Air source heat pump modelling for dynamic building simulation tools based on standard test data

Air source heat pumps (ASHP) are increasingly of interest in the UK and Europe, due to national commitments around emissions reductions and the greater use of renewables. This raises issues around the optimisation of installation design approaches, and the potential for ASHP to contribute to demand flexibility. Dynamic modelling is a useful tool for addressing such issues. It is also beginning to play a role in performance estimation under National Calculation Methodologies. There is currently no broadly accepted method for the creation of models of air-to-water heat pump performance for dynamic building simulation tools based on standard testing processes. Such a method is proposed. An analysis of ASHP theory and behaviour is undertaken, and used to inform a review of modelling methods in the literature. The "greybox" approach is selected, and adapted to work with data of the type output by European Standard EN 14511 for the performance testing of heat pumps. The wide applicability of the proposed modelling method is demonstrated through application to EN 14511 data for 45 ASHP units. Three of the models developed are implemented in building energy simulation tool ESP-r. Simulations results are within the range found in field trials, and are comparable to the predictions of other modelling methods. The method can differentiate between higher and lower quality ASHP, and predictions follow expected trends when the parameters of the modelled heating system are changed. It is concluded that the method is valid for simulations focussing on the integrated performance of building and heating systems. The main limitation found is that humidity can have a significant impact on performance, and EN 14511 performance data does not allow sensitivity to humidity to be assessed. Recommendations are made for extensions to standard testing processes to aid the production of dynamic models.Air source heat pumps (ASHP) are increasingly of interest in the UK and Europe, due to national commitments around emissions reductions and the greater use of renewables. This raises issues around the optimisation of installation design approaches, and the potential for ASHP to contribute to demand flexibility. Dynamic modelling is a useful tool for addressing such issues. It is also beginning to play a role in performance estimation under National Calculation Methodologies. There is currently no broadly accepted method for the creation of models of air-to-water heat pump performance for dynamic building simulation tools based on standard testing processes. Such a method is proposed. An analysis of ASHP theory and behaviour is undertaken, and used to inform a review of modelling methods in the literature. The "greybox" approach is selected, and adapted to work with data of the type output by European Standard EN 14511 for the performance testing of heat pumps. The wide applicability of the proposed modelling method is demonstrated through application to EN 14511 data for 45 ASHP units. Three of the models developed are implemented in building energy simulation tool ESP-r. Simulations results are within the range found in field trials, and are comparable to the predictions of other modelling methods. The method can differentiate between higher and lower quality ASHP, and predictions follow expected trends when the parameters of the modelled heating system are changed. It is concluded that the method is valid for simulations focussing on the integrated performance of building and heating systems. The main limitation found is that humidity can have a significant impact on performance, and EN 14511 performance data does not allow sensitivity to humidity to be assessed. Recommendations are made for extensions to standard testing processes to aid the production of dynamic models