Decarbonising our buildings: heat pumps or hydrogen for the future of heating?

In October, the Scottish Government released the Heat in Buildings Strategy: Achieving Net Zero Emissions in Scotland’s Buildings. The strategy presents the approach to achieving the target for net zero emissions from Scotland’s buildings by 2045 and is a key component of the government’s ambitious climate change targets for wider society.

In the same month, the UK Government also unveiled its eagerly awaited Heat and Buildings Strategy. This includes similarly inspired aims, such as the phasing out of all new fossil fuel based heating system installations by 2035.

The coinciding release of the strategies means that the journey to decarbonisation is gradually becoming clearer to the consumer. Both governments have indicated their ambitions to make housing greener.

However, they also recognise that there is no one-size-fits-all to decarbonising the tens of millions of homes with mains gas boilers. This transition will be hugely complex, most likely requiring multiple technologies and approaches.

Industry contest heating up

The major players in the UK’s domestic heating industry – believed to be worth an estimated £17 billion – are already moving to secure their role in line with the new government plans and commitments.

In the future, there will be little place for the out-of-favour gas boiler. Traditional boiler manufacturers are aiming to evolve and align their products for long-term security,  whilst the manufacturers of technologies in their infancy, such as heat pumps, are presented with an opportunity to reform the industry for good.

It’s led to the cottage heat pump industry facing off against the established big gas companies’ development of hydrogen ready gas boilers.

Heat pumps the main contender

Whilst no quick fix technology is currently available to replace boilers, heat pumps are undoubtedly a viable frontrunner. The electric devices are steadily growing in government promotion and consumer popularity, as sales more than doubled in 2021 to give the industry its best ever year.

And, as a key feature of the Heat and Buildings Strategy, homeowners in England and Wales will be offered subsidies of up to £5,000 from April 2022 as an incentive to convert their gas boiler to a heat pump.

Heat pumps extract energy from a lower temperature source such as the ground or air and increase it to an appropriate temperature for a heat source in the home – via a compressor and a circulating structure of liquid or gas refrigerant. This heat can either be directly blown into the property or transferred into the central heating and hot water systems.

The selling point of heat pumps is their potential to greatly reduce carbon emissions if they are powered by low carbon electricity, which much of the UK now is. A new air source heat pump can lower a home’s carbon emissions by over 23 tonnes over 10 years.

Whilst relatively novel, the technology behind air source heat pumps is well established with evident positives. They are typically safer than combustion systems, have a very long lifespan with little maintenance and can double up as an air conditioner during the summer months.

Despite the UK Government and Climate Change Committee (CCC) pushing heat pumps as a blueprint for decarbonising, they are not free of concerns and complications.

Heat pumps are expensive to buy and install upfront and, similarly to boilers, the cost can vary. According to the Energy Saving Trust, an air source heat pump will generally cost around £3,000- £4,000 for an average sized house pre-installation and around £7,000-£13,000 installed – raising concerns about affordability and the average consumer’s willingness to go green.

They are, however, very efficient once installed. With an average efficiency of 250%-350%, a heat pump is likely to save you money, compared to an old gas and oil-fired boiler or electric heating. In well-insulated homes, heating bill savings of as much as 60% can be achieved.

Sufficient insulation is a critical pre-requisite to heat pump success. Commenting on the release of the Heat and Buildings Strategy, the Green Party’s Caroline Lucas described placing heat pumps in Britain’s poorly insulated homes as like “using a teapot full of cracks: its leaky, its inefficient and it’s a waste of money.“

The UK’s housing stock is among the most poorly insulated in Europe and the current insulation of an ageing stock, like Glasgow’s Victorian tenements, poses a real barrier to the mass roll-out of heat pumps. Whilst heat pumps are suitable for older properties, consumers will need to commit to a considerable amount of insulation upgrades and home disruption to realise their benefits.

Hydrogen

An intriguing alternative that is in the developmental stages to replace gas is the use of hydrogen, the most abundant element in the natural world.

Hydrogen is already being heavily researched as a fossil fuel alternative in transport, and support for its role in heating is growing in popularity.

A study by the Institution of Engineers and Technology (IET) found that there is no clear reason as to why hydrogen gas cannot be seriously considered as a clean and safe alternative on the UK grid. Similar to heat pumps, hydrogen has the potential to be entirely renewable with no carbon emissions.

Hydrogen is also attractive as it requires minimal disruption in terms of new appliances and installation in the home. Consumers would use a hydrogen ready boiler that works almost identically to a traditional boiler. Likewise, the UK’s existing gas pipe system is well placed to make the switch due to the ongoing systematic replacement of old, unsuitable iron pipes over the last 20 years.

However, creating a new national network of hydrogen supply to the country’s homes would be a monumental and extremely expensive challenge that has never been done before. Concerns also exist around the extraction of hydrogen at this scale, as it is likely to be extracted from methane.

The extraction process emits carbon emissions which must be contained and stored through carbon capturing. Carbon capture projects of this scale do not currently exist and the idea is still under development, raising concerns around greenhouse gas emissions as a by-product of hydrogen extraction.

Final Thoughts

It is clear that the challenge of reducing building emissions is no longer just about grand intentions and targets. Whilst these are important to commit to, focus must now turn to ironing out the practicalities of how these will be achieved.

At the moment, the only established technology able to deliver clean heating is the heat pump. Yet, the UK has the worst heat pump sales and second worst installation record in Europe for a country its size. Technology such as hydrogen has potential but is still in the very early stages with many unknowns.

The UK must speed up investment in these industries to meet ambitious targets, with more detail, support and incentives for consumers.


