How is efficiency measured by Dean Still concerning Improved Cookstoves (ICS)?

Relationship between fuel energy supplied and heat transferred to the cooking pot

Dean Still focuses the discussion of efficiency for modern solid-fuel Improved Cookstoves (ICS) on a direct thermodynamic ratio essential for biomass conservation. Efficiency in this specific context is quantitatively measured by determining the relationship between the total amount of useful energy supplied by the biomass fuel (wood or charcoal) and the precise amount of that heat energy that is successfully transferred directly into the cooking pot. This metric highlights the engineering success of designs that use features like combustion control and heat exchange to maximize the useful energy output relative to the energy input, distinguishing ICS performance from older methods where most energy was simply wasted.