Research And Analysis On Thermal Resistance Detection Of Buliding Envelope Insulation Based On Infrared Thermal Imaging

Building insulation systems are an important component of building envelope structures.The evaluation of building insulation performance is a favorable link for the construction industry to achieve "carbon reduction",and thermal resistance is a key factor affecting the thermal properties of buildings.It is an important parameter for evaluating whether buildings meet energy-saving standards and can intuitively reflect the insulation performance of building envelope structures.This article takes the insulation system of low rise public buildings in severe cold areas as the research object.Based on the advantages of infrared thermal imaging technology,the feasibility of using infrared thermal imaging technology to detect the thermal resistance of building envelope insulation performance is studied,and the changes in surface temperature and thermal resistance of insulation layer defects in actual engineering buildings are analyzed.Firstly,this article provides a detailed introduction to the basic theory of infrared thermal imaging technology,analyzing the impact of factors such as object surface characteristics,self-performance,and changes in detection environment on infrared thermal imaging technology in actual detection processes.By introducing the basic theory of traditional thermal resistance detection for envelope structures,analyzing the thermal resistance detection theory of infrared thermal imaging technology,proposing a thermal resistance detection method based on infrared thermal imaging technology and establishing relevant thermal balance equations,providing a theoretical basis for subsequent research.Secondly,on-site testing was conducted on the external insulation system and selfinsulation system of low rise public buildings in severe cold areas.The feasibility of thermal resistance detection of building envelope structures using infrared thermal imaging technology was analyzed through comparison and verification of hot box method and infrared thermal imaging technology.Research has shown that the average thermal resistance of the external insulation system tested by the hot box method is 2.56m2 · K/W,while the average thermal resistance of the self insulation system is 2.574m2 · K/W.Comparing and analyzing the detection results of infrared thermal imaging technology with the average thermal resistance value calculated by the hot box method,the average error of on-site detection experiments for building external insulation systems is 4.1%,and the average error of on-site detection experiments for building self-insulation systems is 8.6%.The experimental results indicate that when the indoor and outdoor temperature difference is 20 ℃,infrared thermal imaging technology has higher accuracy in detecting the thermal resistance value of building insulation systems.Finally,due to changes in outdoor environmental factors,the weak bonding of the building insulation layer can lead to insulation defects,which can have a negative impact on the insulation performance of the building envelope structure.Therefore,the thermal insulation defects of building external insulation systems in actual engineering are analyzed,and the surface temperature difference changes of different defect sizes,areas,and environmental factors are studied through simulation and actual engineering testing.The thermal resistance changes at the defect location are also analyzed.Research has shown that defect size,thickness,and environmental temperature all have an impact on the temperature and thermal resistance of the defect area,and the temperature of the defect area shows an upward trend with the increase of defect size;The thickness of defects shows a linear trend with surface temperature,and the surface temperature of defects increases with the increase of thickness;When the temperature difference between indoor and outdoor environments increases,the high temperature abnormal area at the defect location becomes more obvious.When the temperature difference between indoor and outdoor is 20 ℃,the thermal resistance of insulation layer defects in actual engineering buildings is analyzed.The experimental results show that the thermal resistance of the defect area is significantly lower than that of a normal insulation system,and the impact of increasing defect size and thickness on building insulation performance increases accordingly.