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Regulations of double glazed units

Special Notice...

NEW REGULATIONS IN THE GLASS INDUSTRY FROM 1ST APRIL 2002

Document L

Document L is the part of the Building Regulations for England and Wales that sets the standards for energy efficiency in buildings.

Why are there changes to Document L?

The UK Government is committed to reducing energy consumption for two reasons:

1. As signatories to the Kyoto agreement commitments have been made to reduce emissions of greenhouse gases such as carbon dioxide; almost half the carbon dioxide emissions in the UK result from the generation of the energy we use to heat, cool and light our buildings.

2. More efficient use of non-renewable fuels such as gas, oil and coal.

In fact, in the UK we are lagging behind our European partners, many of who have had much more stringent energy conservation legislation for some time now.

What exactly has changed with the Glazing and Window industry?

The U-Value

The U-value is the rate at which heat energy transfers from one side of a window to the other. The lower the number the more thermally efficient the window is. The U-Values are measured in watts per metre squared Kelvin (W/m2K).

The U-Value that must be reached by a combined glass unit and it's frames is...

Timber and PVC-U windows and doors have to meet - 2 W/m2K.

Aluminium and Steel windows and doors have to meet - 2.2 W/m2K.

Do Replacement Windows have to meet the new regulations? - YES

Whether it is one window or one thousand windows, a replacement window project is covered by the requirements of Document L.

Do conservatories need to comply? - Conservatories that are unheated and separated by doors from the house are exempt.

Just one exception to this is where an individual sealed unit or broken glass pane is being replaced – in which case it is counted as a repair rather than a replacement and is therefore not covered by the new regulations.

How can the thermal performance of a double glazed unit be improved?

Double Glazed Units can be improved in several ways...

By replacing the standard glass with a low emissive (low E) glass.

By replacing standard spacer bars with better insulating 'warm edge' spacer bars.

By increasing the unit’s cavity up to an optimum width of 16mm.

By replacing the air within the unit with an inert gas such as argon.

What is Low-E glass?

This is glass which has an enhanced thermal coating designed to reflect heat back into a building, thus increasing efficiency and reducing wasted energy.

How will the new changes be monitored?

Given that there are approximately 1.2 million replacement contracts per year in the UK alone, a self-certification scheme has been introduced.

The scheme is called FENSA and is monitored by The Glass and Glazing Federation.

All contracts will receive a certificate on completion to confirm that the new installation conforms to the new Document L.

As fuel prices increase, especially with the addition of VAT to domestic fuel bills, the resulting cost savings are becoming increasingly desirable for both domestic and commercial end users. Additionally, environmental pressure will escalate the demand for more energy efficiency in particularly in the construction of homes and commercial or public buildings.

CHIPPING NORTON GLASS LTD IS COMPLYING WITH ALL THE ABOVE NEW REGULATIONS.

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