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Cooling energy consumption of buildings is not only used for decreasing temperature, but for dehumidification. Therefore, cooling degree day (CDD) based on only temperature is insufficient for estimating the cooling energy consumption in buildings. In the present study, we aim to propose an efficient climate index (i.e., CDD based on wet bulb temperature [WBT], WCDD) based on the combination of cooling energy consumption in a building and joint probability of temperature and humidity. In addition, the adaptation of the new WCDD was verified in 14 cities of different climate zones in China. The results showed that CDD based on dry bulb temperature (DBT) (DCDD) can only explain 17%–60% of cooling energy consumption, whereas WCDD explaining 86%–97% of cooling energy consumption in the different climate zones. The optimal base WBTs are generally 17.74, 19.44, 21.04 and 22.56°C for the four climate zones, respectively. The present study reveals that WCDD by combining effects of temperature and humidity on cooling energy consumption can be much more efficiently used to estimate the cooling energy consumption compared with DCDD. More importantly, the WCDD is suitable for reflecting the cooling energy consumption for different climate zones. The collaborative changes of temperature and humidity under the conditions of climate change should be fully considered to take measures for decreasing the energy consumption for decreasing temperature and dehumidification. [ABSTRACT FROM AUTHOR]

Previous studies revealed that building climatic zoning has largely changed in China due to the influence of climate change. However, the possible impacts of changing building climatic zoning on energy consumption for cooling or heating are not clear. In this study, eight representative cities were selected from changed climate zones, and the heating and cooling energy consumption of office and residential buildings of the representative cities under the conditions of the current and new climate zones was simulated to reveal the effect of the climate zone change on building energy consumption. The results showed that there was no heating or cooling energy consumption with the climates changing from hot summer and cold winter (HSCW) and cold (C) to mild (M). Also, no heating energy consumption occurred with the climate zones changing from HSCM to hot summer and warm winter (HSWW), whereas the cooling energy consumption showed a weak decrease. For the climate zones that shifted from severe cold (SC) to C, decreasing heating energy consumption and increasing cooling energy consumption trends were observed, and the total energy use exhibited a decreasing trend. However, in the climate zones changing from C to HSCW, the heating and cooling energy consumption increased, especially for residential buildings (e.g., the heating energy consumption of Zhengzhou and Baoji increased 78.7% and 77.7%, respectively). This study suggests that new climate zones should be fully considered and the new design standard according to the changes of climate zones should be adopted to improve building energy efficiency. The design of residential buildings in the climate zones changing from C to HSCW may not consider the changes of climate zone. [ABSTRACT FROM AUTHOR]

In this paper, 16 cities representing four major architectural climate zones of China were selected, and the heating and cooling loads of office building during the period of 1961–2017 were simulated by using TRNSYS software. Daily extreme heating and cooling loads were determined by percentile methods, and the climate change impact on extreme loads was analyzed. The results showed that the days of extreme heating load of office building significantly decreased in almost all the selected cities, whereas there were no significant changes in the days of extreme cooling load. The daily extreme heating load was dominantly affected by the temperature (R2 = 0.43–0.79), but the daily extreme cooling load was related to multiple climate factors, including temperature, relative humidity, and solar radiation. Single temperature can only explain 3–37% of the changes of daily extreme cooling load, and the combination of multiple climate factors can explain 58–85%. Importantly, the effect of temperature on extreme cooling load showed decrease from the cold to hot climate zones, but the impacts of relative humidity and solar radiation gradually increased. These results suggest that the maximum design capacity of heating systems can properly decrease, and the design capacity of cooling systems may not largely increase with the climate warming. In addition, the combined effect of multiple climate factors rather than the single temperature, as well as the different responses of extreme cooling energy consumption to climate change in different climate zones, should be considered when making measures for improving operating efficiency of air-conditioning system. [ABSTRACT FROM AUTHOR]

