sample.

the sbc, considered by its promoters to be a simple technology because of its uncomplicated design, is able to cook almost any type of food entirely with solar power. in zimbabwe, where much of the country is deforested and where 25%-40% of the average yearly income might be spent on cooking fuel, the potential benefits of solar cooking appear to be enormous: its use could contribute significantly to a decrease in the rate of deforestation, as well as provide benefits which could lead to an increase in the general physical and financial health of the population.

results of the 1992 survey showed that 2-3 years after the promotional workshops, the sbc had been adopted by many of the target population in that they used it to some extent, but the actual degree of utilization of the technology was much less than the climate of zimbabwe could potentially allow. no diffusion of the idea was evident, however: sbc use by other community members was not observed.

traditional factors such as area communication channels, the socio-economic context in which the sbc is utilized, and the innovation itself were examined in order to explain this puzzle. these components, however, do not completely explain why this seemingly ideal technology has not rapidly diffused to a wider area, and other elements, including cultural factors, promotional techniques, and a re-examination of the presumed simplicity of the sbc, are also considered.

numerous constraints to the adoption of the sbc were discovered, including economic, logistical, cultural, promotional/educational, and community-related factors. in the face of these constraints, a re-examination of the assumed "simplicity" of the sbc was made, and a hypothesis proposed: since use of the sbc in zimbabwe demands a change in lifestyle for its target users, the innovation should be considered a "radical" rather than a "simple" one, and the promotional techniques used to advance it must adapt to that definition.

suggested techniques considered include the use of multiple introduction and multiple communication channels, and the active promotion of re-invention.

table of contents

list of figures vilist of tables viichapter 1: introduction 1the introduction of solar box cookers in zimbabwe 15evaluation of the introduction project 16chapter 2: literature review 19chapter 3: methodology 27chapter 4: results and data 38interview results 44informal interviews 65chapter 5: discussion of results 68chapter 6: conclusions and recommendations 74multiple introduction 75radical innovations and multiple introduction 88bibliography 92appendix a: questionnaire 98appendix b: quotes illustrating misunderstanding and incorrect use 103appendix c: summary of recommendations for future promotional efforts 104appendix d: recommendations for further research 105appendix e: instructions for building a solar box cooker 107

list of figures

figure 1: map of africa 4

figure 2: map of study areas within mutare district 5

figure 3: diagram of solar box cooker 9

figures 4a and 4b: deforested and eroded farmland 10a

figure 4c: cutting firewood in the mutare district 11

figure 5: buying firewood in harare 12

figure 6: women cooking 12

figures 7 and 8: sbc owners at interviews 33

figures 9 and 10: typical interview setting, early evening 34

figure 11: cost increases for cooking fuel 43

figure 12: fuel problems 43

figure 13: respondents' present usage of sbcs 46

figure 14: perceptions of saving fuel 47

figure 15: foods cooked with sbcs 48

figure 16: opinions regarding slower cooking 48

figure 17: factors related to success of cooking 49

figure 18: problems with solar cooking, and related reasons 51

figure 19: disadvantages found 52

figure 20: foods which cook best using sbc 55

figure 21: advantages of solar cooking 56

figure 22: differences noted by sbc users 57

figure 23: reasons sbc not used on all sunny days 59

figure 24: diffusion potential 60

figure 25: respondents' awareness of other sbc owners and users 61

figure 26: why don't others use their sbcs more often? 62

figure 27: reasons others don't build cookers 64

figure 28: mud bricks drying 87

figure 29: mutare woman with newly made sbc 91

list of tables

table 1: problems sbcs can potentially impact 10

table 2: participants in the 1989 sbc introduction project 15

table 3: subjects of diffusion research generalizations 25

table 4: data gathered 36

table 5: respondent background information (general) 40

table 6: respondent background information (cooking) 41

table 7: respondent fuel use/fuel availability information 42

table 8: sbc adoption 45

table 9: problems with the sbc 53

table 10: problems for which solutions were found 53

table 11: other uses for an sbc 54

table 12: words describing sbc 58

table 13: other ideas about why others don't use their cookers more 63

table 14: other possible interpretations of adoption results 70

table 15: positive observations relative to sbc use in zimbabwe 74

table 16: summary of identified constraints to sbc use in zimbabwe 83

table 17: addressing identified constraints 85

table 18: quotes illustrating misunderstanding and incorrect use 103

table 19: summary of recommendations for promotion of solar box cookers 104

chapter 1: introduction

problem statement

many technological innovations remain under-utilized in areas of the world where they have been introduced. even innovations which seem to provide the perfect answer to serious and longstanding problems, and which appear compatible with existing social, financial and technical constraints may nonetheless remain virtually unused, even after long periods of time (rogers, 1984).

studies of this phenomenon have identified distinct phases in the processes of adoption and diffusion of innovations, and many diverse constraining factors have been implicated (brown,1981:8). however, the underlying causes of the phenomenon are not easily generalized, since the constraints to adoption of an innovation may differ dramatically from case to case: in a well-known story (made famous by everett rogers) of the use of citrus fruits by the british navy for prevention of scurvy, apparent constraints to citrus adoption included competition and the lack of prominence of the navy physician who tested and promoted the its use (rogers:1971); in "gunfire at sea", etling morison describes constraints to the adoption of continuous aim firing that included disbelief in the potential of the innovation, an inefficient bureaucracy, and a resistance to change in the power structure of the american navy at that period of time (morison:1966); an early 1960's study by richard o. carlson in allegheny county, pennsylvania found that an important constraint to the rapid adoption of modern math by some school superintendents was a lack of sufficient degree of friendship with other superintendents in the same geographical area (carlson:1967). numerous other studies of assorted innovations such as the querty typewriter keyboard, metal ships, family planning, high-yielding seed varieties, the thompson submachine gun, automobile seatbelts, microwave ovens, recycling, the personal computer, etc. provide many hours of fascinating reading.

traditional innovation diffusion research has focused on several elements related to the success or failure of an innovation's adoption and diffusion: the innovation itself, characteristics of the adopter, existing communication channels, time, and the social system within which the innovation will be used. examination of these elements, however, does not always explain why some innovations are rapidly adopted and diffused and others are not. citing a 1946 case study as an example, robert solo offers one explanation when he says:

"(a) new technology (is) not disseminated simply because of its benefits and availability. even when potential recipients were highly knowledgeable and sophisticated scientists, and where no barriers to its transfer existed, the widespread adoption of the new technology required specific commitment and sustained effort to promote an awareness of its potential values, and to the skills required for its use." (solo, 1972: p.18).

everett rogers agrees when he states that even good innovations "do not sell themselves" (rogers, 1983:7). the "selling" of an innovation, therefore, whether commercial or educational promotion, must be examined as well. promotional methods may be an especially important factor in situations where the innovation is not a simple one. in cases where a initial introduction is the only promotion employed for a given innovation, the adoption and diffusion of an otherwise useful and appropriate innovation may stagnate.

to prevent this stagnation, a promotional strategy which incorporates multiple introductions and multiple communication channels, allowing each time for the refining and adaptation (re-invention) of the innovation as well as that of the promotional technique, may be necessary. the use of this strategy becomes even more critical with complex innovations (i.e., those containing complicated physical/theoretical elements) or radical innovations, defined here as those innovations requiring significant changes in the lifestyle of the adopter.

multiple introduction provides a structure for evaluating an innovation in a particular setting, identifying the constraints associated with its use there, and formulating a strategy for improving adoption and diffusion by addressing those constraints.

this research examined the 1989 introduction of a radical innovation, the solar box cooker, in the mutare district of zimbabwe. specific constraints associated with the innovation's adoption in that area were identified, and a strategy proposed to utilize multiple introduction, multiple communication channels, and the promotion of re-invention to increase its potential for widespread use in zimbabwe.



zimbabwe lies in the southern hemisphere and in the southern part of the african continent. mozambique borders its eastern and northeastern sides, with zambia to the northwest, botswana to the west, and south africa to the south. average temperatures range from 15oc to 20oc, with the highest temperatures occurring in summer, between november and may.

mutare and its surrounding district are located at the extreme east of the country, just a few kilometers from mozambique. the town lies in the eastern highlands, about 1200 meters above sea level, and roughly 50 km from the nyanga mountains and mt. nyangani, the highest point in the country.

figure 1: map of africa

figure 2: map of study areas within mutare district

statistics for 1987 give zimbabwe's population as 9 million. its $580 per capita gnp is one of the highest in africa, and life expectancy in zimbabwe (58 years) is also one of the best in the developing world (the international bank for reconstruction and development, 1989).

zimbabwe existed as the british colony of rhodesia from 1890 until 1965, when descendants of the original white settlers declared independence from england in an (ultimately failed) attempt to maintain white minority rule. in 1980, majority rule was established and the country was renamed zimbabwe, translated as "house of stone" from shona, the most widely used local language.

during the 90 years of british rule, the all-white parliament had set aside the best agricultural lands for white settlers, leaving the poorer, less fertile lands to the black majority. in a 1980 post-colonization effort to redistribute land, the new zimbabwean government relocated black zimbabweans from their crowded communal lands to areas that were once for whites only. the new areas, referred to as "resettlement areas", are scattered over much of the country. roughly three quarters of zimbabwe's population still lives in the communal areas.

zimbabwe is fortunate to have a favorable climate and fertile soils for agricultural endeavors. much of zimbabwe is under cultivation, with less than 3% of the country's area unsuitable for any agricultural activity in the absence of irrigation, and since independence in 1980, the country has been largely self-sufficient with respect to food production, producing an average of 1.5 million tons of maize (its staple food crop) per year.

from 1989 to 1992, however, zimbabwe suffered a major drought. in most of the country, little or no rain fell for over 2 years. with relatively few irrigated crops, zimbabwe switched almost overnight from providing grain for much of southern africa to importing drought relief from the united states and other countries. in 1993, the rains began again, and the drought seems to have eased, though long term effects will no doubt be seen for some time.

though much of zimbabwe's population lives in sparsely populated, rural areas, a network of paved roads connect many of the city centers and village centers in the 8 provinces. electricity, telex and telephone service are widely available in urban and suburban areas, and the national railway line connects cities in zimbabwe with each other and with neighboring countries. three satellite stations in zimbabwe allow transmission outside the country, and 7 airports or airstrips allow for international flights as well as in-country hops.

zimbabwe's urban population grew from 14% in 1965 to 26% in 1987, and continues to increase. as in many other countries, this growth is largely a result of migration to urban centers by young men in search of work. half of the urban population, or about 1.1 million people, live in harare, the capital of zimbabwe.

zimbabweans, like residents of many other african countries, are dependent on firewood for most of their cooking and much of their heating needs. largely due to this fact, the thick forests that once covered much of the country have decreased, over the last 300 years, to a small fraction of what they once were. the remaining forest is still being harvested, though reforestation projects have slowed somewhat the overall deforestation rate.

women and children in zimbabwe spend an increasing number of hours each week gathering fuel for cooking. where fuelwood is no longer available to be collected, a large percentage of annual income must be spent to buy either it, or another type of cooking fuel.

