Application Of Infrared Thermography In The Field Testing Of Dairy Barn’s Energy-saving Efficiency

Air tightness of dairy barn windows, heat-transfer coefficients of exterior walls, and thermodynamic disfigurement of exterior building envelopes were detected using infrared thermography at scene in order to understand the status of building’s energy-saving efficiency, and evaluate the thermal performance of exterior building envelopes. Results also contribute to give advice and guidance for designing dairy barns’ exterior building envelopes in terms of thermal performances, project acceptance, and future maintenance in cold areas.The status mentioned above was measured at two scale dairy farms.During measurements for air tightness of dairy barn windows, an appropriate window was selected to be shot. After a wide range of testing, suspicious leaking areas were found and shot additionally. The infrared shooting process included measuring meteorological conditions(air speed, air temperature, relative humidity, cloud covers, and precipitation). Meanwhile, photos of window’s visible-light images were taken to record partial bulges, cracks, weathering, and traces of maintenance. Using a professional software called Quick Report, contents including emissivity, distance, and radiation temperature were revised, and then the info of temperature was extracted and analyzed. Based on the temperature difference and its cause, the possibility of air leakage and leaking areas were diagnosed. Results showed that air infiltration through the gaps between casement windows and window frames were obvious for color-steel dairy barns of Wandashan dairyco., LTD.and air tightness of windows was worse. Same situation happened at brick-and-concrete dairy barns of Yuda animal husbandry co.,LTD. In contrast, air infiltration was negligible, and air tightness was better for color-steel dairy barns of Yuda animal husbandry co.,LTD.The average heat-transfer coefficient of dairy barn walls was calculated using convective heat-transfer coefficient. First, both inside and outside air temperature and outdoor air speed of dairy barns were measured, which led to the calculation of heat flux density of dairy barn walls. Then, infrared thermal images the dairy barn’s northern exterior walls were shot by using infrared thermal imager FLIR E30. Those clear, accurate, and fine thermograms were selected and thermal focusing process was conducted by Quick Report. Contents covering emissivity, distance, outdoor temperature, and environmental radiation temperature were revised to get the distribution of surface temperature and mean temperature difference. Finally, the average heat-transfer coefficient of dairy barns wall was figured out. It came out that using thermal infrared thermography, the maximum absolute error of the heat-transfer coefficient between detected data at dairy barns and theoretical calculation value was 14.5%, and the minimum absolute error 2.1%.When detecting thermodynamic disfigurement of exterior building envelopes, a wide range of detection of the whole exterior building envelopes was conducted before suspected parts were detected in detail. The influence of surrounding environment should be avoided while shooting. At least four thermal infrared images were supposed to be taken at the same position of exterior building envelopes. Visible-light images of specified positions should be shot and attached at the same time. Infrared testings revealed that exterior building envelopes of dairy barns were suffering from significant thermodynamic disfigurements. Those included unfulfilled plasters between brick-wall joints, uneven density of bricks, missing, cracking and hollowing of insulation boards, cold air leakage between roof and wall, and imprecise joints between insulation boards of roof.