The UK has committed to reaching ‘net zero carbon’ by 2050. Warwick District Council declared a Climate Emergency in June 2019 and aims to become a carbon-neutral organisation by 2025. We are committed to facilitating decarbonisation by local businesses, organisations and residents, in order for Warwick District to be as close as possible to zero carbon by 2030.

Improving energy efficiency is not only good for the climate, but it will also reduce your running costs, and increase the lifespan of your building. Nationally, about 20% of all homes were built before 1919, using traditional methods and materials. Maintaining these buildings is a powerful climate action as it ‘locks in’ the carbon used to build these in the first place, so the adaption of an old building is preferred to the purchase of a new building.

For example, when a typical Victorian terraced house is sympathetically refurbished and retrofitted it will emit less carbon by 2050 than a new building constructed to modern standards, when taking into account both energy used in construction and the carbon ‘locked up’ in the home’s materials; construction of a new home of the same size produces up to 13 times more carbon than refurbishment.

Adapting to climate change and conservation of built heritage are compatible aims; we do not need to accept the loss of heritage to achieve our climate goals. The heritage industry is founded on the concept of intergenerational equity that also underpins sustainable development – that we must not prioritise ourselves over future generations. Conservation is, by definition, the process of managed change which sustains significance.

National guidance

Improving the energy efficiency of your home, whether it's listed, in a conservation area or built before 1919, can be done sympathetically and without compromising its historic character.

National guidance is already available from organisations such as Historic England who have published a range of guidance documents relating to Energy Efficiency and Historic Buildings. Their overarching guidance How to Improve Energy Efficiency sets out a ‘whole building approach’ which considers context, construction, condition, significance, factors that affect enery use and energy efficiency strategies.

Historic England have recently updated their own energy efficiency guidance for home owners and occupies and are continuing work on this: https://historicengland.org.uk/advice/your-home/energy-efficiency/

Please note that works to improve energy efficiency may require listed building consent or planning permission, this is depending on the extent and nature of the works proposed. Please contact conservation@warwickdc.gov.uk for further advice relating to listed building consent.

General principles

Buildings from different periods have fundamental differences in how they have been designed to manage heat and moisture, and the skills and materials needed to maintain, repair, and responsibly adapt them. Solutions designed for the 80% of houses built after 1919 may not be appropriate for your home. They can be aesthetically damaging, environmentally ineffective or counter-productive, and in the worst cases cause harm to the health of the occupants. 

We recommend taking into account the following three compatible frameworks when considering ways to reduce the carbon footprint of a traditional or historic building:

1. STBA Retrofit Principles: The Whole House Approach

  • The Whole House Approach is a way of thinking about retrofit in a manner that is holistic and risk based:
  • Consider the three areas of risk: energy, health, heritage
  • Take a whole building approach, accounting for: fabric, services, inhabitants’ needs and behaviour, immediate context (weather, locality), and wider context (embodied carbon, decarbonisation of fuels), integrated for a building in balance.
  • Use a joined-up process (linking assessment, design, construction, feedback)

2. Four aims when enhancing the sustainability of heritage assets

  • Preserve historic fabric
  • Extend the beneficial use of older buildings
  • Reduce carbon emissions using the hierarchical approach
  • Specify environmentally conscious materials

3. The Energy Hierarchy: Be Lean, Be Clean, Be Green

  • Lean: Minimise the energy demands of the building
  • Clean: Use and supply energy more efficiently
  • Green: Supply renewable energy

The most effective way to achieve energy efficiency is to keep buildings in good repair so that they last and do not suffer from decay requiring energy and carbon to rectify. Maintaining a building’s ability to regulate moisture levels is essential to its effective thermal performance; walls can be over a third less energy efficient if damp.

Quick wins

Quick wins bring big energy savings with limited investment or fabric intervention and are often the same recommendations for both modern and traditional buildings. Quick wins can include:

  • Draught-proofing
  • Fitting insulated curtains or shutters
  • Chimney balloons
  • Energy-efficient lighting
  • Switching to a 100% renewable energy tariff.

Windows

Historic England's Traditional windows: their care, repair and upgrading guidance covers both timber and metal windows and is aimed at building professionals and property owners.

