Local thermal comfort-based optimal design of attached sunspace with breathing window for farmhouses in North China

Passive building with solar energy absorption for winter heating is an effective way to reduce building heating energy consumption. In order to solve the problems of uneven indoor temperature distribution and poor thermal comfort that exist in traditional attached sunspace heating, the Attached Sunspace with Breathing Window (ASBW) is studied in this paper. A field investigation and numerical simulation have been conducted on a farmhouse in North China to monitor the variation of indoor temperature. On this basis, three more contemporary ASBW design schemes are proposed, and the characteristics and benefits of the Attached Sunspace with Breathing Window are further studied. The Percentage Dissatisfied (PD) is selected as the index of indoor local thermal comfort to evaluate the performance of the ASBW. The results show that the indoor temperature in the vertical direction increase with the height, with the high-temperature region exceeding 23 °C and the low-temperature region only about 18 °C on sunny days. Simulation analysis of the three schemes revealed that the Bottom outlet scheme and the Top inlet scheme possess better local thermal comfort. The maximum average indoor temperature of both schemes is around 23 °C, and the vertical indoor temperature PD index is significantly reduced to the lowest average value of only about 8% compared to the original design with a single-window of 23.6%. The Bottom outlet scheme and the Top inlet scheme are recommended for the newly-built and existing buildings, respectively.