Replacement Windows

CE Marking and harmonised European Norms for quality compliance.

If you are considering for replacement windows, there are a number of rules, old and new, which need to be complied with. Below is an outline of the latest legislation, but for more information visit the Regulations section.

CE Marking and harmonised European Norms for quality compliance

All products manufactured in Europe, including double glazing window, must now comply with the harmonised European Norms (hENs), to ensure European wide technical standards are met. Double glazing window marked with the CE logo are hEN compliant and it is important to check this before purchasing replacement windows. See CE standards for more information. hENs apply to basic float glass, coated glass, toughened glass, laminated glass and energy efficient glass.

New legislation to make homes carbon neutral by 2016

National governments who have signed the Kyoto Protocol are introducing new measures to reduce their CO2 emissions. The UK has pledged to reduce its carbon emissions by 60% by the year 2050. As over 25% of these emissions in the UK are caused by energy use in the home, a number of environmental certification schemes are being introduced for both new build and existing properties. Prime Minister Gordon Brown has pledged to make all homes carbon neutral by 2016. In order to achieve the new environmental targets, a number of requirements affecting both home constructors and home owners are coming into effect imminently. These laws will mean that care needs to be given when selecting double glazing window for a new construction – or for replacemant windows – as it will affect any eventual sale of the home.

New Energy Performance Certificate required for Sale of Homes

New legislation which came into effect in October 2008 means that homes can no longer be sold without an Energy Performance Certificate (EPC). The new law applies to homes that are already on the market and those sellers without an EPC will be obliged to withdraw their homes from sale. The EPC is part of the UK government’s recently introduced Home Information Pack (see Regulations section for more details). The EPC gives a building an official energy rating from A to G (in a similar way to the energy ratings given for electronic goods), with A being the most efficient.

Window Energy Ratings play a key role in Energy Performance Certificate

Many houses are unable to achieve even a D rating on the Home Information Pack scale. For a home to achieve a C or above rating in the Energy Performance Certificate, the type of double glazing window chosen is crucial and standard double glazing window will not be sufficient.
Heating accounts for 60% of energy used in the home. Double glazing window plays a key role in a home’s overall energy rating as up to 25% of heating used can be lost through a double glazing window. As such, windows have their own labelling system - under the British Fenestration Rating Council’s Window Energy Rating scheme. As with the EPC, Window Energy Ratings are also measured on an A to G scale.
The thermal insulation properties of Low E double glazing window achieves by far the greatest Window Energy Ratings and, depending on their construction, can obtain an A, B or C grade on the WER scale. To illustrate the difference, 1m2 of Low E glass emits 91 kilos less of carbon dioxide per year than 1m2 of standard double glazing window.

The most well known Low E double glazing windows are Planitherm TOTAL by Saint Gobain and Pilkington’s K glass. Further energy savings can be made by using warm edge ‘thermal break’ spacer bars. Warm edge spacer bars can reduce heat lost around the edge of the window by up to 65%. For more information, see Low E glazing and Spacer bars.
As well as complying with legislation, the savings on heating that can be made by improving a home’s window energy ratings are substantial. By selecting the most energy efficient Low E windows (an A on the WER scale), a typical semi-detached home will reduce its heating bills by an estimated £9000 over 20 years compared with a standard double glazing window.


BRE and BREEAM concern new-build properties. The BRE Trust (the Building Research Establishment) is a non-profit organisation which works with construction companies to share research and best practice on construction. BRE has developed a set of standards, for the construction industry in Europe, called BREEAM (the Building Research Establishment Environmental Assessment Method). In August 2008, major European property developers backed the introduction of BREEAM during a meeting of the Central and Eastern European Developers’ Sustainability Forum.
An important part of the BREEAM certification covers a building’s use of natural resources (energy, water, materials and land) with the aim being that the development needs of today do not compromise needs of future generations. BREEAM assesses the performance of buildings under several categories - including operational energy use and carbon dioxide emissions. BREEAM’s EcoHomes certification for housing construction was recently replaced by the Code for Sustainable Homes.
The Code for Sustainable Homes
The Code for Sustainable Homes, based on BREEAM’s former EcoHomes certification, was introduced by the UK government in May 2008. The code is a new, mandatory rating system to measure the energy sustainability of new-build homes. The Code measures the overall design, energy and water use of a home using a 1 to 6 star rating system. The Code also gives homebuyers detailed information about the environmental impact of their new home and its potential running costs.

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