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Unlike cars, houses do not have regular checks and their emissions tested so actual performance data is often limited to calculations and thermal modelling

Calculated steady-state U-values are based upon information provided by material suppliers and allow for quick and easy comparisons to be made between various materials and building elements. However, as the simple calculation fails to consider: thermal storage; build quality; moisture content; fluctuations in temperature and humidity, exposure to sun, wind, and rain, it may be best to only use calculated U-values as a rough guide.


The performance gap