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.

The aluminium in our systems is thermally broken. All of our systems are double glazed with low-E glass as standard, we have tested for water ingress and air permeability and are CE compliant. Increased thermal efficiency can 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.

A low  thermal value 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 broken aluminium, and aluminium tracks reduce thermal loss through transfer

Thermal Value


The thermal rating of a window or door is measured in thermal values, the lower the thermal value the better the rating. 

Many companies will give you a thermal value based on the center pane value or the thermal value of the glass. This value will always be lower than the actual value of the complete window or door. 

All our thermal value calculations are based on the whole door which is frame plus glass.

UK Telephone: 0345 64 64 646

USA Telephone: 786 275 5068
Sales email:
Other enquiries:

The Folding Sliding Door Company is an ISO 9001 and (US) NAMI Quality Assured organisation with nationally recognised accreditations such as CE Compliancy and Document Q in the UK, and Florida Building Code and Dade County in the US.

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