Fitting double glazing

Last updated Wednesday 30 April 2008

Is your heat going out of the window?

Glazing over already? Double glazing doesn't have to be boring - there's cash and heat to be saved.

Did you know that a fifth of your home's heat is lost through the windows? It's no wonder British homes have as much of an impact on the climate as all the fuel-burning cars, buses and other vehicles we use. Double glazing your home could cut your CO2emissions by 740kg a year - that's over 7 times as much CO2 as switching to the best green electricity tariff - and save you a tidy sum on bills.

It could even give you some peace from noisy neighbours.

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Photo: Fitting double glazing

Saves 740kg of CO2 a year

464 Bloomers are doing this

CO2 reduction 2 out of 5

Cheapness 5 out of 5

Popularity 4 out of 5

Cost 4000

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How does it work?

Pub Fact

  • Around two million windows are installed every year in the UK
  • The average household could save around 1.5 tonnes of CO2 a year by making their home energy efficient
  • The gap between the two panes in standard double glazing is 16mm whilst the optimum gap to significantly reduce noise levels is 100mm

Double glazing sandwiches a thin insulating layer of air, or an inert gas such as argon, between two panes of glass. That insulating layer is sealed in and helps prevent heat transfer. In other words, it keeps cold air out and a lot more of your hot air in.

It's more effective than secondary glazing, which simply inserts a second layer of glass inside the existing frame rather than coming as a complete sealed unit.

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How will it make a difference?

A single-glazed window can lose as much as 14 times as much heat as the same area of well-insulated wall. No, no one's suggesting you brick up your windows, but consider the gains from double-glazing them:

  • Double glazing halves heat loss through windows
  • It reduces your heating bills by about 90 a year - enough to fund a return train trip to Paris once a year
  • If everyone in the UK who needed double glazing fitted it, we'd save nearly five million tonnes of CO2 - the equivalent of 800,000 households' total emissions - and about 600m

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What's the debate?

"Double glazing sounds like an energy intensive affair to me"

Windows and doors generally account for about 8% of the average home's embodied energy, according to the EST. While double glazing adds to these not insubstantial , the energy savings from better insulation far outweigh this additional impact within a year or so of installation. The big environmental no-no is aluminium frames, which are a lot more energy-intensive to manufacture.

"Isn't PVC a pretty nasty material?"

Many environmentalists acknowledge that double glazing cuts energy use, but also argue that PVC is a chemical which damages the environment and deteriorates rapidly under the sun's UV rays. If you're concerned enough to spend more, consider sustainable timber frames rather than PVC.

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What's stopping me?

"I live in a listed buildings and I think double glazing is a 'design crime'"

If you live in a listed property, make sure to check with the building controls department at your local authority before doing anything.

"I have lots of windows and too little money!"

If you can't afford to double glaze all your windows, focus on the rooms that you use most and that cost you the most to heat, or try the cheaper alternative - secondary glazing. You could also look for grants (see 'How do I do it?').

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How do I do it?

  • Choose Energy Saving Recommended products from the Energy Saving Trust
  • For hassle-free installation, employ a FENSA registered contractor who will arrange building regulation approval for you. If you choose to DIY, you must make sure that you comply with building regulations and European directives
  • Check for grants. Although there are no national grants available, your local authority may provide grants, particularly home improvement and disabled persons grants where the property requires urgent attention and the owner does not have the means to pay for the work
  • Consult with the local authority's building conservation officer if you live in a historically significant building or conservation area
  • Ventilate. 'Trickle vents' allow you to control the amount of home ventilation and reduce the potential loss of warm air. They are particularly important in the corners of north facing walls
  • If you're removing old PVC and aluminium frames, they should be recycled

For even better energy saving, close your curtains at dusk to reduce heat escaping through the windows and, if you don't have them already, consider installing cavity wall insulation, loft insulation and draught proofing, all of which save more heat than window glazing.

