[Equest-users] Daylight factors for accurate daylighting - summary

Bishop, Bill bbishop at pathfinder-ea.com
Mon Aug 12 09:21:57 PDT 2013

Thanks Mike Andelman, John Aulbach, David Griffin, Umesh Atre and Liam Buckley for your helpful replies. For the benefit of the List, here's what I found out:

-          DOE-2 input functions are not (currently) supported in eQUEST.

-          DOE-2 and eQUEST use the split-flux algorithm to model internally-reflected daylight. The eQUEST daylight calculation works best when the illuminance at a reference point is due to light directly from the windows (not reflected from the interior).

-          Available daylight tends to be overestimated when the reference point is near the back of the room (depth more than three times floor-to-ceiling height).

-          The impact of split-flux<http://www.newegg.com/Product/Product.aspx?Item=9SIA0420P34606&nm_mc=KNC-GoogleMKP&cm_mmc=KNC-GoogleMKP-_-pla-_-Collectibles-_-9SIA0420P34606> method inaccuracies tends to be minor relative to total simulated building energy use.

-          Contact Mike Busman if you have Fiat X1/9<http://rcd.typepad.com/personal/39_2Dfiat_2Dx19.jpg> questions or want your photo taken with a life-sized Big Bird<http://xfinity.comcast.net/blogs/tv/files/2012/10/snl-big-bird.jpg>.

Some reference material:
An, J. and Mason, S., "Integrating Advanced Daylight Analysis Into Building Energy Analysis<http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=5&ved=0CEQQFjAE&url=http%3A%2F%2Fwww.ibpsa.us%2Fpub%2Fsimbuild2010%2Fpapers%2FSB10-DOC-TS06A-02-An.pdf&ei=fvsIUsajJffi4APkgYHoAQ&usg=AFQjCNEuoAY8TAF6h0xBNfe3nM1Ixg0CeQ&sig2=sE8jHhF7RdYtrduN>" Fourth National Conference of IBPSA-USA, 2010.
Kota, S. and Haberl, J., "Historical Survey of Daylighting Calculations Methods and Their Use in Energy Performance Simulations<http://www.google.com/url?q=http://repository.tamu.edu/bitstream/handle/1969.1/90845/ESL-IC-09-11-07.pdf%3Fsequence%3D1&ei=GAMJUoOGJ5Dk4AOWi4D4Dg&sa=X&oi=unauthorizedredirect&ct=targetlink&ust=1376324128641243&usg=AFQjCNGiI8d6ArLsnb4BkuLhah7yBN5Prg>." Proceedings of the Ninth International Conference for Enhanced Building Operations, Austin, Texas, November 17 - 19, 2009.
Koti, R. and Addison, M., "An Assessment of Aiding DOE-2's Simplified Daylighting Method with DAYSIM's Daylight Illuminances<http://www.researchgate.net/publication/229061747_AN_ASSESSMENT_OF_AIDING_DOE-2'S_SIMPLIFIED_DAYLIGHTING_METHOD_WITH_DAYSIM'S_DAYLIGHT_ILLUMINANCES/file/79e414ffee34037ee6.pdf?ev=pub_ext_doc_dl&docViewer=true>." Proceedings of the Solar 2007 Conference in Cleveland, 2007.


From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bishop, Bill
Sent: Thursday, August 08, 2013 1:25 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Input function with daylight factors for accurate daylighting

I am modeling a building with many clerestory windows of various orientations in a complex roof geometry. I would like to accurately model the daylighting savings in eQUEST. Has anyone had luck creating an input function that uses daylight illuminance factors, as described by Steve Baker<http://simulationresearch.lbl.gov/dirpubs/complex_dayltg.pdf> back when Bush Sr. was president and this song<http://www.youtube.com/watch?v=9EcjWd-O4jI> was a Top 10 hit? "Limitations of the Daylighting Calculation" and an "Example of Using Measured Daylight Factors" using an input function are described in the DOE-2 help.


William Bishop, PE, BEMP, BEAP, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer

134 South Fitzhugh Street                 Rochester, NY 14608
T: (585) 325-6004 Ext. 114            F: (585) 325-6005
bbishop at pathfinder-ea.com<mailto:wbishop at pathfinder-ea.com>           www.pathfinder-ea.com<http://www.pathfinder-ea.com/>
P   Sustainability - the forest AND the trees. P

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