Sustainability in Heritage Buildings: Can We Improve the Sustainable Development of Existing Buildings under Approved Document L?

The British government has ambitions to achieve net-zero carbon emissions countrywide by 2050, with their largest challenge being emissions from the construction industry. Approved Document L sets standards for the fabric performance of buildings to regulate their consumption of fuel and power, thereby allowing easier transition to all-renewable grid electricity and the phasing out of fossil fuels. Whilst this approach has shown success in new builds, its effectiveness on retrofits, especially regarding built heritage, is significantly reduced. Responding to this, the paper investigates alternative sustainable design solutions that could feasibly justify revisions to Approved Document L, to improve the sustainable performance of existing buildings and bring them in line the government’s 2050 targets. Trialing solutions on a listed building case study, benchmark figures are used to analyse the energy, carbon, and cost implications of sustainable design approaches relating to passive design, low-carbon technologies, renewable energy, and additional considerations. Using this method, it is reasonable to conclude that the standards of Approved Document L for existing buildings are currently underperforming but can feasibly be revised to encompass the full breadth of contemporary sustainable design solutions.