The climate of Yangtze River Basin in China is cold and humid in winter. Conventional air-conditioning systems may cause high energy consumption and uncomfortable microclimatic conditions especially for lower body of indoor occupants. This study investigated four personalized seat heating systems, in a typical office room in Shanghai during winter, based on heated floor panels including heated floor panels + ordinary chair (HF-OC), heated floor panels + insulated chair (HF-IC), heated floor panels +insulated chair and leg box (HF-IC-LB) and overall personalized heating (OPH). The surface temperature of walls and heated floor panels, and the indoor air temperature at different positions were recorded with thermocouples. The hourly energy consumptions of the proposed personalized seat heating systems were measured and compared with a conventional split type air conditioner. Questionnaires of thermal sensation and comfort were carried out among 10 university students. Compared with HF-OC, HF-IC could improve the thermal comfort to a certain extent, while HF-IC-LB provided the optimal thermal micro-environment for the lower body other than other body parts. The OPH systems were proven effective to provide satisfactory thermal environment for all body parts at lower indoor temperature (12–16°C) with much less energy consumption than room air conditioners.
3 February 2021 in Journal of Solar Energy Engineering
A building-integrated photovoltaic-thermal (BIPVT) system integrates building envelope and photovoltaic-thermal collectors to produce electricity and heat. In this paper, the electrical and thermal performance of roof-based BIPVT systems developed in the recent two decades and their effects on heating and cooling load of the building are reviewed. According to the use of thermal energy from the photovoltaic (PV) panels, the roof-based BIPVT are classified into three classes: cooling of PV, air heating, and water heating. Each class is further divided into several types according to the designs of the integrated PV roofs. Compared with BIPV systems, the total efficiency of most BIPVT systems is significantly improved. However, the decrease in electricity output and adverse impact on the indoor environment is also found for some designs of BIPVT systems in some climates. The advantages and disadvantages of various designs are discussed. Issues to be further studied in the future are also provided in this review.
Photovoltaic (PV) cells integrated with building roof skylights not only generate electricity but also influence the thermal performance of the roof. In this paper, the thermal mathematical model of a semi-transparent photovoltaic insulating glass unit (STPV-IGU) integrated with the roof is established and validated by experiments. Case studies are conducted by using the roof-integrated STPV-IGU in Shanghai, and an equivalent electrical method is used to evaluate the energy performance of roof-integrated skylight STPV-IGU. The equivalent electricity of heat-gain entering the room through STPV-IGU and total equivalent electricity of roof-integrated STPV-IGU is 16.6 kWh/m2 and 12.1 kWh/m2 in summer, respectively. The equivalent electricity of heat-gain entering the room through STPV-IGU and total equivalent electricity of roof-integrated STPV-IGU are −16.3 kWh/m2 and −4.0 kWh/m2 in winter, respectively. Compared with traditional insulating glass unit, the STPV-IGU can significantly reduce the heat-gains through glazing in summer, but increase indoor heat-loss in winter.