Energy Efficiency

Historic England

Historic and traditional buildings make up about 25% of the housing stock. While they are not exempt from EPCs (Energy Performance Certificates), they do require more careful consideration since they are built very differently from modern housing and because listed buildings and buildings in conservation areas are subject to statutory protection. The software that generates EPCs, if not controlled by the Domestic Energy Assessor, could generate ratings and recommendations that are inaccurate, misleading, inappropriate and possibly illegal to carry out. This could lead to unnecessary expense for homeowners, harmful alterations to precious buildings, and possibly claims against the Domestic Energy Assessor. Standard measures to improve energy efficiency which are appropriate for modern buildings, are often expensive, ineffective and potentially harmful when applied to traditional buildings.

Recent research by the Sustainable Traditional Buildings Alliance (STBA) made up of organisations, such as Historic England, SPAB, Historic Scotland etc has outlined:

STBA writes:
The ‘Responsible Retrofit Report’ is calling for an overhaul of the retrofitting process to maximise the effectiveness of sustainability improvements to buildings built before 1919 which account for a quarter of the country’s housing stock.

In response to the STBA’s report findings, the Government is committed to re-writing industry best practice. This includes funding further research and a new retrofit guidance tool specifically for traditional buildings developed by the STBA. Neil May, Project Lead for STBA, comments: ‘Retrofitting the UK’s older buildings is not a one size or tick box solution. There are many gaps in our understanding and many complex interactions to take into account. Our findings reveal that if six million traditional homes are to be radically improved in their energy performance, then we need to see the application of a more informed, learning-based process that acknowledges the uncertainties and engages all parts of the supply chain as well as building users and owners. Our guidance tool will help this new process as well as linking to the best available research. We are glad to be supporting the Government in finding safer and more effective ways to undertake the retrofit of traditional buildings and the DECC has responded very positively to the findings raised in the report. If the recommendations are fully grasped and implemented, then the STBA is confident that the Green Deal and associated retrofit processes could not only transform our building stock but also construction industry skills and public understanding and engagement.’

Traditional buildings perform differently to accepted best practice
The STBA was commissioned by the Department for Energy and Climate Change (DECC) to examine the gaps in research and guidance about the retrofit of older properties. It analysed 521 separate pieces of formal research and guidance, and over 100 pieces of implicit guidance from industry and regulations, and found a significant lack of relevant research on traditional building performance and the outcomes of retrofit. One of the report’s key findings is that traditional buildings often perform considerably better in terms of heat loss through fabric than stated in standard models and assessment methods. It also found that traditional buildings require different assessment procedures and measures when it comes to the control of moisture. Current assessment fails to deal with driving rain, rising damp, residual moisture and moisture movement in traditional construction.? Furthermore there is a significant lack of available research for areas including traditional building energy performance, traditional materials data, occupant behaviour in older buildings, overheating, indoor air quality and ventilation rates. All of these gaps mean that it is almost impossible to predict the impact of retrofit programmes, which may also miss the opportunity for more effective measures.

Interactive guidance tool will end one size fits all approach?
The group claims a step-change is needed in the way the industry approaches the retrofit of older buildings to ensure their success. Working with the DECC, the STBA is developing an interactive guidance tool for the industry that moves away from the notion that there is one solution for every building or problem. Instead the tool takes in all parts and participants in the process of retrofit and links them with the best available research in an open and discursive framework. The DECC is strongly recommending the tool and it will be trialled by Cadw, the Welsh Government’s historic environment service and others in the coming months. ?Users of the tool will be encouraged to feed back their own findings into a dedicated knowledge centre which will use this information along with new research to update the guidance tool and to help formulate standards and policy.

Please see their website:

David Rawlins Ltd can advise the most appropriate improvements to period & listed buildings as an aid to energy efficiency, which should not adversely impact on the original building.


Please see the 2014 Guidance relating to traditional windows and their retention published via Historic England, which puts to bed some of the myths relating to double glazing. 