the mutare district of zimbabwe, where the evaluation study took place, is an excellent representative district for the country as a whole. its urban center, mutare, is itself a large town and well-connected by road and train line to harare (several hours drive away). mutare is immediately surrounded by large expanses of sparsely populated rural "resettlement areas". as elsewhere in zimbabwe, deforestation is a significant problem, though perhaps less so than is evident in the area immediately surrounding harare. plan international has been operating in the mutare district of zimbabwe since 1987. one of its goals for work in the district has been conservation of natural resources, and that, combined with plan's goal of increasing child survival, made the solar box cooker an ideal technology to test.

solar box cookers

the idea of solar cooking and the ability to cook food safely with solar energy have existed for almost 300 years: solar cookers have ranged from simple glass-covered passive solar energy-using holes in the ground to sophisticated high tech energy-storing cookers with reflectors and sun-tracking capabilities. in 1976, an inexpensive, easy-to-build solar box cooker (sbc) was developed by barbara kerr and sherry cole, two arizona women. using their design, and with a minimum of expense and expertise, a solar box cooker capable of reaching moderate (200-2500f) cooking temperatures can be built with cardboard, glass and aluminum foil, and then used for cooking food and pasteurizing water. the sbc, defined by promoters as a simple technology because of its uncomplicated design and easy use, is fashioned to cook almost any type of food entirely with solar power. its simple "box-within-a-box" design (see figure 3) utilizes the greenhouse effect, allowing light energy (sunlight) to enter the box through a pane of glass, but keeping heat energy from escaping. the unique design of the box allows even a partially sunny day to create an oven which can easily reach 225o f in an hour.

figure 3: diagram of solar box cooker (from sci pamphlet)

among its advantages are the facts that nearly any kind of food can be cooked in a matter of hours, there is no need to tend to the cooking, and the fuel is free and plentiful. this last factor is of critical import to women and children in many developing countries who spend hours each week gathering sufficient wood for cooking. also important are the numerous environmental and health problems which the use of solar cooking can potentially alleviate (see table 1, and figures 4a and 4b).

table 1: problems sbcs can potentially impact


    agricultural problems caused by      severe burns to toddlers who     
a shortage of women's labor at       fall into ground fires, or are       
seasons of peak labor demand,        burned by splashing food,            

    health problems caused by            parasite problems caused by      
constant exposure to the smoke of    lack of adequate fuel to pasteurize  
cooking fires,                       water, and                           

    poverty, due to the large            air pollution from smokey        
percentage of income which must go   fires.                               
into purchasing cooking fuel,                                             
    deforestation, and the erosion                                        
of soil caused by deforestation,                                          

realizing its potential as an aid against these types of environmental problems,

especially in the developing world, kerr and cole have placed their sbc design in the public domain for non-profit use.

the food and agriculture organization of the u.n. has predicted that by the year 2000, fuelwood shortages will affect over 2 billion people around the world. (fao, 1981). in zimbabwe, where much of the country is deforested and where 25% of the average yearly income might be spent on cooking fuel, the potential benefits of even partial use of the sbc are therefore significant.

figure 4c: cutting firewood in the mutare district

figure 5: buying firewood in harare

figure 6: women cooking

participants in the sbc introduction project

the original sbc introduction project involved two participants: solar box cookers international (now, solar cookers international) of sacramento, california, and the plan international (formerly foster parent's plan, international) field office in mutare, zimbabwe.

solar cookers international

solar cookers international (sci) is a sacramento, california-based non-profit organization whose mission is to advance, worldwide, knowledge of solar cooking. the organization was formed in 1987 and is mainly composed of volunteers. sci works principally through multiplier agencies -- that is, agencies which deal directly with the community and which multiply sci efforts. the organization has been conducting informational workshops around the world for several years. workshops are arranged in response to a request for information from an individual or (more often) from a group who has heard of solar cooking and wants to learn more. to date, sci has given 1 to 5-day workshops on solar cooking in more than a dozen developing countries around the world.

the organization's goal is that by the year 2000, 2.4 people billion (corresponding to the fao-projected number of people who will suffer from fuel shortages -- see page 11) will have access to information about solar cooking.

workshop participants range from high level country administrators to subsistence farmers and rural homemakers (see table 2). there is generally a small donation of money or materials asked of participants. most of the expenses incurred by sci are covered by grant funding from various agencies -- freedom from hunger foundation and the food industry crusade against hunger being two of the most recent.

introductory workshops are run on a tight budget, and significant funds for formal follow-up to any of the projects have been largely unavailable to sci. at the time of this evaluation, however, sci was in the midst of a continuing evaluation of its workshop projects, using a questionnaire it had developed for that purpose.

plan international

plan international of mutare was the multiplier agency for the sbc workshops in mutare. plan international is a non-profit, non-sectarian, non-partisan organization "serving needy children, their families and communities in developing countries." (description from plan international brochure). once dedicated solely to providing funds for childrens' schooling and health care through individual sponsorship (foster parents plan), plan international has expanded to include backing for projects involving entire communities. in zimbabwe, the plan international office at mutare (hereafter referred to as plan mutare) has financially and logistically supported the building of schools and health clinics, the digging of boreholes (wells), the training of teachers and community workers, the formation of both men's and women's cooperatives, and various other community-initiated projects which employ and train local workers.

table 2: participants in the 1989 sbc introduction project

 participants              role         purpose                           

solar cookers             consulting   promote sbcs in zimbabwe           

plan international,       logistics,   increase community health and      
mutare                    instruction  well-being by creating and         
                                       maintaining programs applicable    
                                       to daily life in mutare district.  

food industry crusade     funding      maintain good community relations  
against hunger                         by assisting in charitable causes  

community development     student      become familiar with building and  
workers (plan)            participants using an sbc in order to pass      
                                       along knowledge to community       

mutare district           student      provide visibility for sbc use to  
community leaders,        participants other community members            
county administrators                                                     

mutare district           student      acquire sbc, and knowledge for     
community members         participants using it, to ameliorate problems   
                                       associated with daily cooking of   

the introduction of solar box cookers in zimbabwe

in june of 1989, sci co-founder dr. robert metcalf, responding to an earlier request from plan, arrived in zimbabwe to assist with a 3-day workshop in building and using solar box cookers. over the course of the workshop, 29 people built solar box cookers and took them home to use.

a contingent of plan community development (cd) workers were part of that group of 29, and over the next year, gave similar workshops in their own communities. one year later, a total of 171 people, including the original 29 cd workers, had attended solar box workshops and built their own cooker.

evaluation of the introduction project

the purpose of this research was to evaluate the progress and success to date of the sbc introduction project by determining the degree of adoption and diffusion of the solar box cooker. the evaluation study took place in july 1992, in the mutare district of zimbabwe.

the sbc introduction project provided a good opportunity for study for several reasons: it had not yet been evaluated, english is widely spoken in zimbabwe, and the time period between the introduction and the evaluation seemed ideal -- the 2-3 year lag time was likely to allow for adoption, diffusion, disinterest and/or discontinuance to begin to occur. with the help of bev blum, the executive director of solar cookers international, i was put in touch with stanley mashumba, the evaluation coordinator for plan mutare. mr. mashumba and i spoke on the phone (in somewhat time-disjointed conversations, due to the phone connection) and exchanged faxes while working out some of the logistics and associated costs.

prior to my arrival, as agreed, mr. mashumba hired interviewers to conduct the evaluation interviews with former workshop participants. as we had discussed on the phone, all the interviewers were women, all were high school graduates, and all spoke both shona (the predominant local language) and english.

also prior to my arrival, the cd workers who had been involved in the original sbc introduction effort contributed to a list of names for those people in their areas who had attended workshops in 1989-90, and mr. mashumba began to make logistical arrangements for locating as many workshop participants as possible.

purpose and scope of the study

on a practical level, the purpose of this study was to evaluate the 1989-90 introduction project and find out what adoption/diffusion-hindering problems might or might not exist with either the solar cooker technology as used in zimbabwe, or as related to constraints associated uniquely with zimbabwe's physical/cultural climate. with these problems in mind, specific recommendations for sbc introduction programs in other locations could then be made.

my hypothesis was that the sbc was a radical innovation whose use would present an assortment of difficulties for the potential zimbabwean adopter to overcome, and which the promoter would need to address if widespread adoption were to occur. on an theoretical level, therefore, the study's purpose was to attempt to identify general techniques which might increase the chances for successful introductions of radical innovations, thereby contributing to current theories on adoption and diffusion.

organization of the thesis

the thesis is divided into 5 sections:

1. the literature review which briefly summarizes relevant diffusion research to date, and shows how this study fits into that research;

2. the methodology section which provides details on how the evaluation work was carried out, from training of interviewers to calculation of data;

3. the results and data section which specifically describes the results of the interviews conducted with sbc workshop participants;

4. the discussion which expands upon, and interprets the results; and

5. the conclusions and recommendations section which puts the preceding discussion into a general framework for examining radical innovations, and which makes recommendations for future sbc promotion, and radical innovation introduction in general.

chapter 2: literature review

the purpose of this study was to identify, through an evaluation of a solar box cooking introduction project in zimbabwe, the constraining factors impeding the adoption and diffusion of this radical innovation.

unlike many other disciplines where "why?" is the focus of the problem statement, the question "why not?" looms large in the background of diffusion research. the processes of adoption and diffusion do not easily lend themselves to universal rules and in over half a century of attempting to answer the question "why has adoption not occurred?" researchers have developed numerous methods to try to understand the phenomena involved.

diffusion models and perspectives

up until and into the 1970's, the classical diffusion model dominated the diffusion literature. starting with gabriel tarde in 1903, and continuing up through rogers' book communication of innovations in 1971, the focus of diffusion research centered on the potential adopter, and the process and rate of diffusion. these elements comprised the classical diffusion model, as rogers later defined it, whereby:

" innovation originates from some expert source (often an r&d organization). this source then diffuses the innovation as a uniform package to potential adopters who accept or reject the innovation. the role of the adopter of the innovation is that of a passive accepter" (rogers 1983:333).

while maintaining its spotlight on the adopter as the pivot around which adoption evolves, the classical diffusion model concentrates its efforts on defining the stages of the adoption process (knowledge, persuasion, decision, confirmation); types of adopters (innovator, early adopter, early majority, late majority and laggard) and their characteristics; and the amount of time in which diffusion occurs (rogers and shoemaker, 1971; rogers, 1983; and brown, 1981).

over the course of the last 50 years, many diverse disciplines have looked at the subject from the perspective of the classical model. development economists relate adoption and diffusion to the adopter's credit availability (feder, 1980), land ownership (ruttan, 1977) or farm size (weil, 1970 and binswanger, 1978); sociologists relate adoption and diffusion to factors such as the type of communication channels (rogers and svenning,1969), or an individual's perception of an innovation's attributes (fleigel and kivlin, 1966). everett rogers gives a summary of the generalizations that could be found in the diffusion research literature to 1971 (see table 3). many of them are conflicting, leaving the question "why has diffusion not occurred?" unanswered. starting in the early 1970's, the classical diffusion model's relevance to real-life situations began to be questioned, particularly as concerned assumptions about an innovation's unchanging and complete nature, the effectiveness of the model's centralized or hierarchical direction, and its pro-innovation bias. (schon 1971, brown 1981, and rogers, 1983, among others).

