Chosen from the evidence available.
Heat loss survey reports for UK installers
Domestic room-by-room calculation reports with inputs, assumptions, emitters and sizing evidence shown clearly for installer teams.
Choose a measured visit when the evidence is weak. Use desktop calculations when the drawings are strong. Before booking, check whether the assumptions, room data and report route are visible enough for design review.
Measured, supplied, and assumed data separated.
Built for design check, not just a number.
Postcode and lead time checked upfront.