Comparison of moisture survey and u-values for a uk 220mm solid brick wall

Existing buildings form a major challenge for thermal upgrade because of individual idiosyncrasies. Estimations suggest some 20% of UK houses are of traditional 220mm solid brick construction and are therefore an important consideration for energy reduction. Although generic U-values are given in published data sets, the validity of these is being questioned because field tests suggest that actual construction gives a better performance, thus creating challenges for government initiatives where payback is dependent on energy savings. Conversely, U-values of existing walls may be increased, therefore worsened, due to moisture content. An eight-week period of moisture surveys and heat flux sensor testing of adjoining north-east and south-east facing 220mm solid brick walls of a small UK dwelling is presented. The aim is to add to the understanding of relationships between moisture readings and U-values, by comparing normal surveying moisture survey results and U-value measurements. The analyses show periods of saturation and patterns of initial drying. The measured U-values of the walls at different moisture readings are presented. Findings were that the U-values increased with above 20%wme moisture readings and with NE over SE orientation, but that they were generally lower than published.

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