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Thermal Efficiency

All our U-Factor calculations are based on the WHOLE door or window (which is frame plus glass).

Thermally insulated aluminum profiles and tracks reduce thermal loss through transfer.

All of our systems have been thermally simulated to indicate the true thermal value, helping you choose the right option for your property and helping you save money on your fuel bills.

All our aluminum profiles and tracks used in our door and window systems include a thermal break (this prevents heat loss or gain through transfer). All products are double glazed (GG series triple glazed) with low-E glass and include Super Spacer® bars fitted as standard to the glass units (non metallic material seperates glass from the outside to inside). Tested for water ingress/air permeability. Increased thermal efficiency can also be achieved by upgrading your glass choice (emissivity options of 1%, 3%, 5% and 10%) or to triple glazed units with Krypton gas, please ask for further details.

Photo of Wintech Testing station and FSDC Global bifold doors
Photo of bifold doors in Bradford showroom, illustates dual rubber seals to door panels


The thermal rating of a door or window is measured in U-Factors, the lower the U-Factor the better the rating.

Many companies will give you a U-Factor based on the center pane value or the U-Factor of the glass (better than ‘A’ rated). This value will always be lower than the actual value of the complete window or door.

A low U-Factor is useful during cold days when heating is needed. It is also helpful during hot days when it is important to keep the heat out. Thermally insulated aluminum, and aluminum tracks reduce thermal loss through transfer.

U-Factors (Btu/h·ft²·°F) of complete units

All our U-Factor calculations are based on the WHOLE door or window which is frame plus glass.

Timber Door Set = 0.19 - 0.30 Btu/h·ft²·°F

Timber is the most thermally efficient material used in the glazing industry.

Aluminum Door Set = 0.31 - 0.57 Btu/h·ft²·°F

All aluminum profiles in our systems include a thermal break for greater thermal efficiency.

Aluminum / Timber Door Set = 1.41 - 1.8 Btu/h·ft²·°F

Solid timber with thermally broken aluminum profiles for combined thermal efficiency.

Glass Door Set = 0.27 - 0.52 Btu/h·ft²·°F

Triple glazed as standard for greater thermal efficiency.

Vinyl Door Set = 0.21 - 0.31 Btu/h·ft²·°F

We use the VEKA Matrix profile, one of the best on the market today.

Thermal efficiency product features include;
  • Weather tested to over 300 pascals or 6.26 psf
  • Tested for water ingress and air permeability
  • Thermally insulated aluminum profiles as standard
  • Thermally insulated aluminum tracks as standard
  • High performance rubber seals and brush seals
  • Double or triple glazed with Low-E glass
  • No condensation
  • Super Spacer® bars fitted as standard to glass units
  • UKAS PAS23 weather tested