If there is a single factor that can make a self build project stand out as something extraordinary, it is the windows. These elements are critical to the overall design and have the ability to make a building look balanced, or otherwise.
Here, Chris Coxon, Head of Marketing at Eurocell, looks at the factors to consider when choosing windows.
“Most self builders will freely admit that specifying windows was one of the most challenging elements of their project. The problem is that they can soon look out of place, either because they are incorrectly sized, have bulky sight lines or do not perform well enough in situ. We’ve compiled a list of some of the factors worth considering to avoid the pitfalls:
Cost versus Energy Efficiency
For most self builders, energy efficiency isn’t just a consideration, it is the most important requirement. With increases in cavity widths, up to 300mm in some cases, combined with additional insulation, the attention has shifted to windows to deliver improvements in performance.
When you consider that most window systems in the UK were designed over 10 years ago, it just shows how pressing was the need for innovation. The situation is only going to get worse. The latest updates to Part L require on average a 6% reduction in residential and 9% reduction in non-residential carbon emissions from buildings, which will result in a greater need for higher Window Energy Ratings (WER). And future updates will be even more demanding.
The fact that until we unveiled Modus all window profile systems were designed over a decade ago, which means that they pre-date energy performance standards (in 2002 Part L required a window U-value of only 2.0W/m_K or a WER band E). Why, when most people choose ‘A’ rated white goods, would self builders want to install windows originally designed to meet band E or worse?
It was for this reason that we designed Modus with a 75mm super-thermally efficient multi-chamber profile capable of delivering a U-value as low as 0.7 with a standard argon gas-filled triple glazed unit, without the need for expensive, esoteric-specification glazing units. It is capable of accepting double and triple glazed units, to give self builder more choice.
Achieving a U-value of 0.7w/m_K means that it meets zero-carbon requirements. In fact, an ‘A’ rated window with an Energy Index of 0 or above loses no energy and could actually allow solar energy into the house therefore achieving further savings.
Scale and proportion
Getting scale and proportion right is essential when it comes to choosing windows. The most pleasing proportion is 1 to 1.618, the Golden ratio. That means if a window is 1m wide it should follow that it is 1.618m high.
Proportion of the window in relation to the shape of your property should also be considered. A tall, narrow building looks better with tall, narrow windows, whilst a building that has a square front elevation should have windows that are more square.
Following these two important rules will create a harmonious relationship between proportion of window openings and facade. However, even then there is potential for getting it wrong as windows can be let down by poor detailing. So if you’re looking to replicate a period style then make sure things such as the beads, glazing bars, and sashes are all carefully chosen. We designed Modus around these factors, which means that its classical architectural proportions are distinctly different to the angled chamfered and sculpted ovolo systems that make up the market.