Overhauling windows to ensure a snug fit can reduce air leakage by 33-50%, without loss of an important historic feature. Where a window is beyond repair on a modern extension, or located on an area that does not contribute towards the significance of the listed building, it may be appropriate to replace with heritage double-glazed units with a maximum thickness of 12mm - or even 6mm vacuum units - allowing for slender frames and installation of glazing bars.

The use of uPVC windows in listed buildings is generally not supported and will not be granted listed building consent. It is also worth considering the amount of energy used in the manufacturing of new windows. The proven lifespan of uPVC is much shorter and, unlike timber, is not a renewable resource and uses more energy to manufacture and dispose of.

It is important to remember that windows are part of the historic fabric of the building and that wherever possible they should be repaired and not replaced. Replacement will only be considered to an original or historic window when beyond repair. On original or historic elevations, windows in listed buildings should generally remain single glazed. Any surviving original or historic glass should be retained and repaired if required, as this forms part of the building’s historic fabric The use of double-glazed units on listed buildings is generally not acceptable when replacing original sash or casement windows with glazing bars. It is usually not possible to obtain the very fine glazing bars to support double glazed units and the view of the window is distorted by the sandwich effect of the two sheets of glass. The integrity of the window is also lost as a historical component and the weight is changed considerably in respect of the original counter-balances in sash windows.

Secondary glazing systems can be installed behind single glazed windows to improve thermal performance, which can be obtained as tailor-made units for historic windows. These can be equally efficient as double-glazed units and, if fitted discretely, need not affect the character of the building. Secondary glazing can usually be installed without the requirement for listed building consent.

Modified shutters with insulation can also reduce heat loss by 60% when closed, with secondary glazing this increases to 77%.

Roofs

The use of solar panels can be permissible on listed buildings as the panels could possibly be disguised within opposing roof slopes and therefore will not be visible, or could be accommodated within the garden of the property. Panels should be located as discreetly as possible, avoiding principal roof elevations unless they are not visible. The proposed installation will be considered on their own merits as to the loss of historic fabric that would take place and the change that would be made to the appearance of the building. In certain instances, a modern roof to the rear of a historic property or a non-visible roof may be appropriate for such tiles. Consideration should also be given to the additional weight of solar panels and an assessment of the roof structure should be undertaken by a structural engineer to ensure that damage does not occur as a result of the installation of the panels. When selecting panels, care should be taken to select discreet styles that will have a low impact. In principle, the Council therefore supports the installation of roof- and ground-mounted solar panels where there is no detrimental impact on the architectural or historic interest of the building and they are discreetly located.

Guidance covering the issues associated with installing solar photovoltaic panels on historic buildings and sites is also available from Historic England. This considers options available, how to minimise damage to historic fabric and potential visual impact on the character and appearance of the building.

Wind turbines may be appropriate as a single feature for an isolated building or to the rear or less visible part of a terrace of buildings or group of buildings within the historic context. Careful consideration will be taken in each case of the need for the appliance and the value that the installation of the appliance will give to the property. Therefore, there are no standard solutions as to the siting of wind turbines within the historic environment.

Regularly check your roof and particularly after stormy weather, to see if any slates are missing, damaged or may have slipped, as this can leave your building vulnerable to the elements.

The introduction of improved insulation if sensitively installed into historic buildings can work effectively to save energy. Historic buildings need to be considered wholistically and appropriate energy audits carried out before any one solution be considered.

We strongly advise not to install foam or polystyrene based insulation on any historic buildings. These are potentially damaging to the building in the long term as historic buildings need to ventilate to allow for moisture exchange - these products restrict this and can lead to condensation problems, including dampness and rot. There are numerous alternatives available, such as sheep wool and wood fibre-based insulation, which will not damage your historic building.

Repairs and upgrades

Replacement of failing cement render with an appropriate lime render gives rise to an opportunity to add breathable insulation to external walls.  If applying lime render, you must first remove any existing paint in order for it to adhere. Please note that whilst planning permission is generally not required to maintain, repair or replace existing render on a like for like basis, planning permission will be required where render is not currently present, which will be assessed and determined on its own merits. In addition, where a listed building or traditional property in a conservation area does not currently have render, or there is an absence of render in the street scene, this is unlikely to be supported.

