Wait, Underfloor Heating Can Cool a House Down as Well as Heat It? Here's How to Use Yours to Drop Your Home's Temperature by 2-3°C
Experts explain how underfloor heating could help your home feel fresh and cool in summer
Summer brings with it so much to love – long lazy evenings outside, the garden in bloom, perhaps a break away from work. However, there is also a side to the sunnier months that isn't so appealing — with hot, sticky sleepless nights and stuffy homes definitely being on the list of negatives.
For many people wanting to cool a room down the first course of action is usually to pull out a fan and close the curtains to shield the space from the sun's rays. Both good ideas, but there are other, more effective, ways to bring down the temperature — and if you have underfloor heating, you are in luck.
It turns out that underfloor heating isn't just for keeping a house toasty and warm. According to the experts, there are ways of using it to turn a sweltering space into a fresh, cool and airy oasis.
How do you use underfloor heating to cool a house down?
By running cool water through a wet underfloor heating system, excess heat is absorbed.
Underfloor heating has long been known for being one of the best ways to keep a house at a constant, comfortable temperature — avoiding hot and cold spots and keeping walls free from radiators. However, what many people don't realize is that, used in the right way, it can also help with cooling.
Sam Jump, head of business development at Wunda Group, explains how the concept works. "During a heatwave, homeowners typically attempt to keep their homes cool with fans and air conditioning systems, but many don’t realize that underfloor heating systems can also play a role in cooling indoor spaces when paired with a compatible heat pump. Cooled water can circulate through the underfloor pipework, absorbing excess heat from the room and creating a cold environment — up 2-3°C cooler than before."
Martyn Fowler, founder of Elite Renewables, elaborates. "The floor absorbing some heat from the room helps to lower the temperature — something known as underfloor cooling, or 'radiant cooling'. It won't blast cold air into the room or remove humidity in the same way an air conditioning unit does — it has more of a gentle background cooling effect."
With a decade's experience, Sam Jump is Head of Business Development at Wunda Group, a British underfloor heating company that has designed and supplied thousands of systems since starting in 2006.
Founder of Elite Renewables, Martyn Fowler is one of the UK's leading renewable technology experts, working with heat pumps for the last 2 decades. His passion for decarbonisation matched with a deep technical experience of the technology make him one of the industry's go-to experts for all things renewable.
Can all underfloor heating systems be used for cooling?
While this is great news for those with wet underfloor heating systems, Michael Zohouri, founder of Pyramid Eco, is keen to point out that not all UFH can be used in this way. "The system needs to be a wet underfloor heating system, and it also needs a heat pump or another type of set-up that can supply cool water safely. A standard boiler-fed underfloor heating system will not do this.
"You also need to know that electric underfloor heating cannot cool a room," continues Michael. "Electric mats and cables work by generating heat under the floor. They do not have pipework, water circulation or a way to move heat out of the room."
"The controls matter too," adds Martyn Fowler. "You need the right thermostats, manifolds and safety controls to stop the floor becoming too cold."
Michael Zohouri is the founder of Pyramid Eco, bringing over a decade of experience to the company. His expertise spans energy-efficient retrofitting projects, including insulation, solar, and heat pump installations.
Is it safe to use underfloor heating as a cooling method?
Expect gentle levels of cooling when using this method – results won't be as powerful or immediate as with air conditioning.
If you have the right type of heating system, there is no reason why you shouldn't use it to provide a little relief from the heat during prolonged hot spells.
That said, Martyn Fowler warns against running the system too cold. "If the floor gets too cold, moisture in the air can condense on the surface — a bit like water forming on a cold glass. That is why underfloor cooling systems should not run ice-cold water through the pipes. They need proper controls to keep the floor temperature safely above the dew point."
According to Martyn, there are other limitations to using this technique too when compared to other methods. "It is slower than air conditioning. Underfloor cooling works through the floor structure, so it is better for taking the edge off heat over time rather than quickly cooling a room that is already very hot."
How do you maximize underfloor cooling?
The type of flooring you have fitted over your underfloor heating will play a part in how effectively it can cool a room.
If you decide to give this method a whirl, there are some ways to ensure you are getting the best results from it.
Firstly, it is important to bear in mind that the kind of house you live in will play a part in how effective this approach will be, as Michael Zohouri explains. "The best results come when the home is already reasonably efficient. Underfloor cooling works better in well-insulated homes because the system is not constantly fighting heat coming in through windows, walls and roof spaces. It also helps to keep the floor surface clear. Thick rugs, heavy carpets and lots of furniture over the floor can reduce the effect because they act like insulation."
"The types of floors you have also matters," picks up Martyn Fowler. "Tiles and stone tend to transfer heat more effectively than thick carpets or heavy rugs, so they usually work better with underfloor cooling. The biggest thing, though, is to reduce heat gain before the system has to deal with it. Close blinds or curtains before direct sun hits the glass, use external shading where possible and ventilate when the outside air is cooler."
FAQs
Is my underfloor heating system suitable for cooling?
Love the idea of this but not sure whether you have the right type of system for it to be a viable option?
"You shouldn’t just assume that your underfloor heating can be used for cooling without checking the full system design," says Martyn Fowler. "The pipework, heat source, controls, floor covering and insulation all matter. It is worth asking an installer whether the system has been designed for cooling, whether the heat pump supports cooling mode and whether dew point protection is included."
"It should be set up properly rather than treated like a DIY hack," adds Michael Zohouri. "The system needs the right controls so the floor stays cool and dry."
Preventing a room getting too hot before overheating becomes an issue is the wisest course of action, but even with the best of intentions, indoors can become unbearably stuffy in a heatwave. It is a good idea to look into how to use a fan to cool down a bedroom if you want a good night's sleep — there are some really clever hacks worth trying.
