[Equest-users] Modeling Light Shelves for Reduction inCooling/Heating Load?

[Chris Jones]

Equest, like DOE2.1e before it provides very 
generous estimates of the lighting energy saved 
using daylighting controls.  I believe that 
taking equest predictions at face value for LEED 
models would be inaccurately providing more 
benefit than warranted.  The Appendix G power 
factor ratings are likely not conservative in 
some cases.  I wouldn't expect to see any more 
benefit using equest's daylighting than I would 
using the Appendix G power factor adjustments.

A paper that attempted to explore various 
daylighting energy reduction savings modelling 
strategies.  DOE2.1e and Daysim are the two programs used for the analysis.
http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/nrcc46761/nrcc46761.pdf


At 03:49 PM 23/08/2010, you wrote:
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>Perhaps these are the answers you’re seeking:
>1.       Building shades and their respective 
>reflectance properties do affect the modeled 
>behavior of space daylighting systems in eQuest 
>models.  Be sure to pay close attention to all 
>three values (and their associated help files) 
>on the right of the following image – they may 
>all play a part depending on what exactly you’re trying to model.
>[]
>
>2.       Based on your query, a 
>caution:  eQuest’s results do not have any 
>inherent degree of accuracy/in-accuracy with 
>regard to the modeled energy consumption 
>resulting from daylighting controls – that 
>depends pretty much entirely on how closely you 
>define the daylighting systems’ behavior to 
>reality.  If you have a program which you 
>perceive to be producing more accurate hourly 
>percentage consumptions for your spaces, then by 
>all means – there’s nothing stopping you from 
>defining a schedule in eQuest to match the other program’s results.
>
>I expect you mean to say you’re utilizing 
>another program to accurately determine the 
>behavior of daylight in response to 
>adding/modifying light shelves, but if you are 
>indeed using another program to determine annual 
>hourly behavior with a weather file, I’d be very 
>interested to hear more about it!
>
>Best of luck,
>
>~Nick
>
>cid:489575314 at 22072009-0ABB
>
>
>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.htm>www.smithboucher.com
>
>From: equest-users-bounces at lists.onebuilding.org 
>[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nilay R. Desai
>Sent: Monday, August 23, 2010 11:35 AM
>To: equest-users at lists.onebuilding.org
>Subject: [Equest-users] Modeling Light Shelves 
>for Reduction inCooling/Heating Load?
>
>E.G. Would it be accurate to model an external 
>light shelve as a horizontal building shade with 
>a high reflectance value on the skyward facing 
>surface? I understand the day lighting benefit 
>in Equest would be inaccurate, but we are using 
>separate software to obtain accurate day lighting results. Thanks!
>
>
>Nilay Desai
>P  626.351.8881 Ext. 237
><mailto:klowe at tmadtg.com>ndesai at ttgcorp.com
>
>
>
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Chris Jones
14 Oneida Avenue
Toronto, ON M5J 2E3.
Tel.  416-203-7465
Fax. 416-946-1005

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