Buildings have become more energy efficient over years as regulations have tightened and energy costs have soared. Environmental impact is also a factor. Around 22% percent of the UK’s greenhouse gas output comes from residential homes and domestic heating (source National Statistics). Reducing heating requirements by making homes as thermally efficient as possible will clearly reduce this level.
Windows and doors play a key part in achieving this. In most houses 20-25% of heat is lost though windows and doors.
Thermally efficient windows and doors therefore have these benefits:
- Make your home noticeably more comfortable
- Reduce heating bills
- Reduce carbon output and greenhouse gases
However this still means that 75% or more of your heat is lost through walls, floors and the roof. Making these areas more efficient though better insulation and draught proofing is obviously essential to creating a low energy home and capitalising on the benefits of using high performance triple glazed windows. Norrsken recommends a holistic approach to the thermal envelope of your building as part of specifying your windows and doors.
With U-values in the region of 0.8 or better, triple glazed windows and doors from Norrsken will lose less than half of the heat of typical double glazed products. Triple glazed windows will therefore provide significantly better thermal performance than double glazed ones.
As outlined above, this benefit is only fully realised when they are included as part of a thermally efficient whole building envelope. In other words, installing them in an unimproved, draughty and poorly insulated home will likely not be worthwhile.
On the other hand, when they are included in a well designed, well insulated home with efficient heating and - ideally - heat recovery ventilation, the benefits they bring go well beyond what simple performance numbers can tell. On a cold day, the glass on the inside of a triple glazed window is several degrees warmer than that on a double glazed version.
Shown below are thermal models of a high performance double and triple glazed window when it is 0 degrees outside and 21 degrees inside. In both cases, the coldest part of the glass is at the bottom of the pane. The inside pane temperature of the triple-glazed model is 2.5 - 3 degrees warmer over its whole surface than the double-glazed version. This internal pane temperature affects the air in contact with it. This translates into a more comfortable feel on the inside, minimal convection of air internally and the sense of not being able to tell how cold it is outside; it is always warm comfortable and cosy inside.
Thermal image showing heat loss through windows. Windows and doors account for 20-25% of heat loss in in a typical home.
"...many of our triple glazed windows have a U-value of less than 0.8 W/(m²K) – 50% better than the best double glazed windows."
Elements of a high performance Norrsken triple glazed window.