[Equest-users] evaporative coolers in equest

[Joe Huang]

This is the wrong way to look at evap cooling performance.  In fact, the whole logic of 
sizing using design conditions falls apart when it comes to evap coolers.  Evaporative 
cooling works by taking advantage of the wet-bulb depression to trade off latent for 
sensible heat.
When the wet-bulb depression (DBT - WBT) is low or when the WBT is high, evap cooling
will provide little cooling.  A better way to size evap cooling is to either minimize the 
unmet
cooling hours, or if there is an AC backup, maximize the energy reductions.

If you're working with a fixed evap cooling size, then you should look at the number of 
unmet cooling hours to see the benefits of a window upgrade, as well as the reduction (if 
any) of  electricity use.

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
www.whiteboxtechnologies.com
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"


On 8/16/2011 1:11 PM, deepika khowal wrote:
>
> This is an existing building with evaporative coolers.
> the proposed design  to upgrade the windows and check the relative benefits.
> I dont see much benefits in energy because  evaporative coolers are sized based on Cfm 
> and not btus, the savings will be in cfms.
> correct me if I am wrong.
> is there any other way I can show the benefit in the proposed case if not HVAC benefits?
> Thanks
>
> On Tue, Aug 16, 2011 at 1:00 PM, Nick Caton <ncaton at smithboucher.com 
> <mailto:ncaton at smithboucher.com>> wrote:
>
>     Hi Deepika,
>
>     I’m not certain any increase/decrease in cooling loads (such as solar loads affected
>     by changing glazing) should have any effect on the reported “space cooling energy”
>     when you’re using evaporative coolers.  Direct evaporative (swamp) coolers of the
>     simplest sort have only fan and pump energies to consider -  no refrigerant!  I
>     would advise looking up the Detailed Simulation Reports Summary page 158/160 to
>     review end use categories and what they cover.
>
>     I am unfamiliar with Bridgeport’s climate, but as a general rule if I observed a
>     significant amount of glazing in a space served by a direct evaporative cooler… I’d
>     be extra cautious to ensure the HVAC designer is carefully considering condensation
>     and potential for other humidity-driven issues along the way.  I’m most used to
>     seeing them applied to well-ventilated and/or open-air spaces such as garages and
>     gyms/hangars.
>
>     ~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 <tel:913.344.0036>
>
>     fax 913.345.0617 <tel:913.345.0617>
>
>     www.smithboucher.com <http://www.smithboucher.com>__
>
>     *From:*equest-users-bounces at lists.onebuilding.org
>     <mailto:equest-users-bounces at lists.onebuilding.org>
>     [mailto:equest-users-bounces at lists.onebuilding.org
>     <mailto:equest-users-bounces at lists.onebuilding.org>] *On Behalf Of *deepika khowal
>     *Sent:* Tuesday, August 16, 2011 1:36 PM
>     *To:* equest-users at lists.onebuilding.org <mailto:equest-users at lists.onebuilding.org>
>     *Subject:* [Equest-users] evaporative coolers in equest
>
>     Hello all
>
>     I am modeling a building in Bridgeport, CA which has evaporative coolers.
>
>     I dont see any benefits if I replace existing clear glass with low-e in cooling
>     energy consumption.
>
>     Did anyone model evaporative coolers/swamp coolers before?
>
>     I want to know whether there is a way to show cooling benefit with such HVAC system.
>
>     Thanks
>
>     Regards
>
>     Deepika
>
>
>
> _______________________________________________
> Equest-users mailing list
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110816/d194f793/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 1459 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110816/d194f793/attachment-0002.jpeg>