Study On Indoor Thermal Environment And Energy Consumption By Night Ventilation Of Residential Buildings In Xi’an

With the development of society and the improvement of people’s living standards,people’s awareness of energy conservation and the demand for thermal comfort are increasing.Night ventilation as a passive building energy-saving technology can not only improve the indoor thermal environment,but also effectively reduce building energy consumption.Therefore,it is of great significance to study the influence of different factors on the nighttime ventilation energy-saving and cooling effect,and to select suitable parameters for the promotion and application of night ventilation technology.In this paper,the combination of experiment and numerical simulation is used to study the effects of different factors on the indoor thermal environment and energy consumption of residential buildings in Xi’an.The experiment mainly tests the indoor ventilation indoor parameters and compares them with the numerical simulation results to ensure the accuracy of the building model and simulation method.The numerical simulation is to explore the nighttime ventilation indoor thermal environment and the trend of energy consumption by changing the parameters affecting night ventilation.The main research contents and conclusions include three aspects:First,the outdoor meteorological data during the experiment is fitted to obtain the sine function expression of the outdoor air temperature.Then,by changing the parameters in the equation,the hourly variation data of the outdoor air temperature under different day conditions are obtained,and finally the numerical simulation is performed.The results show that the indoor temperature of night ventilation decreases with the increase of daily range.When the daily range is increased from 2°C to 14°C,night ventilation can reduce the indoor average temperature of typical meteorological day by 1.42°C,and the mean radiation temperature is the largest reduced by 0.88°C.The energy saving of night ventilation increases with the increase of the daily range.When the daily range is14°C,the nighttime ventilation can reduce the building energy consumption by 46.11%.The maximum energy saving is 4.45kWh/d,saving the air conditioning operating cost index is 0.070 yuan/(m~2·d).Secondly,through the analysis of typical annual meteorological data in Xi’an,three typical meteorological days are selected as representative days,then the nighttime ventilation amount sent into the room during numerical simulation is changed,and finally the energy-saving and cooling effect of night ventilation under different ventilation conditions is selected.The results show that the indoor temperature of residential buildings decreases with the increase of night ventilation.When the number of air changes is 25 ACH,night ventilation can reduce the indoor average air temperature of typical weather days by 2.05°C and the mean radiation temperature by 1.09°C.Under different ventilation conditions,night ventilation can reduce building energy consumption by 28.63%,the maximum energy saving is 2.41kWh/d,and the air-conditioning operating cost index is 0.038 yuan/(m~2·d).Thirdly,by changing the materials of the building envelope structure,the heat storage coefficient and heat transfer coefficient are changed,and then the building models of different envelope structures are numerically simulated.Finally,the energy-saving and cooling effects of night ventilation under different envelope structures are carried out.The results show that the maximum envelope temperature can reduce the indoor air temperature peak of the typical weather day by 0.94°C and the mean radiation temperature peak by 1.05°C.At the same time,the use of heavy enclosure structure can reduce building energy consumption by up to 22.90%,the maximum energy saving is0.92kWh/d,and the air-conditioning operating cost index is 0.015 yuan/(m~2·d).Through the analysis and research in this paper,it can provide a theoretical basis for the promotion and application of night ventilation technology in residential buildings in Xi’an,the effective and balanced realization of indoor thermal comfort and building energy conservation.