The HPCalc project, funded by the Sustainable Energy Authority of Ireland, aimed to analyse the Heat Pump Performance Calculations in Dwelling Energy Assessment Procedure (DEAP) which is used by BER assessors to calculate the energy performance and carbon dioxide emissions of a home’s space heating, water heating, ventilation and lighting, and to provide recommendations for its improvement.
The results of the project are:
1. A detailed description of the calculation methodology used for evaluating performance of heat pumps. This description refers to Excel version of the tool (workbook) and covers the user inputs, the constants used, the actual calculation methodology, including calculation of the Seasonal Performance Factor (SPF) for space heating (EN14825), SPF calculation for water heating (IS EN255-3, IS EN14511), calculation methods for heat pumps that do not have Ecodesign data.
2. A review the current calculation methodology and a number of identified gaps as well as potential improvements to be implemented in a forthcoming version of the tool DEAP. Minor gaps were identified with respect to the standard IS EN15316-4-2:2008, whereas possible improvements for the calculation of thermal capacity and Coefficient of Performance (COP) both in full load and in part load conditions were identified analysing the updated standard IS EN15316-4-2:2017. These improvements include: 1. a method based on performance map to calculate variations of thermal capacity and Coefficient of Performance (COP) at full load as function of the inlet/outlet temperatures and of the temperature spreads across the evaporator and condenser; 2. an analytical method to calculate the COP as a function of the part load ratio in both the continuous and on/off operating modes of a heat pump. In addition, some improvements based on calculations performed by the standard EN 14825:2022 were also identified. It was suggested to account for the energy consumed when the heat pump is working in different operating conditions (i.e., thermostat off mode, standby mode, crankcase heater mode, off mode) when calculating the seasonal space heating efficiency.
3. A review of other studies (SAP 2016 methodology, FactHP, DesignforIU, WP-Effizienzes, WP Monitor, UK Heat Pumps Field Trails, Domestic Annual Heat Pump System Efficiency Estimator). The SAP 2016 methodology provided useful information to calculate the Plant Size Ratio. The other studies provided information about the variability of the heat pump performances (SPF and amount of heat delivered) in the field; results were compared against SEAI data available in BER database, highlighting differences that should be further analysed in forthcoming research projects by collecting a richer set of measurement from large samples of heat pumps installations. The analysed studies also provided information about the preferred boundary to evaluate the SPF (H4).