From Water Boiling Test To Water Heating Test, Case Study Of Indonesia



Clean cookstove initiatives beginning in the early 1980s recognized the need for improvements in the performance of biomass fuel cooking stoves. Recommended test methods were developed at the University of Eindhoven and Bois de Feu, an NGO in France. A review of their methods is instructive because they had resolved several conceptual issues which were reintroduced as part of a Water Boiling Test (WBT) by a VITA-led group in 1985. The original document produced by VITA outlining proposed testing methods presented three complimentary approaches: the Water Boiling Test (WBT), Kitchen Performance Test (KPT) and Controlled Cooking Test (CCT). All of them contain conceptual errors that resulted in the mis-rating of stoves, particularly at low power.

The available test methods at the time were reviewed by Rani, Kandpal and Mullik who noted the problem with the low power metrics and reported on an experiment that showed the amount of fuel required to simmer a pot was independent of the mass of water in the pot, rendering the validity of several reporting metrics questionable.

In the meantime, the VITA WBT emerged as a dominant testing method in the laboratory environment, particularly in the Western world. Around the same time, India and China adopted quite different methods which they have continued to use until now.

The core claim for the WBT is that it supports the standardization and replicability of controlled laboratory testing to arguably allow for the differentiation of cookstoves at their optimum performance.

The performance of a stove is contingent on four factors: (a) the stove, (b) the fuel and its moisture content, (c) the operating procedure or burn cycle, and (d) the cooking vessel or vessels.

The last three factors are highly dependent on the local context, meaning that whatever one chooses for each variable will strongly affect the relative performance rating of ‘the stove’. Performance rating is therefore an evaluation of the combination of factors, not only of the stove. In most cases, a prescribed cooking cycle was written into the test, resulting in performance ratings that are only valid for that particular three-phase burn cycle consisting of a cold star t, hot-restar t of the fire, and a 45 or 30 minute simmering period. The test ignored emissions before placing the pot on the stove and suffered from many other shor tcomings.

Although the WBT has been advertised as simple to conduct and capable of giving useful information to designers, it is not as simple to conduct as either the Indian or Chinese tests and has a larger inherent variability.

Field tests conducted using the VITA CCT were intended to capture an indication of performance based on the cooking practices of local users and “provide an indication of the performance of stoves during actual use”. From the beginning, VITA struggled with, and recognized the challenge of, striking a balance between:

(a) the standardization of testing methods to ensure replicability across testing locations; and, (b) the performance of actual cooking practices in the laboratory environment to better predict the stove’s performance in local usage.

VITA emphasized the distinction between testing “done for local use only (for stove users and others) and testing where the results are intended to be transmitted to other places”.

The core misunderstanding in the stated intention for the CCT is the idea that the performance of a stove is inherent to all circumstances. Test results are only valid for the context in which they were performed. This has been amply validated by the fact that there is little, if any, correlation between laboratory tests in which ‘cooking is simulated’ and cooking in any place that does not ‘cook like that’. A stove tested and optimized using dry fuel will almost always perform badly when tested using wet fuel; whether that is in the same laboratory, another one, or in the field.

Since the WBT occupied a central the role in laboratory testing in the West, using a fixed fuel, fixed burn cycle and fixed cooking vessel, the results proved untranslatable to different global contexts and unable to transcend local variations in cooking practices. A stove ‘recommended’ by WBT results might not be acceptedwhenusedunderdifferentcircumstances.

The CCT was supposed to address the issue of translatability to different cooking contexts. However, if the CCT is able to provide useful information, why was it not used in the laboratory by reproducing relevant cooking cycles there? The answer is not clear. However, there is an apparent belief that performance is ‘inherent’: a ‘better stove’ would always out-perform a ‘worse stove’, with cookstove projects opting to promote the ‘better’ stove on the basis of the WBT lab test.

Because any test conducted ‘differently’ will give a different performance rating, it is critical that a product selection process conducted in the lab or the field be representative of the local context.

It is incorrect assume that any characteristics of a stove are inherent in the design. For example, the particulate matter (PM) emissions vary considerably from the same stove if the moisture content is altered or the fueling rate is changed. Having two different laboratories agree that a stove performs well with 5% moisture fuel does not indicate how a stove will perform with 15% or 25% moisture fuel, levels at which stove performance may not be optimized. Testing performed out of context carries little information about performance, or gives misleading guidance.

Any test reports the performance under that set of test conditions. While a properly documented set of conditions is reproducible, it may not be relevant for the reader’s project area. Where there is no match, there is no useful information conveyed.

The WBT has been significantly altered from its original version to the present Water Boiling Test Protocol 4.2.3 and contains additional output metrics. As a result, test result from different versions are not directly comparable and may not even have the same reporting metrics. Importantly, the core problems with the low power metrics introduced in the original 1985 VITA test have not been addressed. So far is known, the current version never been externally reviewed by independent experts.

