Decarbonising Scotland’s Heritage

 In Blog

After delivering ESOS Phase 1 in December 2015 for the National Trust for Scotland, Synergie Environ are delighted to have recently won the follow up contract to deliver Phase 2. Although the deadline for ESOS Phase 2 isn’t until 5th December 2019 many organisations such as the National Trust for Scotland are already planning ahead to ensure that they comply with the upcoming legislation. We have developed a close relationship with the National Trust for Scotland to understand their unique energy reduction needs in their historic buildings and our previous work identified opportunities to reduce energy costs by 15% and carbon dioxide emissions by ~1,000 tonnes per year across all of National Trust Scotland’s sites.

Across the UK there are number of historical site, with approximately 500,000 listed buildings in England, and a further 50,000 listed buildings in Scotland which are all protected by legislation.

Historical sites and heritage buildings are integral to the cultural fabric of the country and need to be protected, so they can be enjoyed by the generations to come. Preservation of historical sites has traditionally meant protecting the architecture of the buildings, or the valuable historical contents of the buildings, however, we must also ensure that these historical landmarks keep pace with sustainability trends and decarbonise. Listed and historic buildings can be faced with unique challenges when applying methods to improve energy efficiency, reduce consumption, and install renewable generation technology.  Below we discuss a few common measures and technologies relevant to listed and historic buildings.


Energy efficiency solutions


The first step in any energy efficiency program is to assess the practical opportunities to reduce energy consumption and develop a prioritised action plan. This requires the collection and analysis of energy consumption and cost data. Subsequently, individual opportunities to improve energy efficiency can be identified, quantified and prioritised. Commonly identified measures to reduce energy consumption and costs at historic buildings are associated with space and hot water heating, building fabric and lighting. These measures are relatively simple to install in more modern buildings, however, in historic and listed buildings careful consideration must be taken to maintain the materials, visual aspect and character of the building.


Space and hot water heating

When considering options for energy efficiency, reducing heat  demands should be the top priority. This can  be achieved through improved building fabric, replacing older (sometimes 100 years old! See Photograph Opposite) less efficient heating boilers with more modern appliances and ensuring that hot water pipework and storage tanks are well insulated and free of potentially years’ worth of accumulated dirt.

Often overlooked, is the efficiency with which domestic hot water is heated, stored, distributed and consumed. Energy (and water) costs associated with hot water consumption can be significant, particularly at listed and historic buildings which are open to the public, have restaurant areas or have significant numbers of occupants. Implementing simple measures to reduce hot water consumption, such as flow rate controls costing less than £5 each typically payback in less than one year.



Improving the thermal insulation of buildings is a go-to solution for improving the energy efficiency in buildings, which is typically done by improvements to external wall and roof insulation. In listed buildings, however, walls and roof structures are often historically important and protected. Adequate ventilation throughout the building is essential to maintain building fabric and prevent the accumulation of moisture which would lead to damage to the fabric or contents. However, excessive ventilation can increase space heating costs significantly. Therefore, a careful balance must be maintained. In our experience improvements to loft, underfloor, and internal wall insulation offers the best opportunity to reduce heat loss and air infiltration in listed buildings.

Before fitting insulation to internal walls, the potential to conceal historic features of the building must be assessed. Wall insulation will alter the performance of the solid wall and can exacerbate existing moisture-related problems, therefore insulating of damp walls should be avoided. Adding vapour barriers and materials that are highly resistant to the passage of water vapour are not suitable for historic buildings as they will tend to trap moisture and can increase the risk of decay to the fabric.

Planning permission and listed building consent are required for any external insulation to a listed building. Under certain circumstances external wall insulation can be classed as permitted development but the local planning authority should be consulted before any work commences. Therefore, insulation to internal wall is more favourable.



Improved glazing, another staple of energy efficiency projects, can be affected by the existence of historic window features which must be maintained and often cannot be replaced. At some locations this issue can be overcome by the installation of secondary glazing, which is an additional independent internal window to the existing window. It should, wherever possible, be fitted immediately inside existing sashes or at a suitable position within the depth of the window reveal, being fixed either to the case or the surrounding framework. Installation and maintenance of draught proofing measures around windows reduces ventilation heat losses significantly. Using lined, well fitted curtains has been demonstrated to reduce heat loss through windows by 14%, whilst using wooden shutters typically reduce window heat loss by 50%.

