Investigation And Optimization Strategies On The Energy Conservation Of Typical Rural Buildings In Southern And Northern Xinjiang

Southern and Northern Xinjiang Uygur Autonomous Region(hereinafter referred to as “Southern and Northern Xinjiang”)cross the severely cold and cold climatic zones,where the winter is long and cold and the summer is short and hot.For lack of scientific guidance during design and construction,there are a variety of problems facing rural residential buildings in Southern and Northern Xinjiang,such as high energy consumption,inefficient energy utilization and poor comfort.Therefore,it is noteworthy to improve the indoor thermal environment quality of rural residential buildings in Southern and Northern Xinjiang while giving consideration to building energy conservation based on local climatic features.In this study,in-situ investigation on the typical rural residential buildings in Southern and Northern Xinjiang is carried out.Based on the knowledge of spatial distribution,the building envelope materials and the indoor thermal environments in summer and winter of typical rural residential buildings,as well as the living habits of local residents,the heat transfer coefficients of the typical walls of the residential buildings in Southern and Northern Xinjiang are determined.Preliminary analysis of the problems in construction and the thermal performance of rural residential buildings is made.Residents’ satisfaction with current residential buildings and their awareness of building energy conservation are also investigated.e QUEST is used to make optimization analysis of the building envelopes of typical residential buildings.In addition,the optimization effects of different envelopes are analyzed using the control variable method,based on which the energy-saving scheme is obtained and the energy-saving strategies appropriate for the residential buildings in Southern and Northern Xinjiang are put forward.To sum up,the following research findings have been achieved:(1)The residences in Southern and Northern Xinjiang are mostly single-story buildings,8% of which are east-west oriented and 92% of which are facing south.They appear with the mud-brick structure,the brick-wood structure or the brick-concrete structure.No isolation measures are taken on building walls.According to measurement,the heat transfer coefficient of the external walls of rural residential buildings range between 1.519 and 1.602 in Northern Xinjiang and between 1.076 and 1.602 in Southern Xinjiang;neither has satisfied the criterion of energy conservation.Serious thermal loss can be seen at some residential buildings due to the use of wooden windows with single-layer glass.Plastic films with poor corrosion resistance usually serve as the waterproof layer on the roof.In addition,heat insulation and dampproof measures are not adopted on the floor.(2)In winter,the room temperature and the humidity in the mud-brick residential buildings in Northern Xinjiang are-2.29℃ and 42.22% on average,respectively;these figures are 1.77℃ and 32.35%in Southern Xinjiang.It indicates that neither room temperature nor humidity in Southern and Northern Xinjiang has reached the standard level for winter.In summer,the room temperature and the humidity in the mud-brick residential buildings in Northern Xinjiang are 26.6℃ and 51.39% on average,respectively;these figures are 27.13 ℃ and 44.83% in Southern Xinjiang.It shows that both room temperature and humidity in Southern and Northern Xinjiang have reached the standard level for summer.(3)According to the e QUEST-based optimization analysis of the envelopes of the rural residential buildings in Southern and Northern Xinjiang,the energy-saving potential of external windows is only about0.2% in the cooling season in summer and about 0.3% in the heating season in winter.In other words,current external windows perform poorly in energy conservation.Adding a heat insulating layer to the external wall creates larger energy-saving potential than perforated bricks,which can improve the energy-saving potential to 1-7.5% in the cooling season in summer and 7-24% in the heating season in winter.To put it another way,the heat insulating layer brings about desirable energy-saving effect in both cooling and heating seasons.With roof optimization,the energy-saving potential can reach 5-16% in the cooling season in summer and 2-15% in the heating season in winter,implying that roof optimization is an effective way to enhance energy-saving effect.Moreover,floor optimization shows smaller energy-saving potential than external wall and roof optimization.(4)With the benefits and cost of energy conservation taken into overall account,the most suitable renovation scheme for Southern and Northern Xinjiang can be summarized as: external wall: 20mm-thick mortar + 370mm-thick perforated clay bricks + 20mm-thick mortar;roof: 10mm-thick mortar +50mm-thick polystyrene board + 10 mm mortar;floor: 200 mm ± +40mm-thick clay bricks;external window: double-layer wooden window.(5)It is advisable to build south-facing residential buildings and appropriately increase the south-facing window-wall ratio to make full use of the radiant heat of the sun in Southern and Northern Xinjiang.Due to the difference in climatic feature,the energy-saving strategies for the residential buildings in both regions also differ from each other.In Northern Xinjiang,it is better to use plastic steel windows with triplex insulating glass in the south-facing walls and plastic steel windows with double insulating glass in the north-facing walls.Polystyrene boards can serve as the heat insulating layer on the roof and the external wall.But it is also recommended to use the thermal storage wall that is able to collect energy in the daytime and reduce heat loss at night.As for Southern Xinjiang,the heat-taking windows should be built using insulating glass with excellent heat retention performance.Either polystyrene boards or the elevated overhead roof can be taken as the heat insulating measure for the roof.In particular,the south-facing window-wall ratio should be kept lower than 0.5 in both regions.