Scaling Relationships in Life Cycle Assessment The Case of Heat Production from Biomass and Heat Pumps

Life cycle assessment (LCA) studies include a vast amount of different products. Often, extrapolations are necessary to obtain the life cycle inventory of a specific product. This article provides quantitative scaling factors with power (heat output) for product properties and life cycle impact assessment results of heat pump and biomass furnace technologies. Included in the study are 508 heat pumps and furnaces with differences in power over three orders of magnitude per product group. The key properties of the heat pump system were defined as mass, refrigerant use, and coefficient of performance. For the biomass furnaces, the key properties analyzed were mass, electrical input, and efficiency. The results indicated that both the mass and the refrigerant use increased subproportionally to power. For coefficient of performance and furnace efficiency, no scaling effect was found. Subproportional growth was found between two environmental impacts (global warming and ozone depletion) and power for the production phase. This scaling behavior was similar to conventional cost scaling. The results of our study imply that in LCA, scaling factors can be applied to estimate key properties and corresponding life cycle impact assessment results. This is particularly useful for prospective technology assessments with limited data available.