Designing Energy Retrofits for Heritage Buildings: Intergrating Social, Cultural and Technical Concerns into the Design Process

Traditional and heritage buildings have important cultural roles and help shape the character of our urban and rural areas, with British buildings considered to include some of the World's finest architectural heritage (Deloitte, 2017). The Sustainable Traditional Buildings Alliance (STBA) define traditional buildings as those of permeable, solid wall construction built before 1919 (STBA, 2012). The term 'heritage building' includes traditional and listed buildings as well as others deemed of 'heritage value' (Pickles & McCaig, 2017). These buildings, which make up roughly 20% of UK residential buildings (STBA, 2012), provide economic benefits from heritage tourism, a sector contributing over £20billion to UK GDP and deemed responsible for every 1 in 100 UK jobs (Oxford Economics, 2016). Heritage buildings can also play a focal role in regeneration projects, provide a visual link to historic designs and crafts and provide communities with an intangible 'sense of place' and cultural ownership (Deloitte, 2017). Reducing energy use and greenhouse gas emissions (hereafter referred to as carbon) is vital for mitigating climate change.
Approximately 36% of global annual energy consumption and 39% of carbon emissions comes from the
building sector (GABC, 2017). In the UK around 30% of carbon emissions come from buildings and the construction industry (UKGBC, 2017). Some progress has been made in improving the energy efficiency of new buildings
but improvements to the current building stock have proved more challenging. This is pertinent because it is estimated that around 70% of today's UK buildings will still be present in 2050; of these 75% were built
before 1975 which includes most heritage buildings (Pickles & McCaig, 2017, p8).
Heritage buildings provide particular challenges for energy/carbon reductions because any changes must be sensitive to the heritage values (Menzies 2011). In addition, the construction methods of traditional buildings
necessitate significantly different retrofitting approaches to those used in modern construction (STBA, 2012). The design process of retrofit projects must therefore balance a highly complex set of, often conflicting, requirements (Mok & Hyysalo, 2018).