Airtightness test

readytostart

Hi all

I have just got my blower door test done. The results came back as 2.23 in the q50 test. How do i convert this to ACH. Am I right when I multipy q50 by the surface and divide that by the volume. This would be (2.23 x 478) / 703m3 giving me a result of 1.156.
Thanks for any help

MicktheMan

If it's for input into DEAP, you divide the q50 result by 20.

beyondpassive

Correct, divide q50 by volume and multiply by the surface area to get n50

so q50 (permiability) at 2.23m3/hr/m2 multiply by surface area 478m2 is a total flow of 1065.94m3/hr, divided by volume 703m3 is 1.52m3/hr n50 (leakage)

Deap uses q50 at 5 pascals average over/under pressure so divide q50 by 20.

I'm curios though, surface are is usually slightly higher than volume for Irish buildings. Have you counted the floor or any party walls with a neighbour for instance. Have you done a surface area calc?

readytostart

Thanks for the replies.
Beyondpassive the measurements of my house is 16m x 9.1m with a small 1.7m x 1.8m pourch. From floor to roof its 6.25m. That makes it have a surface area of 531m2 not 478m2. the volume is still 703m3.My V50 was 1066 m3/h. Does this sound right?

beyondpassive

6.25 is very high for the (roof) upper ceiling, is it vaulted?

Main block floor and ceiling area 16x9.1=145.6x2=291.2
Main block walls perimeter 32+18.2=50.2xht 6.25=313.75

porch
floors= 1.7x1.8x2=6.12
walls = 6.12x2.4= 14.69

total envelope area is 604.95m2

Vol is 145.6x6.25=910 + (3.06x2.4)= 908.34m3

Flow v50 1066m3/hr

Permiability q50 1.76 m3/hr/m2
Leakage n50 1.17 m3/hr ach

readytostart

Thanks for that Beyondpassive.
The floor heights are high because 200mm of EPS and 100mm of floor screed to go in. That figure seems very good as it is a block build and outside walls are only scratched. When it is fully plastered the results should get alot better.

beyondpassive

readytostart wrote: »

Thanks for that Beyondpassive.
The floor heights are high because 200mm of EPS and 100mm of floor screed to go in. That figure seems very good as it is a block build and outside walls are only scratched. When it is fully plastered the results should get alot better.

I wouldn't need to know the floor build up? my question was; what is the clear finish floor to finish ceiling? as 6.25 seems high

sas

readytostart wrote: »

That figure seems very good as it is a block build and outside walls are only scratched. When it is fully plastered the results should get alot better.

That is unlikely. Regardless of what is being said by various sources, a thick scratch coat is very airtight.

I got 0.32 on my own home with 1/2 the house still to be skimmed. A friend of mine got 0.5 with no skimming done.

readytostart

Beyondpassive
My house is a bungalow with space for rooms upstairs in the future if required. My measurements were from sub floor to internal peak of roof, as my airtight envelope is this. No plasterboarding or flooring has been carried out yet. Maybe my height measurements should have read 3.25m to wall plate level then 3m to peak

SAS
I am hoping my results will get better as I have only a light scratch coat on, and that is only on outside walls. When we done the test alot of air was coming in at the joints between the outside walls and the interior walls. Also there is also some work to be done on the windows and doors also. So were hoping.

Thanks

sydthebeat

QUICK Q to those in the know

to go from n50 to q50 i assume i use beyondpassives formula above, backwards.

q50 = (n50 / surface area0 x volume ??

also, on an air tight test is the leakage volume (V50) the same as surface area?

thanks

fclauson

Syd check out www.greenbuild.ie/PassiveHouseBlowerDoorTesting.pdf

loads of info in this doc