Out of the frying pan, into a flat

The recent July storms may not give you this impression, but overheating in homes, particularly in city flats, is an increasingly common concern we are hearing from clients, co-professionals and personally feeling in our homes. We are not the only ones to have noticed: the National House Builders Council and Zero Carbon Hub have published papers, and the Department for Communities and Local Government (DCLG) recently undertook a review of the problem.

This summer we are conducting our own research into the topic. We are looking at the current literature and regulations in the area and we are also undertaking a survey. However, what has been most interesting so far was the size of the response when we emailed colleagues in our London office to see if overheating was an issue for them and if they would let us put a temperature logger in their homes. We were swamped with people who do suffer from this (particularly when trying to sleep) in mainly new homes, and some older ones too. Bear in mind most of these colleagues are healthy, young(ish) and out of the home during the day. We have installed about 20 loggers for the summer and will report back.

For most of us this is an issue of comfort but for many it is an issue of health. Over 2,000 people a year die due to overheating

The causes seem obvious: tighter insulation standards, high levels of glazing, flats with only one external wall, small openable areas of windows, and more densely occupied cities increasing the “urban heat island” effect. There is also talk of something called global warming.For most of us this is an issue of comfort, but for many it is an issue of health. Over 2,000 people a year die due to overheating

Upon reviewing the literature and standards, it is clear is that the current methodology we are supposed to use to assess overheating in new homes (SAP - Standard Assessment Procedure) needs to be reformed. There are other measures of overheating: the old CIBSE Guide A and the new CIBSE TM52. However, even here it is not clear they are appropriate for homes and there is too much left to the user to make assumptions about the modelling, which make fundamental differences to the answer you get. There is a consensus on the need for a standard.

For most of us this is an issue of comfort but for many it is an issue of health. Over 2,000 people a year die due to overheating. From an economic perspective if we are trying to increase our national productivity a good night’s sleep is a prerequisite. There are commercial concerns as well; we have advised several clients on how to develop standards to reduce overheating in new developments. This will be particularly important in the private rented sectors, where clients do not want to reduce rents when people do not want to live in their overheating flats, or to be forced to make expensive retrofits.

There are a number of possible solutions such as: external shading, fitting cooling to all new flats, reduced glazing levels, and solar control glazing. They all have their problems; portholes may not be the right aesthetic for luxury homes, external shading may make architects and maintenance companies shudder and fitting cooling to every flat will have many up in arms. Even if we resolve this with our new homes, we may have an enormous stock of existing homes that are going to need some form of retrofitting in the future.

If climate change does occur as predicted and our cities continue to densify we may be building ourselves into some hot problems. We will publish our findings and thoughts on this in this autumn.

Barny Evans is associate for energy and sustainability, at WSP | Parsons Brinckerhoff