Buildings – The Achilles Heel of Net Zero
No matter the pious pleas for more action to achieve a net-zero emissions economy for 2050, the world is simply not going to get there. Indeed, it is going to fall far short.
In some areas, people overstate the progress that has been made, proclaiming, for example, the few minutes at a time when wind (mainly) and solar provide for our electricity needs. No-one caveats such claims with the highly restricted conditions, or notes that electricity is less than a quarter of our total energy use.
Gas provides the bulk of our electricity at times – the majority – when the wind is not blowing sufficiently, or at all. That is unlikely to change in the foreseeable future. Electricity storage, the carbon-free alternative pushed by Net Zero advocates, is currently a pipedream because it is far too expensive. Most serious analysts think we will still rely on gas for much of our electricity in 2050.
Even if we retain gas-fired power for when the wind isn’t blowing, Net Zero looks unachievable. So far we have partially decarbonised the grid and little else. If the whole economy – heat and transport and all the rest – is to be weaned off fossil fuels, the generation capacity of the grid will need to triple. Investment in generation capacity from 2030 to 2050 will need to be twelve times higher than over 1990–2020. Investment in grid infrastructure will need to grow almost as much.
In other words, the decarbonisation spending spree, which is already causing severe pain across the economy, will have to be hugely expanded.
If there was enough green electricity to go round, we would not have to worry much about energy efficiency. But it is precisely because of the green electricity shortage and its high costs that we have to worry about the efficient use of energy in buildings.
Buildings are, and have always been, major sources of carbon dioxide emissions. In 2020, they represented about 44% of UK emissions, almost unchanged since 1990.[1] However, over that period the volume of emissions has halved, from 600 to 300 MtCO2e (million tonnes of carbon dioxide equivalent).[2] If we were to continue to improve the energy efficiency of buildings at the same rate, we would just about reach the target.
But that is a big if. All the easy things have been done: industry has almost all gone offshore, a decade of austerity and steep rises in energy prices the last few years have resulted in sharp demand reduction. This has been painful: industrial and public services output have both been constrained, the economy is less healthy and, as a result, there is less money available for investment in the energy transition.
The amount of money that will be required to complete the task of decarbonising the building stock is extraordinary. Consider first what is needed for retrofits. A major pilot project, focusing on 45 social (smaller than average) houses during 2009–2012, achieved a 60% average reduction in CO2 emissions at an average expenditure of £85,000 each. Achieving a 100% reduction in all 26 million homes and also all the other buildings in the country (offices, hospitals, hotels, warehouses etc) might therefore cost over £4 trillion. Efficiencies and learning might – optimistically – half that figure.
However, the limiting factor is not actually money, but human resources. Based on 100 person-days per house, we would need of order 300,000 retrofitters for the next 30 years. The requirements for related manpower in the supply chain and design teams might take the number towards 500,000 – as many as work in the whole education sector.
In spite of 20 years of warning, there has been no substantial recruitment into the retrofit sector needed to get the job done. The national retrofit project has been much talked about, but is not being undertaken at the scale needed to achieve Net Zero.
New buildings must also be considered; demand for housing is already very high, creating an urgent requirement for extra resources that is in direct competition with the Net Zero project.[3]
These new buildings either replace old ones or expand the housing stock. Replacing 1% of the homes more than a century old, and 0.5% of those built in the interwar years suggests we need to replace nearly 300,000 new homes per year just to stand still. But the annual increase in population is about 1%. If we are to maintain the UK average household at around 2.35 people, we must build another 300,000 homes per year, for a total of 650,000 homes per year. for the next decade. The average rebuild or replacement cost for a house (excluding land and utilities) is about £290,000 for a two- bedroom house or £340,000 for a three-bedroom one. That means that 650,000 homes, at current prices) will cost over £160 billion per annum up to 2035, or 6–7% of GDP. If these are to be Net Zero homes, they may be around 20% more expensive.
Currently we spend less than £60 billion per year on new homes!
And even if the finance could be found, the 1.5 million workers required will not be. This is equivalent to the numbers working in the NHS. All this has to be found within existing resources.
When the whole housing sector is taken together, retrofit and new build, it is impossible on four grounds, finance, human resources, materials and public buy-in, that a Net Zero target will be achieved by 2050. Even a command economy will not be enough, as the training of the required professional and skilled trade engineers will take far too long starting from now.
Acknowledgement
I thank Gordon Hughes for material in the 2nd half of this paper, and Andrew Monford for editing and publication.
Notes
[1] The presentation of data has changed over the years. In 1990, 45% of carbon dioxide emissions came from heating air and water in buildings (28% in residential buildings and 17% in commercial and industrial buildings (excluding industrial processes)). In 2020, the combination of emissions from residential and commercial buildings and half of the emissions from electricity used in buildings comes to 44% of the UK emissions, pretty much the same. See 2020-final-greenhouse-gas-emissions-statistical-release.pdf (publishing.service.gov.uk).
[2] Final UK greenhouse gas emissions national statistics: 1990 to 2020 - GOV.UK (www.gov.uk)