When overheating springs to mind

Leo Pyrah, product manager at Pilkington UK, explains what could be holding solar control glass back from being specified more widely, and its role in the road to net zero.

We’re edging closer to the year anniversary of Theresa May announcing the UK’s ambitious net zero target, something that has successfully renewed discussion in government and across the building design industry about how we make our new and existing buildings more energy efficient.

And with springtime upon us, we can soon wave goodbye to winter storms and welcome in warmer weather. Naturally, the turn of the seasons pivots the focus of these discussions towards how we keep heat out, as well as keeping it in.

When glazing’s role is considered for energy efficiency, the building design industry has historically focused on trapping in heat with low-emissivity glass, led by Building Regulations, resulting in reduced demand for heating spaces in colder months. Indeed, improving the thermal efficiency of the glazing used in our built environment will be important to meeting the net-zero target.

But preventing solar energy from being transmitted into buildings through windows and facades, which makes spaces hotter, will be equally important for lowering emissions. Solutions like solar control glass will help alleviate this issue, resulting in less energy used by mechanical cooling systems.

The commercial sector strides ahead in using solar control glass to curb energy use and maintain comfortable temperatures indoors.

However, the UK residential market lags behind. In the Part L (conservation of fuel and power) consultation in England, overheating is expected to be a focus area, not only for commercial buildings but also for residential properties.

Last year’s hot summer drew attention to just how serious the overheating issue in homes currently is. Research by Loughborough University published in the Building Research and Information Journal outlined how deaths related to overheating could triple by 2040.

The Part L consultations could lead to regulations that place more importance on its specification in the home, given solar control glass’s ability to reduce the amount of heat transmitted into buildings via windows, and subsequently reduce the risk of overheating without the need for mechanical cooling.

Currently, Part L only recognises the problem of solar heat gain in non-residential properties, where solar control glass or shading devices are required for large glazed projects to meet the solar gain benchmark.

Now, we’re waiting to learn how the government proposes to address these growing concerns. For new, non-residential properties, the current notional building is based on a maximum g-value of 0.4, where 40% of the total sun’s energy is transmitted. A lowering of this value in the new regulations could drive the market for more highly performing solar control glass. As an alternative to counterproductive designs such as reducing glazed areas, we could also see more importance placed on architect’s specifying glass with better solar control properties in the home.

While we should see more solar control glass in residential buildings, a misconception remains in some groups that its mainly suited for warmer climates outside the UK.

Indeed, at the hot end of the spectrum, 50,000m2 of Pilkington SuncoolOne 30/21 is being installed at the Palm Tower, a new landmark building in Dubai’s iconic Palm Jumeirah district. The advancement of solar control coatings has allowed the whole tower to be clad entirely in glass while resisting the desert heat, keeping a naturally cool temperature inside for occupants.

But closer to home in Derbyshire, UK health and lifestyle organisation Slimming World has used Pilkington Suncool60/31 solar control glass, which allows 60% of light transmission and 31% of the sun’s energy through, as part of a new curtain walling system at its HQ. This has resulted in maximum comfort year-round for staff, and excellent energy efficiency – even with the UK’s more moderate climate.

It’s solar control glass’s increasing ability to be combined with other solutions, such as self-clean or acoustic glazing, that is opening new opportunities for its specification. We’ll also undoubtedly see greater volumes of specifications over the next decade driven in part by increasingly stringent Building Regulations, with each project striving to be a zero-energy building.

Looking ahead, advanced technologies like dynamic and switchable glazing, which can react to daylight exposure and limit heat transmittance, may also provide a solution for homes and commercial buildings.

For now, it will be important for the industry to watch the government’s consultations surrounding energy efficiency and overheating closely. By the end of next year, the specification of solar control glass is likely to extend beyond the large commercial projects we see frequently now and be seen in far smaller commercial and residential projects.