Because of the large inherent variability of the WBT protocol and the clear differences between the prescribed lab conditions and the flexible field conditions, there has been a standing conflict between WBT and CCT results. The desire to ensure repeatability and precision in the lab has never been matched in the the practical field. This has been exacerbated by the impracticality of conducting precise tests in field conditions.

The developers of the WBT suggest that the requirement for the stove performa at low and high power output provide a solid indication of the stove’s performance during actual cooking. While this is theoretically possible, the fixed burn cycle and the poor choice of reporting metrics has resulted in its continued rejection in many circles. The UNFCCC allows for the CCT to be used but has done so without conducting an external review.

Furthermore, concepts inherent to test which made little difference to performance rating in the past have, because of new inventions, come to the fore as significant issues. The most important is the old ‘power station’ idea that the heat transfer efficiency is a good proxy for the fuel efficiency of a stove. The development of stoves that make charcoal concurrent with cooking has resulted in stoves that consume as much or more fuel than a three stove fire.

When rated for their ‘heat transfer efficiency’ (a calculation of the percentage of heat released from the fire that enters the pot) there is a mismatch with ‘fuel consumption’ since the heat contained in the charcoal is not released during burning. The WBT rates the efficiency of the use of energy released, not the efficiency of the use of the energy in all the fuel extracted from the forest. Stoves that are 15-20% efficient from the ‘forest’s point of view’ are being been credited with ‘an efficiency’ that is over 50% because they do not burn all the fuel, it is turned into charcoal.

Whatever happens to that charcoal, or smaller amounts produced by other stoves, is independent of the stove that produced it. How to account for this charcoal requires a programmatic decision apar t from the performance rating.

The idea that ‘simmering’, or performance at ‘low power’, has an ‘efficiency’ is incorrect, also noted by Ranietal. Similarly,theideathatthefinalvolumeof water in a pot represents ‘cooked food’ is incorrect, particularly for foods cooked in water like potatoes or corn.

It is recognized by developers and proponents of the WBT that it does not provide a complete view of stove performance while performing real cooking tasks in a particular local context. The stated purpose of the WBT is to “measure how efficiently a stove uses fuel to heat water in cooking pot and the quantity of emissions produced while cooking”.

The core problem is that even if the metrics were corrected, the idea that a universal test tells us something useful about how a particular stove will perform in any circumstance is fundamentally flawed. This assumption fails to consider, in the lab, the context of that future use. Only contextual performance comparisons are relevant for product selection of biomass stoves.


The Water Heating Test (WHT) method developed through the Indonesian Clean Stove Initiative pilot program asserts that cooking practices are usually complex cycles that are not adequately represented by two measurements at high power and a third at low power. In place of the standardized WBT cooking cycle, the pilot program has adopted a method of creating a contextual burn cycle relevant to the Indonesian local cooking experience. This has been paired with the well-known SeTAR Heterogeneous Testing Protocol (HTP) referenced in the IWA 11:2012. The characterization of the burn cycle is achieved by the triplicate replication of various cooking cycles and measuring the average performance. This is done by local cooks using local fuels and pots in a laboratory setting.

Multiple cooking cycles are combined to create an ‘average burn cycle’ called a Technical Test which reproduces the power levels and its variation. It may include the ‘weighting’ of cooking cycles to represent their relative frequency of use.

Thus the WHT is a testing framework based on the HTP into which any locally relevant cooking cycle or set of cycles can be placed. The HTP testing method is thesame from country to country, from lab to lab, but everything about the cooking is local. A lab in another country could easily reproduce a documented burn cycle from a catalogue of behaviors. In this manner, a manufacturer can test a stove product intended for a foreign market. This accomplishes the intended goal of the WBT to permit stoves to be tested anywhere, for any market. All that is required is a documented Technical Test and the relevant pots and fuels.

In sum, there are multiple clear differences between the WHT and the WBT:
The WHT reports the fuel consumption necessary to replicate a cooking task or a set of cooking tasks; the WBT repor ts the energy consumption, mathematically treating ‘partially burned fuel remaining’ as ‘unburned raw fuel.’

  • The WHT reports the performance while conducting locally relevant cooking cycles while still being restrained to laboratory conditions, thus replicating ‘average field testing’ in the lab; the WBT reports the performance using a fixed, three stage burn cycle, fixed pot and fuel type.
  • The WHT calculates the performance using measurements appropriate for the metric being rated; the WBT uses somewhat arbitrary metrics taken from various sources, not all of which are relevant, correctly calculated or conceptually valid.
  • The WHT has a low inherent variability because it minimizes the influence of experimental variation in calculations; the WBT has an inherent variability of about 30%, largely because of using ‘water mass remaining’ as a divisor for multiple outputs.
  • The WHT has been informally, externally reviewed multiple times as and whenever it is edited.

