How much money can a triple glazed window save?

When considering any home upgrade, the most pressing question will always be: what is my return on investment? You don’t want to spend money and not know when that investment will pay off. Installing triple glazing is a sizeable investment and it is important to understand all the facts and figures associated with it so that you can make an informed decision.

Triple glazing has the ability to significantly improve the heat retention capabilities of your home. This means less heat is necessary to heat up your home, less heat is needed to maintain a stable temperature, and less energy is needed to generate that heat resulting in lower energy bills.

In order to understand the cost saving benefits of triple glazing, it’s necessary to first understand what the cost of heating the average UK household comes down to.


Between 30 and 40% of primary energy use in the UK is through domestic consumption. Homes are being powered by both electricity and gas; electricity being the main energy source for electrical appliances, lighting and air-conditioning, and gas for central heating and hot water.

The most common type of residential property in the UK is a 3-bedroom, semi-detached home. This is deemed as the average home when it comes to determining costs of running a property. This average home is made up of a living room, kitchen and bathroom, with 2 or 3 bedrooms. These homes are mostly built with 220mm solid brick walls and not cavity walls and have double or single glazing windows. They have moderate ceiling and roof insulation and a central heating system.

Based on this type of home then, the average dual fuel energy bill in the UK is £1,326 per year, with electricity consumption being 4,000kWh and gas coming in at 12,400kWh. Of this, roughly half is being used for heating, meaning £663.

With that cost in mind, it is important to note that an estimated 22%, or £146, of generated heat is lost to the outside of the home through its windows. Heat can be lost through faulty installation, leaking insulating gas from between the glass panes, gaps between the walls and frame or damaged windows. But the window itself, being made of glass panels and a frame of wood, aluminium or uPVC that is exposed to the elements, also has a certain level of acceptable heat loss. It is the ability of a triple glazed window to resist this heat loss that makes it a superior heat insulation product.

The resistance to heat loss of a window is measured as an R-value. A higher R-value means that the window offers more resistance to heat transfer from a higher to lower temperature. A lower R-value consequently means less resistance to heat transference. The R-value of triple glazing is 5, compared with double glazing’s 3, signifying a 66% increase in heat resistance. This increase in resistance is due to the additional glass panel, but also the density of the Krypton gas that fill the 2 gaps, the spacers used between the panes and the sealing of the frame around the glass unit.

Another way to measure the efficiency of a window is to determine the rate at which heat is lost to the outside. This is measured as a U-value. A lower U-value indicates a slower rate of heat loss where a higher value indicates quicker loss of heat. Double glazing, which was for a long time considered to be the most efficient type of window, has a U-value of 1.4 while triple glazing boasts a U-value of 0.7. This means that triple glazing is twice as efficient as double glazing when it comes to the rate of heat loss, meaning it can help to maintain a more stable interior temperature in the home. With an interior temperature of 21°C, triple glazing maintains an interior glass surface temperature of 18°C, where double glazing under the same circumstances has a maximum surface temperature of 16°C. Because of its additional glass panel and two Krypton gas chambers, triple glazing reduces the average loss of generated heat of a double-glazed window by up to 50%. This is a significant reduction not only in lost heat, but also in the cost of energy used.


Another great benefit of triple glazing is the heat gained from outside to the interior of the home. Triple glazing makes use of low-E or low-emissivity glass which has a microscopic coating that reflects long-wave or infrared energy. This prevents interior heat from escaping by deflecting that heat back into the room. But it also makes use of extra clear, low-iron glass, maximizing the amount of free solar heat gain into the home.

The above data shows that triple glazing has greatly improved heat retention capabilities and you can therefore expect to see a significant reduction in energy bills. But it is not only the cost of heating and the heat retention capabilities of the property that will benefit from having triple glazing installed. Triple glazing also reduces cold spots throughout your home, prevents drafts and interior condensation and makes for a much more comfortable interior environment.

So how long will it take to get a return on your investment?


Many sources claim that triple glazing is not a good investment because it has a very slow return on investment. What these sources fail to note, is that double glazing has a much slower return on investment, even though it is commonly accepted as the norm in window insulation.

To install double glazing in the average home in the UK, will cost around £5,000. Double glazing has an average energy saving of 10% on your heating bill, or £65 per year, which means when only savings on your energy bill is being considered, it will take around 77 years to recoup the installation.

Triple glazing is significantly more expensive, coming in at £7,275 to install in the average UK home with 3 bedrooms and 15 windows. Triple glazing does however give you an additional 15% energy saving over and above the 10% you get from double glazing, which amounts to £162.50 per year. To recuperate your investment then will take 45 years, based on the annual energy saving only. This already is a much faster return on investment, even if the initial capital investment is greater.

But these calculations are based on the cost of fuel remaining unchanged. Of the Big Six energy companies in the UK, Scottish Power, EDF and Npower have all announced energy rate increases of between 8.4 and 9.8 percent from March 2017, adding £109 annually to the typical energy bill. Because of pressure on governments to reduce their carbon emissions and fuel consumption, energy prices are likely to keep rising year after year. Every time fuel prices go up, the savings made in an energy efficient home increases as well.

Another important factor to consider, is what an upgrade to triple glazing will do to your Energy Performance Certificate. By improving your home’s energy rating from band G to band E could increase your property value by up to £25,000 in some areas, which constitutes a significant return on investment.

Whichever way you calculate it, triple glazing offers savings on your energy bill as well as an increase in the value of your home. The initial investment is something that will pay off whether you sell your property or not, while reducing your carbon footprint. All of these factors contribute to making an upgrade to triple glazing a sound financial investment.

Published on : 3rd March 2017

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