[Equest-users] Ground/Water reflectance

[Alex Krickx]

So changing it to 0.05 to try to account for the reflectance of the water, would actually decrease the reflected solar heat...

Hmmm. I'll play with some different values in eQUEST and see how much ground reflectance impacts consumption, and keep in mind the 0.05 value.

Thanks for everyone's quick and thoughtful responses.

Cheers,
Alex

From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com]
Sent: Tuesday, December 07, 2010 11:08 AM
To: Alex Krickx; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Ground/Water reflectance

Alex,
The default ground reflectance is 0.20. You have to enter a different value for it to appear in the inp file.
Bill
________________________________
From: Fleming, Joe [mailto:joe.fleming at tlc-eng.com]
Sent: Tuesday, December 07, 2010 2:03 PM
To: Alex Krickx; Bishop, Bill; John Aulbach; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Ground/Water reflectance

The albedo of an ocean should probably equal that of a lake on an average basis throughout the day (not a peak hourly basis).  The radiation reflected by water is very low when the incident wave is perpendicular to the surface of the water, and it approaches 100% as the angle of incidence approaches 90 degrees (morning and evening).  As the waves move through the water the incident angle of each zone of water will vary from 0-90 degrees on a constant basis and the reflectance should roughly average out to equal that of a still body of water.
For a lake, in the late afternoon, the reflectance will increase from 0.05 to 0.1 or 0.2.   Later in the evening it will reach closer to 0.8 or 0.9, but at this time the radiation intensity from the sun drops off significantly.
To model the lake on one side is a challenge, your peak loads may not change but your annual consumption may.   If eQuest uses the gnd reflectance values as a multiplier of solar radiation, it may be worth running a few iterations with different values of gnd reflectance to see the results.

Joe Fleming
E.I., LEED AP BD+C, BEMP
Mechanical Engineer I

TLC Engineering for Architecture
Your 2030 Challenge Partner

800 Fairway Drive, Suite 250
Deerfield Beach, FL 33441-1816

phone:

954-418-9096

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954-418-9296

direct:

954-418-4591

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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Alex Krickx
Sent: Tuesday, December 07, 2010 1:28 PM
To: Bishop, Bill; John Aulbach; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Ground/Water reflectance

Thanks Bill and John for your responses.

I guess I would expect that the ocean would be a bit more "turbid" (seems appropriate) - but what about for buildings facing a lake or harbor where the water is calmer? Perhaps the additional reflected solar gain is negligible, but my gut tells me that is not the case.

This project is a retrofit and they talked of having intense heat along the facades facing the water. Perhaps it's more due to the tinted single-pane glass that gets hot (?) but my initial thought was the water is the culprit.

Is it possible to create a 2d shape in the ground plane south of the building, and apply the reflectance to that, or do I need to apply it to the whole ground?

I looked through a previous project and didn't see the term "GND-REFLECTANCE" anywhere in the inp or pd2 files. Is the default to have a ground-reflectance of 0? If so, I guess I'll run one case with 0, and one with 0.05... although I doubt there will be much difference between the two.

Thanks again - any other thoughts on this are much appreciated.

Kind regards,
Alex Krickx


Alex Krickx
Building Energy Specialist
[cid:image002.jpg at 01CB95FF.B9AAD1D0]
1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124

Warning: The information contained in this e-mail may be privileged attorney-client communications or attorney work product and/or proprietary and confidential.  If the reader of this message is not the intended recipient then you have received it in error and any review, distribution or copying of this message is prohibited and you are to notify us immediately by reply e-mail and delete the original message immediately.



From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com]
Sent: Tuesday, December 07, 2010 7:20 AM
To: John Aulbach; Alex Krickx; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Ground/Water reflectance

Alex,

Exterior surfaces have a "Ground reflectance" property - GND-REFLECTANCE, accessible through the Daylighting - Shading - Other tab of the exterior surface. Reading the DOE-2 Help description, the reflectance value for "ocean" is 0.05, implying that most solar radiation is absorbed, not reflected. I'm guessing that the visual glare we perceive does not increase the solar load as much as we would think. Sea monsters do not seem to have been considered by the DOE-2 team.

Regards,
Bill

William Bishop, PE, BEMP, LEED(r) AP | Pathfinder Engineers & Architects LLP
Mechanical Engineer

[cid:image004.jpg at 01CB95FF.B9AAD1D0]134 South Fitzhugh Street             Rochester, NY 14608
T: (585) 325-6004 Ext. 114            F: (585) 325-6005
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________________________________
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of John Aulbach
Sent: Monday, December 06, 2010 8:35 PM
To: Alex Krickx; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Ground/Water reflectance


Alex:



I wonder if the turbidity (word ??) of the water will actually not make a difference. Any harbor will have boats, wind effects, and an occasional sea monster disturbing the "glass" water.



Only in paintings ???


John R. Aulbach, PE, CEM
Senior Energy Engineer
________________________________
Partner Energy
1990 E. Grand Avenue, El Segundo, CA 90245
W: 888-826-1216, X254| D: 310-765-7295 | F: 310-817-2745
www.ptrenergy.com<http://www.ptrenergy.com/> | jaulbach at ptrenergy.com<mailto:%7C%20jaulbach at ptrenergy.com>



________________________________
From: Alex Krickx <akrickx at seriousmaterials.com>
To: "equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>
Sent: Mon, December 6, 2010 5:11:24 PM
Subject: [Equest-users] Ground/Water reflectance
Hello everyone,

I've got a building that is located at the edge of a harbor with the water directly to the south of it. How do I model a reflective surface on the ground that represents the harbor? I feel this is key to include, as this reflectivity will send additional heat through the windows. I looked through the archives but didn't see anything related to ground reflectivity.

If anyone knows how to create reflective objects and/or an appropriate value of reflectivity for water in eQUEST, that would be most helpful.

Thanks in advance!

Regards,
Alex Krickx


Alex Krickx
Building Energy Specialist
[cid:image002.jpg at 01CB95FF.B9AAD1D0]
1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124

Warning: The information contained in this e-mail may be privileged attorney-client communications or attorney work product and/or proprietary and confidential.  If the reader of this message is not the intended recipient then you have received it in error and any review, distribution or copying of this message is prohibited and you are to notify us immediately by reply e-mail and delete the original message immediately.



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