It is the aim of the Indonesian initiative that the a contextually accountable testing process will be achieved through the incorporation the social anthropology of cookstove usage into development of the burn cycles employed at the laboratory. There are multiple documented cycles available. As knowledge on local cooking practices increases, it may transpire that some cycles are relevant to other regions and countries.

Any description of cooking behavior can be used in developing a testing protocol. This does not affect the validity of the measurements made, only the applicability to the target population the burn cycle is supposed to represent. The more locally relevant the information on cooking behavior, fuels, foods and pots, the more likely the lab-predicted behavior of candidate stoves will be reflected in the field.

Thus there are two protocols involved: once for the social science and another for laboratory testing.


This case study sets out to propose an argument for a lab-based stove testing method that reasonably predicts future performance when used in a particular context. One of the aims of the clean stove initiative in Indonesia is to develop and assess an alternative testing method (the WHT) that claims to incorporate critical social factors into the test cycle and therefore into the rating process.

In 2012, the World Bank in collaboration with the Directorate of Bioenergy, Ministry of Energy and Mineral Resources (MEMR), initiated the Indonesian Clean Stove Initiative (ICSI). The central aim of the initiative is to scale up access by 2030 to clean cooking solutions for the 40% of Indonesian households that will likely continue to rely heavily on solid biomass fuels for cooking. Over the next 10-20 years, national economic development is expected to result in the increased adoption of LPG. . It is also expected that households which continue to use biomass cooking fuel will do so with a clean stove. Further, it recognizes that a significant proportion of LPG users (about 70%) also use biomass fuels to heat water. As a result of being a highly mixed fuel economy, the target market of the initiative includes approximately 70% of the entire Indonesian population.

The ICSI comprises four program phases (i) initial stocktaking and development of the implementation strategy; (ii) institutional strengthening, capacity building, and piloting of the strategy; (iii) scaled up program implementation; and (iv) program evaluation and dissemination of lessons learned.

The activities completed in Phase I have focused on in- depth assessments of household cooking fuel technologies and the existing stove market, review of the sector policy and institutional framework, and collation of lessons from the country’s two most successful clean cooking programs for application to the biomass stove initiative.

The next step for the ICSI, Phase II, is to establish stove standards and testing protocols, strengthen institutions and build stakeholder capacity, design and prepare the master plan for rollout of the national program.


The uptake of clean cookstoves by households depends on behavioral change to ensure not only the purchase but the sustained usage of the improved cooking stove. This uptake hinges on a variety of factors which cannot be adequately understood without careful study of local cooking practices. While establishing the stove standards and testing protocols, the World Bank CSI’s technical team in collaboration with the Social/Gender team conducted surveys and group discussions with biomass stove users. The studies were conducted between 11 March and 7 April 2013 in Yogyakarta and Central Java. Findings from these field obser vations and discussions have provided a more holistic view of the range of cookstove usage, fuels and cooking practices.

The purpose of these field visits was to provide “enough ethnographic details about socio-economic interests and relevant macro-contexts… to recognize what improvements in stove technology will be most likely to motivate potential customers belonging to particular stove using groups to buy and use improved biomass stove products”.

Central findings from these field studies that inform a contextually relevant testing method include:

a. Complex demographics of fuel usage in Indonesia

Demographic studies of fuel usage in Indonesia must be carefully read to provide an adequate image of distribution of fuel sources among geographically and socio-economically divided groups. It is common practice for households to use a combination of fuel sources, differentiating between fuels according to the type of cooking task performed. The common usage of a combination of fuels complicates the conceptualization of the actual biomass use or dependency in the country. Despite the Indonesian Government’s conversion programs for both LPG and biogas, 40% of Indonesians indicate that their primary fuel source for cooking is from biomass, however this understates its prevalence. Field survey results from 17 provinces indicate that wood-burning stoves are produced and sold more than any other stove type. Reliance on biomass fuel for cooking is particularly pronounced in rural areas and it is unlikely to decrease in coming years.

Considerations such as time, cost, cleanliness, micro-enterprise applications and convenience are central selecting the choice of fuels and stove model. The typical trend across demographics in Indonesia is the allocation of more biomass to home industry and a shift to LPG for non-industrial cooking. While LPG usage enables families to improve their kitchen conditions (clean pots, convenience, speed), households remain dependent on (typically free) biomass for heating, lighting, and cooking. In Indonesia, of those surveyed, 70% said that though they used LPG primarily for cooking, they also use wood for heating water. As biomass is projected to remain a widely available, free, convenient and renewable fuel source, it is likely that reliance on biomass-burning stoves will continue, par ticularly for heating water, even if LPG is more widely adopted.

The allocation of different fuels to particular tasks is geographically and culturally contingent, which is to say ‘the cooking context’ is local. An observation from field studies highlights the importance of biomass burning stoves for the provision of lighting in the home. Stoves are often used to light the home, notably in rural family and peri-rural households. Illumination will be an important consideration affecting the uptake of a stove if it has a window-less door that must be closed to work at optimum efficiency. Will people use the stove with the door closed? If not, should the stove be tested with the door open, as people would actually be using it? This aspect of the local context must be understood when selecting the test cycle to be applied.

