Air permeability for existing buildings

cdbhaumik · Posts: 7

When producing an EPC for an existing building where a pressure test hasn't been carried out, is it acceptable to use the default air permeability of 10 m^3/hour/m^2? Or are there published figures somewhere for older buildings? I was thinking that 10 might be a bit optimistic for some older buildings!

Thanks, Claire

Pilch · Posts: 16

Hello Claire
I was told on my level 4 training to use 25 for buildings constructed before 2002, 10 for buildings constructed between 2002 and 2006 and 15 for anything since 2006.

cdbhaumik · Posts: 7

This isn't mentioned in any of the documentation. It could be a better idea to use the default of 10 (although it is optimistic) at least it will be consistent.

PaulCarey · Posts: 20 Location: Stalybridge, Nr Manchester

Claire

My comments below:

When producing an EPC for an existing building where a pressure test hasn't been carried out, is it acceptable to use the default air permeability of 10 m^3/hour/m^2?

No not really, I thought you were meant to assume a value of 15m3/hr.m2 much like you would in Part L calculations if it isn't tested.

Or are there published figures somewhere for older buildings?

There are some available from the AIVC but I imagine these are getting a bit dated now. They might be a useful source for older buildings though.

I was thinking that 10 might be a bit optimistic for some older buildings!

For some maybe, but then there are some pretty bad new ones about too.

Thanks, Claire

less · Posts: 36 Location: Birmingham, UK

The value of 25 for existing buildings has come directly from CLG. I am unaware of it being documented, we simply have had an email from the EPBD dept at CLG advising us of this change. For buildings post 2002 then you should use the guidelines in the 2002 Part L2 (attached). I use the following guidelines which I have deduced from the 2002 and 2006 regs:

2002-2006 and < 500m2. The problem occurs when the building owner cannot supply a test result when the building should have been tested. Whilst new buildings over 500m2 should have a test certificate showing less than 10 some flexibility was put in place for buildings not achieving an initial result <= 10m3/m2/hour based on an improvement factor.
All very confusing!
Andrew Confused

less · Posts: 36 Location: Birmingham, UK

Sorry all about last post seems my insert did not work so here goes again:
The value of 25 for existing buildings has come directly from CLG. I am unaware of it being documented, we simply have had an email from the EPBD dept at CLG advising us of this change. For buildings post 2002 then you should use the guidelines in the 2002 Part L2 (attached). I use the following guidelines which I have deduced from the 2002 and 2006 regs:

pre 2002: 25m3/m2/hour
2002-2006 1000m2: 11.5m3/m2/hour (or test result)
2006+: 15m3/m2/hour (or test result)

The problem occurs when the building owner cannot supply a test result when the building should have been tested (2002-2006 mandatory over 1000m2, 2006+ mandatory over 500m2). Whilst recent medium sized buildings should have a test certificate showing less than 10 some flexibility was put in place for buildings not achieving an initial result <= 10m3/m2/hour based on an improvement factor.
Andrew

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