concerns were also raised in the 70s and 80s about equality issues. according to lawrence a. brown (1981), the first decades of diffusion research were undertaken from the traditional adoption perspective, concentrating on the processes by which adoption occurs and the factors related to effective flow of information. in brown's view, because this perspective assumes that all potential adopters have equal opportunity to adopt a given innovation, it concentrates too much on an individual's characteristics, and not enough on the socio-economic conditions within which an innovation is adopted and diffused.

brown espoused a broader view, one which embraces the adoption perspective, but which adds elements from a development perspective (directing attention to the impact of innovation diffusion), an economic history perspective (examining the innovation as a continual process of adaptation), and a market-infrastructure perspective [a supply side perspective which focuses on the diffusion agency and the processes by which an innovation and the conditions for adoption are made available to adopters (brown, 1981).]

other researchers also started looking at other possibilities to explain the wide gap between adoption and non-adoption of innovations, and some began to recognize a need for development of specific promotional programs.

robert solo states that policies should be formulated in developing countries which address promotional programs suited to the circumstances of a particular technical change (solo, 1972). w. paul strassman (1972) finds that though many technologies are transferred to developing countries:

"the strategic core of knowledge (often) remains untransferred" and "the participants' ability to understand, to adapt and to persuade becomes the decisive factor in furthering or impeding transfer of techniques." (strassman, 1972: p.13).

a decade later, brown also broaches the subject of promotion, stating that the traditional two-step flow model (which singles out opinion leaders for first communication efforts, and the general populace for later efforts) may be less effective than one which concentrates on marketing and promotional techniques. (brown, 1981). he also states that "diffusion agency actions are manipulative variables" and that promotional communication is an important part of the market-infrastructure perspective, though he stops short of advocating more research on specific promotional communication techniques.

attention to the idea of promotion became more predominant starting with the development of social marketing. kotler and levy (1969) were probably the first to suggest that commercial marketing principles and the wealth of information gained by the marketing field in many years of consumer research could be applied to social movements and the diffusion of ideas and innovations for non-profit causes as well.

"social marketing is the design, implementation, and control of programs seeking to increase the acceptability of a social idea or cause in a target group(s). it utilizes concepts of market segregation, consumer research, concept development, communication, facilitation, incentives, and exchange theory to maximize target group response." (kotler, 1982: p. 490).

a number of field studies employing social marketing have been carried out to date, though as fox and kotler (1980) note in their early examination of social marketing in the 70's, its use presents some problems with which commercial marketers have not had to deal. its very nature of non-profitability means that social marketing must deal with problems that are perhaps less often present in the commercial world:

decreased availability of elements (especially in developing countries) considered indispensable to marketing -- mass media, disposable income, high literacy rate, transportation infrastructure, etc.

lack of a social marketing counterpart to various marketing job functions,

smaller budgets for case-specific consumer research, and

smaller or non-existent financial returns on investment.

though the use of social marketing is not without its problems, it undoubtedly played a role in helping diffusion researchers to look at the processes of adoption and diffusion from another perspective, since it recognizes that:

"the adoption of an idea, like the adoption of any product, requires a deep understanding of the needs, perceptions, preferences, reference groups, and behavioral patterns of the target audience, and the tailoring of messages, media, "costs" and facilities to maximize the ease of adopting the idea."(kotler, 1975: p. 282).

other research looking specifically at promotion of innovations is rare. among 103 generalizations in rogers 1971 summary of diffusion research, covering hundreds of publications and authors, no mention is made of specific techniques for the promotion of innovations (see table 3). that trend seems to have continued: to date, much of the small body of work dealing with particular promotional techniques (outside of the field of education) concentrates on specific case studies, offering few guidelines for generalized use in diffusion.

in chapters 5 and 6, techniques for promoting radical innovations will be discussed, and recommendations made for using these specific promotional techniques to increase adoption and diffusion of solar cooking and other radical innovations.

table 3: subjects of diffusion research generalizations

 characteristics of                  the adopter                         

earlier adopters and                                                     
- age                               - attitude towards education         
- education level                   - attitude towards science           
   - literacy                       - levels of achievement motivation   
   - social status                  - aspirations                        
   - upward mobility                - social participation               
   - size of holdings (farms, etc)  - integration with social system     
   - commercial orientation         - degree of cosmopoliteness          
   - credit                         - change agent contact               
   - specialized operations         - exposure to mass communication     
   - empathy                        chanels                              
   - dogmatic attitude              - exposure to interpersonal          
   - abstractions                   communication channels               
   - rationality                    - seeking information about          
   - intelligence                   innovations                          
   - attitude towards change        - knowledge of innovations           
- risk attitude                     - higher degree of opinion           
- fatalism                          leadership                           
                                    - system norms                       
                                    - integration of system              
                                    - innovation-decision period         

system effects and individual                                            

later adopters and discontinuance                                        

traditional individuals vs. modern                                       

 influence of opinion leaders        influence of change agent           

heterophilous interpersonal            change agent contact and          
diffusion as related to:            - social status of client            
- opinion leaders                   - client social participation        
- opinion leaders with education    - client education and literacy      
- opinion leaders with mass media   - cosmopoliteness                    
exposure                            - homophily with clients             
- opinion leaders who are more      - extent of working through opinion  
cosmopolite                         leaders                              
- opinion leaders with greater      - credibiliity in eyes of clients    
change agent                        - efforts to increase client's       
  contact                           ability to evaluate                  
- opinion leaders who are more        innovations                        

opinion leaders and                    change agent success and change   
- exposure to mass media            agent effort and                     
- change agent contact              - client/agency orientation          
- social participation              - compatiblity with client needs     
- innovativeness                    - empathy to client                  
- cosmopoliteness                                                        
- social status                                                          

systems norms and                      change agents and anticiaption    
- opinion leaders                   of form, function, meaning           
- opinion leadership                   for clients                       

table 3: subjects of diffusion research generalizations (cont.)

 characteristics of earlier          influence of sociological           
 knowers                             factors                             

earlier knowers and                 legitimizers of collective           
- educational level                 innovative-decisions and social      
- individual innovativeness         status                               
- social status of potential                                             
adopters                            power elite functions in screening   
- mass media                        innovations                          
- interpersonal channels                                                 
- change agent contact                                                   
- social participation                                                   
- cosmopoliteness                                                        

 influence of communciation          the innovation-decision             
 channels                            process                             

type of communication channel and   member acceptance of collective      
the innovation-decision             innovation-decision and degree of    
process                             participation of social system       
                                    members in the decision              
cosmopolite level of communication                                       
channel and the                     member acceptance of collective      
innovative-decision process         innovation decisions and member      
                                    cohesion with social system          
communciation channels and adopter                                       
type                                individual acceptance of authority   
                                    innovation-decision and              
cosmopolite level of communciation  participation in decision-making     
channel and adopter type                                                 
                                    individual satisfaction of           
effects of mass media channels      authority innovation-decision and    
coupled with interpersonal          participation in decision-making     
                                    individual dissoncance and change    
functions in the                    of behavior/attitudes                
innovation-decision process                                              
                                    rate of adoption of authority        
interpersonal diffusion as          innovation-decisions and different   
homophilous diffusion               approaches                           
homophilous interpersonal           particpatory approach as compared    
diffusion as related to             to authority approach and changes    
traditional/modern systems          brought about                        
traditional/modern systems                                               
relative to opinion leader                                               
technical competence                                                     

 rate of adoption                    miscellaneous                       

rate of adoption and                innovations adoption vs.             
- rate of awareness-knowledge       discontinuance                       
- relative advantage of an idea                                          
- compatibility of an idea          innovation-decision stimulators and  
- complexity of innvoation (4-3)    cosmopoliteness                      
- trialability of innnovation                                            
- observability of innovation       initiators of collective             
- degree of communication           innovation-decisons vs.              
integration                         legitimizers of decisons             
rate of adoption related to                                              
involvement of social system's                                           
legitimizers in decision                                                 
rate of adoption of collective                                           
innovations and power                                                    
concentration in a system                                                

chapter 3: methodology

evaluation plan

in order to determine what degree of adoption of the sbc by the treatment group (the workshop participants) had occurred, some measure of sbc use by that group was needed. structured interviews with participants were held for this purpose.

to determine whether or not and to what degree the technology had diffused to other households, interviews were conducted with randomly-chosen members of a community adjacent to that in which the workshops were held. residents of this community had not attended sbc workshops, so any sbc knowledge or information which they might possess would most likely be ascribed to diffusion of the idea from the treatment group.

the objective of the evaluation was, then, to gather data related to the treatment group's opinions about sbcs; how often, and for what sbcs are used in zimbabwe; what factors might separate frequent users, non-users, and occasional users of sbcs in zimbabwe; and possible technical, logistical and/or social-cultural constraints to solar cooking and the use of sbcs in zimbabwe. with this information, a determination of the degree of sbc adoption and diffusion could then be made.

a secondary objective was to determine whether the promotional efforts utilized were effective in that setting, so that recommendations could be made for future efforts to promote solar cooking in general, and in zimbabwe in particular. with the knowledge gained, general recommendations for promotion of innovations could also be made.

interviews with the treatment group (workshop attenders)

in order to evaluate the overall effectiveness of the sbc introduction project, it was necessary to measure the project's impact on the treatment group (workshop attenders). this was done by determining what percentage of the group became sbc adopters and what degree of use that adoption represented. it was also important to find out what the treatment group thought of the solar box cooker, and whether the idea had diffused beyond the group. interviews were used to meet this goal.

questionnaire development

a questionnaire (see appendix a), previously developed by sci for evaluating the success of similar promotional workshops in other countries, was used as the instrument around which the interviews with zimbabwean participants were conducted. the questionnaire consisted of 43 questions, mostly multiple choice. dependent variables included:

traditional cooking methods, customs, and food,

family size and economic status,

availability of, and perceived problems with alternative cooking fuel,

knowledge of, desire for, and experience with solar cooking,

routes through which information on solar cooking was obtained,

suggestions for future educational workshops.

adoption was defined as a decision by an individual to make use of the sbc for cooking, and was determined chiefly by the results of 2 questions (see questions 16 and 22). the degree of use was not considered in defining adoption.


in zimbabwe, interviews were conducted with both participants and non-participants of the solar cooking workshops. the interviews were performed by local high school-educated women, all of whom spoke shona (the local dialect), as well as english.

interviewers were hired by plan's mutare office staff, and were trained for the evaluation project by the plan mutare evaluation coordinator, mr. stanley mashumba, and myself. a two-day training session was held at the outset of the project and included role playing, group discussion, instruction on interview techniques, and a demonstration of solar cooking.


since the identities of all the participants of the original, and subsequent, community workshops were known, a 100% sample survey was targeted. using their own records, workshop organizers and plan community development (cd) workers identified a total of 171 workshop participants. with the help of plan mutare staff and the cd workers, 155 participants, about 91%, were found and interviewed. of the remaining sixteen, nine were said to have moved out of the area, and seven could not be located.

