Choose Your Shell 'Fabric First'
As you will know, the energy requirements of any building are determined by the performance of all of the elements in its encompassing ‘envelope’, i.e. the ground floor, external walls, windows, doors, and the roof including any roof lights, chimneys, or ventilators.
The ‘fabric’ from which these are made and the way they are designed to connect and work together affect the overall performance efficiency of the structure. The ‘Approved Documents’ in the Building Regulations set out performance requirements for these elements. The way these can be achieved is left to the designer (as directed by you) to decide.
Subject to possible exceptions, the following table summarises our interpretation of the minimum performance values and limiting factors for buildings required by Approved Document L – Conservation of Fuel & Power – of the Building Regulations.
These include conventional timber frame, SIP frame, and CLT (solid Cross Laminated Timber) frame. You can also choose from a range of pre-calculated energy performance standards, from basic Building Regulations (‘Bronze’), through economically recommended (‘Silver’) to ‘near no heating required’ (‘Gold’) and on to virtual Passivehaus standards (‘Platinum’).
You can also choose from a range of external doors and windows for the shell, although roof covering, external cladding, rainwater goods and groundworks are generally determined by the Design Code.
Rationalised Specifications & Performances Indicative U-values assume 100mm external brick cladding + clay tile roof. SAP assessments should check these and also need ground floor, windows & door U-values.
