Dear Editor,

THE announcement this week of our government’s Net Zero Strategy, detailing its commitment to reach net zero emissions by 2050, contains a hasty and ambitious investment in heat pumps with a target of 600,000 heat pump installation s each year by 2028 in the 24.5 million homes that need them.

I say hasty because the government’s Department for Business, Energy & Industrial Strategy (BEIS) chose three private sector partners in June 2020 to install 750 heat pumps in a feasibility trial costing around £14.6M. This ‘Electrification of Heat Demonstration Project’ (EofH) is still ongoing having been delayed by Covid-19 and according to E.ON would conclude in March 2022.

E.ON, OVO Energy and Warmworks will each install 250 heat pumps free of charge in Newcastle, South East England and South East Scotland respectively. The trial’s main project objective is to “develop, test and evaluate innovative products and services that increase the appeal of heat pumps and identify optimal solutions for a wide range of homes.” So, why not wait for the project’s conclusion?

The downsides of heat pumps are well known by the government’s BEIS which they highlighted in a briefing with the heating industry in May. Housing Today summarised the meeting with this sensational leading paragraph:”Heat pumps could cost homeowners up to £35,000 each, can emit noise which breaches legal limits and could increase fuel bills, the government has admitted.”

One of the key downsides to combi-boiler owners, around 17 million of them, is that they will have to reinstall a hot water cylinder for the heat pump, this time in the form of a thermal store. Also, because the water temperature from the heat pump is lower than a gas boiler it will require larger radiators, in some cases upgraded to triple panel.

A key problem for new-build home owners is the use of 10mm microbore pipe via manifolds. The flow rates for heat pumps tend to be greater than for the equivalent size of other heating devices. This is due to the relatively low temperature differences between flow and return pipes. Higher velocity water flows rule out using microbore pipe. 

Often these pipes are installed behind dot-and-dab plasterboard walls. The choice then becomes cutting through the walls or installing surface mounted pipework. 

Also, the energy suppliers cabling and fuse in homes may also need to be upgraded from 30/60 to 80/100 amps, which was an issue found in the EofH project. This can extend the typical install duration of 2.5 days as a 10 day notification period is required by UK Power Networks.

The downsides of heat pumps were well explained in a YouTube video in January on the Skill Builder channel, run by veteran construction journalist and heating engineer Roger Bisby, in his interview with Martyn Bridges, Director of Marketing and Technical Support for the Worcester Bosch Group which manufactures both boilers and heat pumps. YourHarlow readers may wish to view this video through the following link: https://youtu.be/4uNKPDREa-Q

If heat pumps are not the panacea the politicos, Twitterati and Eco Warriors believe they are, then what else? Well Roger and Martyn discuss hydrogen boilers. Worcester Bosch and other manufacturers make hydrogen-ready boilers which will run happily on 20 percent hydrogen in the gas supply without modification. To operate on 100 percent hydrogen boilers will require the change of just three components costing around £150. The challenge is to ramp up green hydrogen production. 

Getting full scale hydrogen production will be more than a decade away at the very least, but meanwhile we can improve the insulation of homes. The United Kingdom has the oldest housing stock of EU Member States, with nearly 38% of its homes dating from before 1946 according to the Building Research Establishment. Compare this with 24.3% for Sweden, which is often praised for its heat pump installations and has much better standards of insulation, including triple glazing, which have long been the best in Europe.

Even in the New Towns like Harlow some solid-walled housing was built to save money and I know of some in Old Harlow built using thin timber framing. Heat Pumps may be flavour of the month for Greta Thunberg fans, but the large installation costs, ranging from £7,000 to £12,000 with an average of £9,488 more than a gas boiler replacement according to the Carbon Trust, may be a serious deterrent for low-income households. 

Perhaps a more nuanced approach would be to cut boiler heating costs by ensuring the correct sizing of boilers, better insulation, reduction of limescale in hard water areas (British Water calculated reduced boiler efficiency of 12% for each 1.6mm of scale), improving heating temperature controls, installing triple glazing and solar collectors in existing housing alongside heat pumps in new buildings until hydrogen can be brought on stream.

Unfortunately, our Tory government has set poor targets for low carbon hydrogen production in its Net Zero Strategy with a target of 5GW by 2030, which is pitiful given its target of 40GW for offshore wind by 2030. Whilst the government’s strategy is a step in the right direction it fails to deliver a realistic vision for bold reductions in carbon emissions. However, it may do just enough to undermine the case of protesters glueing themselves to motorways which will please motorists.