a group of area residents who had not been participants in any solar box cooking workshop were also interviewed. these 39 respondents lived in a community adjacent to one in which several workshops had been given. the community was comprised of several small villages, and was chosen on the basis of its location (adjacent to one of the workshop communities), its similar economic status, its similar size, and its proximity to the same road which ran through several of the workshop communities. a random number n was generated, and workers conducted interviews at each nth house, starting at n miles from the nearest intersection to the plan office, and moving at a 45o angle to the main road. it was decided that a comparison group size approximately 25% as large as the total participant group was easily obtainable, and a total of 40 comparison households was targeted.


interviewing workshop participants

during each day of interviewing, the survey team (plan evaluation coordinator mr. stanley mashumba; 4 or 5 interviewers, depending on the area to be surveyed; one of two plan drivers; and myself) would drive to the area where an individual, or group of individuals, lived. by asking questions at the village center or of passersby, we would then locate the individual's home, where mr. mashumba would explain our purpose, and ask the individual for an interview. if the target individual agreed, mr. mashumba then introduced her to the interviewer whose turn it was to conduct the survey, and the rest of the team would go off in search of the next subject. in making his request for an interview, mr. mashumba would request that the person responsible for the majority of the household's cooking be interviewed. in the vast majority of cases, the person who had attended the workshop would be the main cook for a family, but this was not always the case. if that person was unavailable, the survey was administered to another woman of the household.

in some cases, the interviewers lived close to an area in which a number of individuals from the target population lived. in this case, they were able to make their rounds on foot and to interview the target population independent of the survey team.

most of the time, target population individuals were located at some distance from each other, and the team vehicle was needed to find the house and obtain an interview. interviewers often waited for an hour, sometimes more, to be picked up after completion of each interview. several times, where a residence was located very far into the backcountry, we found it more efficient to wait for the interviewer to complete the interview before travelling to the next location.

from conversations with the interviewers, the average interview seems to have taken approximately 30 to 90 minutes. later, the interviewers became more familiar with the questionnaire, and 30 minutes became the norm.

a total of 194 respondents in the mutare district were interviewed for this study, including a comparison group of 39 people randomly selected for interviewing from a community where solar workshops had not previously occurred. all interviews were conducted in shona, the first language of both the interviewers and the respondents. answers were recorded by the interviewer in english on the questionnaire sheet. each interviewer was thus responsible for translation, at the site, of the responses.

interviews were conducted with the person responsible for food preparation and cooking in each household. when that person was not available, the survey was administered to another woman of the household, or to a member of the household familiar with the household's solar box cooker. though no specific data were gathered relative to workshop attendance, in most cases the workshop attender and the person responsible for the houshold's cooking were one and the same.

figures 7 and 8 following are photographs of 1989/90 workshop participants with their sbcs, taken during the 1992 interviews. figures 9 and 10 show a typical interview setting.

figures 7 and 8: sbc owners at interviews

figures 9 and 10: typical interview setting, early evening

during the course of the interviews, and in 3 weeks of subsequent travel around the country, i had opportunity to make additional observations related to the evaluation by:

conversing with some of the participants after their interviews had been completed in an attempt to independently verify what they had stated in their interview -- for example, whether they used their sbc frequently.

noting and taking photographs of the environmental conditions present in the countryside of the areas we visited for interviews,

talking to other community members, as well as to many other people i met in my travels, who asked me what i was doing in zimbabwe, and jotting notes of those conversations,

reading plan mutare reports and talking to plan staff (see following section) about the types of problems present in the mutare district,

talking to plan staff about their experiences with the introduction of sbcs, and their own perceptions (and use) of solar cooking.

table 4 summarizes the sources of data and information gathered during the course of the evaluation.

table 4: data gathered

             workshop    comparison   interviewers community     other       
                         group                     development               
            participant                            workers      zimbabweans  

interview   155         39            no           yes          no           

additional  yes         no            yes          yes          yes          
(re: sbcs)                                                                   

additional  yes         no            no           no           yes          

interviews with plan staff

cd workers

a group of plan mutare community development workers attended (per mr. mashumba's request) the morning session of the first day of interviewer training at rowa in order to allow me an opportunity to talk to them about their experiences with solar cooking. i spoke individually to each of the twelve (5 women, 7 men) present, taking notes. none had done any formal promotion of solar box cookers since the 1990 workshops.


except for one woman in her 30's, the interviewers were all under 25 years of age, and none of them had never seen or heard of solar cooking. because of that fact, i was interested in their perceptions of the technology and encouraged them to tell me what they, as people who had never tried to solar cook, thought of the technology. in the interviewer training, and later after they had interviewed a number of people, therefore, i asked them their impressions. over the course of the evaluation, their opinions changed in an interesting way. (see chapter 4, p. 67).

data processing of interview responses

responses for the interview data (taken from the interviewer-completed questionnaires) were coded manually, using pre-selected numbers to represent each choice of answer. volunteered answers to open-ended questions were coded based on pre-determined categories, with additional categories added as necessary. frequency distributions were then plotted (spss release 4.0) for different categories of response.

chapter 4: results and data

the purpose of this research was to evaluate the 1989 sbc introduction project in zimbabwe to determine the degree of adoption and diffusion of solar box cooking. to that end, interviews with workshop participants were conducted to measure adoption. results of these interviews show that most respondents (over 80%) can be said to have adopted the technology to the extent that they are using their sbc at least some of the time. (the degree of this adoption will be addressed later in this section, and in the following chapter.)

diffusion of solar cooking, on the other hand, does not seem to have occurred to any observable extent. the reasons for this conclusion will be addressed later in this chapter, and in succeeding chapters.

the interview instrument consisted of 43 questions related to adoption of sbcs by respondents, respondents' background and environment, respondents' cooking and eating practices, fuel availability, respondents' familiarity and experience with sbcs, and respondents' perceptions of sbcs. it was anticipated that results of the interviews would provide information on specific obstacles to sbc adoption in the mutare district of zimbabwe.

in order to provide a context for interpretation of survey results, background data obtained from respondents is also presented.

respondent background data

to discover what obstacles might exist to the adoption of solar cooking in zimbabwe, it is first necessary to establish whether the potential for using an sbc exists within the zimbabwean daily eating and cooking regime -- that is, to determine whether a solar cooker:

- is usable with respect to zimbabwean eating times and habits, and

- is equal to, or greater than (with respect to fuel savings, ease of cooking, or any other benefit) the potential adopter's current cooking method.

tables 5 and 6 furnish information to start answering these questions, and provide background information on the respondents in both the treatment and comparsion groups, furnishing descriptive data on respondents' environments, cooking fuel use, fuel supply problems, and cooking/eating practices. though representing different communities, the two groups had similar backgrounds: both were represented by women (86-95%), ages distributed relatively equally from 20 to 50 plus. in both the treatment and comparison groups, most of the respondents were from families of average (for that area) income, though both lower and higher income families were also represented. median family size for both groups was 6-7 people, though smaller and larger families were also represented. most respondents obtained their cookers by building them in the introductory workshops, one third of them stating that they had difficulty in building them.

as can be seen, the majority of respondents are home during most of the day, most of them have a spot near their house which is sunny for a large part of the day, and most find that the hardest part of cooking is the shortage of fuel. more than three quarters of the families from both groups preferred to eat cooked food at all 3 of their daily meals (table 6).

table 5: respondent background information (general)

              age             family        family     gender   cooker       
                            income          size                source       
                             (as compared                                    

             < 20: 0        lower: 18%     1-3: 13%   f 86%    borrowed 4%   
 treatment   20-29: 18%                    4-5: 21%                          
  group      30-39: 23%     average: 59%   6-7: 35%   m 14%    built (no     
             40-49: 27%                    8-10: 24%           problems)     
 n = 155     50 & up: 32%   higher: 23%    > 10:  8%           67%           
                                                               built (w/     

 comparison  < 20: 0        lower: 23%     1-3: 13%   f 95%                  
 group       20-29: 23%                    4-5: 15%                          
             30-39: 26%     average: 54%   6-7: 49%   m 5%                   
 n = 39      40-49: 23%                    8-10: 23%                         
             50 & up: 28%   higher: 23%    > 10: 0                           

table 6: respondent background information (cooking)

              whereabouts   meals/day      hardest part           sunny     
              during day    eaten hot      of cooking             spot      
                            (cooked)                             near       

             mostly        3 meals: 78%   time for food prep:    yes: 97%   
 treatment   home: 72%                    9%                                
 group                     2 meals: 14%                          no: 3%     
             mostly                       time attending food:              
 n = 155     away: 28%     0-1 meals:     5%                     don't      
                           8%                                    know: 0    
                                          fuel shortage: 48%                
                                          smoke, burns, heat: 0             
                                          nothing is hard: 7%               
                                          other: 9%                         
                                          don't know: 22%                   

             mostly        3 meals: 79%   time for food prep:    yes: 87%   
 comparison  home: 87%                    13%                               
 group                     2 meals:  21%                         no: 10%    
             mostly                       time attending food:              
 n = 39      away: 13%     0-1 meals:  0  13%                    don't      
                                                                 know: 3%   
                                          fuel shortage: 33%                
                                          smoke, burns, heat:               
                                          nothing is hard: 0                
                                          other: 3%                         
                                          don't know: 35%                   

despite the preference or custom for cooking most meals, however, most respondents (ranging from 70% - 87%) do not have a special stove for cooking and employ a hearth (3-stone) method (table 7). the large majority use wood almost exclusively as their cooking fuel (88% vs. 100%), and many (72% vs. 56%) list the scarcity of fuel and the need to spend time gathering it as their main fuel problems.

table 7: respondent fuel use/fuel availability information

              main cooking    type of stove    spent          fuel          
              fuel                             collecting    problems       
                                               cooking fuel                 

             wood: 88%       3 stone hearth:    0 hrs: 2%    scarcity: 72%  
 treatment   kerosene: 9%    70%              1-2 hrs: 33%   time/distance: 
  group      charcoal:  1%   welded stove:    3-4 hrs: 24%    51%           
             gas: 1%         13%              5-6 hrs: 15%   expense: 27%   
             electric:  1%   misc. other:     7-8 hrs: 11%   misc. other:   
                             17%              > 8 hrs: 15%   7%             

             wood: 100%      3 stone hearth:    0 hrs: 0     scarcity: 85%  
 comparison  kerosene:  0    87%              1-2 hrs: 21%   time/distance: 
 group       charcoal:  0    welded stove:    3-4 hrs: 36%    59%           
             gas:  0         10%              5-6 hrs: 18%   expense: 5%    
             electric: 0     misc. other: 3%  7-8 hrs: 13%   misc. other:   
                                              > 8 hrs: 12%   8%             

of interest in this research was the question of whether a potential adopter's background and environment helped or hindered the adoption of solar cooking: in particular, whether or not a shortage of options regarding cooking fuel increased the adoption of solar cooking. results show that most respondents found the cost of wood -- in both money and labor spent to gather it -- to have risen over the year previous to the survey (see figure 11). over one quarter of those surveyed spend at least one hour per day gathering fuel for cooking, and among their fuel problems, over 70% of respondents listed scarcity, 50% listed time and distance for gathering wood, and 30% listed expense as critical problems (see figure 12).

figure 11: cost increases for cooking fuel

figure 12: fuel problems

these results indicate that if sbc adoption is less extensive than otherwise expected, it should not be ascribed to the absence of need for an alternate method of cooking. on the contrary, in this case one would expect there to be a significant percentage of adoption, based on the critical shortage of firewood for cooking.

