Measurement And Energy Impact Of Airtightness Of Exterior Windows In A Dwelling House In Changsha

With the rapid development of China’s economy,building energy consumption has continued to increase.How to reduce building energy consumption has become one of the hot spots in the field of building technology.Building air tightness has a strong correlation with energy consumption.Improving building air tightness has a significant impact on reducing building energy consumption.Most of the researches on air tightness in China focus on buildings in the north,and relatively little attention is paid to the buildings in hot summer and cold winter areas,and the study on air tightness of buildings in this area cannot be ignored.This article takes a typical two-bedroom and one-living house in Changsha as the research object.First,the airtightness test about the exterior windows of the room and the analysis of the influencing factors were carried out.The test was conducted from December 13 to 14 th,2019.Tracer gas method was used to different rooms to perform five times simultaneously during the test.The airtightness test of the exterior windows was based on the carbon dioxide monitoring data and the parameters of each room to calculate the air permeation amount per unit infiltration length.The airtightness differences in different rooms and different test periods were compared and analyzed.The results show that the difference about exterior windows in air penetration amount per unit of permeation length of different orientation rooms in the same period is greater than that of the same orientation room,where the different orientation rooms are not only affected by the orientation and position differences,but also The external temperature difference will also have a significant impact;the air penetration of the same permeation length of the room towards the room varies depending on the position of the window,but the difference is small.Further analysis shows that the air permeability per unit length of exterior windows in the same room in different periods is also significantly different.During winter in Changsha,within a certain range of indoor and outdoor parameters,When based on the same wind direction,the northwest wind direction,for the north-south room,the air penetration per unit length is affected by the outdoor wind speed and the indoor and outdoor temperature difference,both related to the quadratic outdoor wind speed,but the difference is that the north-facing room and the temperature difference There is a positive relationship,especially when the wind speed is small,the effect of indoor and outdoor temperature difference is significant;the southward room has an inverse relationship with the indoor and outdoor temperature difference,and the heat pressure and wind pressure function are opposite,which has a certain inhibitory effect on the southward room air penetration.In order to further understand the impact of the air penetration of the exterior windows of the house on the load during the test period,based on the test data,the Design Builder software was used to simulate the energy consumption of the house.Through analysis,it was found that although the time and meteorological parameters of the test stage are limited,the cold air infiltration load of the room and the difference is small,but the impact of air penetration on the long-term energy consumption of the house cannot be ignored.According to the result of a single-family house exterior window generating 254.8Wh cold wind infiltration load a day,if inferred from this,100 houses will generate 1930 k Wh cold wind infiltration load throughout the heating season.In actual conditions,the outdoor temperature during most of the heating season will be much lower than during the actual measurement period,and the cold air penetration load and the difference in the room will be more obvious,so the load caused by air penetration cannot be ignored.Finally,according to the classification index of airtightness of exterior doors and windows of buildings from level 1 to level 8 of "Airtightness,Watertightness,and Wind Pressure Resistance Diversity and Test Methods of Exterior Doors and Windows of Buildings",the residential energy performance about airtightness changes of exterior windows during the whole year was simulated.The results show that: in different period of the whole year,in this area the cumulative load of the house and each room decreases with the increase of the airtightness level of the exterior window.Among them: The impact of the cooling season load affected by the airtight is greater than the heating season and the transition season.When the exterior window airtightness level is increased from level 1 to level 8,the cumulative load reduction ratio during the cooling season reaches 25.9%;and when each airtightness level is increased,the average cumulative load reduction ratio during the cooling season was4.2%.In addition,the load of the south-facing room is more affected by air tightness than that of the north-facing room.When the airtightness level of the exterior window is increased from 1 to 8,the average annual cumulative load reduction ratio of the south-facing room reaches 32.8%.Therefore,although the change of the airtightness of the exterior windows has different effects on the cumulative load of the rooms in different periods and in different directions,for the residences in this area,improving the airtightness of the exterior windows of the rooms and reducing the external air penetration will help reduce the building energy consumption,and bring energy-saving benefits obviously.