Retrofit is the single biggest lever the UK has for cutting carbon and fuel poverty — and the single biggest source of unintended consequences when done badly. Add insulation without managing airtightness, thermal bridging and ventilation and you can move the dewpoint into the structure, creating hidden condensation and mould. This pillar sets out how to retrofit safely, in the right order, with moisture risk designed out from the start.
A house is a system — fabric, airtightness, ventilation, heating and moisture behaviour are interdependent. The guiding principles are 'fabric first, plant last' (reduce the demand before sizing the heating) and 'build tight, ventilate right' (never tighten without ventilating). The articles below cover each insulation route — internal, external, solid wall, loft, roof and floor — and the whole-house strategy, sequencing and risk management (PAS 2035) that tie them together.