Energy Saving

Emerald A-Rated Glass

At Emerald we manufacture all of our products using the highest quality glass from Pilkington, a low-emissivity (Low-E) glass which carries an A-Rated Energy rating with the British Fenestration Rating Council (BRFC). The BFRC Scheme is the UK's national system for rating the energy efficiency of windows and is recognised within the Building Regulations as a method to show compliance for your replacement windows installation. Window Energy Ratings use a consumer-friendly traffic-light style A-E ratings guide, which allow consumers to make informed choices about the energy efficiency of the windows you are looking to purchase. All Emerald products have an 'A' rating and offer you the following benefits:

  • Improves the energy efficiency of your home
  • Reduces the amount of energy you use
  • Saves you money on your heating bills
  • More effective than single glazing or standard double glazing
  • Provides you with the reassurance of Pilkington quality
  • Manufactured to the highest European quality standards
A-Rated Windows

Typical U-Values

In the UK we express the rate of heat loss in "U Values". The lower the U-Value the greater the thermal insulation and savings on your fuel bills.

The U-Value of single clear glass is 5.4.
With ordinary double glazing this is improved to 2.6.
With Low-E Glass the U-Value is reduced to 1.8.

Low-E Glass is a type of insulating glass that helps keep homes warmer in the winter and cooler in the summer.

How does low emissivity glass work?

Low-E glass has a special metal coating on one side: either pyrolytic (hard coat) or sputtered (soft coat). The microscopically thin and almost invisible coating acts as a filter, blocking long wave radiation (infra-red heat) and letting in short wave radiation (ultra violet and visible light).

How Low-E windows work

When the sun's short wave radiation passes through a window into a room, it is absorbed by the carpet and furniture in the room. That energy is then transformed into long wave (thermal) radiation in the form of heat, i.e. the sun warms up the carpet and furniture in the room. During the winter, heat (long wave radiation) in the room naturally wants to escape through the glass in the windows but Low-E glass reflects it back into room, keeping the room warm. If you touch a standard pane of glass in the winter it feels very cold, even if the room itself is hot. But if you touch a pane of low emissivity glass in the winter it feels much warmer.

During the summer months it is hot outside, but Low-E glass does not let the infra-red thermal radiation (long wave) pass through it, reducing the overall solar heat gain of the building.

How is Low-E glass manufactured?

There are two types of Low-E glass: hard coat and soft coat.

How Low-E windows work

Hard coat Low-E glass has a thin layer of molten tin poured over it whilst the glass is still slightly molten. The tin welds to the glass making the coating very strong and difficult to scratch or remove. Soft coat Low-E glass has silver, zinc or tin applied to it in a vacuum chamber filled with an electrically charged inert gas. Molecules of the coating metal are sputtered on to the surface of the glass where they stick. This coating is very easy to scratch, therefore the coated side is always used on one of the inner faces of the double glazing, where the argon gas held between the panes prevents oxidisation.

Emerald's Environmentally Friendly uPVC Products

At Emerald we use uPVC for all of our products that is manufactured by Duraflex, who are fully committed to producing environmentally friendly products by:

  • Exercising due care in waste disposal produced as a result of company activities, developing plans to reduce waste, and increase efficiency.
  • Taking practical steps to prevent pollution, to reduce energy, raw materials, water consumption and waste.
  • Encouraging the re-use of material wherever feasible, when it does not compromise product or service.
  • Aiming to reduce impact on the environment and implement environmentally responsible policies/products throughout their operations.
  • Minimising their environmental footprint, by working towards sustainability.

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