Energy efficiency- Part L and small extensions

PMBC

If i got it right, the energy requirements of current Part L are relaxed for an extensions where the envelope is les than 25% of the original building envelope.

PMBC

Excuse that last brain-f**t. That might have had some applcability ot major renovations.
So where an extension is thermally separated from the rest of the dwelling the average U value of its elements should not exceed 1.4.? If you have very few windows it cant be that hard to achieve 1.4 with say 100mm in walls and floor and even with a flat roof 100 or 150 EPS.

sydthebeat

PMBC wrote: »

Excuse that last brain-f**t. That might have had some applcability ot major renovations.
So where an extension is thermally separated from the rest of the dwelling the average U value of its elements should not exceed 1.4.? If you have very few windows it cant be that hard to achieve 1.4 with say 100mm in walls and floor and even with a flat roof 100 or 150 EPS.

nope

only windows and doors can be averaged at 1.4

the average u value allowed for each element is listed in column 2 of table 5

PMBC

Thanks Syd. I just found notes from a course that I started but didnt progress and I had Table 5 highlighted. But it would have taken me some time to get to that point!!

Gumbo

PMBC wrote: »

Excuse that last brain-f**t. That might have had some applcability ot major renovations.
So where an extension is thermally separated from the rest of the dwelling the average U value of its elements should not exceed 1.4.? If you have very few windows it cant be that hard to achieve 1.4 with say 100mm in walls and floor and even with a flat roof 100 or 150 EPS.

How can it be an extension to the dwelling and thermally separated?

PMBC

As in TGD 2019 2.1.2.5 .....extensions which are thermally separated from the adjacent spaces (original building ? PMBC) ... by wall, doors etc.