[Equest-users] window replacement

[Alex Krickx]

Hi Ben,

Vikram makes a good point below - you should check first check to make sure results and expectations are reasonable.

Regarding your original question: in your parametric runs you can set frame width to zero: window/basic specification/frame width. In that way, when you enter your full frame U-factor and full frame SHGC (actually I think you need to enter this as SC) you will no longer have to worry about the U-factor of the base-case frames in your parametric run. There is a lot of concern about putting in one value for U-factor and one value for SHGC. So the alternative is what Carol suggested: to import the window into eQUEST after creating it in WINDOW5 (LBNL's free window tool). The problem with that is that I don't believe that eQUEST imports frame data. So you would need to import the glass, determine the improved frame U-factor (probably around U-1.0 for TB aluminum) and set your parametric run with 2 components: 1 to change the glass, and 2 to change the frame conductance.

Hope this helps!

Cheers,
Alex


Alex Krickx
Building Energy Specialist
[cid:image001.jpg at 01CB437B.E3F62970]
1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124

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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
Sent: Tuesday, August 24, 2010 9:53 AM
To: Ben Pressman; equest-users at lists.onebuilding.org
Cc: Justin Murray
Subject: Re: [Equest-users] window replacement


Ben,

I would first go back to your base model and examine what percentage of the building load is actually coming from the glass. Your LS-C reports will give you your peak load components, and LS-F will give you your Monthly load components - a better indicator of overall energy usage.



Keep in mind this doesn't factor in ventilation loads. You will need to look at the SS-D report to get an overall picture of the loads your system sees, and work backwards from that to get a picture of what the ventilation component is. So for example - if your LS-C shows a peak cooling load of 1000kBTU/hr and your SS-D Shows 1500 kBTU/hr, then your ventilation loads will be 500 kBTU/hr. [eQUEST users - please correct me if I'm wrong here]



So if your glass conductance + Solar is 15% f the overall load, then a 5% savings is pretty significant, however, if its 50% of the load, then there might be a problem with your model.





Hope this helps






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


-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Ben Pressman
Sent: Tuesday, August 24, 2010 12:21 PM
To: equest-users at lists.onebuilding.org
Cc: Justin Murray
Subject: [Equest-users] window replacement



  Thanks, Carol, for your quick response. I think my question might have

been too specific. My baseline model agrees to within 5% of the actual

gas and electric bills for the building. The exterior walls, especially

north and south elevations, are about 30% windows by area. By replacing

single-paned windows with double-paned, modern windows, I am expecting

about a 23% reduction in energy usage based on simple heat equation

estimations. eQuest is only returning a 5% savings. I suspect I am not

defining the replacement windows correctly, but it seems there must also

be a problem with how eQuest is calculating my heating loads through the

windows. I specified the windows' estimated percent wall area, and also

drew custom windows everywhere to match what the actual building looks

like. What is the best way to approach solving this problem?



Thanks again,

Ben



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