Peak heat loss calculator

A step-by-step wizard for calculating a building’s peak heat loss from its fabric elements and ventilation — the number heat-pump sizing starts from.

What you can do here

• Work through the steps — add fabric elements (walls, roofs, glazing) with their areas and U-values, set ventilation, and review.
• Submit — the result is saved as an insight on the site, so the calculation and its inputs stay with the building it describes.