Heritage Retrofit

BCD SPECIAL REPORT ON HERITAGE RETROFIT FIRST ANNUAL EDITION 11 has run a local energy-efficiency advice service in the Bristol and Somerset area for more than 20 years, including home visits for complex cases. It is regularly called upon to advise householders in traditional homes on how to improve efficiency (mainly by reducing heat loss). Three things are becoming increasingly clear to CSE advisers as they deliver these services: • Residents of traditional homes often have little knowledge of the construction techniques used in them, or the way in which moisture moves through the building. This is compounded by a tendency to believe (perhaps because of the marketing techniques of modern housebuilders) that moisture movement in or through walls should be resisted at all costs, and that it is a sign of an underlying problem with the house. • Very few people understand the meaning of the term ‘significance’ when applied to historic properties. Householders typically fail to distinguish between impacts on historic significance and impacts on the physical fabric of the building when proposing change. They are not the same; one can be present without the other – for example poorly fitted insulation which increases condensation could lead to physical damage in the first instance by creating a build-up of damp between a stone wall and internal wood panelling. If the wood panelling then has to be removed as a result, then not only is there physical damage but ultimately loss of historic significance as well. However, it is also possible to damage only the historic significance of a building, for example by obscuring decorative brickwork with external wall insulation where this measure has no detrimental effect on the physical fabric of the building. Conservation officers may well object to proposed retrofit simply because it will damage historic significance, a concept that the householder often finds vague and elusive, without causing actual physical harm to the building. • It is very common for householders to want to make changes based on a desire for a particular product or measure (such as double glazing), rather than a desire to see a particular outcome (such as reducing draughts), often because they have received some sort of marketing literature about the product in question. Particularly where buildings are listed or in a conservation area, these three factors are the source of a great deal of conflict with local authority conservation and planning teams who expect greater justification for the installation of potentially damaging measures than many householders are prepared to give. More guidance is also becoming available to support local authorities in framing their decisions. The forthcoming Historic England conservation research report The Sustainable Use of Energy in Traditional Dwellings (authored by CSE, expected Spring 2017) is targeted at local authority planning and conservation officers and explores how to use legislation and policy to guide decision-making. Where the building is neither listed nor in a conservation area, there is no such oversight from local authority experts, and these three factors (alone or in combination) mean that many householders are making changes to their properties that can be hugely damaging to their value, both from a heritage point of view and also in physical terms. To try to cut through some of this potential for conflict, the Centre for Sustainable Energy produced a booklet titled Love Your Old Home in 2014. The booklet guides homeowners through a four-step process to evaluate what makes their home historically significant, and what that means for the types of energy efficiency improvements they could make. CSE is also working with the National Trust on guidance for applying for and securing consent for traditional home retrofit, which is primarily aimed at helping residents in protected buildings to understand how to apply for consent for appropriate measures, but will also be a useful resource for local authority officers. An accompanying online resource is also being developed to provide technical advice on a range of retrofit measures THE ENERGY HIERARCHY The energy hierarchy is an excellent framework for thinking through the range of possible changes: • first reduce energy demand (for example by changing behaviour in the home) • then ensure energy is used as efficiently as possible The Centre for Sustainable Energy’s Love Your Old Home booklet (2014) Damp and mould caused by poor external wall insulation (Photo: Centre for Sustainable Energy) LEAST INVASIVE INVASIVE MOST INVASIVE WALLS Gap filling Internal solid wall insulation External solid wall insulation Insulating within depth of timber frame ROOFS Loft hatch insulation Rafter insulation (heated loft) Loft insulation (unheated loft) Flat roof insulation FLOORS Gap filling and floor coverings Under-floor insulation (suspended floor) Under-floor insulation (solid floor) Under-floor heating Over-floor insulation WINDOWS Thermal curtains and blinds Refurbishing or reinstating shutters Refurbishing and draught-proofing original windows Replacing non-original or badly damaged original windows with timber double glazing or slim-line timber double glazing Film secondary glazing Framed secondary glazing DOORS Door draught-proofing New high-performance thermal doors Door refurbishment Creating a draught lobby CHIMNEYS Chimney blocking