The use of externally applied solid wall insulation will significantly alter a building's appearance and is not generally supported on historic or traditional buildings, particularly those with solid wall construction. These buildings rely on the transfer of moisture from within the wall so that it can be dissipated as vapour. This process relies on adequate ventilation, otherwise insulation is likely to cause harm to fabric due to the increase in levels of damp and interstitial condensation between the existing wall surfaces. A desire is expressed for natural breathable insulants, such as hemp fibre, wool and cellulose. Breathable paints and decorative treatments (including wallpaper) must also be used to ensure that moisture can dissipate. Cement-based insulating products are discouraged.

A boiler upgrade is a highly effective method of reducing your energy usage. Renewable energy technologies, ever smaller and quieter, can often be sited in a discrete location, or effectively screened, and connected to existing pipework. They are especially welcomed where they allow for the removal of a large gas or oil tank, although will need to be combined with fabric improvements and be used in tandem with underfloor heating or oversized radiators to ensure that they work efficiently.

Detailed Guidance

Historic England have produced a more detailed range of guidance offering practical advice for owners and builders on the principles, risks, materials and methods of installing insulation and draught-proofing of:

Useful advice is also available from the Society for the Protection of Ancient Buildings (SPAB)

Energy Efficiency and the Building Regulations in Historic Buildings

Part L of the Building Regulations seeks to improve the energy efficiency of all buildings. For historic buildings a balance needs to be achieved between improving energy efficiency and avoiding damage both to the significance of the building and its fabric.

The Building Regulations Approved Documents for Part L make it clear that a reasonable compromise on the energy efficiency targets may be acceptable in order to preserve character and appearance and to avoid technical risks. They do this by specifically including some ‘exemptions’ and circumstances where ‘special considerations’ apply for historic buildings and those of traditional construction.

Having regard to the research and wider guidance listed above, Historic England have produced specific guidance to help prevent conflicts between the requirements of Part L of the Building Regulations and the conservation of historic and traditionally constructed buildings.

The advice acts as ‘second tier’ supporting guidance in the interpretation of Approved Documents L1B and L2B that should be taken into account when determining appropriate energy performance standards for works to historic and traditionally constructed buildings.

The following areas are covered in the guidance:

  • The background to the legislation and the need to reduce greenhouse gas emissions
  • An interpretation of the regulations themselves as applied to historic and traditionally constructed buildings
  • Understanding the buildings before carrying out upgrading works
  • Meeting the requirements of part L
  • Advice on the thermal upgrading of various building elements

Resources and further reading

Historic England: Climate Change, Sustainability & Energy Efficiency. A gateway to Historic England’s extensive advice and research, worth exploring. Particularly pages Practical Guidance on Energy Efficiency and Generating Energy in Older Houses and overarching guidance documents:

Planning responsible retrofit of traditional buildings (PDF) Sustainable Traditional Buildings Alliance (STBA). Part of the ‘Responsible Retrofit Series’. The STBA is a collaboration of not-for-profit organisations supported by CITB, Historic England, Historic Environment Scotland, and Cadw.

Responsible Retrofit Knowledge Centre and Guidance Wheel. Developed with funding and support from CITB and the Department of Energy and Climate Change, now part of BEIS.

Society for the Protection of Ancient Buildings (SPAB): Knowledge Base. A growing resource on conservation old buildings including categories Common Problems, Maintenance, and Energy Efficiency.

Old House Eco House: A Practical Guide to Retrofitting for Energy Efficiency and Sustainability (2019) Suhr & Hunt in association with SPAB

A Bristolian’s Guide to Solid Wall Insulation (2015) STBA, DECC, Bristol City Council. This illustrated guide is now used by homeowners throughout the UK to make more informed decisions about how to insulate their homes.

Love Your Old Home workbook (2014) Centre for Sustainable Energy (CSE), a homeowner’s guide to significance and planning energy efficiency improvements in traditional homes.

Heritage Counts Research published by Historic England on behalf of the Historic Environment Forum, particularly: There’s No Place Like Old Homes: Re-use and Recycle to Reduce Carbon (2019)

Case Studies including the Zetland Passive House ‘the UK’s greenest retrofit’ in Chorlton Conservation Area, the eco-retrofit of a Grade II listed Clapham townhouse. Slightly deviating from domestic examples but closer to home: Going Green at Wimpole, and an ‘exemplary retrofit’ at Trinity College Cambridge

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