Home energy: What is hybrid heating, is it green and how does it work?

When considering how to heat your home, it’s not a binary choice between a fossil fuel boiler or an electric heat pump, according to Wolseley Group’s Nick Coad. He explains how hybrid systems which combine both technologies can bring the energy-efficiency and ecological benefits of heat pumps while retaining the assurance that comes with gas-fired heating when the mercury drops below a certain point.

Home heating is responsible for a stubbornly high proportion of greenhouse gas emissions in Scotland and the UK. So it has become a particularly hot topic of conversation in recent times, given soaring energy costs and the drive to reach net zero.

But while many homeowners would likely say the choice comes down to whether to stick with gas for as long as possible or change to a newer electric heat pump system now, there has been little talk so far about hybrid heating systems, which combine a smaller heat pump with a conventional gas boiler.

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The future of gas boilers has been in the spotlight in recent weeks, with the Scottish Government announcing a ban on their installation in all new buildings from next year to help reach carbon neutrality by 2045. As yet, however, there are no rules forcing householders to switch away from gas or to stop people upgrading an old system.

So for millions of existing properties that are already heated by gas, a hybrid scheme is something of a half-way house: bringing the environmental benefits and typically lower running costs of heating by heat pump, but with the back-up of gas for colder days. And it’s usually cheaper to install.

Hybrid systems are essentially like a conventional heating system – featuring a gas boiler, central heating and pipework to supply hot water, but also have a small heat pump attached.

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Most of the time, the heat pump – which runs on electricity – keeps the water warm in the radiators and the system will automatically vary the heat depending on the outside temperature. But if the outside air temperature drops to a point at which the heat pump would struggle, the boiler kicks in instead. And the hybrid control system automatically selects the cheapest and most efficient energy source, based on the current tariff.

While hybrid systems are a little more expensive to buy than conventional gas heating – around £6,500, compared to a ballpark of £3,500 for gas-only – and still use the gas boiler to provide hot water, for most homes they will be considerably cheaper to install than full heat pump alternatives, which will typically set you back £11,000 or more. Hybrids can also save money on energy bills.

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Much of Scotland’s housing stock is old or in tenement blocks, which can be more difficult to fit out with a full heat pump system. This ‘third way’ of heating gives householders an extra choice. It is also an important option that can help drive decarbonisation of domestic heating and allow homeowners time to invest in other energy-saving measures such as insulation.

Nick Coad is director of innovation at Wolseley Group, which specialises in plumbing, heating and cooling systems

For homeowners, hybrids can typically be ‘retrofitted’ onto existing central heating and plumbing systems, often with no need to change radiators or add to insulation, significantly reducing disruption on installation.

An additional benefit is that hybrids are easier for the installer to size properly, meaning that heating engineers who spend most of their time dealing with gas-fired heating will need as little as a day’s training to be able to fit hybrids too.

Many householders and landlords want to switch from gas but are put off by the purchase and installation costs of heat pumps, and concerns about whether their homes will stay warm. Hybrids are an ideal bridging technology to sustainable home heating.

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In time all heating systems will use fully sustainable energy sources, and gas boilers will be phased out as the country transitions to a more environmentally friendly way of life.

In the meantime, hybrid systems can play an important part of achieving the scale of transition the government has set in motion. They offer a new alternative for people wanting to take a step into renewable heating and reduce their energy bills, but without losing the reliability and familiarity of the gas boiler.

Nick Coad is director of innovation at Wolseley Group, which specialises in plumbing, heating and cooling systems