In circumstances where an existing building element (e.g. a facade) is being retained it is acceptable to incorporate them into the modelling of the ‘standard building’ baseline, for the purpose of undertaking passive design analysis.
All other building elements should be modelled with fabric performance equivalent to that of the local Building Regulations Notional Building (or for Scotland, an equivalent compliant building) and without the passive design measures (where feasible i.e. building orientation is likely to be fixed).