Buildings and Energy

Retrofitting existing buildings is one of the most difficult problems in the energy transition, for both technical and social reasons. Why it matters enormously: Approximately 80% of the buildings that will exist in 2050 have already been built. In the EU, approximately 35% of all buildings are more than 50 years old, and approximately 75% of the building stock is energy inefficient. If these buildings are not retrofitted, they will continue consuming enormous energy — regardless of how much clean electricity is generated. The IEA estimates that building renovation rates must triple to 3% of existing stock per year (from ~1% today) to meet NZE 2050. Why it's hard: (1) Disruption: Retrofitting a home (external wall insulation, new windows, heat pump installation) typically requires the occupants to vacate for weeks, or at minimum tolerate significant disruption. (2) Upfront cost: A full deep retrofit in the UK costs approximately £30,000–60,000 per house. Even with grants, the upfront barrier is high for low-income households. (3) Split incentive: If a landlord owns a house and tenants pay energy bills, the landlord has no incentive to invest in insulation (they don't pay the energy bills). If tenants own, they lack capital. (4) Planning: Heritage buildings and conservation areas restrict external changes. In the UK, approximately 400,000 listed buildings cannot have standard external insulation. (5) Supply chain: Certified Passivhaus retrofit installers, heat pump technicians, and competent fabric retrofit teams are in short supply globally. The most effective retrofit programmes combine: mandatory minimum efficiency standards (EU EPC), grants targeted at low-income households, green mortgages (favourable rates for efficient buildings), and public information. The UK's ECO4 (Energy Company Obligation) and EU's Renovation Wave are the most ambitious active programmes. Source: IEA Buildings 2023 · UK BEIS Retrofit statistics · EU Renovation Wave documentation.