Please check my calculation.

JonMac

We've had a technical assessment for a heat pump grant. However the assessor wasn't forthcoming when asked what kilowatt rating the heat pump should have.
I've had a go at calculating it but I'm not sure if it is the correct way. He classified the building as 180 kW/m2/yr.
He gave the heat loss area of the walls, roof, floor and windows as 310 square metres. This gives 55,800 kW per year, or 6.4 kW per hour on average all year long. Is this how it is done?
In addition there is the energy needed to heat the hot water.
Any suggestions about the size of the system to cover the heating during the colder months?
Thanks.

Why calculate it instead of measuring it?

JonMac

No idea. He wasn't very cooperative. It is a timber frame house and he wouldn't factor in the insulation between the studs because he couldn't see it; didn't ask about insulation under the slab\; ignored the low-e glass in the double glazing, etc.

Measurement will always be more accurate and less subject to human error. I tend to beat these types out the door with their clipboards.

JonMac

He was the 5th one I tried to get to come and do the assessment.
Was my calculation correct?

You tell me. Measure it.