data from the interviews were tabulated in frequency tables and graphs. the frequency of responses to each question is indicated by percent (%) responding in the summary graphs which follow in the next section. results are presented in 3 sections: adoption of sbcs and patterns of current use, profile of user experience with/perception of sbcs, and diffusion. (note: since none of the individuals from the comparison group had any experience with sbcs, data related to experience were inapplicable for that group and will therefore not be found in this section.)

interview results

adoption of sbcs and patterns of current use

with respect to adoption and patterns of current sbc use, survey results contain both positive and negative news for the prospects of sbcs in zimbabwe. on the negative side, 52% of respondents said they used their cooker less frequently in 1992 than they had in 1991. on the positive side however, 82% of respondents said they still used their cooker sometimes, with 71% asserting that they used it most sunny days (see table 8 and figure 13).

in this study, adoption was defined a decision to use the sbc, to any degree, for cooking, and was determined mainly by the results of two interview questions: "if you have ever tried to cook in a solar cooker yourself what was your experience?" and "how often do you solar cook?" (see questions 16 and 22). by this definition, 82% of the treatment group can be said to have adopted, to some extent, solar cooking.

table 8: sbc adoption


                    tried once or twice/used for                 
                    awhile, didn't like it:    3%                
                    liked it, but don't use anymore: 15%         
                    still using sometimes:  82%                  

 frequency of                                                    
 use                most sunny days: 71%                         
                    several days/month: 22%                      
                    several days/year:  5%                       

 frequency of                                                    
 use compared       more: 27%                                    
 to last year       less: 52%                                    
                    same: 20%                                    

figure 13: respondents' present usage of sbcs

explanation for this magnitude of adoption, notwithstanding its broad definition, may be at least partially related to fact that 99% of respondents found that using their sbc saved them fuel. seventy-seven percent also reported saving time and work (see figure 14).

figure 14: perceptions of saving fuel

as shown in figure 15, a wide variety of foods were, or had been, at least experimentally, if not regularly, solar-cooked by a large number of individuals in the treatment group. most respondents also report that solar cooking is "nice because (they) don't need to watch or stir" (see figure 16). results of these questions help corroborate the adoption of sbcs by the target group, though as will be seen in the next chapter, alternative explanations for the magnitude of that adoption are also possible.

figure 15: foods cooked with sbcs

figure 16: opinions regarding slower cooking

other questions related to respondents' current use of sbcs were intended to determine if any knowledge/technique problems they may have experienced were related to a decision not to adopt. figure 17 shows the results of an interview question concerning respondents' customary starting time for solar cooking: results show that a majority of respondents are (properly) putting food in to cook by or before mid-morning.

figure 17: factors related to success of cooking

nearly all respondents indicate that they often worry about the weather when solar cooking (figure 17). this worry may affect sbc adoption rate in mutare district in two ways: unpredictable rains, clouds, or duststorms may interrupt solar cooking, leading to decreased success for those who attempt it on the wrong days, and/or the fear of bad weather and the risk associated with spoiling food, may prevent an sbc user from using the cooker on an otherwise appropriate day.

profile of user experience with, and perception of sbcs

an important part of treatment group interviews was the gathering of information related to user experience with, and perception of sbcs. one significant piece of information sought was the exact type of solar cooking problems the group had experienced, and whether those problems negated the user's perception of sbcs as otherwise useful and advantageous.

results (figure 18) show that many individuals did experience some problems in cooking, and that they could (when asked as part of the interview) list a variety of disadvantages. the single most important problem experienced by sbc users seems to have been undercooking, reported by 42% of respondents. overcooking, by comparison, was seldom reported (1% of respondents). 8% of respondents reported poor taste or texture of some foods they had solar cooked (see figure 18).

figure 18: problems with solar cooking, and related reasons

among the stated disadvantages (figure 19), 53% of respondents listed the need for special equipment (dark pots), 29% that the fact that the box wears out and/or requires maintenance, 24% the fact that cooking takes too long, and 14% the fact that cooking at night (the usual cooking time for the evening meal) is not possible.

figure 19: disadvantages found

respondents were also asked about any problems they may have had that were specifically related to the sbc itself, as opposed to problems with its use. table 9 shows those results: 9% had problems with cooker wear and tear, 5% experienced problems with broken glass, and 5% had problems related to sbc response to weather, sunlight and regular (non-dark) cooking pots.

table 9: problems with the sbc

question # 35:            fell        broken   usage problems      other  
have you had any         apart        glass    (available light,          
problems with the                              pots, weather,             
cooker itself?           (tape/foil/          wind)                       
                          worn out)                                       

number responding "yes"   9%          5%       5%                  2%     

in a related question, respondents were asked if they had found solutions to any problems. though relatively few respondents replied affirmatively, 6% reported repairing and/or strengthen their sbcs (table 10). moreover, 31% of respondents found alternate uses for their sbcs (see table 11), including heating water for bathing, storing food and utensils, heating an iron, and making floor polish.

table 10: problems for which solutions were found

question # 36:           repair/maintenance of box:   3 %            
were there any problems  strengthening of box:   3                   
you found solutions      increasing insulation:   1                  
for?                     learning to set for maximum sunlight: 1     
                         using metal hinges:     1                   
16% responded "yes"      watching sbc more closely:  1               
                         suggested solutions which could not be      
                         implemented because of expense:  3          
                         other, unexplained "yes":   3               

table 11: other uses for an sbc

question # 37:           ornament for house:    1 %                  
have you found other     warming water for bathing:   3              
uses for a solar cooker  storage for utensils:    1                  
besides cooking?         heating an iron:    1                       
                         dehydrating / drying meat:   3              
31% responded "yes"      demonstration lessons for class:  2         
                         making floor polish:    1                   
                         keeping leftovers:    2                     
                         hiding money:    1                          
                         keeping food warm:    1                     
                         other, unexplained "yes":   15              

most respondents also recognized positive elements in solar cooking, and almost all were able to list numerous kinds of food that they had successfully solar-cooked, including food from nearly every major type eaten in the area. 43% listed meat, poultry and fish as foods which cooked well in their sbc, and 31% also listed grains (mainly rice) and bread as successfully cooked foods (see figure 20). as can be seen, the frequency with which each type of food is solar cooked is roughly proportionate to the success respondents have had in cooking it. (see also figure 15.)

figure 20: foods which cook best using sbc

most respondents agreed that sbcs were advantageous in numerous ways, with savings of time and fuel listed by 93% of respondents, and flavor and convenience by 74% (see figure 21). under "additional comments" respondents offered advantages such as the need for less water in washing pots; heating water for bathing; keeping food warm, and the sbc's usefulness as a place to store food.

figure 21: advantages of solar cooking

survey results related to respondent experience and perception also show the type of features respondents found most different from their usual cooking method in terms of sbc use: this gives an indication of some of the factors which may present obstacles to widespread sbc use in zimbabwe. of note is the fact that 53% found the use of "special pots" to be an important difference, perhaps because of the cost concerns associated with having to buy "special equipment (see figure 22). 18% found the cooked food itself to be different, although only 8% described the food as poor in taste or texture. however, these perceived differences could be significant to some sbc users in their contrast to promotional information, which describes sbcs as easy to use, low cost, and able to cook nearly anything.

dark pots

figure 22: differences noted by sbc users

in an attempt to find out more about respondents' perceptions of their sbc, one interview question offered respondents some choices for describing their cooker. table 12 shows that most respondents chose adjectives which were positive (durable 36%, easy to carry 62%, attractive 34%) as opposed to negative (flimsy 9%, immoveable 1%, unattractive 2%). one pair of words (too light 45% / too heavy 11%) did not offer a positive choice.

table 12: words describing sbc

question # 34:           number responding       
do any of the           "yes"                    
following describe                               
your cooker?                                     

 durable                   36 %                  

 flimsy                  9                       

 too light               45                      

 too heavy               11                      

 easy to carry           62                      

 immoveable              1                       

 attractive              34                      

 unattractive            2                       

 other                   1                       

respondents were also asked the main reasons that they did not use their cookers on sunny days, for those days when they did not, and what would help them in trying again. figure 23 illustrates those results: 21% gave reasons for not using their cookers on some sunny days: 7% of respondents had broken cookers, 3% did not have a cooker, 2% said the cooker was too hard to use, 2% said it didn't cook right, and 3% said that cooking outside was a problem. no one claimed to need more information and no one had problems finding a sunny spot to cook near their home.

all respondents said they would try again, saying that recipes, cooking demos, affordable cookers, and parts for repair would help.

figure 23: reasons sbc not used on all sunny days

diffusion of solar cooking technology

although almost 90% of respondents said they told others about solar cooking and over 65% told at least 10 others (see figure 24), nevertheless there seemed to be little direct or indirect evidence that the decision to use solar cooking was made by anyone other than treatment group individuals. no sign of diffusion of sbc use into adjacent communities or households was observed, and no solar cookers outside of the respondents' were noticed during the course of the study, however as mentioned previously, respondents and their neighbors were often separated by long distances, limiting opportunities for informal observation of neighboring households.

figure 24: diffusion potential

figure 25 shows the results related to treatment group individuals' perceptions about the existence of other sbc owners, and how often those owners use their cooker. as can be seen, though half the group surmises that all owners use their cooker at least some of the time, the other half feels that various percentages of owners (ranging from all other owners to 25% of other owners) do not use their cooker at all.

figure 25: respondents' awareness of other sbc owners and users

figure 26 outlines the reasons respondents give for why other sbc owners don't use their solar cookers. the most common answers were variations on 2 themes: that sbcs are a new idea to which people haven't yet adapted (15%) and that the slowness of solar cooking gets in the way of easy use (19%). there were many other suggestions, however, and table 13 lists some of the comments which were generated by 57% of the treatment group: their comments may also provide some insight as to why they themselves do not use their own cookers more often.

figure 26: why don't others use their sbcs more often?

table 13: other ideas about why others don't use their cookers more

"some people have to be away during the day."                            

"because of the large numbers in families."                              

"there is no food (to cook)."                                            

"they may just be too lazy."                                             

"some don't have the right kind of food to cook in there; some don't     
have the time to attend to the cooker."                                  

"lack of food; a matter of ignorance."                                   

"maybe they have other fuel."                                            

"some forget they have a cooker; they underestimate."                    

"maybe they have a lot of wood; it needs special attention, otherwise a  
goat may cause breakage of glass."                                       

"sometimes no time to wait for the food to get cooked."                  

"lack of interest and failing to set it properly."                       

"some people may not be able to use it properly."                        

"the time of cooking and time when the sun is hot contradict."           

"people did not get enough training concerning the setting of the        
cooker, some people never put this cooker in the right position and to   
them it does not work."                                                  

"some people need hot foods, so they have to use wood."                  

"may not have suitable utensils."                                        

"our culture cannot allow us to leave the food on its own because of     
the bewitching of each other which exists."                              

"some will be doing their (other) jobs like watering the garden."        

"it might be wind."                                                      

"they will be at work and can only use it on weekends."                  

"we don't have suitable pots, the ones we have are very thick to         

"time consuming -- they will be rushing for work."                       