Many original vertical sliding sash windows incorporate original crown glass, which is much lighter than modern glass, but offers light refraction: any such glass can be expensive to replace: Whilst care will be necessary with young children, it must be remembered that it is very rare for such glass to be broken. I was recently asked to inspect the windows of a school constructed in 1860. The Headmaster was concerned that, for reasons of Health & Safety and the presence of significant condensation, the windows should be replaced with double glazing or toughened glass. This was despite the fact that no child had ever been in danger of being hurt by broken glass. A scheme was worked out to enable the original windows to be retained whilst offering improved safety, but with further advice with regard to the likely causes of the condensation and the action necessary to reduce the excess moisture in the building.

Of course, the windows are a particular feature of the Property and should be retained where at all possible. Many argue from a perspective or historic point of view. However, it should be remembered that the original windows were constructed of timber which was of much better quality than is commonly found today. The timber invariably originated from trees which had been growing for in excess of 100 - 150 years. Under the circumstances, the growth rings were relatively close together, providing significant strength and resistance to decay (Heartwood). Most decay & infestation tends to occur in timber taken from the outer part of the tree (sapwood). Most modern timber is now made up of sapwood rather than heartwood due to the rapid growth of the modern trees. Hence, any replacement joinery is likely to have a much shorter life span than the original, unless action is taken to find timber of similar quality to the original. The type of paint used can also contribute to decay if moisture in the timber is not allowed to evaporate.

Consideration should also be given to the fact that when decay is found in window, on most occasions, it affects the sill and bottom part of the window only. Why replace the full window if the only the rot affected areas require replacement?

I hear the argument to replace the original windows with plastic incorporating double glazing. The double glazing contractors are very ready to argue the energy efficiency advantages of their windows and the significant reduction in the requirement for maintenance. However, little seems to be said with regard to the costs in use of such windows, or the likely impact on the building itself. How many purchasers read the small print of the contractors guarantee? Whilst there are clearly improvements being undertaken all the time, there is no question that some guarantees specifically exclude the matters that go wrong, invariably just after the guarantee period has finished! For instance, how many guarantees in the market offer a 1 year warranty on the hinges & handles, 5 years on the sealed double glazing units, (*Seals to double glazed units are known to fail after 6 - 15 years and sometimes less.) but also specify that their guarantee will be invalid if the windows, including the PVC, glass & gaskets around are not cleaned every three months, and the hinges &handles greased? Basically, all windows, whether of plastic or timber, require regular maintenance.

Consideration must also be given to the fact that, at present, plastic is inclined to degrade over time and therefore tends to have only a limited life, particularly when subject to ultra-voilet suns rays. Whilst they been developed & improved over the last 25 to 30 years, the current anticipated life span of a UPVC double glazed window is clearly open to question. We are increasingly coming across house owners who wish to replace the ‘defective plastic double glazing’. If one considers the costs of manufacture, the costs of transporting the windows into this country or to the area of installation, plus the other costs to the environment when the windows come to be taken out or disposed of; plus the number of times such windows need to be replaced to compare with the proven life span of the original traditional windows, the argument for replacement of the original windows must surely be questionable.

When one considers the question of heat loss, the BRE (Building Research Establishment) accept that the replacement of the original sash windows in uPVC would not be justified on insulation grounds alone: Double glazing to windows and doors reduces heat loss through their openings by about half but they represent only a small proportion of the external surface area of the building and the "payback" is long in terms of energy savings (100 years?). As an alternative, a good case can be made for well-designed and carefully installed draught-proofing or secondary glazing.

Thermal and acoustic improvements can be realised by repairing and upgrading existing windows, offering a far more sustainable and energy efficient approach. The Governement promote a series of energy saving measures including the installation of modern double-glazing, but they agree that if the window frames are not rotten, then investing in double-glazing and destroying the originals are not cost-effective in terms of energy payback. This point is often ignored.

