ABSTRACT
This chapter focuses on thermal performance of the fabric, but there are many synergies with these other factors. The building fabric and services design are the two key aspects of a building’s performance. A thermally efficient building envelope will need to be well built, structurally sound, airtight, weatherproof, fire resistant and have good acoustic performance due to the insulation and airtightness. The challenge when detailing and delivering a building is to keep the thermal envelope continuous. Continuity of insulation and airtightness is often not prioritised when designing the structure and services penetrations. The windtight barrier protects the insulation from ‘wind washing’, which produces ‘thermal bypass’ that hugely reduces the performance of the insulation. The windtight layer can take the form of a variety of different materials such as brick, render or a membrane over the insulation. The airtight layer should be tight up against the insulation with no air gaps between.