"it is difficult to preplan for most people."                            

"some don't have sunny areas at their home; some yards not fenced so     
that domestic animals can get it easily; also because they are just      
used to fire."                                                           

"some people only cook foods like sadza."                                

a formal survey is needed to clarify the issue of why, considering the large numbers of family, neighbors and friends who should have heard about the solar cooker from the respondents, there is no sign of diffusion of the technology beyond the limited group of workshop participants. treatment group individuals themselves furnish some clues while providing their own perceptions regarding why other people do not build cookers. by far the most common answer for this question was associated with the cost of building a solar box. fifty-one percent of all respondents speculated that the cost of the building materials was the hindering factor. twenty-seven percent felt that the lack of help for building an sbc was important, 19% percent said that the difficulty of obtaining materials played a role, and 5% said that people didn't build sbcs because they didn't know about them (see figure 27).

figure 27: reasons others don't build cookers

informal interviews

another source of information relative to solar cooking in zimbabwe were my discussions with plan community development workers and with the interviewers who carried out the survey.

community development workers

my conversations with plan cd workers were enlightening on two fronts: placed as they are in a situation where they are simultaneously of the community and also to some extent answerable to it through their work with a community development organization, their perspective is unique. on the one hand, they are users of the technology, having built their own sbc in a workshop, and as such, they have personal opinions regarding its utility. on the other hand, they were part of a program to disseminate information about sbcs, and therefore have an advantageous vantage point with regards to adoption and diffusion of the sbc in the study area.

all 12 of the plan mutare community development (cd) workers independently chose cooking fuel scarcities and/or time spent gathering wood and the disappearance of trees as the main reasons for interest in solar cooking for residents of their communities. the cd workers were enthusiastic about solar cooking in general, but had a number of reservations about its immediate possibilities in zimbabwe. said one:

"people are ready (to build sbcs) if they have the materials: this area is deforested -- but where are they going to get money to build solar box cookers? and who is going to train them?"

most of the cd workers echoed the concerns about training and education. one stated:

"solar boxes are good to use: (it's) only that most people in the communal areas are illiterate and they really need education. if the exercise of making the cookers was done continuously, i foresee more people being interested in using them."

another cd worker continued:

"this is a very good, and simple and inexpensive way of cooking, but for the people of remote or rural areas: they need assistance in getting the materials for building the sbc and a training in building them."

asked what advice he would give to groups wanting to promote solar cooking, another worker recommended:

"make them out of durable materials."

nearly all the cd workers spoke of the difficulties of finding building materials, especially glass and foil, and several mentioned the fact that sbcs are not durable.

asked about their own use of solar box cookers , four of the twelve cd workers said that they used their own cooker for demonstrations only; three used it only occasionally; and five used it most sunny days during the solar cooking season.


at the beginning of training, all five interviewers expressed skepticism that a cardboard box could cook. however, as they conducted more interviews and heard testimonials to the sbc's soundness as a method of cooking, the interviewers all began to ask questions. by the time 3 weeks of interviewing had passed, all were convinced of their utility, and wanted to build one. one had even saved the foil wrappings from our boxed lunches so that she wouldn't have to worry about finding foil for her solar box cooker. it was a small but interesting example of the acceptance of an idea after repeated encounters.

summary of results

as presented in this chapter, the results of interviews indicate that some degree of solar cooking adoption occurred with a large majority (over 80%) of respondents. diffusion of the technology beyond the original workshop participants, however, was not observed, despite the probable transfer of the idea itself. the next chapter will examine these results and offer some possibilities for their interpretation.

chapter 5: discussion of results

the purpose of this research was to measure the degree of solar box cooker adoption attributable to an sbc introduction project consisting of an initial large workshop subsequently followed by several smaller workshops, and to assess whether that technology had diffused to nearby areas where workshops had not been held.

earlier, adoption was defined as a decision by an individual to make use, to any degree, of their sbc for cooking. results have shown that 82% of respondents in the treatment group are using their sbcs to some degree. this percentage is probably somewhat inflated however, and may reflect a problem with self-reporting in a situation where verification through independent observation was not possible. the adoption rate of 82% does not appear to represent frequent, so much as occasional or intermittent sbc use: in response to the question "how often do you solar cook?" 70% of the treatment group asserted that they used their cooker "most sunny days". yet to question # 20 ("compared to last year, do you use a solar cooker more, less or about as often"), 52% of the treatment group answered "less". this somewhat contradictory information might also be related to the ambiguity of the questions (i.e., did the respondents mean they used their sbcs fewer hours per day this year rather than fewer days per year? did respondents understand "sunny" to mean exclusively hot and bright summer days, as opposed to merely bright, but cool? if the latter, at what temperature did the respondent consider the weather to be too cool to solar cook?), or it may also simply indicate an unwillingness to express dislike of the sbc (see table 14).

other possible interpretations of results may be suggested (see table 14). one possiblity is that in the time immediately following the building of their solar cookers, many respondents used the cooker to some degree every day, as opposed to the year of the survey when regular solar cooking may have stabilized at some lesser degree of use. weather may have also played a part: some respondents commented that they used the cooker less often since there was less food to cook. as can be seen, problems associated with respondents' self-reporting, as well as the wording of several of the survey questions and suggested answers make an exact determination of adoption percentage difficult. further research is needed to clarify this important question to arrive at an estimate of the actual degree of adoption of solar cooking in zimbabwe.

it seems certain however, that some degree of solar cooking adoption has occurred and though information to quantify adoption may be lacking, qualitative findings related to user experience and perception are not.

table 14: other possible interpretations of adoption results

                  workshop                     possible alternate          
                  participants                 interpretations             

 current use     tried once or twice/used     unwillingness to express     
 (question #     for                          dislike of the sbc.          
16)              awhile, didn't like it:  3%                               
                                              don't use sbc as much since  
                 liked it, but                less food to cook this       
                 don't use anymore: 15%       year.                        
                 still using sometimes: 82%                                

 frequency       most sunny days: 71%         misinterpretation (by        
 of solar                                     respondents) of "sunny" to   
 cooking         several days/month: 22%      mean "hot" or "hot and       
 (question #                                  bright" when only sunlight   
22)              several days/year:  5%       (not high ambient            
                                              temp-erature) is required    
                                              for solar cooking.           
                                              "most sunny days" means      
                                              respondent would use on      
                                              most sunny days if the       
                                              (weather, drought, etc.)     

 frequency       more: 27%                    "more" refers to "more       
 of use                                       days/yr", "more hrs/day" or  
 compared        less: 52%                    "more types of foods"        
 to last                                      depending on the             
 year            same: 20%                    respondent.                  
 (question #                                                               

survey results related to user experience and perception show that the treatment group had a wide variety of problems with solar cooking, ranging from broken glass to undercooking of food to weather problems and timing of meals. at the same time, however, many also found solutions to those problems they encountered, and some discovered new uses for their solar cooker. in addition, many individuals in the treatment group found solar cooked food to be both "flavorful" and "convenient", and almost all agreed that time and fuel were saved with its use.

in spite of this, and in spite of zimbabwe's suitable climate and increasing problems with firewood shortages -- and the fact that most individuals already had a solar cooker to use -- it seems clear that few respondents perceive solar energy as a main source of cooking fuel. why?

as was seen earlier, interview results indicate that worries about weather and the undercooking of food, the need for special equipment (dark pots) and sbc maintenance, and fears of poisoning are some of the respondents' concerns. thus, the risk associated with using sbcs seems to be a key factor in respondents' perception of solar cooking. this may be especially true in drought years (as was the case during the years previous to the survey), when the usual sources of food have disappeared and even the traditional "innovator" would be hesitant to use a dubious or uncertain new technology. whether the risks are tenable or not, their perception by potential adopters will doubtless greatly influence the degree of adoption, and the need for a promotional technique which addresses them becomes criticial to the success of an introduction program. addressing perceived risks through the use of multiple introductions is discussed in the next chapter.

despite the fact that most respondents told others, ranging from a handful of others to hundreds, about solar cooking, there was no verifiable sign of diffusion of sbc use to a comparison group located in an adjacent community of similar demographics and environmental features. several factors may be responsible for the lack of diffusion: first, a very pragmatic consideration is that most of the homes in both the treatment group study area and the adjacent comparison community were well separated from their neighbors. if diffusion works best where an innovation is easily viewed and frequently observed, it seems likely that it would take a much longer time for even the awareness of the existence of sbcs to diffuse to an adjacent community.

secondly, any member of a nearby household or adjacent community who might have heard about sbcs and become interested in owning one would have had to find the components herself, whereas individuals in the treatment group had access, through attending a workshop, to everything they needed -- including instruction. the workshops, moreover, provided materials to participants at a fraction of their cost. when materials costs for non-workshop participants are added to the cost of special cooking pots, the risk associated with the cost of owning an sbc may become too great for many otherwise-interested individuals -- even despite the fact that it might pay for itself (in saved cooking fuel) in a relatively short time. considering the potential risks associated with wasting resources to build a box which might not work, it is not really surprising that diffusion is not in evidence.

finally and probably most important, if the adopters themselves are using their own sbcs only intermittently or sporadically, it is unlikely that diffusion of the idea to another community would occur: an incomplete adoption by the treatment group in all likelihood indicates that they have not completely accepted the idea of solar cooking. the question then becomes one of determining why sbcs have not been completely accepted by those who partially adopt them. it is apparent that methods related to sbc introduction projects must be examined, particularly as concerns introductory workshops: it seems likely that a single workshop is not sufficient for demonstrating the utility of an sbc to potential adopters, nor does it allow for taking into account the complexity of the innovation and the social system and environment in which it must function.

the next chapter presents a framework for additional interpretation of the solar cooking situation in zimbabwe and elsewhere, and offers recommendations for future sbc promotional work in the country.

chapter 6: conclusions and recommendations

although the 82% adoption rate obtained in interviewing the treatment group is questionable and probably excessively high considering the self-reporting issues and question ambiguity discussed in the last chapter, there is still reason for optimism with respect to the future of sbcs in zimbabwe. the constraints to sbc use which were identified by informal observation and conversation with respondents were conspicuous and significant (summarized in table 16), but none of them seems totally insurmountable, and some observations (table 15) were positive with respect to the potential future of sbcs in zimbabwe:

table 15: positive observations relative to sbc use in zimbabwe

   zimbabweans seem receptive to the idea of solar         

   most of the cookers made are still in use some of the   

   the climate of zimbabwe is well-suited to solar         

   materials for constructing solar boxes are available    

   a solar industry already exists, to some extent, in     

considering the above, changes in the promotional methods used for sbc introduction projects might significantly increase sbc adoption, particularly the degree of use, by providing information and techniques for addressing the constraints which exist with respect to solar cooking in zimbabwe. the most important change is to implement multiple introduction.

