[Bldg-sim] Infiltration

[Paul Carey]

Tim,

 

Infiltration is something we need to model in the vast majority of the
buildings we simulate.  

 

There is a mass of empirical data that has gone behind the tables provided
in the CIBSE guides, which was mostly collected by both the UK BRE and
BSRIA.  You could also try the AIVC which has a number of publications on
infiltration testing and in particular a useful book called "Numerical Data
for Air Infiltration and Natural Ventilation Calculations" by Orme,
Liddament & Wilson.  It was reprinted with amendments in 1998 and so is
slightly old now, but it is a good starting point for looking at the overall
numbers to use and the basis for why.  

 

I think you should also try CIBSE Guide A which has some useful tables on
infiltration rates to use - an example and extract of which is below (Part L
denotes UK building regulations for energy consumption):

 


Air Permeability 

Infiltration Rate (ac/h) 

	
Peak 

Average


20 (leaky) 

0.95 

0.70 


10 (Part-L 2002) 

0.50 

0.35 


7 (Part-L 2006) 

0.35 

0.25 


5 

0.25 

0.20 


3 

0.15 

0.10 

>From CIBSE Guide A Table 4.13 for 2 storey 500m2 naturally ventilated
offices, normal exposure

 

Generally if you've got a cavity wall installation the chances are the
infiltration rates unless very well monitored for construction quality will
be considerably higher than for something like a composite panel system.  We
see a lot of huge warehouse buildings that have significantly lower
infiltration rates than domestic dwellings (per m2) because of the ease of
constructing large warehouse with good detailing.

 

Hope this helps.

 

Paul

 

 




Dr Paul Carey

BSc (Hons) PhD FRSA

Director

Low Carbon Energy Assessor

 

Zero Energy Design Ltd

10A Portland Place

2-22 Mottram Road

Stalybridge

SK15 3AD

 


T:  0161 3386200

F:  0161 3031281

M: 0789 4098012

E:  paul at zed-uk.com

W:  www.zed-uk.com

 


 



 

 

 

 

 

 

 


 



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-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Tim Johnson
Sent: 09 June 2009 22:52
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Infiltration

 

I have the task of evaluating the benefits of continuous insulation compared
to insulated wall cavities.  The idea behind the continuous insulation is
partly that it will make a tighter building and not allow as much
infiltration.  I realize that continuous insulation eliminates the thermal
break in the wall and I am able to quantify that, but I do not know of a
good way to quantify the difference in infiltration.  Does anyone know of
studies that have been done on building infiltration?  What values do you
normally use for new construction in your energy modeling?

 

Thanks,

 

Tim Johnson, EIT, LEED AP

P: (208)577-5645

F: (208)343-3531

timj at ctagroup.com 

 

 

 

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