We put this reference guide together because we use this information regularly in our own work and wanted a simpler way to access it.
Whether you are producing an EPC, carrying out SBEM modelling, checking compliance against Part L, benchmarking a design, or working on a project that sits under an earlier set of regulations, finding the right values can sometimes take longer than it should. Our aim with these pages is simply to bring that information together in one place and make it easier to search, compare and use.
What is a U-value?
A U-value, or thermal transmittance, measures how much heat passes through a building element for a given temperature difference between inside and outside. It is expressed in watts per square metre kelvin (W/m²K). In simple terms, the lower the U-value, the better the thermal performance of the element.
U-values are used throughout UK building energy assessment and compliance work, including SAP calculations, SBEM modelling, EPCs and Part L compliance. They also appear across wider sustainability and performance frameworks such as BREEAM and LETI.
© Building Performance Explained 