News on Surrey's Greener Future

This blog is part of a new series written by Surrey residents who will be sharing their personal experiences of making changes to reduce their carbon footprint. We hope the blogs will provide other people with inspiration and guidance to make changes of their own. If you think you would like to contribute, please submit an expression of interest via this form.

Ken from Buckland shares his experience of installing renewable heating in an older house.

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Most of us now are thinking about how to reduce our carbon emissions but find it hard to know what we can do that will have the biggest impact. Reading up on this, we came to realise that, for most of us living in larger or older houses, the biggest thing we can do to reduce our carbon emissions is to switch to renewable heating in our house. This led us to install an air source heat pump at our house in 2020, to replace our old gas boiler.

What is renewable heating?

There are a few options for renewable heating of houses but the one that is likely to be most suitable for most people (at least for the next ten years) is installing a heat pump. A heat pump draws heat from the air (even when it is -10 outside!) to heat your house. There are two main types of heat pump – ground source and air source. Ground source heat pumps are more expensive to install, and usually require a large area of land outside to install them on, so an air source heat pump is likely to be a more practical and affordable solution for most houses.

An air source heat pump is a box a bit like an air conditioner that is installed outside your house (usually against an external wall). They are very widely used in other European countries (including in Scandinavia), but have until recently been very little used in the UK.

Air source heat pumps use some electricity, but modern ones produce about 3.5 kWh of heat for each 1 kWh of electricity drawn from the grid, drawing the rest from the air. They will normally replace your gas or oil boiler and provide both central heating and hot water for your house.

Is it suitable for an older house?

Our house is an old four-bedroom house, originally built in the 1860s and extended twice during the 1970s. The older part of the house is solid wall construction. We therefore use a lot of energy to heat our house . We had heard that heat pumps may not be suitable for older and larger houses, or that they may need supplementary heating, but we learned that they can work well in many older and larger houses.

The industry standard for heat pumps is that the system should be specified so that it can heat your house to 21 degrees when it is -3 degrees outside, so provided it is properly specified, it should not require supplementary heating. Our experience over the first year of using it is that the house has remained cosy throughout the winter (including down to a temperature of -7 degrees outside).

Does your house need to be well insulated?

As with traditional gas boilers, it makes good sense to do what you can to improve the insulation in your house to reduce your heating bills. Good insulation helps heat pump efficiency, so If you are considering a heat pump, it makes sense to do this before you install it.

To be eligible for the current government grant, any cavity walls in your house need to be insulated, and your loft insulation needs to be up to modern standards. We’ve done this in our house, but we still have uninsulated solid walls in the older part of the house, and single glazing, as we found that it would be very expensive to do these while maintaining the character of our house.

Will a heat pump work with my existing radiators?

Heat pumps provide a gentler heat and normally work most efficiently by maintaining a constant temperature in the house 24 hours a day. To keep the house cosy with the gentler heat can require upgrading some of your radiators - this is worked out by the installer for each room in the house. In our case, we upgraded about half of our radiators (because they are a modern design, they are not actually bigger than our old radiators).

Is it noisy?

We’ve hardly noticed it. Modern heat pumps are now much quieter – they make about the same noise as a fridge, so are unlikely to be heard inside the house. When it is warm enough for you to be sitting outside the house, it is very unlikely that the heat pump will be running.

What is involved with installation?

Heat pumps are installed by specialist heat pump installers, who should be certified by the industry body (MCS). The certified installer will come and do a survey of your house and recommend a specification for a system to meet your needs (including new radiators if needed), and provide you with a quote for the work. They should also advise you if your house is not suitable for a heat pump.

As this is a fast growing industry, some certified installers have less experience than others, so it makes sense to look for installers who have installed many systems in houses like yours, and to check references. We invited three experienced installers to quote for the work.

In most cases, planning consent is not required, but you should check with your local council.

What does it cost to install?

The cost of installing a heat pump will depend on the size of heat pump needed for your house, the detailed layout of your house, and whether you need to upgrade radiators or hot water tank. In a typical house, an air source heat pump can cost £6-8,000. As an older and larger house, we needed a larger than normal domestic heat pump (14 kW), and the installation cost was c. £11,000. With new radiators, the total installation cost came to c. £13,000.

This is considerably more than the cost of a new gas boiler (typically c. £3,000), but to offset the cost, the government offers grants under the Renewable Heat Incentive scheme (correct at the time of writing). The grant available varies with the size of your system, but should cover most of the cost, and is paid over seven years. In our case, we will receive a total grant of around £9,000, which brings it close to the cost of a new gas boiler in the end, although there is a higher initial cash outlay.

What does it cost to run?

Most modern heat pumps will provide c. 3.5 kWh of heat for each kWh of electricity drawn from the grid, with the rest coming from the air (free!). A modern gas boiler will provide about 0.9 kWh of heat for each kWh of gas used. However, at present, 1 kWh of electricity is around four times the price of 1 kWh of gas, so the energy costs are likely to be similar to a new gas boiler. If you are replacing an old gas boiler, or an oil boiler, you are likely to see significant savings – in our case we reduced our energy bills by around 20%.

More recently, we have achieved further savings by using one of the new off-peak tariffs (available from a growing number of electricity suppliers) and timing our hot water to heat overnight using this cheaper tariff.

Air source heat pumps are simple to maintain and an annual service is usually recommended. The cost is likely to be similar to the cost of an annual service of a gas boiler.

What impact will it have on my carbon emissions?

If you own an older or larger house heated by gas or oil, it is likely that the carbon emissions from heating your house will be the biggest single component of your household emissions.

On the basis of the current mix of fossil and renewable energy in the national grid, installing a heat pump should reduce the carbon emissions from heating your house by around 85%. This should improve further over time as more of our national grid energy comes from renewables. If you use a green energy supplier, it will reduce it even further, to close to 0.

Useful Links for Further Information:

• Energy Saving Trust: Useful information on how heat pumps work, costs and benefits, government grants, etc.

energysavingtrust.org.uk/advice/air-source-heat-pumps/

• Government’s Renewable Heat Incentive scheme:

ofgem.gov.uk/environmental-programmes/domestic-rhi/about-domestic-rhi

• UK Committee on Climate Change (for evidence on need for wholesale shift to renewable heating in UK homes)

www.theccc.org.uk/publication/uk-housing-fit-for-the-future/

• UK Planning Portal on installing heat pumps Planning Permission: Air source heat pump | Heat Pumps | Planning Portal