Meteorological parameters are the basis for building energy-saving design and operation of Heating, Ventilation and Air Conditioning systems (HVAC). In this study, changes in meteorological parameters of Harbin, Tianjin, Kunming, Shanghai, and Guangzhou, representing the five major climate zones of China, were analyzed to determine the effects of climate change on meteorological parameters. The results demonstrated that outdoor design temperatures for heating or air-conditioning significantly increased in all five climate zones. The increasing rate of design temperatures for both heating and air-conditioning in winter were in the range of 0.2 °C–0.7 °C/decade, and the rate of design temperature for air-conditioning in summer was in the range of 0.1 °C–0.4 °C/decade. The design load was calculated by outdoor design temperature. Compared with the design load during 1961–1990, the heating design load decreased 2.8% and 4.4% in Harbin and Tianjin during 1981–2010, respectively. The design load for air-conditioning in winter decreased 1.7%, 1.4%, 2.4% and 3.2% in Harbin, Tianjin, Shanghai and Guangzhou, respectively. By contrast, design load for air-conditioning in summer during 1981–2010 increased 0.8%, 1.1%, 2.9% and 2.2% in Harbin, Tianjin, Shanghai and Guangzhou, respectively. On average, the effect of climate change on design loads is more intense in winter than summer, which may be beneficial for building energy-saving design. The results in this study suggest that climate change has evident effects on design meteorological parameters and design load. It is necessary to note that responses of design meteorological parameters to climate change are apparently different in five climate zones. Hence, different design strategies for building energy-saving should be considered appropriately according to different climate change characteristics in different climate zones. [ABSTRACT FROM AUTHOR]

Exploring changes of building energy consumption and its relationships with climate can provide basis for energy-saving and carbon emission reduction. Heating and cooling energy consumption of different types of buildings during 1981-2010 in Tianjin city, was simulated by using TRNSYS software. Daily or hourly extreme energy consumption was determined by percentile methods, and the climate impact on extreme energy consumption was analyzed. The results showed that days of extreme heating consumption showed apparent decrease during the recent 30 years for residential and large venue buildings, whereas days of extreme cooling consumption increased in large venue building. No significant variations were found for the days of extreme energy consumption for commercial building, although a decreasing trend in extreme heating energy consumption. Daily extreme energy consumption for large venue building had no relationship with climate parameters, whereas extreme energy consumption for commercial and residential buildings was related to various climate parameters. Further multiple regression analysis suggested heating energy consumption for commercial building was affected by maximum temperature, dry bulb temperature, solar radiation and minimum temperature, which together can explain 71.5 % of the variation of the daily extreme heating energy consumption. The daily extreme cooling energy consumption for commercial building was only related to the wet bulb temperature (R2= 0.382). The daily extreme heating energy consumption for residential building was affected by 4 climate parameters, but the dry bulb temperature had the main impact. The impacts of climate on hourly extreme heating energy consumption has a 1-3 hour delay in all three types of buildings, but no delay was found in the impacts of climate on hourly extreme cooling energy consumption for the selected buildings. [ABSTRACT FROM AUTHOR]

As an important component of building energy consumption, wall heat loss needs to be studied urgently. Wall implanted with heat pipes (WIHP) is one of the latest research hotspots in this field. Firstly, the internal temperature distribution characteristics of WIHP are studied by numerical simulation in this paper. Secondly, the thermal conversion efficiency is proposed to evaluate the utilization of solar energy by WIHP. Finally, the energy saving potential of WIHP in heating season is analyzed. The results show that: (1) WIHP has a significant anisotropic heat transfer characteristic compared with the conventional wall; the average time lag of the inside surface is reduced by 2.3 h, and the average decrement factor is increased by 0.008. (2) The time lag difference between the upper and lower parts of WIHP is 6 h, and the time lag of the WIHP structural layer is increased by 1 h compared with the conventional wall. (3) The heat transfer of heat pipe increases with the increase of solar radiation, but the thermal conversion efficiency decreases. (4) WIHP can decrease the heat loss of the wall by 56% on average, and the cumulative heat loss is reduced by 5.29 kWh/m2. • WIHP has a significant anisotropic heat transfer characteristic. • The thermal conversion efficiency as a new evaluation indicator is proposed. • The thermal conversion efficiency of WIHP decreases with the increase of solar radiation. • The time lag of WIHP inside surface is reduced by 2.3 h. [ABSTRACT FROM AUTHOR]