Comprehensive energy efficiency study of different climate -adapted BIPV roof forms in single-family houses for five climate zones of China based on PV energy substitution rates (PVESR)

Abstract As a type of energy production construction, building integrated photovoltaics (BIPV) roofs are contributing for achieving NZEB goals. Considering building sites’ climate attributes with possible size of PV systems can help to reduce the initial investment and energy consumption of building operation and maintenance. This paper investigates the energy production and energy consumption patterns of single-family houses, which is designed to evaluate the comprehensive energy efficiency of BIPV roofs to meet energy demands by photovoltaic energy substitution ratio (PVESR) calculations. Five typical cities were selected, corresponding to the five climate zones in China; eight forms of BIPV roofs were developed according to single-family houses’ common scale and spatial characteristics. The results show that (1) The PVESR varies significantly between different climate zones and different forms of BIPV roofs, so pre-survey of BIPV roof application sites and comparison of roof forms are relevant in preliminary architecture design. The climate zones where energy balance can be achieved are hot-summer & warm-winter zones, hot-summer & cold-winter zones and moderate zones, and the average PVESR based on the eight roof prototypes are 0.987, 1.136 and 2.272 respectively; the corresponding PVESR for cold zones and severe cold zones are 0.807 and 0.475. (2) The peak and trough values of capacity and energy use are not exactly matching in the five climate zones, especially in severe cold zones, cold zones and hot-summer & cold-winter zones’ winter. (3) The high heating demand in winter is the main reason for the failure to balance BIPV production and energy consumption in severe cold zones and cold zones. The comprehensive energy efficiency evaluation method of BIPV roofs proposed in this paper can provide data support and application guidance for form design and size determination of BIPV roofs in five climate zones in China.