Energy efficiency requirements for buildings are included in Building Regulations (Part L). However, buildings in a designated conservation area are exempt from these if ‘compliance would unacceptably alter their character and appearance’. Nonetheless, it is preferable that traditionally constructed buildings are adapted to improve their energy performance and ensure their continued use in the future. Alterations for energy conservation should minimise disturbance to the existing fabric and be easily reversible.
Traditionally constructed buildings perform differently to modern ones. Their construction makes them more porous and naturally ventilated so they ‘breathe’. They generally include softer materials such as lime-based plasters and mortars which respond to air and moisture differently. Care should be taken that alterations do not harm the natural thermal behaviour of the building.
Insulation
Repairing cracks and holes in construction is the first stage in improving the efficiency of older buildings. This can often be done at a relatively low cost with limited disruption, and doesn't require planning permission. Care should be taken to provide enough ventilation to control internally generated moisture.
The council encourages loft, floor and internal wall insulation where these would not have an adverse effect on the fabric of the building. Works should avoid damaging the building by using existing voids and reversible techniques and detailing. The use of insulation materials which are compatible with traditional permeable construction (such as wool) will also minimise the risk of damage.
Planning consent would be required for external insulation applied to a building in a conservation area. It might be suitable on rendered, rear or less visible facades. Window frames, sill and lintel details, doors, frames, porches and architectural details would need to be appropriately reconstructed.
Windows
The conservation of traditional windows is very important in the context of heritage assets. Installation of secondary glazing is usually preferable to replacement: this can insulate effectively while also limiting draughts. Well designed secondary glazing units can be both discreet and reversible, while the installation of double glazed units would usually require replacement of the whole window. New double-glazed timber or high-quality metal windows may be suitable where these match the original window details and do not result in unsuitably thick frames or glazing bars.
Renewable energy
The installation of micro-generation technologies such as solar panels in conservation areas will be accommodated where possible, in ways which don't harm the historic environment. Historic fabric should not be disturbed or destroyed. Where possible, equipment should be installed in discreet locations where it will not affect the character and appearance of the historic environment.