multiple introduction

as mentioned previously, a single promotional workshop may be insufficient for introducing a complex innovation, especially if it does not first take into account the specific social system and the environment in which the innovation must function: the use of solar cooking in an area where the tradition is to cook with fire demands a major change in thinking on the part of the potential adopter, as well as a drastic change in cooking custom and daily routine. innovations which demand such a change in routine or custom, hereafter referred to as radical innovations, may require a different type of promotional method, one that can overcome not only the socio-economic, cultural and logistical obstacles associated with the adoption of any innovation, but also the additional constraints connected with the need for changes in routine. all other factors being equal, successfully adopted radical innovations may include an element which is lacking in the case of unsuccessful ones: multiple introductions. a promotion incorporating multiple introduction would include 4 phases:

the initial introduction,

a structured follow-up,

adaptation (re-invention) of the innovation, and

(at least one) re-introduction.

following an initial introduction, a follow-up would be performed to pinpoint real or potential problems which could interfere with long term use or widespread adoption of the innovation. adaptation, or re-invention, of the innovation could then occur, improving on the original design and allowing a subsequent re-introduction to succeed. this process may be particularly important where social or cultural constraints (for example) have not been taken into account in the design of the original introduction project -- which may often be the case with radical innovations.

radical innovations

in simple terms, the adoption of an innovation is a question of constraints vs. utility. for those who eventually adopt an innovation, the utility end of the balance weighs more than the constraint end -- that is, the adopter has managed to overcome enough constraints to make use of the innovation worthwhile. a radical innovation, however, has the additional constraint of requiring a significant adjustment in routine or custom. for example, successful solar box cooking requires that food be put into the cooker hours before it will be eaten, necessitating early morning to early afternoon meal planning, a significant change from cooking over a fire minutes before mealtime. in many cases, the requirement for such an adjustment in daily routine may be just enough of a factor to tip an adoption decision to the constraint side, resulting in non-adoption or discontinuance of an otherwise appropriate innovation. multiple introduction, which provides opportunities for potential adopters to both find a way around obstacles as well as to recognize the potential benefits of an innovation, might tip the balance back the other way. the case study represented by the introduction of sbcs in zimbabwe illustrates how the constraints associated with a radical innovation may prohibit its eventual adoption and diffusion: considering the risks, problems and necessary change of routine associated with building and using a solar box cooker, it is not surprising that signs of widespread adoption and diffusion are not in evidence. following is a summary of the constraints found through this evaluation, with recommendations for using multiple introduction to address them.

constraints associated with use of sbcs in zimbabwe

observations i made through 7 weeks of working and travelling in zimbabwe reinforce what the results of interviews show with regards to the solar cooking situation in the mutare district. as with the interview results, some of these observations pinpoint serious problems with sbc use in zimbabwe:

materials are scarce and expensive: strong cardboard is difficult to find in zimbabwe. aluminum foil was available in mutare's grocery stores, but was not evident in smaller towns' markets where i looked for it. the same is true of white glue. sheet metal for use in the bottom of the box was found in a metal market in mutare, but there was little of it, and it was expensive. black chalkboard paint for painting the sheet metal was available in mutare, but is scarce outside of the larger towns. glass was the most difficult item to obtain, and the single most expensive item of the materials needed for building a solar box. though several stores in mutare had window glass, it is almost impossible to obtain outside of a large town, and the cost is prohibitive for many people.

the total cost of building materials, not including the cardboard, which was given to me by plan mutare, was approximately $20. this represents 15 - 25% of the average yearly income of women who have an income, most of which probably derives from bartering and selling miscellaneous items in the market.

sadza is difficult to cook in a solar box cooker: sadza, the staple of the zimbabwean diet, is a type of corn meal mush which is traditionally cooked over fire, the bubbling mixture requiring nearly constant stirring. there has been limited success with cooking sadza in an sbc, though it is possible to make a close facsimile. the fact that sadza cannot be solar-cooked seems to have caused some people to avoid using their sbc on a regular basis.

glass breakage is common, difficult to remedy: though it was not a specific interview question, many people told of broken glass being a problem in solar cooking. goats are responsible for many of the breaks, climbing/kicking on the glass to get at the food which they see or smell. once the glass has broken, little can be done in a rural area, even if money were available, to repair it.

misunderstanding/misinformation and incorrect use are common: numerous respondents stated that they were not presently using their cooker because "it (is) winter, and therefore too cold". though it was indeed winter, and though drought conditions prevailed, with cool mornings and rapidly dropping temperatures at sunset, on most days the temperature rose to the high-70's/high 80's by noon, and, more importantly, the sun shone all day, making for perfect solar cooking weather.

there also seemed to be an impression that solar box cookers are designed to function as substitutes for other cooking fuels. this erroneous impression may cause some people to avoid using the sbc altogether when its limitations (related to time, weather, maintenance, etc.) are discovered.

the sbcs in use are not being used to their full extent: there was little indication that people were using their sbc as a supplement to other methods of cooking. for example, sadza for the evening or mid-day meal can be quickly cooked over fire after using an sbc during the day to cook the meat or stew which generally accompanies sadza. i saw and heard no evidence that this occurred, though it would have been the ideal way to use an sbc for zimbabwean cuisine.

the distance factor makes diffusion difficult: the areas where members of the treatment group live are very rural, and very separated. in locations like these, where neighbors do not often see each other, it is likely that diffusion of the idea will be limited and the opportunity for the exchange necessary for transfer of information -- or social pressure -- will not often occur.

reluctance to build sbcs without cost-subsidizing: many people asked when more workshops would be given so that their family or friends could also make a solar box: when asked why they did not just build an sbc, most stated that they could not afford the materials. it seems likely, therefore, that the desire for workshops is at least partly related to sbc subsidies rather than a sole desire for information. some stated that they would prefer to go to a plan workshop because they would get better instruction there than from an individual.

the gender tug-of-war: new-technology (men's arena) vs. cooking and food preparation (women's arena): in a conversation i had with dr. jeremy ascough and mr. garikai bajaba of the university of zimbabwe, one of the problems discussed was that of gender. as dr. ascough explained, new technologies in zimbabwe are in the purview of men; cooking and food preparation belong exclusively to women, and where the two come together, there may be problems.

dr. ascough felt that in the case of sbcs, where there is overlap in gender spheres of influence, what may happen is that men (though they do not traditionally concern themselves with cooking) may become interested in the new technology and claim it for themselves. indeed, i talked to several men who had built a cooker in a workshop, and who stated that they did not permit their wives to use it.

mr. bajaba contended that many men had little interest in the problems their wives had in finding fuel (or the money to buy it) for cooking. the perception, he told me, is that as long as hot meals still appear, there is obviously still wood available to be gathered, in the same way that if one turns on the tap during a drought and gets running water then "a water shortage must not be a problem."

when asked if the men do not, though they may have little empathy for the walking distances and hours required of women and children to find fuelwood, realize that the shortage of fuel will eventually affect them as well, mr. ascough replied that one man told him

"when there is not enough wood available to cook a meal, i will marry another woman who can find wood further away as my first wife cooks for me."

cultural limitations: some respondents told of missing the insect-repellent qualities of having a fire burning near the house. several complained, as well, about the absence of the proper "smokey" taste, though that complaint was not common. a more frequent comment was that of missing the warmth of a fire near the house, and of not being able to bake bread at night. several people mentioned feeling insecure about leaving their food out where an enemy might poison it. one older woman said that solar cooking was "unnatural", and went against god. another common complaint was related to visitors. zimbabweans, especially those in rural areas, must travel long distances to visit with friends and family, and, in the absence of phone lines and telephones, may drop in unexpectedly to visit. numerous people, as well as the interviewers responding to my questions regarding their thoughts on the sbc, told me that a big drawback of the sbc was its inability to cook fast enough so that visitors could be greeted with a meal.

the solar box cooker as radical innovation

the switch from a cultural tradition where the cooking fire is a social hub to one where it is completely replaced by a solar box cooker is probably as undesirable as it is unlikely. a solar box cooker can neither completely supplant other cooking fuels, nor will it substitute (for many reasons) as a social gathering place. yet some change in cooking methods is clearly inevitable, as increasing deforestation in zimbabwe leads rapidly to a time when there will no longer be any choice in the matter.

efforts to introduce the technology of solar cooking have succeeded in demonstrating to numerous individuals how solar cooking might be a desirable option in their lives, but diffusion of the practice from early adopters to additional individuals is wanting. regular use of solar cooking by adopters in zimbabwe is lacking as well.

solar box cookers seem to have a great deal of potential for mitigating problems of health and environment, but there are serious constraints to their use in certain cultural, geographical, and/or economic landscapes. observations and interviews have identified some of the important constraints to the use of sbcs in zimbabwe, which help explain why regular use of the solar cooker and diffusion of the technology have not occurred.

table 16: summary of identified constraints to sbc use in zimbabwe

 cultural                 logistical              socio-economic         

the staple food in       materials are scarce.   materials are           
zimbabwe (sadza) is                              expensive.              
difficult to cook in                                                     

gender tug-of-war:       more training needed:   reluctance to build     
new technology (men's    misunderstanding/misinf sbcs without            
arena) vs. cooking &     ormation/incorrect use  cost-subsidizing.       
food preparation         are common, sbcs in                             
(women's arena).         use are not being used                          
                         to their full extent.                           

habitual cooking/baking  glass breakage is                               
times don't always       common, difficult to                            
coincide with sunny      remedy.                                         

loss of fire for         the distance factor                             
warming oneself at       makes diffusion                                 
night.                   difficult.                                      

fear of providing                                                        
opportunity for                                                          
poisoning by enemies.                                                    

solar cooking seen as                                                    

no smoke for                                                             

lack of smokey taste in                                                  

can't cook quickly for                                                   

many of these constraints could potentially be overcome, with a resulting increase in both adoption and diffusion, if the radical nature of solar cooking were addressed through the use of multiple introduction. in this case, the follow-up (roughly equivalent to the research undertaken with the present evaluation) identified the constraints summarized in table 16 above.

the initial introduction

a structured follow-up

adaptation (re-invention) of the innovation

(at least one) re-introduction

the third element of multiple introduction, adaptation of the innovation as well as of the introduction program, would address those constraints (table 17). adaptation includes taking the knowledge gained and the recommendations generated and using them to supplement the initial introduction of the innovation -- that is, to re-introduce it in the same geographical area.

taking into account the present results of promotional efforts for sbcs in the mutare district, the next step for solar cookers international and plan mutare should be to focus on addressing the problems found in this evaluative follow-up. (a summary of recommendations, and recommendations for further research are provided in appendices c and d.) concentrated efforts to adapt the sbc for use in the area by soliciting the help of local sbc users would be well-spent, with the aim of subsequently re-introducing an improved sbc technology in the same basic geographic area.

table 17: addressing identified constraints

 cultural constraints          possible adaptations of sbc and           
                               introduction program                      

staple food (sadza) is        encourage use of sbc as a tool for         
difficult to cook in sbc.     supplementing, not replacing, traditional  
                              cooking methods.  research workable        
                              recipe for making sadza in a solar         

gender tug-of-war:            provide workshops directed solely at       
new technology (men's arena)  women, and/or                              
vs. cooking & food                                                       
preparation (women's arena).  provide workshops for both men and women,  
                              but stress the use of the sbc for          
                              benefiting whole family, stressing need    
                              for use by the cooking members of the      
                              greater emphasis in workshops on           
                              deforestation and erosion.                 

habitual cooking/baking                                                  
times don't always coincide   solicit ideas from individual users at     
with sunny hours.             workshops.                                 