The mixed demographics of fuel usage in Indonesia reveal that, despite the introduction of new energy carriers, biomass remains an integral part of Indonesian household cooking. Past attempts to improve indoor air quality were directed at fuel switching (e.g. from kerosene to LPG). Considering the contextual complexities and the inhomogeneity of fuel allocation for cooking tasks, adequately conceptualizing what local choices will be made is difficult. sIt is clear from the surveys that there will be a continued reliance on biomass for some aspects of domestic cooking, particularly water heating. Evolving consumer demands and culturally-rooted performance requirements are intrinsic drivers of domestic energy choices in Indonesia. The continued improvement of biomass stoves and the use of contextually relevant evaluations must become a permanent facet of the domestic energy policy framework.

b.Convenience and economic costs as determinant factors

Field research revealed the main determining factors affecting the choice of fuel source and type, and stove type. Convenience and economic costs feature centrally in these choices. Widespread access to free biomass fuel wood as well as the low cost of traditional cooking stoves make biomass cooking a popular option, especially for lower income, rural households.

Higher income households have been quicker to adopt LPG as well as electric rice cookers which reduce the time required for gathering firewood and the cleaning of soot from pots.

“By cooking rice in an electric cooker, biomass using households reduce the amount of firewood they must gather by about 25% and they also reduce the amount of time spent cooking for the family by the same factor”.

Keeping pots soot-free is important to consumers. The desire for convenience, cleanliness and low cost cannot be neglected when developing a contextually relevant and user-accountable product evaluation method.

The projected continued easy access to free firewood as well as a lack of economic means in rural areas to adopt alternative cooking solutions, including LPG fuel and rice cookers, suggests the long term centrality of biomass cooking stoves in the domestic energy market.

c.Avoiding standardization of questionnaires to assess stove and fuel users

Analysis of the field study revealed concerns about the Clean Cookstove Questionnaire developed to assess household fuel and stove usage as well as with the reasons for the uptake of a par ticular cooking stove.

The wide systematic variation, as a result of geographic (forest cover, type of farming, and altitude), economic status (income level) and cultural variables fundamentally shape the biomass economy.

A random survey is arguably incapable of providing an informed view of cookstove usage in Indonesia. The varied realities of the biomass economy in Indonesia must be incorporated into the survey questionnaire as well as the testing cycle applied. This can be used to ensure that an agreeable standardized, countrywide testing method is adopted, while recognizing the necessity of identifying locally relevant cooking cycles to be used with the method. The selection of a single ‘national cooking cycle’ would fail to address the vast differences in the Indonesian biomass economy. The distinction between a test protocol and a cooking cycle is not well recognized. Therefore, they are often lumped together. Identified as separate components of a national regulatory framework, contextual testing can be done for any community of users based on a common protocol. This addresses all the geographic, socio-economic and cultural variables affecting performance. A well-constructed survey correctly that informs the cooking cycle to be applied during assessment.


With the aforementioned results of the field studies, the technical team has noted that using the WBT v4.x method does not provide an adequate, relevant or holistic view of what is taking place in the biomass economy. The WBT closely follows the metrics and ‘performance tiers’ in the Interim Workshop Agreement (IWA 11:2012). The inability of the test method and the questionability of some of the metrics means it cannot rate stoves in a way which reasonably predicts future performance. This threatens the ability of the ICSI to provide a classification framework that is beneficial to the Government, local vendors or users.

The WHT burn cycles and testing framework developed during this initiative provide meaningfully accurate relative performance rankings by replicating average local household practices in a controlled lab setting. Furthermore, the metrics used and the calculations made have been reviewed for relevance and correctness.

a. Distinction between technical vs social solutions

The development of the WHT, a revised version of the more general Heterogeneous Testing Protocol (HTP), has centered on describing and blending culturally relevant cooking cycles that can be used in a lab setting within an already validated testing framework. This approach overcomes the long-standing and conflicting demands for a well-controlled, accurate, technical assessment that can be done while measuring a realistic cooking event. Previously these goals have been thought of as incompatible, separate assessments which usually resulted is incomparable and/or completely misleading performance ratings, since what was done in the lab was so different from what is done in the field. The HTP allows the ‘field’ to be brought into the’ ‘lab’.

A persistent tendency within the stove world has been to confuse the test and evaluation method with the burn cycle employed during that test. The WBT method has historically only used a single three-stage burn cycle. The method and the burn cycle have often been confabulated into a ‘single thing’. Combined with the misunderstanding that performance ratings are somehow valid independent of the fuel properties and burn cycle, the stove community has been repeatedly let down when field performance turned out to be very different from predictions made in the lab.

