Energy storage Key Performance Indicators for building application

Energy storages are key elements for the design and operation of nearly-zero-energy buildings: They are necessary to properly manage the intermittency of energy supply and demand and for the efficient use of renewable energy sources. Several technologies (electrochemical, thermal, mechanical etc.) to be applied at building scale are already available on the market, or are in final stages of research and development. These technologies are characterized by heterogeneous features and performances, therefore it is necessary to develop a procedure to compare these technologies in term of a techno-economical assessment. This paper summarizes the current status of energy storage systems at building scale, and proposes a set of simplified Key Performance Indicators (KPIs), specifically identified to simplify the comparison of storage technologies in the decision-making/designing phase and the assessment of technical solutions in the operational phase. The defined KPIs are finally applied to 10 case studies analyzed within the IEA-ECS Annex 31 “Energy Storage with Energy Efficient Buildings and Districts”.