Heat pumps are getting hotter

Peter Apps

Heat pump manufacturers are closing the temperature gap with gas boilers, says Peter Apps.

Previously a major achilles heel of heat pump technology has been its inability to generate comparable temperatures to a gas boiler. A regular air source heat pump hits temperatures of around 55°C, but ran more efficiently at around 35°C to 45°C.

Gas boilers on the other hand get water up to a temperature of 60°C to 75°C, meaning the blast of heat out of the radiator in a gas home is much more intense.

This is something that has both put consumers off and meant that housing providers have needed to install insulation before making the switch to electric heat.

But newer models coming onto the market have narrowed this window. Vattenfall announced a product in January last year which could hit the same temperatures as gas boilers. The manufacturer, working in collaboration with Feenstra, recently completed a ‘soft roll out’ of the technology with Dutch housing providers.

“We can consider the soft launch a success, in that we were able to prove that the system performed in line with our initial claims,” a spokesperson told elemental. “At the moment we are still unable to say when we will be in a position to bring the system to the UK, but we know that it could be the solution to low carbon, gas free heating for thousands of homes.”

Other providers are moving in a similar direction: Daikin has had a higher temperature heat pump in its line up for some time, and there are believed to be other systems which are close to the market.

“We’re moving towards a market where heat pumps will be able to operate at high temperatures as standard,” says Daniel Logue, a consultant at Energy Systems Catapult, which has been carrying out an Electrification of Heat Demonstration project for the government.

The big question for providers of housing is should this impact their decarbonisation strategies?

Fabric first

Most are following a ‘fabric first’ strategy in which the initial focus is on improving the thermal performance of homes, before moving to heat pump roll out when this is done.

But if heat pumps can produce similar heat to a gas boiler, couldn’t we just jump straight to their installation – cutting millions of tonnes in carbon emissions as well as vastly reducing the cost of hitting Net Zero? The answer is a theoretical yes, but a practical no.

In theory, once a heat pump is producing the same levels of heat as a gas boiler, it could go into a home without insulation, or require less extensive retrofit.

“Advances in heat pump technology can potentially have an impact on the amount of insulation needed for retrofitting homes,” says Khalid Hamid, a researcher at the Norwegian University of Science and Technology, who has published academic papers on higher temperature heat pump models.

The Vattenfall spokesperson adds that while they “strongly recommend installing [energy efficiency] measures over time” its technology “can be installed in suitable homes without the need [for] costly insulation”.

“Fabric first provides a big consumer benefit, as well as lowering peak demand on the whole grid,” says Daniel Logue.

“But if we are looking at how to electrify all homes, there are examples where you would potentially be able to electrify the heat prior to fabric improvements or despite being unable to.”

Cost effective

This is where the higher temperature heat pumps may work. Indeed, the National Infrastructure Commission’s assessment of the UK’s Net Zero plans, published earlier this month, said: “Installing high temperature heat pumps could be more cost effective for homes [which are difficult or expensive to retrofit] than carrying out extensive energy efficiency improvements.”

The problem, though, is energy bills.

“Our advice is always put a heat pump in somewhere that’s fairly well insulated. Because otherwise it will cost the resident an enormous amount of money,” says Nicholas Doyle, a director at Adecoe. “Yes, they will deliver lower emissions than gas but they will definitely be more expensive to run. Electricity is still massively more expensive than gas and a higher temperature heat pump simply requires more energy. It’s just physics.”

This means housing associations – whose residents are particularly vulnerable to price rises – are unlikely to switch tactics any time soon.

“We’re looking at the best solution for tenants and the planet because ultimately, that’s what it’s all about,” says Sion Roberts, head of asset management at Grŵp Cynefin, a housing association based in Wales. “Electricity is more expensive than gas, so if we don’t worry about ensuring the house is well insulated then the tenant will be stuck with a more expensive form of heating. So it’s got to be a whole property approach.”

Insulation is important in keeping the cost of a heat pump down because it means the heat, once generated, will stay within the house for longer.

“Running a heat pump in a house without insulation is like turning a kettle on with the lid open. It just keeps bubbling away, it doesn’t stop” says Tom Boome, head of technical, innovation and climate at Welsh association ClwydAlyn. “It’s like that with a heat pump. If your home can’t retain the heat that is generated by the heat pump, it will keep on trying to top it up. The fabric first emphasis is like putting the lid on the kettle.”

Nigel Sedman, Executive Director of Homes at ForHousing, adds: “The most important thing for us is the running costs. At the moment if we put a heat pump in without doing that fabric first work, we’d get a major uproar from tenants saying their energy bill has doubled.”

Heating systems

This is not to say however that higher temperature heat pumps will be of no benefit. Aside from the insulation, the other major piece of work in terms of switching to a heat pump is changes to pipes and radiators to accommodate the new heating system. Higher temperature models could take this need away, and function more as a ‘drop-in’ solution. It may also change the resident’s experience for the better.

“If you could get an air source heat pump with a higher output temperature, I think that would address quite a number of issues especially with regards to using being able to use existing pipework,” says Sion Roberts. “Currently when you put in an air source heat pump physically the radiators have to become bigger, but to the touch the customer feels something that’s warm rather than hot. That’s always an issue psychologically, and potentially you can get quite a number of complaints from the customer to the call centre.”

The technology may also become more important down the line. Insulating some homes is going to be extraordinarily difficult. Solid wall properties, for example, where internal insulation would reduce floor space and external insulation is impractical face a very difficult journey.

As a result, some social landlords are considering selling them off. But this may be short-sighted. Higher temperature heat pumps are more expensive now because electricity is more expensive. But that is largely due to taxes and subsidies, which may be reversed over time. As the grid decarbonises, the reduced cost of producing electricity from the sun and the wind will also see electricity bills come down.

Hard-to-treat homes

It is a long road until 2050, and technology may yet provide solutions for homes which currently look impossible to decarbonise. With this in mind, selling them to the private sector may prove a mistake.

“The housing sector’s superpower is time,” says Nicholas Doyle. “It holds on to and manages homes way, way longer than anybody else. Victorian terrace houses or other hard-to-treat stuff might still be good homes in the right places for the people that we want to help. We can’t do those yet. But let’s wait and see if the technology can solve it later down the line.”

The recent advances in higher temperature heat pumps do at least show that this wait may not be forever.