What is a U-value?

U-value, or thermal transmittance, is a crucial measurement that quantifies how effectively a building element prevents heat from escaping or entering a structure. Measured in Watts per square meter Kelvin (W/m²K), this standardised value is particularly important when evaluating the thermal performance of skylights and roof windows.

The U-value specifically indicates the rate of heat transfer through a building component – in this case, a Rubber4Roofs skylight. The lower the U-value, the better the thermal insulation properties and the more energy-efficient the skylight will be. This translates directly to improved temperature regulation in your home and potential savings on heating and cooling costs.

Current UK Building Regulations establish specific U-value requirements for various building elements to ensure energy efficiency standards are met. For skylights and roof windows, existing dwellings must achieve a maximum U-value of 2.2 W/m²K, while new construction projects typically require more stringent values between 1.2 and 1.7 W/m²K, depending on the specific application.

Our premium skylight range exceeds these regulatory requirements, with models featuring advanced glazing technologies that deliver exceptional U-values as low as 0.9 W/m²K in some configurations. This superior thermal performance contributes to reduced energy consumption, a smaller carbon footprint, and enhanced comfort through consistent interior temperatures regardless of external weather conditions.