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Cutting carbon

Heat pumps: low carbon home heating

Illustration of a homeowner outside her house looking lovingly at a heat pump.

Heat pumps are a greener way of heating our homes - and demand for them has soared in the first half of 2021. Could this be the end of the big British love affair with gas boilers?

One of the biggest challenges for decarbonisation in the UK is changing the way we heat our homes, which accounts for around 14% of our total carbon emissions. In a bid to move away from gas-dominated set ups, the International Energy Agency (IEA) has already recommended a ban on new gas boilers from 2025

Heat pumps can warm homes around the country without the need for fossil fuels. In fact, the Climate Change Committee (CCC) has said that 5.5 million heat pumps need to be installed before 2030 for the UK to reach net zero by 2050. But heat pumps are still unfamiliar to lots of us. So, how do they stack up?

Heat pumps work like a fridge in reverse 

While traditional heating systems burn fuel, heat pumps use electricity to move existing heat energy from outside your home to inside it. Heat pumps transfer thermal energy from a heat “source”, like the air or ground outside, to a heat “sink” like your home’s hot water tank. 

Diagram showing an air source heat pump using refrigerant to absorb heat from the air.
Diagram of a ground source heat pump absorbing heat through underground pipes.

They're more efficient than oil and gas boilers 

Heat pumps are very efficient, producing 4 kilowatts of heat for every 1 kilowatt of electricity they use. And green electricity is readily available to run heat pumps in homes across the UK.

A well-installed heat-pump needs little maintenance, and has a lifespan of around 20 years. You need a bit of garden space to install a ground source heat pump, but air source ones are about the same size as an air conditioner unit. 

Speaking of air conditioning, heat pumps can cool your home during the summer, too. They do this either by removing warm air from the building (‘passive cooling’) or by generating chilled water or air to cool your home (‘active cooling’).  

Heat pumps heat your home gradually, over a longer period

Boilers are designed to be reactive, reaching temperatures of 60-80°C by burning fuel on demand to heat your home or hot water. In contrast, heat pumps use less energy because they operate most efficiently between 35-55°C. Heating your radiators at slightly lower temperatures over a longer period of time is a much more efficient way to warm your home.

Heat pumps may not be suitable for everyone just yet

The UK has some of the least energy-efficient housing in Europe and two-thirds of UK homes are currently rated D or below on their Energy Performance Certificate (EPC). Homes will need to become better insulated to meet net zero, independent of heating technology - but a poorly-insulated house needs a bigger heat pump, so it costs more to install and run.

Heat pumps can be installed in buildings of any age, but because they run at lower temperatures, they aren't a like-for-like replacement for gas boilers or conventional electric heating. They’re a great solution for underfloor heating systems, or well-insulated homes with standard-size radiators. But if you have particularly small radiators, it'll be harder to feel the benefit.

The Renewable Heat Incentive is a government scheme to save on the cost of installation

Heat pumps have a relatively high upfront cost. An air source heat pump will usually set you back between £6,000 and £8,000, including installation. A ground source heat pump involves a lot of digging, so the installed cost is higher.

The Renewable Heat Incentive (RHI) can help offset the cost of your heat pump installation through quarterly payments over seven years. You can see how much you could receive through the Government's RHI calculator. This scheme closes on 31 March 2022. The Clean Heat Grant, which provides a grant of up to £4,000 to install a heat pump, is proposed to replace it.

The RHI works differently to other European incentives.The European Heat Pump Association (EHPA) reported that by the end of 2020, there were 14.84 million heat pump units installed in 21 countries. France and Germany are in the top 3.

The French Government has reduced taxation on less carbon-intensive fuels and removed tax exemptions for high-carbon products. The CITE (Tax Credit for Energy Transition) covers up to 30% of capital costs of energy-efficient and renewable energy equipment, and 0% interest loans are available for insulation and renewable energy equipment.

Germany has successfully transitioned away from oil towards heat pumps, particularly in new builds and district heating. The 2019 Climate Policy Package bans the installation of oil heating systems in new and existing buildings after 2026. The KfW development bank also offers grants and low-interest loans (up to € 30,000) for low-carbon heat investments. 

Heat pumps could reduce CO2 emissions in the UK, but they need a few cheerleaders

Decarbonising our heating isn’t just a win for the climate, it could potentially lead to lower bills, warmer homes and the creation of jobs in the industry. 

With around 86% of properties currently using a gas central heating system,and a limited number of workers skilled in heat pump installations, decarbonising home heating is no small task. Heat pumps are a neat solution, but of course they’re only green when they use electricity from renewable sources, like the power we supply our members at Bulb. The IEA’s ban on new gas boilers from 2025 will go some way to raising awareness of alternative heating technologies. 

Some interesting new research by the University of Sussex Business School suggests "enthusiastic" heat pump users willing to share their experiences are vital to meet the government's goal. This follows a study where 1 in 3 homes in Finland claim a crucial factor in their decision to get a heat pump was seeing others posting on internet forums about their experience. 

And in that spirit, we want to hear your thoughts and questions about heat pumps over in the Bulb Community

By Cara Sloan and Melisa Gooding