All comments to be attributed to Phil Brown, European regulatory marketing manager at Pilkington United Kingdom Limited, part of the NSG Group:
Last month saw the Met Office issue its first ever extreme heat warning, as temperatures soared to more than 30°C across several parts of the country. This type of weather is no longer a rare occurrence. Heatwaves are becoming increasingly common in the UK, with experts warning that we are likely to see temperatures of almost 40°C every other year by 2050 as a result of climate change.
In the UK, architects are well-versed in measures to keep homes warm in winter. Insulation and glazing solutions have long been specified to make buildings more energy efficient and reduce the need for heating. And, in newer developments, architects have been able to make the most of the latest insulating solutions, making new builds airtight and even more effective at retaining heat during the winter.
But in heatwaves, these measures can serve to exacerbate the problem. If excessive heat is coming through the windows into houses with insufficient ventilation, this can lead to serious issues with overheating.
According to a study by Monash University, some 8,000 deaths annually can be attributed to high temperatures in the UK.
This is the challenge that new building regulations coming into force from June 2022 aim to address, by implementing changes to reduce overheating in homes in the UK.
Part regulations
Referred to as Part S in Wales and not yet assigned a letter in England, though being referred to as Part , the regulations are expected to impact on glass specifications, changing the way that architects must design new dwellings to prevent extreme temperatures such as those experienced in July.
Importantly, the new regulations create different rules for buildings in Greater London and those elsewhere in England.
For new residential buildings in London with more than two fabric elements and openings on opposite facades, they state that maximum glazing area should be 13% of floor area and shading should be provided on glazing between North East and North West (turning clockwise via South). For residential buildings with two or fewer fabric elements and openings on facades which are not opposite, then maximum glazing area should be 15% of floor area. Where shading is required, glazing with a maximum g value of 0.40 and a high light transmittance of 0.70 is one of the accepted solutions.
However, for residential buildings outside of Greater London, there’s no requirement for shading up to a maximum glazing area of 21% floor area.
In effect, the new regulations create a tiered approach by location to the issue of overheating, where Greater London is deemed to require more significant measures to prevent high internal temperatures.
Yet residents in other UK cities are just as vulnerable to excessive temperatures as those in London. For example, research by the University of Manchester found the urban heat island intensity (UHI) – the actual temperature difference between urban and rural areas – in Manchester to be comparable to the UHI in London.
This ‘urban heat island’ effect was experienced by Ian Forrester at BBC Manchester, whose new build flat in the city reached excessive temperatures this summer due to a lack of solar control glass. In The Times he detailed some of the consequences – food goes off very quickly, children in the building have had heatstroke, and a neighbour’s dog died in the heat. Residents have been forced to install costly and energy intensive cooling systems in order to keep temperatures bearable.
A missed opportunity?
With overheating a clear and growing problem in residential buildings across the country – including major cities outside of Greater London such as Manchester, Birmingham and Leeds – it raises the question, is the double standard set out in new Part regulations an oversight? Is a failure to acknowledge the risk of overheating outside of London a missed opportunity to create more sustainable cities across the country? Maybe, but it doesn’t have to be.
It remains to be seen what exactly the new building regulations will stipulate when they are published later this year, but even if standards in Greater London differ from elsewhere, architects and clients should consider specifying high performance solar control glass in residential buildings in all cities to help prevent overheating.
Ultimately, it may not be changes to building regulations that cause measures to be implemented to avoid overheating, but rather residents’ need to avoid increasingly unbearable temperatures. This is especially the case where retrofit is concerned, as it’s unlikely that regulations will ever be implemented to enforce upgrades to be made in existing properties. The Government’s Climate Change Committee have warned that more than half a million homes have been built since 2017 which will need to be retrofitted to ensure they stay cool, and they have estimated the costs of retrofitting mitigation measures into a property to be four or five times that of if they had been included at the building stage.
By specifying not just to meet regulations, but exceed them, architects can help futureproof buildings against climate change and reduce the overall carbon footprint of a development, making it more attractive to both investors and residents.