loss of fire for warming      encourage continued adaptation of sbc,     
oneself at night.             and demonstrate successful adaptations --  
                              e.g., develop a way to lock box; use       
                              bricks in box                              

fear of poisoning by          and close lid after sundown to keep food   
enemies.                      warm; use solar heated bricks as heating   
                              elements on cold nights, etc.              

solar cooking seen as                                                    

no smoke for                                                             

lack of smokey taste in                                                  

can't cook quickly for                                                   

 logistical constraints        possible solutions                        

materials are scarce.         adapt the cooker:  for example, use mud    
                              bricks instead of cardboard (see figure    

more training needed:         address in the workshops, where immediate  
misunderstanding/misinformati clarification can be given to the user:    
on                            hold follow-up workshop for after people   
/incorrect use are common;    have tried their cookers at home.          
                              for language errors, translate             
sbcs in use are not being     instructions for building and using sbcs   
used to their full extent.    (see appendix e) into shona, subsidize     
                              writing of a zimbabwe cookbook.            
                              greater emphasis in workshops on sbcs as   
                              supplements, rather than replacements of   
                              other cooking fuels.                       
                              greater promotion of sbcs as innovations   
                              for pasteurizing water.                    

glass breakage is common,     use heat-resistant polyester film          
difficult to remedy.          (possibly manufactured by 3m company's     
                              zimbabwe plant) instead of glass.          

the distance factor makes     expand promotional efforts to include the  
diffusion difficult.          use of a mass medium such as radio, and    
                              (in the larger towns) perhaps even         
                              provide for a permanent/semi-permanent     
                              local resource where previous workshop     
                              attenders can find help with their solar   
                              cooking problems, and where potential      
                              adopters can find answers to their         

 socio-economic constraints                                              

materials are expensive.      utilize local resources to provide         
                              low-cost materials for building or         
reluctance to build sbcs      repairing cookers; form buying coops.      
without cost-subsidizing.                                                

figure 28: mud bricks drying

radical innovations and multiple introduction

the following hypothetical case study is presented as an illustration of the importance of multiple introduction in adoption and diffusion of radical innovations.

mrs. adido, a woman living in a small village, attends a coop meeting in which she sees an innovation (a new and less expensive tuber variety) for the first time. she examines the tuber, listens to a talk in which a health worker tells how the tuber can increase nutrition, but she notes that the new tuber takes longer to cook than the variety which she now uses, and that growing it requires twice as much water as the old variety. she realizes that, for scheduling reasons, she would have to water the tuber field in the afternoon instead of the morning since it would require two trips to carry water back and forth. mrs. adido considers all this information, including the fact that the tuber costs less, and decides against planting any of the new tuber. the change in her daily schedule, and the subsequent changes which that imposes cause her to see this innovation as undesirable, or perhaps unattainable.

in this example, the potential adopter makes a decision based on facts and comparisons she has heard only once. if that is all she ever hears about the new tuber, it is unlikely that she will later have reason to change her mind and reconsider what might be a beneficial idea. multiple introduction to the idea, however, may lead her to reconsider the value of the innovation.

some time later, mrs. adido hears from a neighbor that the new tuber is tasty, and easy to grow. her children mention that they have also seen the new tuber, during science classes in school in which nutrition is taught. still later, she hears a radio program in which the name of the new tuber is mentioned.

she starts to reconsider, not necessarily because of new information, but because she has had multiple introductions to the innovation, and the idea's advantages are beginning to seem valid for her own situation. what she once thought was unattainable or undesirable now looks attractive, and less risky than before.

here, multiple communication channels also play a role in the potential adopter's thinking: it is probably safe to say that hearing the same tuber information several times in presentations at her women's coop would have much less impact on mrs. adido than hearing about it from multiple sources such as her neighbor, her children and a radio program. whether intentional or not, the use of multiple communication channels is likely to increase effects seen with the promotional use of multiple introductions.

mrs. adido decides to try the new tuber. she buys some seed and plants it, and several weeks later, when the new plants have sprouted, she begins to walk to her vegetable plot twice a day, carrying extra water for the tuber plants. contrary to her original understanding, the plants cost her a little more because she must pay for the water. a more difficult constraint, however, is the timing of watering. the vegetable plot is only a mile away, but she can no longer carry adequate water to completely water (according to the quantity the women's coop recommended in their instructions) her vegetable plot in one trip. since she sells dry goods and vegetables in the morning market, she only has time to make one trip with water before she leaves for market. consequently, when she returns from the market in the afternoon, she has to make another (special) trip to water her tubers. this second trip not only costs more since she must buy additional water, but it uses up her precious afternoon time when she would normally be dying cloth for the market.

mrs. adido briefly starts giving the plants half the recommended amount of water, but notices within days that they fare poorly without it.

clearly, without a change in the situation, the potential adopter will eventually be forced to choose between making a living and eating more nutritiously. this is where re-invention becomes important. in this example, there is a (probably) useful innovation that is not quite suited to a particular situation. without an adaptation or re-design of the system for using the innovation, it is probable that this potential adopter will discontinue its use.

mrs. adido, forced to choose between earning a living and eating more nutritious food, reluctantly decides that she must discontinue growing the new tuber. on her way to the field to water her plants that morning, she stops by a friend's house. while talking with the friend, she notices that the little garden the friend keeps in the space between houses also has some of the new tubers, and that they are growing well. mrs. adido mentions her problem with water, and the friend seems surprised, saying that her tubers grow well with the little water that she gives them. walking back from her vegetable plot later, mrs. adido remembers that the area between the two houses where the tubers were growing was shaded, and she wonders if the shade is what kept the friend's tuber plants healthy with less water. the next morning, she brings a grass mat with her, and constructs a small shaded area over part of the area where her tuber plants are growing. after only a few days, she can see a difference between the shaded and unshaded plants.

she covers the rest of her tuber crop with grass mats and maintains her once-per-day watering, successfully harvesting her first improved tuber crop at the end of the season.

in this hypothetical case study, multiple introductions (through, in this case, multiple communication channels) and adaptation allowed the adoption of this radical innovation to occur: an absence of either element would have resulted in the non-adoption or rapid discontinuance of the new tuber variety.

promotional programs attempting to foster the best chance for adoption of any innovation should include some use of the elements of multiple introduction, but their inclusion is especially critical to the promotion of radical innovations. in the case of solar box cookers in zimbabwe, the absence of the adaptation and re-introduction elements of multiple introduction is portentous: their lack may mean that the use of this otherwise appropriate and useful technology does not catch on, despite the promising beginnings reflected in the face of the woman shown in figure 29, who is carrying her sbc home from a workshop she has just attended. in a region with critical shortages of cooking fuel, another attempt, utilizing multiple introduction, at promotion of this potentially priceless innovation could yield valuable results.

figure 29: mutare woman with newly made sbc

(photograph courtesy of dr. robert metcalf, 1989)


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appendix a: questionnaire

appendix b: quotes illustrating misunderstanding and incorrect use

table 18: quotes illustrating misunderstanding and incorrect use

 misunderstanding                     incorrect use                       

"it is winter, we cannot use the     "food is undercooked"                

"you cannot use water when you want  "you can use it for drying fruit     
to cook with it"                     and meat"                            

"you can only cook solid foods,      "with large amounts of food, the     
special foods"                       texture isn't right"                 

"you may get food poisoning"         "it does not work"                   

"when you have a big family you      "you need a thermometer to gauge     
can't use it"                        the heat"                            

"the solar cooker is only for                                             

"you have to keep on shifting the                                         
box or adjusting the stick"                                               

"when away for the day (to work -                                         
author's note), you can't use it"                                         

"you have to use only black pots,                                         
not clay pots"                                                            

appendix c: summary of recommendations for future promotional efforts

the suggestions for adaptation of the sbc and its introduction program, which were listed in table 17, comprise the recommendations made in this evaluation for addressing promotion of solar box cooking in zimbabwe. table 19 summarizes them.

table 19: summary of recommendations for promotion of solar box cookers

adapt the solar box cooker for use in the individual area                
- promote stationary cookers, utilizing mud bricks,                      
- translate the directions for building and using sbcs into shona, and   
have a cookbook written for zimbabwe cuisine,                            
- experiment with techniques for cooking sadza,                          
- develop a low-cost locking mechanism for locking an sbc                

set up a permanent/semi-permanent local resource                         
- a knowledgeable person/group of sbc users in the area, and/or          
- regular meetings/workshops for building sbcs; a clearinghouse for      
information, and/or                                                      
- a building or room with demonstration solar boxes, where research or   
new ideas for cooking/building could be tried out                        

form buying co-ops:    buy items in bulk, to be sold later at cost       

training workshops changes                                               
- emphasize the sbc as supplement, not substitute.                       
- encourage/facilitate discussion re: constraints and hearsay            
- stress that the sbc is designed to be used by the member of the        
family who does the cooking.                                             
- incorporate information on adaptations (for example, a lock for the    
cooker) into training.  solicit ideas for other possible adaptations.    
- use and/or build adapted boxes in workshops.                           
- put greater emphasis on the use of sbcs for pasteurization of water    

materials availability                                                   
- approach 3m about possibilities for making polyester heat-resistant    
film in zimbabwe.                                                        
- encourage the substitution of bricks for cardboard, and other locally  
available materials for hard-to-come-by materials                        

intensify efforts, in the same geographical/cultural area,               
re-introducing adapted/refined sbcs using information discovered during  

provide for follow-up after each introduction project                    

appendix d: recommendations for further research

this evaluation has probably raised as many questions as it answered, and opportunities for further research on the use and diffusion of solar cooking technology in zimbabwe, and in other locations worldwide, are numerous:

frequency of use

the results of some survey questions yield inconsistent information when compared: in an example discussed previously, answer to a question dealing with respondents' use of their sbc this year as compared with last year are inconsistent with answers to a question regarding how often the sbc is now used. more research is needed to clarify frequency of use.

questionnaire development

the concept of multiple choice is not necessarily an intuitive one to an individual who has not previously experienced it, and in many educational systems outside of the united states, including many european countries, it is completely unknown. in zimbabwe (and probably much of africa) therefore, a survey composed of open-ended questions may be more likely to result in valid information. supplementary questions related specifically to a country or cultural group could provide important information -- for example, survey questions related to attempts to cook sadza might prove illuminating with respect to solar cooking potential in zimbabwe. research is needed to determine how best to adapt questionnaires to a specific environment.


a formalized diffusion survey should be done in the communities adjacent to the study area to better quantify the amount of diffusion that may have occurred, and to clarify why there seems to have been little or none.

technical research on sbcs

technical research, such as that related to

- a method for solar-cooking sadza,

- the use of durable materials (such as bricks) in building a box, and

- the use of local language teaching materials

is also needed.

use of sbc as a supplement to other cooking fuels

information related to the use of an sbc as a supplement to traditional cooking methods needs to be gathered. questions related to the supplemental use of an sbc should probably be added to all follow-up surveys.

multiple introduction

research on the use of multiple introduction promotions needs to be carried out.

appendix e: instructions for building a solar box cooker

(excerpted with permission of solar cookers international from

"how to build a solar box cooker")


figures 4a and 4b: deforested and eroded farmland, mutare district

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