Air contradiction: how to cool and heat your house for free

The energy we dedicate to powering our air conditioning units in the UK has reached alarming levels, accounting for up to a tenth of our total electricity consumption. With energy prices creeping up and summer temperatures soaring, might there be a better way of keeping ourselves cool?

Air conditioning units on wall

A chilly calamity

Most of us take the welcome relief of air conditioning for granted. But is pumping wave after wave of cold air into our houses, offices and shops really the best way of doing it?

“When you go into commercial buildings they’re generally all air conditioned, but they use a lot of energy.” Explains Dr Ben Hughes, a reader in Energy from The University of Sheffield, who’s building alternatives to conventional air conditioning that reduce our carbon footprint and energy bills. “Because we’ve got used to these air conditioning systems, the temperature we feel comfortably cool at has changed and that’s increased the energy we use by about 20%.”

To put that into perspective, compared to buildings that cool by simply opening a few windows, air-conditioning emits 30% more CO2. That’s 117 million tonnes of greenhouse gasses being forced into our atmosphere every year, just to keep heat at bay.

In a typical UK office, 30% of electricity goes on air-conditioning each year, with demand only set to increase. It’s not much better news worldwide either: installed air-con units around the globe are expected to increase from 700 million to a hefty 1.6 billion by 2050 in what is a growth market.

For Ben and his research team, that ‘better way’ is FREECOOL, a cooling system designed and licensed in Sheffield after years of dedicated research. FREECOOL uses sealed tubes filled with cold water called ‘heat pipes’, which cool warmer air from outside as it passes through. This is a passive process – there’s no energy used. But the system can lower indoor temperatures by 12-15°C and our demand for conventional air con by up to 40%.

What’s more, by reducing energy FREECOOL also lowers harmful CO2 emissions, while using outdoor air (compared to recirculated air from conventional systems) improves indoor air quality. What really sets it apart from competitors, however, is its ability to cool incoming air with so little energy input, something the World Society of Sustainable Energy Technologies recognised last year by awarding Ben and his team with a first-place Innovation Award.

With his patented products already on the market, clients such as the Dover Discovery Centre are turning to this technology to help them meet their demands at minimal energy and expenditure.

“People overcomplicate buildings and they overcomplicate design and I think that’s where a lot of the problems lie. We end up putting in systems to make things comfortable, but if we designed it properly in the first place we wouldn’t need to.”

But this stretches further than ventilating just houses and offices, as Ben’s biggest and most unexpected venture demonstrates…

Air conditioning units in row

Getting the ball rolling

In countries far hotter than the UK, boasting temperatures that could melt tarmac, Ben’s developments already have exciting global potential: his passive cooling system will be used to keep the world’s most renowned footballers cool during Qatar’s 2022 World Cup.

He’s quick to highlight that this is the same system as FREECOOL – lowering the temperature of hot air from outside by passing it over heat pipes – just on a much larger scale. But there are clear challenges with delivering this kind of cooling to 40,000-seater stadiums in a country where even winter temperatures can reach 29°C. A gradual temperature transition from the hot outdoors to the cold stadium is vital to avoid people getting ill, while 90 full minutes of running, kicking and sweating means that players need to be kept at a lower temperature to the crowd. Even the wind blowing onto the pitch has to be taken into account so it doesn’t interfere with the ball during gameplay. All of this is controlled by giant plastic nozzles that are strategically placed throughout the stadium, complete with moveable parts to push the air towards a specific area.

The same technology is also delivering the first zero-energy cooled school in Abu Dhabi, which has inspired teachers and pupils at Shaikh Khalifa bin Zayed Bangladesh Islamia School to form a science club that teaches school children all about modernising traditional cooling systems in the Middle East. It’s an exciting prospect that a generation of budding young engineers, much like Ben himself, might one day emerge from a school club.

For the last 30 years we’ve been lazy. We just stick an air conditioning unit in because we know it’ll work and how much it costs, but as energy prices escalate we’ve got to find better ways of doing it.

Dr Ben Hughes

Reader in Energy at the University of Sheffield

Hot and bothered

What if we could warm the cool air we’re currently expelling from spaces using the same principles as FREECOOL?

Ben’s latest work is exploring whether the passive process behind his air conditioning could provide a cheaper, greener alternative to conventional heating.

The theory – currently being tested with prototypes in Sheffield’s Advanced Manufacturing Research Centre – is that heat recovery technology can be retrofitted onto existing ventilation structures called ‘wind towers’, which currently fulfill basic air circulation functions. You might’ve seen wind towers before (they look like vents and sit inconspicuously on top of buildings) and it was Ben himself who developed them during his PhD over a decade ago, after leaving school at 16.

“I took the PhD because it was an opportunity to make a building energy-efficient but using different technologies,” he reflects. “Since then wind towers have become a massive market, but the actual technology behind them hasn’t changed.”

Ben firmly believes this will have just as much impact as his work on the next World Cup: “We’ve got something that’s very easy, very simple and can reduce energy. I think it’ll be really good for the UK and could have a huge impact.”

Drastically lower energy consumption for both the sweltering hot and bitterly cold seasons without compromising on our own comfort could one day be a reality. But the prospect that energises Ben is potential for passive to appeal to pressing environmental concerns and consumers budgets.

No matter how sustainable we’re trying to be, that cost efficiency, Ben concludes, is where people’s interests really lie. “Nobody cares about energy. There’s nobody, myself included, who’s going to be convinced to turn the air-con or heating off in their house – we only care about how much it costs,” he says. “The higher the tariff goes, the more interested and more sustainable we’ll become. As long as you can show people that by investing in this system and learning more about how they use energy they’ll get that money back in a short period of time and be better off, you’re onto a winner.”

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