As we seek ways to lower carbon emissions in our homes, we need to switch from heating that relies on high-carbon fuels to cleaner, low- or zero-carbon alternatives. Here we explain how heat pumps work and their potential to help us transform how we heat our homes and businesses in the future.
Heat pump is a term you’re going to be hearing a lot of from now on. That’s because heating our homes and businesses accounts for 37% of UK emissions and 85% of our homes are heated with gas. Switching to cleaner, low-carbon options will play a critical role in tackling climate change.
In the run up to net zero 2050, we’re going to see a transformation in the way we heat our homes. The challenge is sizable – over 20,000 homes every week will need to switch to a low carbon heat source between 2025 and 2050.
In simple terms, a heat pump takes heat from the ground or air around a building and increases it to a temperature that keeps homes and businesses warm inside.
They’re set to become much more common in the future. According to government figures from 2020, there are currently around 1.7 million gas boiler installations every year. But, by the mid-2030s, the aim is for all newly installed heating systems to be low-carbon or have the potential to be converted easily to a clean fuel supply.
Recently, in the Energy White Paper 2020 the Government outlined its ambition to increase the installation of heat pumps from 30,000 a year to 600,000 a year by 2028, to accelerate the decarbonisation of heating.
When it comes to heating, think of a heat pump as a refrigerator working in reverse – instead of keeping your veg and dairy products cool, it’s warming your home using a refrigerant, which can evaporate into gas and condense into liquid.
A heat pump works like this:
As the ground and air outside always contain some warmth, a heat pump can supply heat to a house even when it’s cold. It’s important that good energy efficiency is installed in homes so that heat pumps can work at their best.
An air-source heat pump takes heat from the air and boosts it to a higher temperature using a heat pump.
There are two main types of air-source heat pumps – air-to-water and air-to-air. Air-to-water heat pumps take heat from the outside air and feed it into your wet central heating system (similar to existing gas central heating). As the heat produced is cooler than that from a conventional boiler, you may need to install larger radiators or underfloor heating in your home to make the most of it. Air-to-water heat pumps may be best suited to new-build properties or those that are energy efficient.
Air-to-air heat pumps take heat from the outside air and feed it into your home through fans. This type of system can be used for heating but can’t produce hot water.
A ground-source heat pump system harnesses natural heat from underground by pumping water through it in pipes. The heat pump then increases the temperature and the heat is used to provide home heating or hot water.
The pump performs the same role as a boiler in a central heating system. But it uses ambient heat from the ground, rather than burning fuel to generate heat.
Ground-source heat pump systems are made up of a ground loop (a network of water pipes buried underground; the larger your home and heating needs, the larger the loop) and a heat pump at ground level.
A mixture of water and anti-freeze is pumped around the ground loop and absorbs the naturally occurring heat stored in the ground. The water mixture is compressed and goes through a heat exchanger, which extracts the heat and transfers it to the heat pump. The heat is then transferred to your home heating system.
You can then use this heat in a radiator, for hot water, or in an underfloor heating system.
A hybrid heat pump system, also called a dual energy system, integrates a heat pump (air source or ground source) with your traditional gas boiler heating system, or potentially even your hydrogen boiler in the future.
A hybrid heating system monitors the temperature outside and automatically chooses the most energy efficient option to keep your home consistently warm and your hot water running.
Yes, taking heat from the air or ground in a constant cycle is sustainable and renewable, with low or no CO2 emissions.
Yes, heat pumps do use electricity but they can produce two to three times more heat output than they consume in electricity input.
Heat pump systems are designed to efficiently extract a greater amount of heat energy from the surrounding environment than the energy they consume to create heat.
Also, electricity generation is progressing towards net zero and has already decarbonised by 66% in the last seven years. Last year (2020) was the greenest year on record, with renewable energy like solar and wind increasingly powering the system.
Yes, the heat pump cycle is fully reversible and heat pumps can provide year-round climate control indoors – warming in winter and cooling in summer.
According to the government’s Energy White Paper, fewer than one per cent of homes in England currently use a heat pump. So clearly the pace of change and scale needs to pick up in this home energy transformation. There is no ‘silver bullet’ for home heating, as different low-carbon heating solutions may be required for different types of buildings and locations. Heat pumps are expected to make an important contribution to decarbonising heat.
Our own research, which investigated what matters to consumers in the transition to lower-carbon heating, has highlighted the knowledge gap between good intentions and daily lives; 93% of people said climate change was a serious or very serious issue but only 5% identified heat as a main contributor to the UK’s carbon emissions.
That said, heat pumps are set to become one of the new clean alternatives to fossil fuels alongside biomass boilers, which burn plant-based materials like wood pellets, hydrogen boilers and heat networks for densely populated areas, like the one our Innovations team is currently prototyping.
It’s likely that homeowners will be offered a mosaic of solutions, including heat pumps, rather than a one-size-fits-all decarbonised heating solution.
Our research found that key to the home heating transformation will be:
Read more about the future of heating and our recommendations