The measurements and calculations performed by a protocol are standard no matter what one does with the stove during the test. One is a measurement system, the other is the thing being measured. A test method can be validated independently of the burn cycle employed. A validated test method used with an unrepresentative burn cycle will give a misleading prediction of future performance. A defective protocol used to evaluate a stove tested while conducting a locally relevant cooking cycle will still give an unreliable rating. To make a valid assessment, the test method must be valid and the burn cycle, fuel and pots must be relevant to the community in which that stove will be used. That assessment is not necessarily valid for any other community unless the pattern of use and fuels happen to be similar. No assessment is ‘generally true’. No stove has generic performance characteristics, and cer tainly not characteristic fuel consumption or emissions of smoke since these variables alter according to local circumstances.

Cooking stoves have been proposed as a viable solution for a variety of global social problems. This has been termed the “technologisation of social issues” involving the use of “technologisation of social issues” involving the use of “technical panaceas” and “encompassing solutions”. The policy focus of the ICSI public health due to well established links between poor air quality & negative health consequences. The overarching goal of the program is to provide access to modern technology through the adoption of more efficient stoves which reduce household air pollution (HAP).

Abdelnour’s critique of the promotion of “efficient stoves as a panacea for rape risk” presents useful insight into the importance of understanding the local context and the root causes of social problems. He reminds project teams to remain mindful of the variations in social context and the importance of developing a holistic view of the local biomass economy in order to ensure the needs of local users are fully met.

“Rather than engage with complex reality, technical panaceas legitimate the delivery of universal ‘solutions’. As our study demonstrates, this amounts to a subtle yet profound shift in humanitarian agendas and the technologizing of humanitarian space: the struggle to understand and prevent sexual violence is replaced by the quest to design, produce, promote, and deliver the most fuel-efficient stoves”

The tendency of organizations involved in cookstove initiatives has on occasion been to attach multiple agendas to technical solutions that reflect the aspirations of marketers and manufacturers and a variety of governmental and non-governmental organizations. This ultimately overshadows the needs and aspirations of users. The aspirational targets of users are contextually dependent and have been regularly overlooked or misinterpreted by testers, donors, and proponents of various cookstove initiatives. These complications must be addressed.

The methods used in this pilot program seek to address health impacts and the needs of consumers in the context of Yogyakarta Province. The incorporation of the social cooking context into the evaluation method allows results to be weighted both for technical and social considerations and includes and social considerations and includes new metrics that span both fields. This is expected to overcome the shor tfalls of the past and positively impact the eventual widespread uptake of high performance stoves cer tified by the ICSI.

b. Results-based financing to ensure accountability of initiative to users

The results-based financing used in this CSI will provide subsidies to manufacturers for their cookstoves at two levels of consumption and usage: 1. 70% of determined subsidy will be granted to the manufacturer based on the sale of the product. 2.The remaining 30% of the subsidy is granted to the manufacturer only if field visits confirm that consumers are using the product.

The purpose of an RBF approach is to ensure the accountability of manufacturers and provide an incentive for the maintenance of a high standard product as classified through testing. Fur thermore, manufacturers are held accountable to consumer demands and needs through the requirement that the stoves must be proven to be in use once purchased.

“The promotion of clean cooking solutions should understand market segmentations, adapt to local conditions, and be consistent with and adjust to long-term development patterns”.

The initiative’s RBF mechanism sets out to ensure that the policy of the public sector and its objectives are met, and that the private sector is rewarded for delivering these desired outcomes. The objective of the program is not solely to introduce clean cookstoves to local markets but to ensure that they are actually used once purchased in order to deliver the health benefits sought by the public sector.

The behavioral change required by consumers in order to ensure sustained uptake of the clean cookstoves cer tified in the CSI is variable based on current local practices determined by varied geographical, socio- economic and cultural factors. The onus of ensuring the continued use of the stoves is placed in par t on the producerasaresultofRBF.

Furthermore, RBF seeks to distort the local market as minimally as possible and enable local producers to shape the biomass market economy. This is unlike traditional subsidy models which “[distort] the supply of stoves by subsidizing production runs on stove materials. The subsidy model which has been applied commonly by cookstove projects keeps prices of cookstoves artificially low while providing few opportunities to local producers to develop sustainable business practices that meet local needs through local market exchanges.

c. Involvement of manufacturers in testing process

Phase II of the initiative gives an opportunity to assist stove producers and marketers to improve the technical performance and social acceptability for their stove products after receiving critical feedback on its performance on CCTs. At this stage, manufacturers and vendors have the opportunity to introduce changes to the design, components, materials, and operating instructions for their stove. This may dramatically improve either the stove’s technical performance, social acceptance, or both. This stage fortifies the initiatives’ emphasis on local demands and market control.

The proposal of pre-screening of stoves prior to inclusion in the field testing has been put forward as a result of the field study inquiry. Pre-screening is done before the top choices for cooking stoves are presented to the general public. This is to ensure that it is not a free-for-all access of manufacturers to local market, in part to guarantee quality of product as well as provide a mechanism for the protection of local manufacturers from global competitors.

