Many of us are familiar with energy ratings attached to fridges, dishwashers and a wide variety of electrical goods allowing us to choose the most energy efficient products for our home and recently this scheme has been extended through the British Fenestration Ratings Council (BFRC).
BFRC issue Window Energy Ratings (WERs) based on the specification of each individual window. The ratings are produced in the form of a label which many of you will be familiar with.
The label displays the rating band from the best “A” rated to the poorest performing “G” rated. Please ensure that the energy label has your window supplier’s name on it and that the label applies to the products you intend to purchase.
Benefits of “A” Rated Windows
- Lower Fuel Bills.
- Greater Comfort.
- Resists Internal Glass Condensation.
- Fewer Draughts and Cold Spots.
- Less CO2 Emissions.
Understanding Window Energy Ratings (WERs)
The label comprises three main components:
Thermal Transmittance (“U” Value)
Thermal transmittance of the whole window (glass and frame combined) which is confirmed as a “U” Value. The Window Energy Rating label above demonstrates our window has a “U” value of 1.4 Wm²K. “U” values are a measurement of heat loss where a heat source is applied to one side of the product then measured on the other to see how much is lost. A window which achieves a low “U” value for Thermal Transmittance provides better insulation. Our “A” rated windows use high performance 70mm frames and 28mm glass sealed units which provide magnificent insulation which in turn will produce lower fuel bills, reduce the chances of condensation and provide greater comfort for your home.
Solar Factor (“G” Value)
The calculations for WERs also take into account that every window can allow naturally occurring heat from the sun to pass through our windows into our homes which can contribute to the heating within our homes. This is shown on the label above as the “G” value. In this case the higher the “G” value the better. In our case the “G” value is 0.45 Wm²K. Many “A” rated windows utilise high performance sealed units which allow greater solar gain and therefore improve the performance of the window.
Effective Air Leakage (“L” Value)
The final factor in WER calculations label is the “L” value or leakage. The leakage in our “A” rated product is 0. Wm²K. This is the best figure that can be achieved.