Setting national voluntary performance targets for cookstoves
Overview
This document was prepared to support countries in setting voluntary performance targets (VPTs) for cookstoves and clean cooking solutions, such as those developed by the International Organization for Standardization (ISO) published in 2018.
Section 1 provides the background of the document, with the objective and target readership. Links to other documents are described, including module III of the “Clean Household Energy Solutions Toolkit” (CHEST) to support countries in designing and using a national strategy for cleaner household energy. The document is intended to assist policy-makers and technical staff in ministries responsible for standards and policies on cleaner household energy.
Section 2 describes the development of standards for cookstoves in lower- and middle-income countries. These include the new ISO laboratory test protocol and the VPTs. The latter comprise five tiered targets for each of five laboratory test parameters, tier 0 being the lowest performance (e.g. open fires and simple solid fuel stoves) and tiers 1–5 indicating increasingly good performance. The role of these targets in reducing the burden of disease and injuries associated with use of traditional solid fuels, cookstoves and kerosene is explained with reference to the WHO guidelines on indoor air quality: household fuel combustion (WHO GIAQ/HFC).
Section 3 provides background information on the new ISO standards for cookstoves and clean cooking solutions and the laboratory testing protocol (ISO 19867-1:2018), which provides information on device performance for assessing tiers of VPTs. The five parameters in the standard, namely efficiency, emissions of particulate matter (PM2.5), emissions of carbon monoxide (CO), safety and durability, are defined and methods for their assessment outlined. ISO Technical Report 19867-3 describes how the tier values for each test parameter were determined, including for air pollutants, and the relations of levels of emissions to health risk.
Section 4 provides an overview of the ISO VPTs for thermal efficiency, emissions (CO and PM2.5), safety and durability and derivation of the tiers for these five parameters.
Section 5 provides an example of laboratory test results for a particular stove and the relation of the results to the default VPT tiers.
Section 6 describes the basis for VPT tiers according to the health risks associated with exposure to emissions of PM2.5 and CO as evaluated in the WHO GIAQ/HFC.
Section 7 provides examples of application of laboratory performance results to obtain tiers of exposure and how they should be reported and interpreted. As circumstances differ, the ISO VPTs also provide tier ratings for “high” and “low” ventilation scenarios, which are explained, with examples.
Section 8 considers circumstances in which user-defined tiers are determined with the WHO Performance Target (PT) model. Two scenarios are examined, one characterized by poor ventilation, small kitchens PAGE vii and longer stove use (which would require lower emission rates to meet air quality targets) and one characterized by better ventilation, larger kitchens and shorter stove use (in which air quality targets could still be met with higher emission rates). This user-defined approach to setting tier values should be applied carefully, with fully justified input data for the model, and cautions and recommendations for reporting included.
These sections build on each other: section 2 provides the justification for the ISO standards for cookstoves, technical resources and WHO’s contribution to the ISO standards. Sections 3 and 4 show how the ISO harmonized laboratory test protocols and the VPTs have led to international consensus on assessing the performance of the stoves and fuels that may be developed, marketed and used as people move from traditional solid fuels and kerosene to cleaner alternatives. Section 5 provides an example of laboratory test results for a stove and the association with default VPT tiers.
Sections 6–8 describe the basis for VPT tiers in default emission tiers for PM2.5 and CO, alternative scenarios for PM2.5 and CO in high- and low-ventilation scenarios and user-defined emission tiers for PM2.5 and CO based on the WHO PT model. Section 9 discusses key considerations in applying the ISO standards and VPTs in a policy for a transition to cleaner, safer household energy. While very clean, safe, efficient, modern energy carriers (including electricity) may be the ultimate target, it is recognized that this goal may not be achievable by all in the short term.
Consideration of a policy for the promotion of devices and fuels that meet intermediate rather than the highest tiers of performance must be justified and reviewed regularly. Section 10 provides six interrelated resources for planning more efficient, cleaner, safer household energy. The first three are ISO products, namely the laboratory testing protocol, VPTs and a field-testing protocol (ISO 19869:2019).
The other three are WHO products: an online emissions model that can be used to generate customized performance target tiers when the conditions differ markedly from those on which the ISO VPT default tiers were based (the WHO PT model); a database of studies that provide model input variables (kitchen volume, air exchange rate and duration of stove use per day); and protocols for measuring these three model inputs when the published values are considered too few or otherwise inapplicable. As for all standards and related resources, the document will evolve as practical experience in countries increases and new evidence on best practice becomes available. Feedback on this document is welcome and can be sent to householdenergy@who.int
