Guest post: insulate Britain or miss net zero

Jack Marley, The Conversation

The UK is failing to enact the policies that would put it on track to reach net zero emissions by 2050, according to a progress report by the Climate Change Committee. The head of this expert body, which advises the government on its climate strategy, described the UK’s record on home insulation in particular as “a complete tale of woe”.

Gas heating in draughty homes is one of the country’s biggest sources of carbon emissions – and a leading cause of poor health and poverty as energy prices remain sky-high. So what would it take to turn this around?

“The transition to net zero emissions is often framed as a race to make new stuff – such as electric vehicles and wind turbines – as fast as possible,” says Ran Boydell, a visiting lecturer in sustainable development at Heriot-Watt University.

“That’s actually the easy part. The hard part will be modifying what already exists – and that includes people’s homes.”

Cavity wall insulation, triple-glazed windows, solar panels, low-carbon heating systems such as heat pumps which run on electricity: all of these things and potentially more are needed to neutralise the contributions to climate change made by 26 million homes (the number of existing homes Boydell anticipates will still be around in 2050). That would eliminate 68 million tonnes of CO₂, which is about 15% of the national total.

“The idea is to ensure that no home emits greenhouse gases by burning fossil fuels for energy and that, eventually, each home could produce as much energy as it uses,” Boydell says.

According to analysis by the Climate Change Committee, the average cost of retrofitting a single home to net zero standard is £26,000. Energy savings would make up for this after 20 years, but most households would struggle to make such a big upfront investment.

“Considering energy efficiency measures purely in terms of financial payback will never stack up,” Boydell says. “They must be considered in terms of carbon payback. Carbon payback is how quickly the reduced carbon emissions from daily life in a net zero home take to make up for the carbon emissions that went into making and building all the different parts.”

A home operating at net zero standard would compensate for the carbon that went into building it after just six years, Boydell estimates. But it’s the responsibility of the government – and not individual homeowners – to juggle these considerations, he says.

“Infrastructure, like roads and railways, is the only stuff people build which counts its payback periods in decades. The government needs to think of a mass retrofit programme for our houses in those terms: as critical national infrastructure.”

Fund, regulate and overhaul

Matthew Hannon and Donal Brown study green policy at the universities of Strathclyde and Sussex. They say that:

“At an absolute minimum, the government should be aiming to install insulation in 1.3 million homes a year – a rate it managed pre-2013.”

To reach that level, Hannon and Brown have four suggestions. First, increase annual funding for retrofitting homes from £1 billion to £7 billion – enough to retrofit 7 million homes by 2025, they claim. Next, shift the burden of raising this money into general taxation and away from energy bill levies which strain the poorest households and inflate the cost of heating homes with zero-carbon electricity.

Insulating hundreds of homes at a time, neighbourhood by neighbourhood and coordinated by local authorities, could help to retrofit housing deeper and faster than tackling homes one by one,” they say. For this, collaboration with local groups and businesses who know the community well will be key. Hannon and Brown argue the government will also need a separate, well-funded programme to install heat pumps and other low-carbon heating systems, while phasing out support for gas boilers.

An engineer adjusts the external fan unit of a heat pump on the side of a house.
Heat pumps, if powered by renewable electricity, can decarbonise heating. I AM NIKOM/Shutterstock

Once a national campaign to renovate Britain’s homes to net zero standard is underway, there are certain to be teething problems. The Labour Party offered a comprehensive programme of home insulation at the 2019 election. At the time, Jo Richardson, a professor of housing and social inclusion at De Montfort University, and David Coley, a professor of low-carbon design at the University of Bath, described the obstacles that will need to be overcome.

“The UK construction sector is highly fragmented – and different subcontractors are often responsible for the walls, roof and electricity in a single house. This makes quality control difficult. There’s also a skills shortage, especially when it comes to the detailed knowledge required to build a zero-energy house. And if energy-consuming extras such as underfloor heating or electrically driven windows are added, the energy savings from design may be lost,” they say.

The Climate Change Committee noted that new homes are rarely net zero standard, with 1.5 million built in recent years that will need to be retrofitted. The preferred solution for Richardson and Coley is to mandate each new home to Passivhaus standard, which certifies that it produces as much energy as it uses.

“Passivhaus only works if the right design decisions are made from day one,” they caution. “If an architect starts by drawing a large window for example, then the energy loss from it might well be so great that any amount of insulation elsewhere can’t offset it. Architects don’t often welcome this intrusion of physics into the world of art.”

Increased funding, new regulations and an overhaul of architectural norms will be necessary to roll out zero-energy homes and retrofit existing ones. “That’s a tall order,” say Richardson and Coley. “But decarbonising each component of society will take nothing short of a revolution.”

Jack Marley, Environment + Energy Editor, The Conversation

This article is republished from The Conversation under a Creative Commons licence. Read the original article.

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

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: