Part F Ventilation Airtightness

Brave Harvey

What are the requirements for airtightness tests and where does it state anything about it in the regulations? In table 1 Part F, note c it states

Equivalent areas to be increased by 40% where air permeability is less than 5m3/(h.m2).

It doesn't state any maximum level, and doesn't mention the air changes per hour that I hear a lot of from airtightness tests. What are the requirements of air changes per hour to meet the current building regulations??

sinnerboy

Look to Part L

Brave Harvey

Look to Part L

Thanks, Part L says on page 20 top left that a performance level of 7m3/(h.m2) represents a reasonable upper limit. Where in the document does it give a min/max standard. And how can you convert this 7 figure given to a.c.h.?

sydthebeat

Brave Harvey wrote: »

Thanks, Part L says on page 20 top left that a performance level of 7m3/(h.m2) represents a reasonable upper limit. Where in the document does it give a min/max standard. And how can you convert this 7 figure given to a.c.h.?

why do you want to convert it to air changes per hour? thats just an approximate figure used.

There is a minimum level or air tightness to be achieved, 7m3/hr/m2.... as set out by the regs.... this is de facto compliance. If you want to argue some other method to comply then its up to you to argue that with your certifier.

You either achieve that and comply or you dont achieve it and dont comply.

Obviously theres no other "maximum" level other than what you you can possibly achieve..... the ultimate is a 0 value.

Brave Harvey

why do you want to convert it to air changes per hour? thats just an approximate figure used.

ACH is all what I hear been used and it would be nice to convert the values to relate the two different units.

There is a minimum level or air tightness to be achieved, 7m3/hr/m2.

Yes, the 2008 Part L stated a minimum of 10m3/hr/m2 with 7m3/hr/m2 being good practice. On the 2011 Part L is states 7m3/hr/m2 represents a reasonable upper limit but it doesn't sound like it holds you to that figure, I guess its the Ber assessment that will need a good result to reach the passing of the regulation.

sydthebeat

Brave Harvey wrote: »

ACH is all what I hear been used and it would be nice to convert the values to relate the two different units.

the air tightness result is the proper means of comparison.

The achr is that figure divide by 20 and only offers an approximate figure for actual air changes per hour, so its stupid to use that as a comparative value.

Brave Harvey wrote: »

On the 2011 Part L is states 7m3/hr/m2 represents a reasonable upper limit but it doesn't sound like it holds you to that figure,

take it from me that it is the minimum figure to be achieved.

The regs are full of vague language, but unless you have some other method of compliance you HAVE TO take the inherent values as gospel.

Brave Harvey

The achr is that figure divide by 20 and only offers an approximate figure for actual air changes per hour

Just want to clarify this 7m3/hr/m2 is equal to (7/20) = to 0.35 ach, and the passivhaus requires less than 0.6 ach. Hardly?

sydthebeat

Brave Harvey wrote: »

Just want to clarify this 7m3/hr/m2 is equal to (7/20) = to 0.35 ach, and the passivhaus requires less than 0.6 ach. Hardly?

no, why do you think passive requires 0.6 ach???

go back and read again.

you are picking up some of teh information but not all of it.

its 0.6 ach at 50 pascal pressure.

Brave Harvey

you are picking up some of teh information but not all of it.

I am attending an airtightness course soon so hopefully i will pick up all the information!!

sydthebeat

Brave Harvey wrote: »

I am attending an airtightness course soon so hopefully i will pick up all the information!!

comparing 'passive' and 'building regs' is slightly complicated because they used two different measurements.

The regs require a min Q50 of 7 (thats 7m3/hr/m2 at 50 pascals)

Passive require a min N50 of 0.6 at 50 pascals.

thats how youd compare.
But beware that the measurements for Q50 and N50 are slightly different.

sinnerboy

I simplified terms Q50 tells you how much air leaks through the fabric of your building ( it's base floor , walls and roofs etc) during a test.

n50 tells you how many times the air inside the building changes during a test.

Divide Q50 or n50 by 20 to get an approximate rate at normal pressure.

Twins but not identical .

fclauson

this is a very useful document on blower door testing
www.greenbuild.ie/PassiveHouseBlowerDoorTesting.pdf

I have no relationship with this company