Air permeability for existing buildings

cdbhaumik · Posts: 8

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: 76

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: 8

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

Andrew Bairstow · Site Admin Posts: 343 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

Andrew Bairstow · Site Admin Posts: 343 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

johnmcc · Posts: 12

This is a confusing topic as, sometimes DB defaults to 10 and sometimes its defualt to 25, not sure where it takes its information to make this assumption. Working on an offices building 1970s construction and its defaulting to 10, but other industrial units 1930s contruction have been defaulting to 25. Would be nice to see some clear direction from the CLG?

Andrew Bairstow · Site Admin Posts: 343 Location: Birmingham, UK

It should be when you first specify the type of assessment (add building) that the air permeability is set. If you set Build Regs then it should be set as 10, if EPC it should be 25. If there are circumstances where this changes depending on building type then please let us know. I am not aware that this parameter is set when selecting building type or construction type. Would you like to check this again and let us know if it is still happening.
Andrew

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