Research On Night Ventilation Cooling Technology Of Office Building In Beijing

With development of the energy and indoor environmental quality problems, building energy conservation and sustainable development has become the main direction of the construction industry. According to the Annual Report of China Building Convseration of 2009, the air conditioning load during high temperature summer has accounted for 30%to 50% of the total load of the residents. Reducing energy consumption of air condtioning refrigeration of public buildings in summer has become an important way of building energy efficiency for public institution in China. The night ventilation passive cooling technology using the outdoor environment of the cold air at night as a refrigerant intermediary to refrigerant the indoor air and the building envelop. In the daytime, the building envelope takes out the cooling capacity from the retaining structure and releases it into the room. Thus this tehchnology reduces the indoor air temperature, improves the confort level of indoor enviroment and reduces energy consumption of air conditioning system.This paper chooses the office building in Beijing area as the research object. We investigated architectural form, retaining structure, air conditioning system form and the operating mode. Based on the investigation, we also has summerized the type of government office buldings and operational characteristics in Beijing.According to the climate conditions of large diurnal temperature difference in Beijing. Firstly, a typical office building night ventilation model was built by DeST-C architecture simulation software. Secondly, the influence of the different effects of ventilation quantity, ventilation time, the structure of the retaining structure, the outdoor temperature and the different influence on the night ventilation were analyzed. At last, we presented the suitability and energy saving potential of the application of passive cooling technology in Beijing area. By using the method of net present value and the static payback period for economic evaluation.The results show that:1) When the average outdoor temperature is lower than 26℃, and the maximum temperature and minimum temperaturet difference is greater than 9℃, It is suitable to use passive cooling of the night ventilation technology in summer.2) When the night time ventilation air exchanges 6 times/h and the ventilation time is during from 0:00 am. to8:00 am., the technical economic benefit is the best. It can reduce 26% of air-conditioning cooling load and the overall energy saving rate reaches 9.2%.3) Night ventilation can reduce about 3～8℃ of the indoor temperature in summer. The temperature decrease is influenced by the outdoor mean temperature, the outdoor minimum temperature and the diurnal temperature difference.