Evaluation on distributed renewable energy system integrated with a Passive House building using a new energy performance index

The newly built Passive House school buildings have broadly employed a novel distributed renewable energy system for heating energy supply in Germany. This article proposed a distributed renewable energy system and investigated its performances (energy and thermal comfort) through numerical simulations in a school building. A new energy performance index has therefore been defined to evaluate this renewable energy system in the school. The energy system simulation (ESS) methodology and numerical models were validated by typical on-site measurements, including borehole outlet temperature and COP of heat pump. In addition, more numerical simulations relevant to energy performance of the proposed renewable energy system have been conducted based on the effects of the borehole outlet temperature and heat recovery efficiency. Several important findings can be achieved as follows. 1) Increasing the heat recovery efficiency of water-water heat exchanger facility would not only significantly improve COP, but also reduce obviously electricity use and energy costs. 2) A comparison, between the systems with heat recovery efficiency of 0.9 and without heat recovery, demonstrated the reduction of CO2 emissions up to 5.3 kg per typical winter day in Germany. 3) There is a significant correlation between the heat pump COP and the heat recovery efficiency. 4) In addition, most environmental measurements in the reference rooms in the school building fall in the comfort zone in winter, which indicates the heating energy supply based on this distributed renewable energy system could support a proper level of thermal comfort.