[Equest-users] Ground/Water reflectance

Bishop, Bill wbishop at pathfinder-ea.com
Tue Dec 7 11:07:32 PST 2010


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
fax: 
954-418-9296
direct: 
954-418-4591
website: 
www.tlc-engineers.com
 
  <http://www.tlc-engineers.com/> 
 
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
 
1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124
 
Warning: The information contained in this e-mail may be privileged
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notify us immediately by reply e-mail and delete the original message
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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
 
 134 South Fitzhugh Street             Rochester, NY 14608
T: (585) 325-6004 Ext. 114            F: (585) 325-6005
wbishop at pathfinder-ea.com           www.pathfinder-ea.com
<http://www.pathfinder-ea.com/> 
P   Sustainability - the forest AND the trees. P  
________________________________

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

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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