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Embodied carbon can't be ignored

Planning consultant Daniel Scharf argues that net zero targets mean a focus on delivering 300,000 homes a year in England must be questioned

A number of recent reports have explored carbon accounting in housing delivery, finding that new housebuilding comes with major carbon costs.   The investigation starts with the Whole life carbon assessment for the built environment 2017 produced by the RICS, which found that 50% of carbon emissions attributable to housing are embodied at the stage of practical completion i.e. before occupation.  This forms part of the evidence being used by the Committee on Climate Change in its report Fit for Purpose 2019 and the UK Green Building Council’s Framework Definition for Net Zero Carbon Buildings 2019.  Even the NHBC have agreed that about 50% of carbon emissions are attributable to new housing.

This is a challenge to those who think that building 300,000 new dwellings in England each year is the way to address the housing crisis/shortage, particularly if these involve new settlements.  The carbon emitted in the construction of new houses, and other buildings and associated infrastructure, has to be reduced to close to net zero during the next decade.  Furthermore, buildings may represent the best chance of reaching ‘carbon negative’ given the problems being faced by transport, manufacturing, power generation, agriculture and the military. Finally, climate justice dictates that the UK has to lead while expecting less from countries that never benefitted to the same degree from cheap fossil fuels.

If new housing is to continue, there will have to be a scaling up of the use of timber (subject to trusted sustainable supplies), stone, slate, lime based mortar and renders, and low carbon Modern Methods of Construction.  There are unlikely to be low carbon substitutes for the steel, aluminium, glass and concrete being used in services like roads and drains.  And the target has to be carbon negative within a decade, without the offsetting that will be the refuge of the other sectors of the economy.

Starting at the top, the MHCLG has been asked many times about its position on embodied carbon as successive ministers look to volume housing as the response to housing problems.  The Ministry is aware of the consensus surrounding the scale of carbon embodied but says that it will not formulate policy to deal with the issue in the absence of an ‘agreed methodology’. Meanwhile the mission of Homes England, the ‘Government’s housing accelerator’, includes the sustainability of the homes being promoted but, under questioning, accepts that this is strictly for the MHCLG to decide.

The Communities Select Committee looked at housing and concluded that, 

“To meet its target to eradicate the UK’s net contribution to climate change by 2050, the government should embrace every opportunity to reduce carbon emissions. It should be ambitious in setting carbon reduction targets for the built environment both during construction and in use (emphasis added). The building regulations should set more stringent energy performance targets for homes to take into account achievable levels of energy efficiency. MMC should be used to deliver more efficient homes now to avoid costly retrofitting of homes later to comply with more rigorous energy efficiency targets."

But there is no sign the Ministry will rise to the challenge of its own Select Committee. The Government has just opened a consultation on revising building regulations. However, it does not include embodied carbon since it is not considered to be a matter of safety or how the buildings are used.

The seriousness of the issue of embodied carbon has been highlighted by the UKGBC pointing out that, “Annual embodied emissions alone are currently higher than the Green Construction Board’s target for total built environment emissions by 2050." That is, higher than the allowance for the next 30 years!

This nettle needs to be grasped. Policies are being drafted for the next decade.  Permissions are being granted, the commencement of development allowing completion at the original standards. This is not intended as an argument for building fewer new homes. Instead we must place the onus firmly on all those who advocate for, and prepare and support local plans with large scale housing proposals, to explain how this can be achieved within carbon budgets.

The recently retired head of Defra proposed a new Ministry for 1.5 Degrees C to advise on the behavioural changes required.  He suggested that it would probably find that replacing 30 million privately owned fossil fuelled cars with EVs could not be achieved within carbon budgets.  It should not be a surprise if such a ministry would also find that the low carbon sharing economy and climate justice extended into the provision and use of housing. Lowering carbon emissions will mean sweating assets rather than building new.

Homelessness will not go away as resources, including carbon emissions, constrain the supply of new housing.  One way to redistribute the housing space that already exists, almost all of which is in need of a deep energy refit during the next decade, is to concentrate resources on subdividing existing properties.  If those languishing on the statutory self-build registers, with diminishing prospects of being found a serviced plot, can assist in this process (of ‘custom-splitting’), then the transition to low, zero, and then negative carbon housing could have multiple benefits.

The RTPI is secretariat to the All Party Parliamentary Group on Housing and Planning and is perfectly placed to have the issue of embodied carbon properly investigated and to suggest what could be done.

Daniel Scharf MRTPI is a planning consultant at PfT Planning. He blogs at

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