How heat escapes the wall

greenTEG:  A new article presents the results of a recent study commissioned by the Swiss Federal Office of Energy about the assessment of the insulation quality of buildings.

The heat transfer coefficient (U-value) is a key parameter for planners and builders. Recommendations for renovations proposed by energy consultants are often based on this value. Thanks to a novel method, the U-value of a wall, a roof or a window front can now be determined with a non-invasive method on site. The measurement method can be used to renovate of old buildings and buildings protected under historic presevation laws, a study co-financed by the Swiss Federal Office of Energy shows.

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The graph clearly shows the main result of the study: the measured U values (red) are generally much lower than the values stored in the GEAK calculation tool (green). The values shown in blue represent the result from a calculation of the U-value with material-lambda-values from the building material characteristic table of the SIA (SIA 279). These computational values often agree well with the measured values..