Window thermal performance & CE markings

Sashed energy saving windows and doors are manufactured to high standards from top quality materials and components that comply with European manufacturing quality standards. Complying with both EU and UK legislation and quality standards, all our energy efficient windows and doors are supplied with the required CE marking which includes our Declarations of Performance (DoP) for thermal performance. Thermal performance for windows and doors are measured in ‘U-values’.

U-value is a measurement of the rate of heat loss from the warm inside of the house through the window or door to the colder outside. The lower the U-value, the smaller the loss of heat, i.e. better energy management. U-values are applied to both the glazing and the whole item. U-values for glazing is commonly referred to as centre pane U-value and the U-value for both the frame, sashes, and glazing is commonly referred to as the whole item or overall U-value.

The majority of our timber windows and doors come with either 24mm or 18mm double-glazed units. Our 24mm double glazing units consist of 4mm glass on the outside, 16mm space filled with Argon gas to prevent heat transfer and 4mm glass on the inside (4/16Ar/4), offering excellent U-Values with soft coat low emission (low-e) Argon filled units and a centre pane U-Value of 1.1 W/m²K. Our 18mm glazing units consist of 4mm glass on the outside, 10mm space filled with Argon gas and 4mm glass on the inside (4/10Ar/4) and have a centre pane U-Value of 1.4 W/m²K.

Our standard triple glazed products are glazed with Low-E Argon gas filled units. The standard triple glazing units consist of 4mm glass on the outside, 8mm space filled with Argon gas to prevent heat transfer, another 4mm of glass, another 8mm space filled with Argon gas, and 4mm glass on the inside (4/8Ar/4/8Ar/4). Our triple glazed products offer superior U-Values with soft coat low emission (low-e) Argon filled units and a centre pane U-Value of 1.0 W/m²K. Triple glazing is available on our 193mm depth spring balanced sash windows.

Centre pane U-Values as low as 0.5 W/m²K can be achieved by using triple glazing units consisting of 4mm glass on the outside, 18mm space filled with Argon gas to prevent heat transfer, another 4mm of glass, another 18mm space filled with Argon gas, and 4mm glass on the inside (4/18Ar/4/18Ar/4). We can use this type of triple glazing in sliding patio doors.

Since 1st of July 2013 all manufactured products sold in the EU are required to have a Declaration of Performance (DoP).

This Declaration of Performance is then printed on a CE mark or label and is a legal document, policed by Trading Standards, rather than building regulations. Any person selling goods without the CE mark or making a false or incorrect declaration may be subject to prosecution, resulting in fines or even imprisonment in the most extreme cases. CE marking is a key indicator of a product’s compliance with EU legislation. The CE mark is specified by the EU, but refers to the relevant country’s regulations. In the UK, the CE mark enforces compliance with building regulations (Part L), which apply to all external windows and doors.

Sashed makes Declarations of Performance on, and CE marks all of our products with a CE label, to show that they comply with the relevant standards.