[Equest-users] Window Comparison

[Sami, Vikram]

Brett,
Just a cursory glance shows you have a lot of unmet loads - mostly on heating. Try enabling night cycling - that should reduce that and show better savings on the high performance glass.



Vikram Sami, LEED AP
Sustainable Design Analyst
1382 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462    f: 404.892.5823       e: vikram.sami at perkinswill.com   www.perkinswill.com<http://www.perkinswill.com/>
Perkins+Will.  Ideas + buildings that honor the broader goals of society


From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Alex Krickx
Sent: Monday, November 08, 2010 5:34 PM
To: Bob Fassbender; Wolfe, Brian
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Window Comparison

I looked through the file (novice user myself) but did notice some things that seem odd:

Are both your 1st floor plenum and 2nd floor plenum exposed to the outside? Are both of your "floor" elements designated as touching the ground? That's what it looked like when I opened up your model... That alone would double the envelope loads on the ground floor and roof (which means that windows as a percentage will be less effective).

I would check that before going onto determine the effectiveness of windows.

Cheers,
Alex


From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bob Fassbender
Sent: Monday, November 08, 2010 2:21 PM
To: Wolfe, Brian
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Window Comparison

I agree with Brian. I have done similar studies and found that in certain climates the savings offset. However, 3% sounds a little low, especially with 30% glass.

There are other issues that come into play as well with VAV systems. What probably is happening is that the airflows are different and the VAV minimums are affected (or perhaps they are identical which could also cause a lack of savings).

You may want to compare using the sim file, the number of hours running at VAV minimum, since the better glass may actually be eliminating "free reheat" during certain times of the year. I have seen this often. Make sure all of your design airflows are the same by locking them into place in both runs (since I'm guessing you are not changing the fans).

Bob Fassbender
Cosmo Logic LLC
Energy-Models.com
On Mon, Nov 8, 2010 at 4:02 PM, Wolfe, Brian <bwolfe at hksinc.com<mailto:bwolfe at hksinc.com>> wrote:
I couldn't get it to open to check, but since there's a total of 3% change, you might check the difference between space cooling and heating.  The difference might be counteracting each other enough to reduce the benefits that you thought you'd see.  The location and internal loads might have some affect as well.

BRIAN J. WOLFE, CDT, LEED AP BD+ C
SUSTAINABLE DESIGN COORDINATOR
HKS, INC.
1919 McKINNEY AVENUE
DALLAS, TX 75201
214.969.5599 ext.3669
bwolfe at hksinc.com<mailto:bwolfe at hksinc.com>
www.hksinc.com<http://www.hksinc.com>
If you are sending file(s) always use my Thru DROPBOX<https://hks.thruinc.net/drop_box.asp?toemail=bwolfe@hksinc.com>

From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org>] On Behalf Of Brett M. West
Sent: Monday, November 08, 2010 3:38 PM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] Window Comparison

I am doing a model for a two story office building with the windows making up approximately 30% of the building's exterior. My goal is to find what type of energy savings the owner can expect by replacing all the existing single pane windows with double pane, low e windows. When I change the window type to a double pane low-e window I am seeing savings that are very small, around 3% of the total building kWh.

For reference, the buildings HVAC system consists of two air handlers (one per floor) ducted to a VAV system with hot water reheat.

Has anyone else tried to do this type of comparison and if so what type of energy savings did you find? I have attached my model pd2 and inp files for reference. Thanks in advance for any information.


Brett West

RMF Engineering, Inc
Ph: 843.971.9639
bwest at rmf.com<mailto:bwest at rmf.com>


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