[Equest-users] u-values

Nick Caton ncaton at smithboucher.com
Thu Aug 30 09:38:11 PDT 2012


Hi Tim,

Your LEED reviewer is spot on:  refer to Appendix A7/7.1 in 90.1. The "fallback" ASHRAE values provided for various constructions/elements (incl. doors) are there as a means of last resort.  If you can determine the correct value, you should use it.

One can only speculate at what inputs you used (or didn't use) to arrive at a given U-value for your doors... sounds like you didn't reference the actual product/specification and should adjust to match as appropriate.

The online tool you found is in a sense already built into eQuest, and as such is probably a more time-efficient way to determine, define, & document construction thermal properties (i.e. in one step).  Choose to define your constructions in layers, and you'll find there's a library of materials similar to that online tool.

There can be multiple right answers, but your attic sounds like an unconditioned space of its own, which in turn should be defined with exterior surfaces (walls/roofs), and the spaces immediately below should have interior surfaces to match the insulated ceiling construction.

If you find yourself mostly "stuck" on the specifics/fundamentals of defining the constructions thermally, you might more time-efficiently engage your favorite MEP designer/consultant ;).

Best of luck!

~Nick
[cid:489575314 at 22072009-0ABB]

NICK CATON, P.E.
SENIOR ENGINEER

Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of tim
Sent: Thursday, August 30, 2012 10:41 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] u-values

I let my eQuest model generate U-values (see LV-I report - page 2 of attached pdf)

The U-values don't seem to make any sense.  The LV-I report says a door has a U-value of 2.080.
I looked up hollow metal insulated doors on the internet and found one that has a value of 0.16.
Why is there such a difference?

I know how to change u-values in detailed edit mode, but wonder what experience others have had with determining what U-values should be used.
I used an online calculator to find the u-value for a wall like mine (also attached).
Having trouble figuring out how to determine/ enter u-value for a roof assembly that is a trussed attic with insulation above ceiling as well as others.

I also realize ASHRAE has basic u-values listed, but my leed reviewer commented saying ASHRAE U-values should be used only if the actual U-values are unknown.  I assume this means if the makeup of a wall or assembly cannot be determined.

Thanks for your help in advance!
Timothy W. Hill
tim.JRGA at fuse.net<mailto:tim.JRGA at fuse.net>

John R. Grier, Architect
11309 Deerfield Road
Cincinnati, Ohio 45242
(513)489-3690

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120830/c08413e8/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 1459 bytes
Desc: image001.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120830/c08413e8/attachment-0002.jpg>


More information about the Equest-users mailing list