The built environment contributes around 40 per cent of the UK’s total carbon footprint and is therefore a key area for climate change mitigation.
While the majority of existing and emerging Local Plan development policies on carbon reduction and energy efficiency are currently focused on new build development, the carbon emissions from the redevelopment of existing buildings is now coming under increasing scrutiny.
The repair and re-use of existing buildings is usually less carbon intensive than either demolition and rebuilding or new build on greenfield sites in terms of the materials and processes used in construction.
It may not always be possible to reach the same level of operational energy efficiency as a new build due to the constraints of the existing building and heritage status. However, lifecycle carbon emissions can still be addressed and there will be significant opportunities to reduce a building’s overall carbon footprint while preserving its historic significance.
Currently greater weight is often given to the preservation of a listed building over sustainability, and this is an area where further guidance is needed if the UK is serious about meeting its 2050 net zero carbon commitment.
What does the opportunity look like?
Historic buildings typically have low energy performance, due largely to limited insulation, single glazing and poor air tightness.
The Heritage Counts report by Historic England published in 2021 showed that carefully retrofitting improved energy performance measures into historic homes can lead to substantial carbon savings in the long term. According to the report, carbon emissions can be reduced by up to 84 per cent in a detached Victorian home, 62 per cent in a Georgian terrace, 58 per cent in a 1900s terrace, 56 per cent in a Victorian semi-detached and 54 per cent in a Victorian terrace.
These reductions translate into cost savings for the occupier, particularly in relation to electricity.
Improving the energy performance of historic buildings: where to start?
Improving wall and/or roof insulation and the addition of secondary glazing are two of the most cost effective measures for reducing emissions. There are many different options available and each building will need to be evaluated to assess the most suitable method, both in terms of the historic significance of the building and energy performance.
Applying a solar film to windows is another relatively straightforward and inexpensive way of helping to control heat, reduce glare and control UV rays. Another route might be the introduction of thermal roller blinds, which reflect light and retain heat to improve energy efficiency. Both of these options can easily be added to a historic building without adversely impacting the historic significance of the building.
Upgrades to improve ventilation levels or control moisture transfer can also deliver significant savings associated with reduced running costs while also protecting the future of the building. Good ventilation helps improve the indoor environment for occupiers, remove pollutants and control condensation thus protecting the building itself.
In many cases the replacement or enhancement of existing heating and electrical systems will make a considerable difference to energy consumption. The introduction of low energy lighting and low-use water fittings are also worthy of consideration as simple, low cost changes.
Once the efficiency of heating and lighting systems and fabric improvements have been addressed, the potential to install solar panels or heat pumps can be considered, however this is not always appropriate where there are heritage constraints.
What about listed buildings?
Improving the performance of listed buildings is undoubtedly less straightforward, not least because any works will require listed building consent, as well as planning permission where external works are proposed.
There is clearly a balance to be struck between improving the energy performance of a listed building and the impact sustainability measures can have on the significance of a heritage asset.
Paragraph 202 of the National Planning Policy Framework states that 'where a development proposal will lead to less than substantial harm to the significance of a designated heritage asset, this harm should be weighed against the public benefits of the proposal, including, where appropriate, securing its optimum viable use.'
Reducing the carbon footprint of a listed building is deemed a public benefit due to its positive environmental impact and contribution to the UK’s target of net zero carbon. Therefore, the benefits of energy efficiency measures should be weighed against any harm to the listed building.
However, local planning authorities (LPA) will give considerable weight to the preservation of listed buildings which is a requirement under Section 66(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990. This elevates the preservation of the listed building above that of a general planning consideration and therefore LPAs are likely to attach greater weight to building conservation than energy conservation.
The balance between building conservation and energy efficiency is becoming increasingly important and therefore further guidance is needed for LPAs to assist them in making that judgement.
Given the increasing pressure on the UK Government to address the climate emergency, the imbalance described above may come under scrutiny, as global conservation is given greater weight than local conservation.
What about net zero carbon commitments?
Organisations are increasingly keen to commit to achieving net zero carbon. However, if an organisation owns or occupies one or more historic buildings this may not be possible through onsite means alone. Once all options to reduce the carbon emissions from the building itself have been reviewed, different carbon offsetting approaches will need to be considered to reach the net zero target.
Historic buildings represent a significant opportunity in the drive to reduce carbon consumption. For listed buildings, this needs to be carefully weighed against the need to protect their special architectural and historical significance but this is now an area where further guidance is needed.
As there is no ‘one size fits all’ approach to energy efficient retrofits, the issue is often avoided. However, through close collaboration between sustainability, heritage and architecture teams, effective solutions can be implemented that improve efficiency without impacting heritage significance.
Considerations for privately rented property owners
A recent consultation on 'Improving the energy performance of privately rented homes' made a number of proposed changes to the EPC and minimum energy efficiency standards process for the private rented sector (PRS) – including the raising of the cap on spend from £3,500 to £10,000 in order to achieve band C of the Minimum Energy Efficiency Standards (MEES).
Owners of historic buildings within the PRS would be wise to undertake works that do not cause unacceptable alterations or harm to a property. Previously, this would have seen relatively minor works undertaken before the works surpassed the £3,500 cost cap, however if the cost cap is increased to £10,000 more significant works will fall within the scope of the EPC, even in heritage buildings.
Owners should no longer presume they fall outside the scope of MEES and instead reconsider the energy efficiency of these properties on the assumption that upgrades may be required. It would be preferable to formulate a contingency plan in the event that an EPC and, therefore, compliance with MEES becomes necessary, whether that involves applying for alternative exemptions or implementing well-considered upgrades.
Savills recognises real estate is responsible for 40 per cent of carbon emissions and, to coincide with COP26, it is launching its latest research examining how the sector is adapting to meet climate change challenges. Savills is committed to achieving net zero carbon in its operation by 2030. Through Savills Earth it brings together the expertise of more than 100 specialists to support and advise clients on their sustainability, energy and carbon strategies. Visit Savills Earth to find out more.
Further information
Contact Rebecca Bacon or Joe Lloyd at Savills Rural Research
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