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INSULATION Futureproofing our heritage


The restrictions that apply to alterations to listed buildings can be significant and challenging, particularly when it comes to balancing energy efficiency and condensation control, as Callum Anderson from A. Proctor Group explains


control. Strategies to upgrade the energy performance of existing buildings must be considered carefully and holistically, as actions affecting one area may have unforeseen consequences elsewhere. For example, we must recognise that we cannot simply upgrade thermal insulation without addressing the balance of moisture movement and air leakage.


Airtightness


In listed buildings, this priority will need to be balanced against retaining architectural features, maintaining the character of the building and aesthetic qualities, and ensuring the internal spaces remain large enough to be fit for purpose


P


rotecting listed buildings is about more than celebrating buildings of special architectural or historic


interest. The world is facing enormous challenges from climate change and the need to reduce CO2


emissions, to the threat


of energy security and scarcity, coupled with the impacts of rising inflation and a cost-of-living crisis. Increasingly, there is recognition of the urgent need to improve buildings’ energy efficiency. In doing so, national, and global strategies for retrofitting existing buildings are crucial. In addition, the efficient use of resources, minimising waste, and preserving and extending the life cycle of buildings is equally important. Work to a listed building that involves alterations, extensions or demolition, and which will effect its character externally and in some cases internally, requires listed building consent. The restrictions that apply to alterations can be significant and challenging, particularly concerning energy efficiency and condensation


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While not factored into U-value calculations, air leakage through cracks, gaps, holes, and improperly sealed elements – such as doors and windows – can cause a significant reduction in the performance of even thermally insulated envelopes. The industry is increasingly turning to air barrier membranes as an essential part of the process in achieving the most effective means of controlling and reducing air leaks. Modern new build homes typically have wall U-values of around 0.2 W/m2K, while traditional older properties with solid walls will be more like 2.0 W/m2 K, which will have a significant effect on the heating bills of the property and the quality of life of the occupants. This has substantial impacts where occupants are in fuel poverty or belong to a vulnerable social group such as the elderly.


In listed buildings, addressing this needs to be balanced against retaining architectural features, maintaining the character of the building and aesthetic qualities, and ensuring the internal spaces remain large enough to be fit for purpose.


Refurb choices


There are some challenges when evaluating the choices for refurbishment projects of listed buildings. Traditional building materials used in older properties such as lime-based mortar and plaster have very different hygrothermal properties from their modern equivalents. Adding insulation of low permeability, such as rigid foam, can


ADF FEBRUARY 2023


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