Variations in the U-Value measurement of a whole dwelling using infrared thermography under controlled conditions

Marshall, AS, Francou, JY, Fitton, R ORCID:, Swan, WC, Owen, JO and Benjaber, MAA 2018, 'Variations in the U-Value measurement of a whole dwelling using infrared thermography under controlled conditions' , Buildings, 8 (46) , pp. 1-17.

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U-values of building elements are often determined using point measurements, where infrared imagery may be used to identify a suitable location for these measurements. Current methods identify that surface areas exhibiting a homogeneous temperature—away from regions of thermal bridging—can be used to obtain U-values. In doing so, however, the resulting U-value is assumed to represent that entire building element, contrary to the information given by the initial infrared inspection. This can be problematic when applying these measured U-values to models for predicting energy performance. Three techniques have been used to measure the U-values of external building elements of a full-scale replica of a pre-1920s U.K. home under controlled conditions: point measurements, using heat flux meters, and two variations of infrared thermography at high and low resolutions. U-values determined from each technique were used to calibrate a model of that building and predictions of the heat transfer coefficient, annual energy consumption, and fuel cost were made. Point measurements and low-resolution infrared thermography were found to represent a relatively small proportion of the overall U-value distribution. By propagating the variation of U-values found using high-resolution thermography, the predicted heat transfer coefficient (HTC) was found to vary between 183 W/K to 235 W/K (±12%). This also led to subsequent variations in the predictions for annual energy consumption for heating (between 4923 kWh and 5481 kWh, ±11%); and in the predicted cost of that energy consumption (between £227 and £281, ±24%). This variation is indicative of the sensitivity of energy simulations to sensor placement when carrying out point measurements for U-values. View Full-Text

Item Type: Article
Schools: Schools > School of the Built Environment
Journal or Publication Title: Buildings
Publisher: MDPI
ISSN: 2075-5309
Related URLs:
Depositing User: AS Marshall
Date Deposited: 19 Mar 2018 15:31
Last Modified: 15 Feb 2022 23:01

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