Heat, cooling, water, light and air. Providing people with comfort day and night whilst emitting just 5 per cent of current emissions is the greatest challenge in the built environment, and the thermal challenge is its most important aspect.

An insulated building envelope, high-performance glazing, sun protection, airtightness and ventilation with heat recovery are the primary ingredients for comfort – and thus also the basis for limiting the energy demand required to achieve it. Limiting heat demand is a sine qua non on any transition pathway. Over the entire lifespan of a building, the energy consumption of a non-insulated building carries greater weight due to the reuse or otherwise of materials. If a high-quality building envelope seems unachievable, demolition and reconstruction is often the better alternative – with valuable historic architecture being the main exception. Saving on the building envelope means compromising on comfort, and certainly so in changing climatic conditions.