Open Tables in the top bar and choose Heat loss. Every element of the envelope is listed with its area, its U-value and its U × A, section by section — walls, windows, doors, roof, ceilings, slab — and totalled in W/K. Like the takeoff, nothing is stored: it is derived from the drawing every time you look at it.
The heat-loss sheet is a Pro feature.
The envelope is read, not declared
You do not tag anything as external. A wall with a room on one side and nothing on the other is the envelope; a wall between two rooms is internal; a garden wall with rooms on neither side is not envelope at all. Draw the building correctly and the sheet follows.
Areas are measured exactly as the quantity takeoff measures them — storey-rectangular walls with openings deducted — so the two sheets can never disagree about the same wall.
Nothing is guessed
An envelope element with no build-up, or one whose U cannot be known, reports its area with no U-value and stays out of the total. That is deliberate: a missing build-up shows up as a gap you can see, rather than quietly inventing a number. Give it a build-up and it joins the total.
What it is not
This is fabric transmission only. Read the limits before you use the number for anything:
- No ventilation, no infiltration, no thermal bridges (ψ), no solar or internal gains. It is not a compliance calculation and must not be presented as one.
- U-values are indicative, from typical material conductivities in the EN ISO 6946 form. Windows and doors carry typical figures by type.
- The ground slab is counted at the same temperature difference as everything else. A full calculation reduces it — the ground under a house is far warmer than the design outdoor air (EN ISO 13370) — so the slab’s share reads high, often by around half. It is stated rather than corrected by a factor nobody can see: every row stays a plain U × A.
Used the way it is meant — comparing two versions of the same house, seeing which element dominates, sizing insulation — it answers the question long before an engineer’s model would.
Getting it out
Tick Heat loss in the export dialog and it prints as its own sheet in the PDF set.
Next
Build-ups and U-values is where the U comes from, and design options is how you compare two schemes of the same house side by side.