“It does not make sense for the CSI Program to simply start a wild stampede between local and international stove manufacturers and vendors without going through a preliminary multi-stage screening process to decide what candidate stoves, producers and vendors (market aggregators) for inclusion in its RBF program”.

Therefore, one of the purposes of pre-screening is to ensure that local producers are not at a disadvantage in comparison to international competitors which could be interested in entering the Indonesian market.


The collation of lessons from field studies and the resultant socially accountable business plan has informed the development of the Water Heating Test to ensure the desired outcomes of all stakeholders are met. The previous discussion intends to show that different stove programs, users and distributors have particular priorities which must be accommodated by technical testing and functional evaluations. The WHT Technical Test used in the ICSI lab implements this holistic, contextual testing approach.

a.Replication of local cooking practices in test cycles

This pilot program is evaluating a testing methodology that considers the local context of cooking and provides consumers with a cookstove classification system that is a solid indication of whether or not the stove they are purchasing will serve their cooking needs. While not the first to break from the WBT, it specifically recognizes the need for a standard testing protocol that delineates what to measure and how, while replicating common cooking cycles. The ‘local context’ in this case consists of the common cooking cycles, pots and fuels popular in Yogyakarta province.

The goal is to predict the in-home performance and acceptability of a candidate stove.

The cooking cycles that will be replicated in the YDD lab include:

a. A typical ‘breakfast cooking cycle’. Boil 1 liter of water to parboil rice; bring to boil another pot containing 2 liter of water preparing the rice steamer; reducing the heating power to steam the rice; finally, increasing the heating power to boil of 3 liters of water for drinking.

b. A common cooking cycle for ‘coconut milk chicken soup’. Boil coconut milk to a high power; reduce the heating power to a low level to simmer the soup for a long time; replace the pot with wok for cooking “sambal” still using low level to frying the chilli/sambal.

Note: Other cooking cycles may be selected with the goal of covering the cooking power range needed in that culture, as many different cycles as are needed to achieve this. A stove that exhibits the required range of functions (such as holding the pots securely, igniting in a reasonable time, raising, lower or tapering the heating power level and efficiently combusting the available fuels) is assumed to be acceptable in the market as well as in line with the program goals. Cooking cycles can be combined, as well as weighted for frequency of use, to produce a numbered Technical Test heating cycle. It is the appropriate Technical Test that is replicated in the controlled conditions of the laboratory.

It is recognized that the Technical Test does not predict the performance or acceptability of the same stoves at other locales where the fuels, cooking cycles, pots, foods and power range requirement are significantly different. It does however overcome the long-standing problem of laboratory-based stove performance ratings made using an arbitrary cooking simulation. An arbitrary cooking simulation offers little information on a stove’s performance in any community. The WHT instead prescribes what will be measured, how and when, and what calculations will be done to provide the repor ting metrics while leaving the simulated tasks to be defined according to the local context.

For example, one criticism of the high and low power testing procedure of the WBT is that the sequence high-low sequence measured when the stove is already hot gives a performance rating advantage to high mass stoves.

High-mass stoves are able to store heat from the cold start and use this during the simmering stage following a second high power start. Fur thermore,

“A stove might operate inefficiently if too much power is provided for the needed task. Test results are highly dependent on the power level chosen. Some guidance should be needed to boil the standard 2.5L and 5L of water. We should collect data on observed firepower from regional testing laboratories to provide a range for users”.

While the heat storage by a high-mass stove may be an attractive feature in some cultures, in other contexts where the cooking cycle is short this is a disadvantage and results in lowered efficiency.

The Technical Test applied in the ICSI seeks to evaluate performance during typical use. By using a cooking cycle based on local practices and utensils, the test does not advantage any stove unfairly, such as witnessed previously with the WBT and high-mass stoves. Rather the stove is tested in the lab how it will be used, on average. In short, it advantages the stoves capable of delivering the requirements of local users.

The Technical Test simultaneously corrects a number of conceptual and mathematical errors embodied in the original WBT still affecting the results of its descendants. This anticipates the work being done by the Working Groups of ISO Technical Committee 285.

a.Indicators: Particulate matter (PM), carbon monoxide (CO), and efficiency

The focus of the Indonesian pilot program is on providing improvements in HAP and related health benefits. This focus impacts the differential weighting applied to indicators of “clean cookstoves”.

The WBT test indicates that the pollutants of primary importance for measurement are CO (carbon monoxide) and PM (particulate matter). While the measurement of both compounds has value, the context-specific testing method utilized in this pilot program urges the careful consideration of the local environment of risk factors associated with biomass cookstoves in applying weight to the health impacts of that will be used ‘tomorrow’. That would include any usable charcoal produced during the which, depending on the local culture, be saved or discarded. Actual behavior strongly affects actual fuel consumption. A WBT always starts with new fuel and treats remaining charcoal as unburned raw fuel when determining the ‘energy consumption’. No fuel from previous replications is used in subsequent tests. If users normally extinguish the charcoal immediately after cooking (a common practice in some cultures and for which there are purpose-build clay containers) the emissions into the home are impacted, thus affecting the fuel consumption rating.

