Our planet has arrived in unknown territory; all kinds of records are being broken. During four consecutive days in July 2023, Earth experienced the hottest day ever. And the North Atlantic Ocean has the highest surface temperature ever recorded at present.
Unprepared
Jack Marley, editor to The Conversation, recently visited his uncle in Utah, US. It felt cooler than London, where he lives. Partly, this is due to air humidity. London is sticky in summertime, whereas Utah is very dry. But buildings are part of the equation as well. His brick house absorbs heat and stores it; whereas each building he visited in the US was either well-ventilated, or had air conditioning. But the world heats up. Will the UK succeed in keeping it’s homes and offices comfortable without air conditioning?
Jesus Lizana, Nicole Miranda and Radhika Khosla of Oxford University tell us that Northern Europe is dangerously unprepared for the heat to come. ‘Of the ten countries with the greatest relative change in cooling days (as heating is larger than 1.5oC now and is bearing 2oC), eight are situated in Northern Europe,’ they write. Moreover, buildings in the Northern hemisphere are constructed primarily for liveability during the cold season: they keep inside solar heat and minimize ventilation. The solution would seem to be: let’s all change to air conditioning.
Coal-powered air conditioning?
But according to Mehri Khosravi, things aren’t that simple. She does research into energy at East London University; she warns that ‘cooling down will cost huge amounts of energy, prscisely at the moment when demand is high already.’ According to her, the UKand other countries should concentrate instead on minimizing the demand for cooling. In winter time, she says, we should better minimize heat demand, because ‘it is much more difficult to heat a house than to prevent heat from escaping.’ In other words: how do we prevent Northern European houses to heat up too much?
In order to answer that question, we should take a different view of the weather. In Northern Europe, we still look upon heat as ‘good weather’. But Northern Europe should take a better look at Southern Europe. There, they use shutters and shade to prevent sunlight from entering, natural ventilation that allows heat to escape if it is cooler outside, and houses that reflect sunlight through mirrors or light colours. In Spain, public life comes to a halt as it is hot. Curtains are drawn during daytime; at night, people open up windows in order to prevent houses from heating too much.
Cooling down smarter
But there might be even smarter methods to cool down. In Austria, researchers recently proposed a ‘ventilation first’ approach, even where air conditioning exists. They propose to use ventilators as long inside temperature is below 27oC. Heat pumps might be part of the solution. These can keep the houses cool in summertime. They can act as a kind of reversed air conditioning: in wintertime, they draw heat into the building, in summertime they reversely push the heat out. Heat pumps have an efficiency of 200 to 400%. That means that they have a heat effect that is at least double the energy required to operate them.
For households, this means the use of one single device, during summer and winter. It will provide both heating and cooling, reduces energy bills, and prevents the installation of climate worsening air conditioning. But heat pumps cannot do everything. Their installation is costly, many older homes need to adapt, and there is a lack of appropriately schooled engineers. But this needs to be supported, if it is to become an important alternative to air conditioning.
Solar heat from the roof
And yet, heat pumps are a smart solution to cooling, in combination with devices like shutters and ventilators. In combination with solar roof panels, they even become more sustainable. For houses with solar roof panels can produce electricity on the hottest moments of the day – precisely when air conditioners and heat pumps work hardest.
We already have a model for treating energy use in winter time – ‘insulation first’. For it is much harder to heat a home than to insulate it. Tom Rogers and colleagues of Nottingham Trent University hold that solar energy will play a ‘pivotal role’ in the ‘treatment of heating in the summer and better climate resilience’: by treating cooling requirements first.
Southern Europe
About the same holds true for Southern Europe. There, they start with passive cooling measures, in order not to pay too much attention to mechanical cooling. It implies:
- shadow and blinds in order to prevent sunlight from entering
- natural ventilation in order to let heat escape when it is cooler
- light-coloured and reflecting surfaces that will reflect sunlight
- orient buildings in such a way that they will capture a minimum of heat
- trees and green infrastructure for cooling neighbourhoods.
The researchers analysed satellite images and concluded that solar collectors will be able to provide ‘almost a third’ of a town’s energy demand. If we add smarter construction, and passive cooling, houses will be able to stay safe as well as low in energy use.
More solutions
The Australian medical journal published a review of a simple and yet effective solution: a ‘fan-first’ approach. According to this publication, ventilators are best suited to our requirements up to 27oC. These move the air and produce a comfortable feeling, because it will let sweat evaporate. This may make a difference of 4oC already. Above 37oC, other strategies will be better, like wetting the skin, relocate to a cooler spot, or turn on the airco.
Alternatively, we could cool down the house before the inhabitants arrive late afternoon. We could use ait conditioning to that end, in combination with solar systems. In short, there are strategies that can protect us from heating up – and we might even discover more.
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