Matthew D. Baffa
Assessing Overall Thermal Conductance Value of LowRise Residential Home Exterior AboveGrade Walls Using Infrared Thermography Methods
626 - 636
2018
12
6
International Journal of Civil and Environmental Engineering
https://publications.waset.org/pdf/10009118
https://publications.waset.org/vol/138
World Academy of Science, Engineering and Technology
Infrared thermography is a nondestructive test method used to estimate surface temperatures based on the amount of electromagnetic energy radiated by building envelope components. These surface temperatures are indicators of various qualitative building envelope deficiencies such as locations and extent of heat loss, thermal bridging, damaged or missing thermal insulation, air leakage, and moisture presence in roof, floor, and wall assemblies. Although infrared thermography is commonly used for qualitative deficiency detection in buildings, this study assesses its use as a quantitative method to estimate the overall thermal conductance value (Uvalue) of the exterior abovegrade walls of a study home. The overall Uvalue of exterior abovegrade walls in a home provides useful insight into the energy consumption and thermal comfort of a home. Three methodologies from the literature were employed to estimate the overall Uvalue by equating conductive heat loss through the exterior abovegrade walls to the sum of convective and radiant heat losses of the walls. Outdoor infrared thermography field measurements of the exterior abovegrade wall surface and reflective temperatures and emissivity values for various components of the exterior abovegrade wall assemblies were carried out during winter months at the study home using a basic thermal imager device. The overall Uvalues estimated from each methodology from the literature using the recorded field measurements were compared to the nominal exterior abovegrade wall overall Uvalue calculated from materials and dimensions detailed in architectural drawings of the study home. The nominal overall Uvalue was validated through calendarization and weather normalization of utility bills for the study home as well as various estimated heat loss quantities from a HOT2000 computer model of the study home and other methods. Under ideal environmental conditions, the estimated overall Uvalues deviated from the nominal overall Uvalue between ±2 to ±33. This study suggests infrared thermography can estimate the overall Uvalue of exterior abovegrade walls in lowrise residential homes with a fair amount of accuracy.
Open Science Index 138, 2018