Considering the perovskite-based building-integrated photovoltaics, we use the single box model of 4 × 4 × 3 m3 to illustrate a promising solution for the zero-energy residential building and the distributed power generators in the Wuhan urban area in China (N30° E114°), where we have the high ratio of façades on the tall buildings. According to our estimation, the energy gains from the solar cells on the façades could be competitive with the ones on the rooftops. In comparison with the perovskite/silicon tandem solar cells, the perovskite-based single-junction solar cells could boost the annual energy gains more than 1.5 times on the façades. It is because of the perovskite-based single-junction solar cells being less angle-dependent, even if their efficiencies under the vertical illumination are lower than that of the perovskite/silicon tandem solar cells. Within the same single box, the energy demands caused by the air-conditioning system are simulated by the program THERB with 100 and 65% solar irradiation; the previous one is the standard case, and the later one assumes that 35% of solar irradiation is converted to the electricity. To control the indoor temperature above 18°C in winter and below 26°C in summer, the single box could achieve zero-energy demand except for January and December. And the annual surplus photovoltaic energy gains of 3071 kW h could be used as the distributed generator for the resident downstairs.

The energy consumed in residential buildings has become a key factor in China. An energy-efficient and low-emission fuel cell co-generation system (FC-CGS) is a promising electric and thermal energy generation technology to enhance the energy-saving effects for residential application. SOFC-CGSs and PEFC-CGSs are the two major types of residential FC-CGSs. This paper aims to analyze the energy-saving effects of FC-CGSs for residential buildings in Chinese hot summer and cold winter areas. Changsha city is selected as an example. This study at first outlines SOFC-CGSs and PEFC-CGSs, introduces the simulation methods and develops a standard family model for simulation, then calculates domestic demands of the system, and finally compares the primary energy consumption and CO2 emissions of FC-CGSs with those of a traditional power and heat generation system based on gas and electricity. The results show that residential PEFC-CGSs offered primary energy reduction of 8.8% in winter. However, the average reductions of primary energy and CO2 emissions of SOFC-CGSs were 15.1% and 9.9%, respectively.

Taking a demonstration project of a ground source heat pump system under karst geological conditions in Guilin as the research object, based on the measured data under operating conditions in a typical season, and sorted according to the importance of influencing factors, this paper mainly studies the influence of system at very low load rate and unit load rate on the operation effect of ground source heat pump system. The research results show that the ground source heat pump system is in good operating condition when the system load rate is lower than 30.00% and the unit load rate is higher than 80.00% in typical seasons, and the proportion of power consumption of units and pumps meets the energy consumption requirements of transmission and distribution system. During the operation of the heat pump unit in July, the average refrigeration performance coefficient of the unit is 4.48, and the average refrigeration energy efficiency ratio of the system is 3.59; during the operation in January, the average heating performance coefficient of the unit is 4.26, and the average heating energy efficiency ratio of the system is 3.32; the energy saving rate in summer and winter is 30.72% and 35.93%, respectively. The energy-saving effect of the ground source heat pump system is remarkable, and it is worth popularizing and applying in Guilin.

：Taking the rural dwellings in the areas with rich solar energy in Zhongwei of Ningxia as a research example, through on-the-site survey and field-test, the paper analyzes the effects of space layout, the construction of envelope and the method of heating on winter indoor thermal environment. The results show that the solar energy resources are rich in local areas, nevertheless, the unreasonable space layout, simple construction of envelope as well as the lower solar energy utilization in existing dwellings have led poor winter indoor thermal environment. Based on the local natural conditions and climate characteristics, in consideration of full use of solar energy resources, the paper proposes the improvement of energy saving for the traditional dwellings, offers some references for the construction of local dwellings.