sap

We live in a 3 bedroom semi built in 2011. I have the original EPC / SAP. In 2013 we also added an orangery 3x4m to the rear. Now we're having a Supalite roof replacement including building regulations submission. Once that is done - we want to remove the patio doors leading to the 'former...

Ahead of commissioning a proper SAP calc, I'm trying to construct a rough rule-of-thumb, so that I can be reasonably sure I don't have to massively revise any details/wall thicknesses etc. for a new-build resi project. The doors and windows I want to specify fail the target U-value by 25%, and...