Integrated gas heat pump (GHP) system for residential complexes: modeling cooling, hot water, and electricity generation

• An integrated fuel-driven cooling and power system is modeled for residential use. • An equivalent COP based on fuel energy input is introduced and evaluated. • The system reduces grid electricity demand while providing cooling and power. • Heat recovery improves the overall energy performance of the integrated system. This paper presents the performance of a gas engine-driven heat pump system, which can supply building cooling, electricity generation by a generator, and domestic hot water by means of waste-heat recovery from the engine. The novelty of the proposed system consists in integrating the refrigeration cycle and the on-site power generation by using a unique gas engine; both the refrigeration compressor and the generator are driven by the same engine in a fully integrated multi-generation configuration. The gas heat pump cycle is simulated in Python using R410A refrigerant, while the required cooling and electrical loads are derived from a building simulation performed in DesignBuilder for a residential complex in the hot and humid climatic conditions of Bandar Abbas, Iran. The refrigeration COP eq is defined as the ratio of the evaporator cooling capacity to the primary energy input (fuel) and is used to assess the cooling performance. The Primary energy ratio (PER) can be defined as the ratio of the total useful outputs (cooling, recovered heat, and generated electricity) to the fuel energy input and gives an indication of the overall efficiency of the multi-generation system. The accuracy of the model is ensured by comparing the simulation results with available experimental data and validated studies. The results show that the system meets the peak cooling load of 391 kW with a COP eq ranging from 0.1947 to 0.9467 during the warm months. The PER varies between 0.55 and 1.147 without heat recovery and increases to 0.91–1.5 when heat recovery is included during the warm months. The system produces approximately 2.511 m3/h of domestic hot water through waste heat recovery, resulting in a monthly production of approximately 1808 m3. The generator’s electrical output, as an independent product of the system, varies from 161.5 kW during winter to 81.54 kW during summer. These results demonstrate that electricity generation, cooling, and waste-heat recovery can be integrated into a single gas engine, offering a practical pathway for energy efficiency in buildings. This also supports the development of small-scale multi-generation systems for building-sector applications.