A feature of the Framing Opinions campaign has been to demonstrate how good quality softwood timber was used in the C18th and C19th even on comparatively humble and jerry-built dwellings. It is virtually impossible to replace these today. Indeed the modern softwoods available in the UK are of such poor quality that they have to be subjected to copious amounts of chemical preservatives to resist decay. Another reason for the longevity of original joinery was the use of lead-based paints, particularly on the critical joints. It was the very toxicity of this paint that prevented fungi and insects proliferating where conditions were favourable to such infestations. Now, of course, it is banned except on Grade I and II buildings and scheduled ancient monuments. The current media attention given to children licking old, neglected pant has highlighted a potential hazard where advice from the Health and Safety executive will often be to remove all vestiges of the original decorative coating. Consequently, any planning supervisor under CDM ("Construction Design Management") regulations seems almost bound to instruct such a course of action given that advice. However, removal itself can be even more hazardous and English Heritage and the planning industry believe it is often safer and better for the longevity of windows, if the lead pant is retained in situ and encapsulated in additional coats of non-toxic paint.

Since 1st April 2002 the Building Regulations require householders to install more energy efficient options when replacing windows, central heating boilers, heating controls and hot water cylinders. If any changes of this type are in hand or have occurred recently then it will be necessary to ensure that the Building Regulations will be, or have been, complied with. You should consult the Building Control Department of the Local Authority. Every installation must be certified as being installed and commissioned by a 'competent person'. This can be achieved either:

  • For the work to be done by a competent person who provides self-certification using an approved 'commissioning certificate'. The competent person is defined as a GasSafe registered installer for gas installations; an OFTEC registered technician for oil installations; a HETAS registered installer for solid fuel systems; registered operatives who comply with Building Regulations G3 for hot water systems; a FENSA registered installer for glazing. The Competent Person should provide you with appropriate Certification on completion of the work.
  • You should apply for approval through the local Building Control Department and obtain a Building Regulations Completion Certificate on completion of the work.

Further information can be obtained for glazing from the Glass and Glazing Federation (GGF) telephone 0207 403 7177 ( for heating systems and controls from the Central Heating Information Council (CHIC) telephone 0845 600 2200; for general energy efficiency advice the Energy Efficiency Advice Centre telephone 0800 512 012.

Regulations from 1 April 2006 and 2010 require even greater requirements on Energy Efficiency, potentially with a significant impact on insulation and heating requirements, particularly when there is any change to more than 25% of a “Thermal Element”, such as the roof, floor, or walls; or there is a Change of Use to the building, such as Barn Conversion or Loft Conversion. Hence, the new Regulations (Part L1B) will be particularly relevant should you decide to alter the building, to replace the windows, or to upgrade the central heating boiler, which will also impact on heating controls, including the probable insistence on additional zoning of the heating system, as well as the provision of thermostatic valves to the radiators.

We are all now well aware that the Government now insist on the provision of energy rating reports on all houses sold on the open market. It is unlikely that any building of solid construction will meet the highest energy efficiency requirements. In an effort to reduce global warming, such requirements can be balanced against the needs of the building when located in a Conservation area, or as a Listed Building. However, full compliance with such Building regulations will not necessarily be ideal for a building of this age & construction, due to the implications, for example, with regard to ventilation, loss of heat through the fabric of the building etc. Indeed, some “recommendations” may cause significant harm to a building of solid construction, irrespective of whether it is Listed or not.

For this reason, special Guidance Notes are available where properties are Listed Buildings or located within Conservation Areas (see Historic England and who also provide advice on Energy Efficiency in traditional buildings), and will be particularly relevant where such measures would unacceptably alter the character or appearance of the building. Older properties, not located in a Conservation Area and not regarded as "historic" elsewhere, do not currently have this protection. An increase above the minimum requirement to one area can be balanced against a reduced provision elsewhere as long as the overall rating for the building meets minimum standard for a typical building of its type. There is also a recommendation to use long-life light bulbs.

Traditional buildings: are all buildings of a solid wall construction built with permeable fabric that both absorbs and readily allows the evaporation of moisture. These mostly predate the 1920's when cavity wall construction and the use of damp proof membranes became more widespread. However, even where an old house is not Listed or does not lie within a Conservation Area, careful consideration must be given to the sustainability & costs in use of the current materials, windows, brickwork etc.