Retrofit of existing housing stock
‘Deep’ retrofits are more robust in reducing energy use regardless of occupant behaviour. Retrofit measures may damage rather than improve the fabric or lead to unintended consequences. Owing to the complexity and interaction of different building retrofit measures, the whole building needs to be considered during retrofit design. Fabric moisture and water penetration may occur post-retrofit, owing to reliance on inaccurate moisture modeling tools or use of unsuitable retrofit materials and techniques. Post-retrofit, occupied buildings often do not achieve the energy and carbon reductions predicted pre-retrofit. Inaccurate predictions pre-retrofit may also lead to potential fabric damage or increased energy use post-retrofit, owing to the ‘unintended over-specification’ of certain measures. Deep retrofits are a sounder way of achieving energy reductions, regardless of occupant behaviour post-retrofit. Existing housing should benefit from the highest fabric energy-efficiency standards that can be afforded - ideally to at least zero carbon standard.