Further reading: more on energy efficiency and decarbonisation from The Knowledge Exchange blog:

Close to home: getting to net zero means decarbonising the UK’s housing stock

Photo by Erik Mclean on Unsplash

Two years ago, the UK became the first major economy in the world to pass a law pledging to bring all greenhouse gas emissions to net zero by 2050. Achieving net zero means balancing the amount of greenhouse gases we emit with the amount we remove, and it’s a critical factor in tackling climate change by reducing global warming.

But, according to the government’s independent adviser on tackling climate change, the UK will be unable to meet the net zero target without the near-complete elimination of greenhouse gas emissions from 29 million homes. 

The necessity: why buildings need to be decarbonised

In 2014, emissions from domestic properties accounted for 34% of total UK greenhouse gas emissions. A combination of high energy prices and improvements in energy efficiency brought that figure closer to 19%. But those reductions have stalled, and because the UK’s building stock is one of the oldest and most energy-inefficient in Europe, the need to decarbonise is even more urgent.

The benefits: environmental, health, economic

While achieving net zero is one good reason for making our buildings more energy efficient, decarbonisation offers further dividends.

Energy efficient homes are cheaper to run, reducing the levels of fuel poverty that affect millions of households. They can also bring health benefits in the form of healthy air temperatures, lower humidity, better noise levels, and improved air quality.

In addition, a nationwide programme of decarbonising buildings could make a vital contribution to the recovery of the economy from the coronavirus pandemic. A recent inquiry by the House of Commons Environmental Audit Committee  (EAC) found that investing in energy efficiency alone could create 34,000 full-time jobs within the next two years. In the longer term, energy efficiency investment could support an estimated 150,000 skilled and semi-skilled jobs to 2030.

The problems: high costs, skills uncertainty and a “disastrous” insulation scheme

The UK government says the cost of decarbonising homes is between £35 billion and £65 billion. But the EAC believes that this seriously underestimates the cost of upgrading the energy efficiency of homes. With 19 million homes in England requiring energy efficiency installations, this could cost £18,000 per home, even before the installation of a heat pump.

Another area of concern is skills. Brian Berry from the Federation of Master Builders told the committee that every tradesperson in the country needs to be upskilled in retrofit techniques in order to secure overall competency in the supply chain:

“We need to upskill people in the building industry because there is a need to understand how their skills interrelate to one another. You cannot just pick out one bit of this. It has to be seen holistically, which is why I think there needs to be a national retrofit strategy, a clear political direction and a commitment to reducing carbon emissions in our homes.”

The EAC was also outspoken in its criticism of the government’s flagship home insulation scheme. The Green Homes Grant was launched in 2020 to offer £1.5bn in subsidies for insulation and low-CO2 heating. However, only 6.3% of the money has been spent, despite exceptionally high demand.

The committee said the scheme was rushed and poorly implemented, and described its administration as “nothing short of disastrous.” Just six months after its launch, the scheme has now been scrapped. Instead, energy saving upgrades and low carbon heating will be delivered to homes through local authorities in England.

The recommendations: strategies, incentives and insights from overseas

There’s no shortage of suggestions for driving decarbonisation forward. The EAC has called for a government strategy for the next decade to give industry and tradespeople time to upskill and to give households the right signals to invest in energy efficiency. The committee also recommends that VAT on the labour element of refurbishment and renovations is reduced to 5%, a measure also supported by the Royal Institute of Chartered Surveyors.

It’s also worth looking at ideas from overseas. In February, research by the University of Edinburgh reviewed the heat decarbonisations policies in nine European countries. The report highlights particular progress made by the Nordic countries in decarbonising buildings’ heat supply and in making greater use of electricity as a potential future source of low-carbon heating.

The solutions: putting promises into practice

While the challenge of decarbonising homes may be daunting, a growing number of housing providers are taking steps to cut emissions from domestic properties.

The Welsh Government has provided £20m in funding for Optimised Retrofit. Through this scheme, 28 social landlords can retrofit homes and test the ways heat and energy are produced, stored and supplied. If it’s successful, the scheme could be the model for decarbonising all of Wales’ 1.4 million homes by 2050.

Last month, Sutton Council launched an energy-efficiency programme to transform draughty properties with high energy bills into net zero carbon houses which are warmer and cheaper for residents. The programme is based on a successful Dutch initiative known as Energiesprong (energy leap). In the Netherlands, 1300 net zero energy refurbishments have been completed, and a further 500 are being built. The initiative involves insulating the external walls and roof areas, replacing windows and doors and installing new solar panels to power a new central heating and ventilation system. Sutton is the first London borough and the latest UK housing provider to adopt the programme, which has already been taken up in Nottingham and Maldon.

Many housing associations are at the start of their journey to net zero, but a National Housing Federation survey has shown that two thirds of social housing landlords have started planning to make their homes greener and warmer. Three quarters (74%) of survey respondents expect to retrofit homes in 2020-21. A similar proportion (73%) expect to retrofit homes in 2021-22. However, the survey also reported that lack of finance and continuing policy uncertainty remain major obstacles to decarbonising homes. That’s important, particularly given the cost of decarbonisation of social housing – £104bn by 2050.

The future: decarbonisation begins at home

Local authorities, housing associations, and the construction industry are all keen to transform existing homes into greener, warmer places to live in. At the same time, residents – especially those having to make the choice between heating or eating – need to be taken out of fuel poverty. And, as we’ve seen, achieving net zero will only be possible by making the nation’s housing stock more energy efficient.

With so much riding on decarbonisation of domestic properties, the need for more funding as part of an ambitious policy approach is clear. As the UK prepares to host the critical climate change talks in Glasgow this year, there has to be a better understanding that tackling the climate emergency starts on our own doorstep.


Further reading from The Knowledge Exchange blog on housing and energy efficiency