‘…old buildings, after all, may have existed for centuries and been through much extreme weather. Just as people changed clothes to adapt to changing seasons, they also used additional layers such as tapestries, external awnings and blinds to adapt their buildings to the weather, with no additional energy expenditure.’
– Sarah Khan for the RIBA Journal
The RIBA Journal is the official publication of the Royal Institute of British Architects and as such is often at the forefront of innovation when it comes to designing buildings and new innovations.
Conservation Architect Sarah Khan discusses how low-tech solutions to heating and cooling, such as solar shading, are particularly important in older buildings.
There are over 500,000 listed buildings in the UK, according to research conducted by Strutt & Parker in 2016 but a building doesn’t have to be listed for it not to be suitable for modern heating and cooling practices.
Current practices of retrofitting buildings with air-conditioning or adding heating options to make traditional buildings more efficient are damaging buildings aesthetically and can have a detrimental effect on the integrity of the building itself.
Sarah Khan ran a study over three weeks in winter and three weeks in summer to look at how low-tech alternatives to heating and cooling buildings could work with modern living and whether their efficiency stood up to their energy-hungry counterparts.
During the summer experiment temperatures reached as high as 30C inside the building. The study then examined use of night-time ventilation and external blinds to reduce this internal temperature, which they successfully achieved. Blinds are a low-impact method of reducing solar gain – without disrupting the fabric of a building.
‘These low-impact solutions enhance rather than compromise the historic character of listed buildings’
Overheating doesn’t just affect older buildings however. The BBSA conducted a similar study in conjunction with London South Bank University where they monitored a newly renovated North London flat over a 16-day period. Operative temperatures as high as 47.5c were recorded in an apartment with no window shading.
Different shading treatments were trialled, and the data proved that external blinds reduced temperatures by between 11 – 18C and internal blinds by between 9 – 13C.
It is estimated that some 20% of UK homes are suffering from overheating. Passive solutions such as effective solar shading are important contributors used to control temperatures for the health and wellbeing of occupants, whilst also helping to reduce the energy usage of other cooling methods.
‘Many of the measures proposed can be adapted to current uses and can be used with modern services. They could be equally applicable to modern buildings. External awnings and shades, for example, have been the hallmark of many sustainable modern buildings. Passivhaus designs, for example, include strategies such as external shading, stack ventilation and night flushing.’
Solar shading should be considered as a first line of defence to help control overheating in both modern and older buildings. As discussed by Sarah Khan in the original article, external shading prevents heat from entering the building so there is not then the challenge of removing hot air caused by preventable solar gain. But as the London South Bank University study showed, correctly specified internal shading can also have a significant benefit in reducing internal temperatures.
Overheating homes, Zero Carbon Hub: https://www.shadeit.org.uk/type/publications/
BBSA/LSBU full study: https://www.shadeit.org.uk/resource/solar-shading-reduces-overheating/
London South Bank University: https://www.lsbu.ac.uk/
RIBA Journal: https://www.ribaj.com/