Retrofit vs Rebuild Report

In London, buildings account for an estimated 68 per cent of London’s carbon emissions. These emissions arise from the construction, operation, and demolition of buildings.

If London is to meet the Mayor’s 2030 net zero target, there is an urgent need to reduce emissions from buildings and to retrofit our housing stock.

The London Assembly Planning and Regeneration Committee carried out a two-part investigation into London’s built environment, focussing on how decisions are made to either retrofit or rebuild properties and the carbon implications for both.

Whilst operational carbon emissions (the energy used to run buildings, heating and cooling systems) are regulated through building regulations, the Committee found during its investigation that embodied carbon is treated differently, and the building industry is not currently required nationally to measure and reduce the embodied carbon arising from construction.

Whole Life-Cycle Carbon (WLC) Assessments are a way of measuring all the emissions arising during the entire lifecycle of a building, from its construction to its potential demolition or change of use. The London Plan 2021 set a policy requirement for developers to carry out WLC Assessments for major developments, to be submitted during planning stages.

The Committee has published a report – ‘Retrofit vs Rebuild?’ - with six recommendations for the Mayor and Government, including:

• The Government should introduce a mandatory requirement in national policy to undertake WLC Assessments for buildings, looking at the policy on minimising greenhouse gas emissions set out in the London Plan’s Sustainable Infrastructure Policy 2 Part F as a potential model.
• The Mayor should publish annual data gathered from WLC Assessments to enable the success of the policy to be tracked, and to identify improvements needed. The GLA should analyse the data and provide an estimate of the amount of embodied carbon emissions associated with London developments, broken down by type.
• The Government and the Mayor should assemble a working group to identify the support that local authorities need, in terms of their skills and capacity, to promote whole life carbon and circular economy approaches; and how this support could be obtained.