[Equest-users] U-Value unexpected impact

Alex Krickx akrickx at seriousenergy.com
Thu Oct 13 10:39:02 PDT 2011


Hi Omar,

Another thing to check is that you are modeling a glass with a low-Solar Heat Gain Coefficient (SHGC). Low SHGC glasses and glass-units are best for situations where there is no need for passive heating (hot climates and internal load-dominated buildings).

You can still maintain high VT (>0.5) with low SHGC (<0.3), so it doesn't need to sacrifice aesthetics and daylighting options.

Great point on the internal loads Chris.

Cheers,
Alex

Alex Krickx, LEED AP
Building Energy Specialist
Serious Energy, Inc.
1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124
akrickx at seriousenergy.com

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________________________________
From: equest-users-bounces at lists.onebuilding.org [equest-users-bounces at lists.onebuilding.org] On Behalf Of Christopher Schaffner [chris at greenengineer.com]
Sent: Thursday, October 13, 2011 10:04 AM
To: Omar Osama; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] U-Value unexpected impact

In mild weather, with high internal heat gains, the losses through the glazing reduce the cooling load. In this situation, increasing the performance of the glass will cause increased energy consumption.

This counterintuitive result is often the result of an overestimation of internal heat gains.   You should perform a reality check on your internal heat gains, before you determine if this result is correct.

--

Chris Schaffner, PE
LEED Fellow
Founder and Principal

The Green Engineer, LLP
Sustainable Design Consulting
50 Beharrell Street
Concord, MA 01742
T: 978.369.8978
M:978.844.1464
chris at greenengineer.com
www.greenengineer.com

The Green Engineer, LLP is a Certified B Corporation

From: Omar Osama <o_osama at live.com<mailto:o_osama at live.com>>
Date: Thu, 13 Oct 2011 16:07:13 +0200
To: <equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>>
Subject: [Equest-users] U-Value unexpected impact

All,
    I'am modelling a mid-rise, curtain wall, office building in Egypt (hot humid climate 2a). while I do decrease the glazing's U-value, below 0.5, the energy consumption tends to increase. does this issue have a reality related explanation, is it a problem in my file, or is it a software bug issue?


Thanks for consideration,

Omar AlRawi
Project Engineer ,  EA Sustainable Building Consultants
www.ea-buildingconsultants.com<http://www.ea-buildingconsultants.com/>
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