[Equest-users] Modeling Light Shelves for Reduction inCooling/Heating Load?
Chris Jones
cj at enersave.ca
Mon Aug 23 14:02:42 PDT 2010
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 youre 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 youre trying to model.
>[]
>
>2. Based on your query, a
>caution: eQuests 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 theres nothing stopping you from
>defining a schedule in eQuest to match the other programs results.
>
>I expect you mean to say youre 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, Id 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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