Evaluation and demonstration of actual energy efficiency of heat pump systems in buildings, IEA EBC Annex 88
International Energy Agency, Energy in Buildings and Communities (IEA EBC) Programme has launched its 88th R&D project entitled “Evaluation and Demonstration of Actual Energy Efficiency of Heat Pump Systems in Buildings” (Annex 88, July 2022 to June 2027). In collaboration with IEA Heat Pumping Technologies (HPT) Programme and its Task Force, Annex 88 aims to establish the scientific basis for more accurate estimation of the energy efficiency of heat pumps when used in buildings and for more reliable and transparent design strategies for building applications of heat pump systems. When the energy efficiency of heat pump systems is evaluated, there are building-level evaluations and product-level evaluations. For the former evaluations, for example, the influence of sizing and consequent part load operation should be focused for each building, and a relationship between the part load ratio and energy efficiency of heat pumps is actually used in many relevant energy calculation methods. For the latter evaluations, the maximum load is assumed to be close to the full capacity of the product inevitably regardless of the buildings to be installed. As a basis for Annex 88 works, the state-of-the-art report was published by Subtask A in October 2024, and it reviews four focal areas to be studied in-depth during the rest of the working period. The focal areas are 1) load-based test methods of air-to-air and air-to-water heat pumps, 2) field monitoring methods and data, 3) methods of energy use calculation especially for building energy codes, and 4) design guidelines of heat pump systems for HVAC designers with quantitative information. This paper will focus especially on characteristics of load-based test methods and energy calculation methods for heat pump systems (air-to-air and air-to-water heat pump systems) to be used in total building energy use calculation methods for building energy codes.