Energy Loss vs Energy Saving

August 9th, 2018

Whilst a major concern with old single glazed windows is that they simply let in too much noise, there is a shining problem with energy efficiency that they have also inherited. Often new double glazed, energy efficient windows, will offer a marked 30% increase in heat preservation compared to the old brand.

Poorly constructed, or often times simply old, doors and windows will let in drafts causing heat loss during the winter months. Whilst stop-gap options such as draft excluders can help curb this issue, the only sure fire way to deal with it is to get replacement windows.

The outmoded single glazed unit used to be this country’s staple; from the ubiquitous bay-windows of Victorian era houses to the two-up two-down terraces. Most new builds are instead fitted with double glazed for a variety of reasons:

  1. The technology required to construct double glazed windows has advanced and costs have fallen.
  2. They offer significantly greater guarding from noise pollution.
  3. They offer a far larger reduction in energy loss.

To give you some figures, let’s consider a typical house in the UK. Replacing single with double glazed windows you can expect a saving of, on average, £170 on the heating bill. This is not only cost efficient, meaning that there’s extra money in the kitty every year, but also goes some way to lowering your carbon footprint: in terms of emissions, this saving off-puts around 680kg of carbon dioxide per annum.

Double glazing units achieve this by maximising their insulating efficiency – by creating the optimum space between the two panes and filling it with heavier gases such as Xenon, Argon and Sulfur Hexafluoride (though the latter is a large contributor to greenhouse emissions and is best avoided). If the space between the glass is too large, this allows for convection currents of the room to pass into the insulating gas, and eventually for heat transfer out of the building. Too thin and the heat is lost via diffusion between the panes. Alternatively vacuum filled, hermetically sealed double glazing units are manufactured that eliminate heat loss due to convection, though this technology brings with it its own problems such as increased stress across the glass and costs.

When buying double glazing the main thing to be aware of is the Window Energy Rating (WER), which is a scale that runs from A (the best) down to G. Although double glazing with an A rating will be considered to offer optimal heat insulation, most windows with a rating of C are considered to be energy efficient, with the better rated only offering slight increments in energy efficiency.

One drawback that might put some off replacing their single with double glazed windows is the aesthetic. Everywhere we go we see the white uPVC frames that most homes have installed. These cheaper frames won’t suit the look of many houses and may interfere with the décor. However this needn’t be a concern as aluminium and bespoke wooden frames are also available kitted out with energy saving double panes that will better suit individual tastes.

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