Keeping cool with less environmental damage

This summer’s heatwaves have triggered a significant increase in demand for air conditioning units, but Andrew Warren, chair of the British Energy Efficiency Federation, argues in a column in the September issue of Energy in Buildings & Industry (EIBI) that there could be more healthy and less environmentally damaging ways of reducing indoor temperatures.

 

Alternative ways to keep our buildings cool

This summer was almost certainly the hottest summer on record for the UK, according to an early assessment by the Met Office. Endless studies have concluded that humid weather makes working less efficient and infinitely less enjoyable, and a good night’s sleep more difficult to achieve. All potentially pretty bad for our health.

We have long acknowledged that being too cold delivers all of these problems. Consequently, we have set out to try to counter such concerns by improving the efficiency with which we run the buildings we live and work in. It is one of the reasons why one of the most prominent parts of building regulations in every European country is billed as “the conservation of fuel and power.”

It remains a lot harder to warm a house economically and efficiently, than it is to stop heat escaping in the first place.

So, buildings in the northern hemisphere have long been primarily designed to withstand cold seasons, frequently by maximising solar gains and minimising ventilation. Rather like greenhouses.

The solution seems obvious to non-professional commentators to hot summers: let’s all install air-con.

John Lewis has been selling 8% more portable air-con units over the last year compared to the year before. Currys saw a jump in orders of 140% in June  compared with the same month in 2024.

But such units operate very differently in practice to those installed to address the cold. Once you have paid for  better insulation or for high efficient windows, subsequently your outgoings will not increase. Unlike air con, these are essentially “passive” measures.

Instead, financial outgoings reduce, because less fuel is being bought. And so payments  on fuel bills decline. A key reason why  dealing with “fabric first” is the priority accepted by every building professional.

Cons of air con

In contrast, running a single air con unit costs approaching £6 per day. And that unit will only deal with just one room. Additionally, there are the environmental problems caused by using more electricity. Fortunately, warmer temperatures are also a boon for rooftop solar, installation of which can obviously help defer the costs of running any air con system.

It isn’t just the familiar question of addressing the burning of fossil fuels to generate electricity. There is every reason to be concerned about how the cooling chemicals used in air-con devices contribute to climate warming.

Most air conditioners in the world use some form of hydrofluorocarbons (HFC), which are extremely potent greenhouse gases that trap substantially more heat in the atmosphere than an equivalent amount of carbon dioxide (CO2). An HFC can be thousands or tens of thousands of times more potent depending on the type, according to the US Environmental Protection Agency.

HFCs can escape into the atmosphere if air-con units are damaged or not properly disposed of. Poorly made ones can also leak chemicals gradually.

 Sick buildings

One of the most common concerns among people considering an air conditioner is whether or not it makes them ill. Dr Primrose Freestone, an associate professor in clinical microbiology at the University of Leicester, says it can lead to symptoms for what is known as sick building syndrome.

“What air conditioning does is to change the composition of the air, so the air is cooler and the air is drier. The effect on you is it dries out your mucus airways in your nose and the back of your throat.”

This can lead to some people developing issues such as coughs or runny noses, but air-con tends only to lead to serious infections when units are poorly maintained or unclean.

“Viruses can be transmitted, and bacteria as well, by air conditioning systems because they cool air. That means you get condensation and you get water build-up, unless the air conditioning system is well maintained.”

There is every reason therefore to consider what other “passive” measures can be used to address the problems caused by very hot days. First of all, let us look to southern Europe for inspiration, where 35 degree C summers have long been commonplace.

One obvious difference Britons would do well to copy is the automatic installation of window blinds and shutters, deliberately designed to block sunlight before it enters the building. There is no question that such “passive” building measures must grow enormously in importance as summers become hotter and hotter.

Better choices

There is also more obvious reliance, now incorporated into English building regulations,  upon improved natural ventilation design to let heat escape during cooler hours.  And of course, reflective or light-coloured buildings that reflect sunlight are proven winners. As are the type of old fashioned fans, to be found in every respectable Edwardian parlour.

In southern Europe, the hottest hours in the middle of the day are for siestas. Outdoor activities are paused. There is far more commercial activity in the early morning and into the evening. There is wide appreciation that keeping curtains closed during the day, and windows wide open at night, can help prevent overheating.

For the past decade, the official advisory body, the Committee on Climate Change, has been warning about our failure to address the implications of record summer temperatures with sufficient urgency. It is all too easy to sit back, thinking that air con units (already in use in 10% of UK homes) are the only obvious route. If so, that could prove to be a rather expensive and potentially ecologically damaging solution.