Introduction of renewable energy, in particular the use of solar energy is one of the most efficient strategies to improve building energy efficiency. The objective of this study is to clarify the whole system efficiency of the solar collector combined with gas-driven auxiliary boiler to supply both domestic water and floor heating system. The verification of simulation results based on TRNSYS17 was performed first by comparing to the measurement results, which has been confirmed well. Another objective of this study is to optimize the use of solar energy. In the combined system, three using options of the solar energy gathered by solar collectors are considered reasonable, to supply to floor heating system only, to supply to domestic water system only, and to supply to the both. On the other hand, the efficiency of the gas-driven auxiliary boiler, varies with the inlet water temperature, also affects the system performance, and in consequence links to the primary energy consumption. System control strategy depends on several elements, including weather condition, schedule of domestic water supply, return water temperature of floor heating and the water temperature in tank for heat storage. The total primary energy consumption is consumed as the index to evaluate the whole system performance. (c) 2015 The Authors. Published by Elsevier Ltd.