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Anonymous 2009-12-04

Our loft extension was built to the latest building standards, with triple glazing. It's now so hot just from the body heat of two people sleeping in an unheated room with the lightest of summer weight duvets even when its below freezing outside that the windows have to be open so heating up the outside world. Time for the standards to be rethought I think.

Anonymous 2009-08-25

All our windows in our house are double glazed, we save alot of money from the heat we keep in over winter.

Anonymous, London 2009-01-15

Sounds great but I live in a flat. All windows are double glazed except one- could you add tips for people who are renting like me? Maybe there's some tape or something else?

Anonymous 2009-01-09

I have recently fitted thin double glazing from a company called Histoglass ( into the existing windows of my Victorian cottage and it worked brilliantly! The heat saving over the last 2 months is considerable and it feels so much more comfortable in the house. Worth checking them if you are worried about fitting thin double glazing into a listed property!

Anonymous 2009-01-07

I'm afraid we couldn't stretch to the wooden frames, so we have pvc. There are definitely fewer draughts now, so our heating bills must be lower. Have had no condensation problems, and they are easy to keep clean.

Breadon, Pershore 2008-10-16

The glasier has fitted the new units now. One thing to be aware of is that we now have to paint the wooden frames. I guess the glasier couldn't do this. A light undercoat was applied but this won't last the winter!

Anonymous 2008-09-04

Read about this on the JustMeans All Things Reconsidered blog.

Breadon, Pershore 2008-08-30

We have the original wooden double glazing put in when house was built. One of the panes has condensation. (Its in the kitchen, by the kettle!) We did get quote for uPVC replacement but it was around 8000. (They even quoted for replacing the aluminium patio doors with plastic!) A local glasier has quoted under 500 to replace to unit with condensation and fit a double glazed unit into our existing single glazed back door. We went with lower quote!

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Glossary terms used on this page
CO2, or carbon dioxide, is made up of the elements carbon and oxygen. It exists quite naturally in our atmosphere, as part of the carbon cycle. Everyday processes in the plant and animal world both add CO2 to the atmosphere and take it out. However, because it is a greenhouse gas - meaning it affects the temperature of the earth - the exact level of CO2 is important. Burning fossil fuels releases CO2 into the atmosphere, hence the anxiety that extensive use of these fuels is causing climate change.
Embodied energy
Embodied energy - sometimes referred to as 'embedded energy' - is the energy used (and therefore the CO2 emissions) in manufacturing, packaging and transporting a product, material or service. So when calculating the CO2 savings from a new energy-efficient product such as a boiler or washing machine, its embodied energy needs to be taken into account. Usually the energy saved in use will quickly compensate for the embodied energy, but in some cases - such as small urban wind turbines - it may be that a product will use more energy in its manufacture than it will save across its lifetime.
Emissions are the CO2 (and other greenhouse gases) produced by energy use, usually calculated and stated as an annual tally: also referred to as your carbon footprint. Your personal emissions can be direct - such as the gas you personally use to heat your home or the petrol you burn to power your car - or indirect - meaning the energy use that has gone into the products or services you buy. The latter, such as the emissions caused by the manufacture of your new TV, or the packaging your food comes in, are also referred to as embodied emissions.
Energy efficient
definition to follow
Energy intensive
An energy-intensive process uses a great deal of energy - and therefore produces high emissions - relative to its useful output. As an example, beef production, has recently been cited as an especially energy-intensive industry, while tumble dryers are energy-intensive appliances. Products that are manufactured in an energy-intensive way are also said to be 'emissions heavy'.
Inert gas
Inert gases are those, including helium and neon, that are not normally chemically reactive. The inert gases argon and krypton are often used in sealed double glazing units because they don't conduct heat as well as air, so they provide better insulation.
Listed buildings
Listed buildings are those included on a government-approved list as having special architectural or historic interest. Special consent for any alterations is required.
Secondary glazing
Secondary glazing is a less effective form of double glazing, used where the latter is unaffordable or undesirable in some way (such as in listed buildings). A separate layer of glass or plastic is fitted to the inside of the existing window frame. The gap between the two panes determines its effectiveness in insulating against heat loss and noise. navigation


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