[Equest-users] Modeling Infiltration and Windows

[Nick Caton]

I tried to fire back a reference for you yesterday but it seems to have been held up a bit...  

 

Here's where you can find some ACH as a function of airtightness of construction/temperature:

 

Table 7, Chapter 28, 2001 ASHRAE Handbook-Fundamentals

 

~Nick

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

Check out our new web-site @ www.smithboucher.com 

 

From: Pasha Korber-Gonzalez [mailto:pasha.pkconsulting at gmail.com] 
Sent: Monday, March 08, 2010 10:47 PM
To: steve clark
Cc: Nick Caton; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Modeling Infiltration and Windows

 

A good rule-of-thumb assumption for any new construction is ACH=0.20.  I believe this is based on an ASHRAE reference.  For existing building construction it can be slightly higher than that up to significantly higher depending on the construction type and age of the building.

 

Generally for new construction 0.20 is a good solid assumption.

 

pk

On Mon, Mar 8, 2010 at 6:06 PM, steve clark <scstevemclark at gmail.com> wrote:

Hi Nick,

Do you have a reference for the ASHRAE ACH estiamtes you mentioned?

thanks!
Steve

On Mon, Mar 8, 2010 at 7:47 PM, Nick Caton <ncaton at smithboucher.com> wrote:

	I've done exactly that in the past for the exactly the same purpose!

	 

	The only difference is I believe I always punch in the differences in the metric of ACH.  ASHRAE fundamentals provides some guidance regarding air change rates to expect for various classes of construction as a function of outdoor design temperature, and that was the best I could base my existing construction off of from what info I had available.

	 

	Come up with a  "leakiness" for both you construction, old and new windows, and do the weighted average jig =).

	 

	Kudos on your fancy facade spelling also ;)! 

	 

	~Nick

	Error! Filename not specified.

	 

	NICK CATON, E.I.T.

	PROJECT ENGINEER

	25501 west valley parkway

	olathe ks 66061

	direct 913 344.0036

	fax 913 345.0617

	Check out our new web-site @ www.smithboucher.com <http://www.smithboucher.com/>  

	 

	From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Alex Krickx
	Sent: Monday, March 08, 2010 6:05 PM
	To: equest-users at lists.onebuilding.org
	Subject: [Equest-users] Modeling Infiltration and Windows

	 

	Hello all,

	 

	I am interested in modeling the energy savings that occurs when windows are replaced with lower-infiltration alternatives. In the wizard mode, the only place that I see infiltration is under the "Building Envelope Constructions"  Screen. 

	 

	I'm hoping someone can confirm my methodology:

	 

	Can I input a weighted average of window and wall air infiltration here?  If I'm looking at a building with 20% Window to Wall Ratio, and the windows have 0.1 CFM/ft² while the walls have 0.04 CFM/ft²can I apply an area weighted average into this box? I would take (20%*0.1+80%*0.04) as the façade infiltration value.

	 

	That way I could use the same formula to determine the area weighted infiltration of the façade if better windows were installed.

	 

	How do other people model this?

	 

	Thanks in advance!

	 

	Alex Krickx

	 

	 

	Alex Krickx

	Building Energy Specialist

	Error! Filename not specified.

	1250 Elko Dr, Sunnyvale, CA 94089

	(t) 408.541.8124

	 

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-- 
Steve Clark, MS PhD RESNET BPI ITC
ClarkEnergyConsultants.com
484.477.7525



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