Difference in heat loss by U value

[moguk]

Current new build regs require a wall u value of 0.2w/m2k.

With our wall construction, achieving this requires a PIR board thickness of 120mm, or 100mm if battens are used creating an air gap between the plasterboard and PIR.

Ideally, it would be more practical to use 60mm PIR, but this would only achieve 0.3w/m2k.

My question is, does anyone know what difference in energy use would the difference of 0.1w/m2k make.

 

[Dereekoo]

If its leaking 0.2 and then its leaking 0.3 then the increases in heat leakage is (0.3 -0.2)/.2 = 50% more .

 

[John D v2.0]

Of course the real question is whether the insulation will pay for itself, which you might do based on how long the building will last or how long you will live there. Who knows what energy prices and the climate will do in that time.
Also is the room full of bifold doors and what is the floor to perimeter ratio.

Just for example (caveat lots of massive assumptions ahead just for illustration)
At the moment it would be a couple of watts extra per square metre in winter, so on 100m2 of wall that might be a couple of hundred watts or 5p an hour extra in cold winter. Making say 50 pounds a year extra?

Given your extra insulation would add 20 pounds a sheet? It would cost 600 pounds extra for insulation so 30 years at current prices. Based on lots of massive assumptions off the top of my head.