Study On Exterior Wall Reconstruction Of Existing Public Building In Severe Cold Areas

Exterior wall is the largest part of the heat loss in the envelope structure,both existing energy-saving renovation of public buildings is mainly to transform the external wall.Based on the survey area of Harbin and Yichun in the severe cold areas,this paper divided the investigation area into each city,and investigated the external appearance of the typical buildings by objective interview and on-the-spot test(including the wall structure forms,thermal performance,weatherability,sound insulation,indoor thermal comfort).On the basis of this,theoretical research is conducted on the existing insulation materials and structural forms used in the external wall modification,thus the ways of reforming the external wall of the existing public buildings are proposed.And the use of computer numerical simulation methods for different ways to transform energy-saving performance,economic performance,weathering performance and sound insulation performance analysis,the best way to transform.Finally,the conclusions of the study are used to carry out energy-saving retrofit on a specific public building and track the thermal performance of the external wall.The results show that:(1)The contribution rate of energy conservation is positive when the thermal insulating layer is added on the external wall,and the contribution rate of building energy saving gradually increases with the increase of the thermal insulation layer thickness,and the increase rate of the energy saving increases from large to small.Combined with the cost of operation and maintenance,the optimum thickness of different insulation materials is 90 mm for EPS,75 mm for XPS,50 mm for PUR and 65 mm for PUR.(2)With the increase of the thickness of insulation layer,the temperature of the inner surface of the insulation layer gradually increases,and the increase rate decreases from large to small.At the same time,it is found that as the thickness of thermal insulation layer increases,the temperature stress on the inner and outer surfaces of bond mortar gradually decreases,and the decreasing range decreases from large to small.(3)The increase of insulation thickness has little effect on the sound insulation performance,however,as compared with the external wall without thermal insulation system,the amount of sound insulation has been increased after adding the thermal insulation layer.