All internal alterations to listed buildings should always be carried out with careful consideration to avoid acceleration of the decay that could shorten the building’s lifespan. Listed Building Consent will be required for all alterations and improvements in building fabrics but planning permission may not be required for internal alterations.



Investment in energy saving lighting can significantly reduce electricity consumption, particularly at sites with display lighting and visitor facilities.  Many historic sites are home to light sensitive artefacts and care needs to be taken to ensure that replacement lighting does not accelerate colour deterioration. Synergie Environ recommend energy efficient LED lighting and lighting controls which take into account light intensity, colour emission and visual requirements to ensure that the needs of the artefacts and visitor are met whilst ensuring optimum energy consumption. Although the capital cost of light emitting diode (LED) lamps and smart lighting controls can be higher than conventional lamps, the extended lifespan of LED lamps should result in significant whole life cost savings.


Renewable energy


Installation of renewable energy technologies at listed buildings usually requires a Listed Building Consent, planning permission and that the architectural integrity of the building be maintained. To minimise the potential for visual intrusion and potential impact on the building fabric care should be taken in the design, location, installation and operation of renewable energy technologies. New developments should not be visible from public view.

Suitable locations for renewable energy installation on heritage sites can be on the ground to the rear of the building, using an existing outbuilding which is remote from the main property, a modern extension to the rear of the building (providing that no part is higher than the main building), or in the internal valley of a roof (provided that no part projects above the ridge). In addition, location in a Conservation Area places further constraint on the potential to install renewable energy technologies around the site. For example, aerial views may also be required to remain as historically accurate as possible.

Synergie Environ have worked with a number of historic building owners, and we have identified three main renewable generation technologies that provide significant economic and environmental benefit, while enabling a variety of install options with minimal impact on historical buildings and grounds.


Biomass Boiler Systems

Biomass systems require wood-burning equipment, a boiler house, fuel and thermal storage, pipework and flues. Development of a biomass system at historic site requires careful consideration for siting and design. Care should be given to the system design, location of chimneys/flues and the fuel store, and the repurposing of existing chimneys for the biomass system is encouraged. If a new chimney or flue is required, it should be designed to be unobtrusive in views of the building. The installation of biomass heating systems at rural estates often raises the potential opportunity to use existing woodland as a fuel supply. This contributes to fuel security, reduces the volatility of fuel supply costs from external sources and can enhance woodland management at the site.


Water-source Heat Pump

Water source heat pumps (WSHP) take a proportion of the heat from a lake, river or stream and use this to provide heat to a building or buildings. The efficient operation of a WSHP typically requires lower operating temperatures than oil, gas or biomass fuelled boilers and consequently WSHP can supply lower temperature heat for maintaining a suitable temperature to preserve the building fabric in older buildings. The installation and design of a WSHP should have minimum effects on the external historic appearance. Once the WSHP is installed, the pipework could be covered over with soft or hard surfaces. The principal considerations for historic features are the need to avoid damage to underground archaeology and to find an unobtrusive location for the pump equipment and any surface pipework.


Solar Photo-voltaic (PV)

Photo-voltaic technology can be incorporated into building materials such as roof tiles and requires cabling distribution equipment. In general, solar PV system developments on historical buildings should be installed on inconspicuous areas of a roof, such as the inner slopes of a roof valley, or where a flat roof is obscured by a parapet.

When installing PV systems principal elevations should be avoided, and if the building is located in a Conservation Area the appearance of the building from higher vantage points should be carefully considered. It is desirable to mount PV modules over existing slates (as opposed to replacing historic fabric with photovoltaic panels designed to look like slates) to maintain the integrity of the building’s appearance. Synergie Environ did just this when working with the owners of an estate dating to the 14th century to deliver a Solar PV system on the roof of a castle.

Whether your energy reduction needs are of a historic or modern building type, Synergie Environ have a highly qualified team with expertise and extensive experience of helping companies to comply with ESOS. Our team can guide you through the compliance process from the very early stage to the final stage. Our support includes managing the data collection, analysis and report production required for ESOS compliance and we make sure your business will comply fully with all ESOS obligations.

The ESOS energy assessment will be reviewed and signed off by our highly qualified and experienced ESOS Lead Assessors or Lead ISO50001 Energy Management Systems Auditors as appropriate.

As part of our energy audits, we will identify suitable energy-saving measures and identify the potential cost and energy savings your business can achieve.

Why not call 0141 263 0020 today for an informal chat or email:

Recommended Posts
Contact Us

If you would like more information please send us an email and we'll get back to you, asap.