[Equest-users] Window Comparison

[Bob Fassbender]

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> 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
>
> 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] *On Behalf Of *Brett M. West
> *Sent:* Monday, November 08, 2010 3:38 PM
> *To:* 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
>
>
>
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