[Equest-users] Ground/Water reflectance

[John Aulbach]

Found under EXTERIOR-WALK Command.

Play with this.

John


 
GND-REFLECTANCE
Defines the solar reflectance of the ground in the vicinity of the 
EXTERIOR-WALL. 

Table 6  Typical Ground Reflectance Values
Surface GND-REFLECTANCE 
Asphalt (Paved) 0.18 
Concrete (Bituminous) 0.10 
Concrete (Light-Colored) 0.32 
Concrete (Old) 0.22 
Field (Green) 0.12 - 0.25 
Field (Wheat) 0.07 
Grass (Dry)  0.24 
Ocean 0.05 
Rock (Crushed) Surface 0.20 
Soil (Dark) 0.08 


________________________________
From: Alex Krickx <akrickx at seriousmaterials.com>
To: "Bishop, Bill" <wbishop at pathfinder-ea.com>; John Aulbach 
<jra_sac at yahoo.com>; "equest-users at lists.onebuilding.org" 
<equest-users at lists.onebuilding.org>
Sent: Tue, December 7, 2010 10:28:24 AM
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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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 
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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® 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
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

________________________________

PartnerEnergy
1990 E. Grand Avenue, El Segundo, CA 90245
W: 888-826-1216, X254| D: 310-765-7295 | F: 310-817-2745
www.ptrenergy.com| jaulbach 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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