Why do I get negative heat loss values on the External Walls?

The main reason for this is that the calculated total wall area will be less than the window and door area combined. This will lead to a negative external wall area, which in turn will result in negative heat loss.

In our software, the external wall area is calculated using the formula below.

External wall total perimeter Type A x Room height = Total wall area type A
External wall total perimeter Type B x Room height = Total wall area type B

External wall area type A = Total wall area type A - (Window area type A + Door area type A)
External wall area type B = Total wall area type B - Window area type B

While measuring the external walls you will need to measure the entire perimeter and enter this value into our software. Our software will calculate the external wall area accordingly.

Please watch the below video which will explain in detail on measuring the external walls, windows, and doors and enter those dimensions into our software to avoid user errors.