[Equest-users] Simple question...hopefully

[Nick Caton]

In a recent project,  our architect decided to "upgrade" to nicer (more
expensive) glass.  These fenestrations had marginally better thermal
properties, so I had the same surprise to find the annual energy figures
going UP...

 

After some investigation, it turned into an important design lesson
which may or may not apply to your case:   This project had a
significant amount of daylighting, and the "improved" glass had a
significantly lower Tvis figure.  Less light in means more energy spent
on the lighting system!

 

In the role of lighting system designer, I used to ignore things like
glass transmissivity, as I was taught to design around the worst case
(i.e. nighttime where window contributions have little/no effect)... now
I pay very close attention when daylight harvesting is a part of the
project!

 

Hope this helps either your current situation, or otherwise in the
future!

 

~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: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of David
Delasantos
Sent: Monday, November 16, 2009 11:02 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Simple question...hopefully

 

I ran a very quick and dirty EEM to compare the effects of using a
different glass type when compared to the baseline model, which was
created in the SD Wizard.  Contrary to my expectations, the higher
performance glass resulted in higher annual energy usage!  The glazing
is the only component I changed in the model.  If anyone can speak to
this result, I would appreciate it.

Thank you...DD 

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