Investigations On Indoor Thermal Environment In Summer And Energy Saving Potentiality In Natural Ventilating Buildings In China

The energy from ambient atmospheric environment can be used for cooling or heating room air and keeping indoor air freshen in natural ventilating (NV) buildings, and high level comfortable indoor thermal environments in such buildings can be get without additional energy by using some proper control. The ACS (the adaptive comfort standard) is a new adaptive thermal comfort standard received in the reversion of ASHRAE standard 55, and there were no standard about indoor thermal environment for NV buildings before the ACS been promulgated. If the ACS is applied to a mixed-mode (NV+HVAC) building, the air-conditioner might be used in a limited way to keep more extreme temperatures from rising past the acceptability limits of ACS. There are the large differences between set point temperatures by upper limits of ACS and ASHRAE Standard 55, and therefore, the potential energy savings that might result. In the present study, the ACS is employed to obtain the energy saving potentials in the typical cities in China by using the tested data of indoor thermal environment and the change of enthalpy of indoor air.In the present study, indoor air temperature and relative humidity in NV buildings in Datong, Xian, Shanghai and Guangzhou cities, and outdoor air temperature and relative humidity in Shanghai and Datong cities were monitored continuously in summer, and the indoor thermal environment in the four cities were analyzed and estimated by employing ACS. The results show that for the indoor thermal environment, the rates of accumulative hours that 80% people satisfying are about 95% in Datong, 82.8% in Xian, 64.4% in Shanghai and 52.6% in Guangzhou, respectively. More energy is required in Shanghai and Guangzhou for keeping a suitable thermal comfort.Some of cooling Energy could potentially be save if an air-conditioner need not to maintain conditions within the more narrow ASHRAE Standard 55 comfort zone, and the energy savings would be proportional to the difference between set-points defined by the upper limit of the ACS, compared to typical set-points used in an air-conditioned buidlings. The energy potential of ACS in typical cities of China is higher than 49%. From the estimation of the present study, the value is about 60% or so in Shanghai, Datong and Xian, but in Guangzhou, which the value is relative low, remains at a level about 49.0%. Assuming that people have direct control of the operable windows, and are also free to adapt their clothing, it is concluded that the large potential for saving energy by using natural ventilation instead of air- conditioning in many residential and commercial buildings. For unit mass of air, the savings of enthalpy changes are 6538 kJ/kg, 16714 kJ/kg, 29991 kJ/kg and 35192 kJ/kg in Datong, Xi'an, Shanghai and Guangzhou, respectively. These results indicate that it has more energy potential in the hot climate zone with the application of the ACS.