The WHT measures fuel consumption based on the behavior of local users by providing a new definition of ‘fuel consumption’ as distinct from ‘energy consumption’. Where cooks re-use the remnant wood and charcoal, this behavior is replicated in a series of tests which disregard the first in the series. Meaning, the first test is conducted with raw fuel, after which remaining fuel is carried forward to the subsequent test. Only the subsequent test results are considered.

Where users allow the charcoal to continue burning after the cooking cycle (for example to provide light or dry fuel for the next day) the remaining fuel is allowed to burn and measurements are taken until the end of the burning process. This ensures that all emissions from this post-cooking burning are accounted for in the measurements of fuel efficiency, CO, and PM. Two sets of metrics can be reported if desired: the performance of the stove itself during cooking, and the influence on air quality of the local culture which depends on what happens to the remaining fuel.

The ICSI’s WHT considers partially used, burnable fuel and incorporates it into the test cycle. Because not all stoves can accept remnant fuel, the WHT considers it ‘consumed’. If the stove manufacturer indicates what portion or type of fuel can be ‘recycled’, the stove is tested accordingly. While most (but not all) stoves on the market in Indonesia can re-use partly-burned stick fuel, few are capable using remaining charcoal. Therefore, it is impor tant to take into consideration the ultimate disposition of this charcoal after the completion of cooking cycles. Is it allowed to burn out, removed from the room, or extinguished?

The WBT (always conducted with new raw fuel) attempts to deal with the same issue by assigning an energy content to the remnant charcoal but makes no provision for dealing with partially burned, dry and re- usable sticks. The WBT calculates the amount of energy consumed, not the amount of raw fuel needed to replicate the burn cycle. This quantity of energy is not analogous to the consumption of raw fuel because the energy in remaining fuel, even if in that culture it is thrown away, is considered to be ‘unconsumed fuel’ in the energy accounting calculation.

The WHT breaks with the WBT both conceptually and practically by determining the actual amount of new, raw fuel required to replicate any test cycle, in a series of identical cycles, save the first (which is used to generate the first ‘leftovers’).

A detail of the WBT’s energy deduction for remaining charcoal is that the ash remaining is, according to the protocol, treated as unburned charcoal. Depending on the fuel type, this can lead to a large error. The Environmental Protection Agency (EPA) has used a WBT variation which determines the actual energy content of the charcoal. However, this is not standard practice as most labs cannot make this determination. Other options remain but this is considered a WBT- specific problem that only arises when one attempts to determine the energy consumption according to the WBT, rather than the fuel consumption, which is the ICSI program goal. The WHT’s conceptual and mathematical treatment of ash correctly rates the stove regardless of the ash content of the fuel. Different pollutants. CO is arguably of less importance in the Indonesian context due to the open-air nature of the typical kitchen in this tropical region. The ceiling height and permeability of typical homes makes the concentration of CO at dangerous levels unlikely.

Furthermore, the relative importance of pollutants is politically determined by policy decisions that propose clean cookstoves as solutions for certain health, social or environmental issues. In the case of the Indonesian stove program, the government has emphasized the role that clean cookstoves can play improving public health. As a public health policy initiative, the value of measuring PM outweighs the perceived value of fuel efficiency due to the correlation between HAP by particulate matter (PM) from solid fuel combustion versus the easy availability of sufficient fuel.

The indicators measured in this pilot program include: carbon monoxide (CO), particulate matter (PM), and fuel efficiency. The better the performance, the more performance ‘stars’ are awarded to that model of stove. The stars are allotted based on performance on these three indicators. As a result of the CSI’s Indonesian context as well as the pilot program’s focus on clean cookstoves for public health benefits, differential weight is applied to each of the three indicators in order to provide a classification system that is reflective of the desired outcome of the ICSI.

Due to the high level of air flow and openness to the outdoors of the typical Indonesian household, CO is a minor health concern with little risk of high levels of accumulation. On the other hand, moist fuels tend to create more particulate matter. Thus PM reduction is of particular interest to the program and an integral measurement to ensure that cookstoves which reduce this type of HAP remain central to the cer tification process.

The number of stars available for each of the three indicators is yet to be confirmed. However, the expectation is that more stars will be available for attainment of larger reductions in PM emission compared with CO. This method proposes the payment of subsidies to manufacturers based on the total number of stars earned while allowing for a different number of attainable stars for each indicator.

