[Equest-users] Does eQUEST derate equipment for altitude?

[Nick Caton]

Kenda,

 

I'm curious as to whether you received any responses to the query below.

 

I have incorporated a practice of manually setting the site altitude in
my eQuest models to "0," because (1) as designers we do not specify
equipment with CFM's at sea level, it is already "corrected" for
altitude in this sense, and (2) those who review models tend to miss the
significance of the altitude factor in the SV-A reports and complain of
incorrectly entered airflow rates.

 

I don't know if this constitutes a "best practice," but I know it is
common to a number of the regular contributors to these lists besides
myself.  As it stands, current standards (90.1-2007) don't have us
"de-rate" or otherwise adjust required minimum SEER/EER values for
altitude... so inversely it seem appropriate to remove the altitude
variable when modeling for a performance rating... thoughts?

 

~Nick

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

Smith & Boucher Engineers

25501 west valley parkway

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 Kendra
Tupper
Sent: Thursday, September 02, 2010 1:53 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Does eQUEST derate equipment for altitude?

 

All,

 

I'm trying to get clarification on exactly how eQUEST handles the
altitude above sea level that is entered in Site Parameters. My
understanding is this affects the airflow sizing calculations for cfm,
but does not change the hourly air density for all calculations. If that
is correct, then the altitude only corrects the cfms at the zone and
system level, but does not derate equipment efficiencies. So, if you
were to enter the altitude above sea level, you should then enter your
airflows at sea level, but enter all equipment efficiencies at the
derated conditions for that altitude.

 

Is that correct?

 

Kendra Tupper, PE, LEED AP
Senior Consultant
Built Environment Team

Rocky Mountain Institute  |  T  303-567-8641 |  F  303-245-7213  |  
www.rmi.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110120/54db2870/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 1459 bytes
Desc: image001.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110120/54db2870/attachment.jpeg>