Squaring the Circle

Abstract

Research into building-physics in the UK over the last 15 years has demonstrated the significant constraints to the extent to which the energy efficiency of historic buildings can sensibly be improved. While some of these include risk to character and heritage significance, others are linked to moisture movement, mould growth and the comfort of building fabric and users. In parallel with this research and project work, the UK has signed the Paris Accord and committed to delivering zero-carbon by 2050. Although there may be alternative sources of energy, such as hydrogen, to deliver the decarbonisation of industry and transport it seems unlikely that these will make a significant contribution to the decarbonisation of building energy use. In these circumstances electricity will be the sole zero-carbon energy supply for the heating, ventilation and lighting of all existing and new buildings. This dependence suggests that any supply-side limitations on the energy available will inform or impose a requirement for improved performance and thus on the scale and nature of retrofit measures required to each building. This paper establishes potential energy allowances for existing residential buildings from the published future energy supply scenarios and cross references these with the existing metrics for retrofit and with the available post-occupancy performance data on completed retrofit projects for historic residential buildings. This analysis provides an indication of the nature and extent of the level of retrofit that will be required to existing buildings in order for the UK to deliver on its zero-carbon commitment and suggests the kind of approach and methodology that should be adopted for retrofit in order to avoid the fabric risks identified above.