The purpose of allocating stars based on the relative importance of each indicator in the health-focused pilot program is to ensure greater control over the translation of stove benefits to potential consumers. With HAP and its resultant health impacts as the focus of the program, a contextually-relevant and consumer-focused initiative must present test findings to the public in a manner that adequately indicates if a particular cookstove is capable of addressing and mitigating the health risks in question. Therefore the differential weighting of the three indicators seeks to ensure the maintenance of emphasis on the health impact of dirty or traditional cookstoves.

a. Measurement indicators

A stove’s fuel efficiency rating is impacted by the protocol’s mathematical treatment of remnant charcoal. The WBT has not dealt adequately with this matter causing fuel consumption ratings to conflict with actual fuel consumption. WBTs do not consider what happens to re-usable fuel remaining from ‘today’

d. Definitions of terms and metrics

This testing method additionally seeks to address possible confusions with common definitions and metrics, including those used by the WBT.

a. Fuel Consumption

The amount of new fuel required to initiate and complete a task within a sequence of repetitive uses. Residue of char or partially pyrolyzed wood is a significant element of the calculation – is it discarded, or is it used in next fire-making cycle?

For calculating GHG emissions, the use of residual char for combustion in a secondary device or any non- combustion use is an important factor for some programs.

a. Fuel Consumed (Fc)

The fuel consumption of a biomass burning stove is defined as the mass [kilograms] of new fuel drawn from a supply that is sourced outside the cooking system needed to conduct any one of a series of identical replications of burn cycle, save the first.

The WBT defines ‘wood consumed’ as “the mass of wood that was used to bring the water to a boil found by taking the difference of the pre-weighed bundle of wood and the wood remaining at the end of the test phase; though that is not the whole story. Because of the conceptual differences in the treatment of remnant wood and charcoal, the two fuel consumption metrics are not directly comparable.

c. Heat Available in the Fuel (HF)

The total heat available from the perfect combustion of the Fuel Consumed calculated from the heating value per unit mass As Received [AR]. HF is expressed in unit (MJ).

d. Net Heat Gained (HNET)

This is the net heat retained by a cooking vessel during a burn cycle and is expressed in units of MegaJoules. It includes the heating of the pot and its contents plus the heat of evaporation of water, but excludes other heat flows through the pot, specifically radiative and convective losses from the pot sides and top.

e. System Efficiency (ç)

The ratio of the net heat [HNET] gained by a cooking vessel divided by the heat available [HF] in the fuel consumed [FC], expressed as %. Synonyms include Overall Thermal Efficiency and Overall Energy Efficiency.

This is the WHT’s thermal efficiency metric. It is [HNET] divided by [Fc] expressed as %. It is the same as the fuel consumption (as most people understand it) and used for comparing the relative fuel consumption of different stoves performing the same tasks with the same pots and fuel.

It is significantly different from the ‘thermal efficiency’ or ‘energy efficiency’ numbers of other test methods, including the WBT, that calculate the heat gained by the contents of a pot divided by the heat theoretically released by the fire – a metric analogous to the ‘heat transfer efficiency’. The heat transfer efficiency of a stove is a poor predictor of its system efficiency (= fuel efficiency).

f. Carbon Monoxide mass per MJNET

The mass of carbon monoxide emitted per MegaJoule of energy gained by the pot is the WHT metric used to rate performance. The number of MJ of energy gained by the pot is the useful energy. People cook until the task is completed, not until a mass of fuel is consumed. Therefore, this metric uses the energy available for cooking (in the pot), rather than a mass of fuel or the energy released by the fire in the denominator.

g. PM2.5 mass per MJNET

The mass of PM2.5 emitted per MegaJoule of energy gained by the pot is the WHT metric used to rate performance. The number of MJ of energy gained by the pot is the useful energy. People cook until the task is completed, not until a mass of fuel is consumed. Therefore, this metric uses the energy available for cooking (in the pot), rather than a mass of fuel or the energy released by the fire in the denominator.

h. Heat Flow Rate (HFR) into the pot, per unit area (heat flux)

The rate at which heat enters a cooking vessel per unit area of heated surface, normally taken to be the area of the bottom of the vessel. It is a measure of cooking power per unit area expressed in units [J/s/cm2] or [W/cm2].

The measurement may be made for any diameter of pot used during a test cycle, but is usually repor ted for the largest diameter. The diameter should be reported together with the HFR value, or indicated by clear implication in the body of the report. Sunken pots and skirted pots will be treated differently, with the heated surface area calculated appropriately.

This metric is used to rate the cooking performance in order to estimate whether or not the cooks in the locale of interest would accept the ‘cooking power’ of the stove.The HFR is analogous to the ‘cooking speed’ and can be applied to any pot size because it reports the number of watts per square centimeter. It is not the fire power, or the total cooking power, but is the cooking power factored for pot size. Acceptable cooking power is culturally determined so it varies from region to region. If a stove meets the requisite HFR, customers will not complain that it is ‘underpowered’.

This is also called the Heat Flux or the Density of Heat Flow depending on which language is used.