Jean,
Clarifying�. I have a tool from LBNL which cconverts tech data (solar reflectance and thermal emittance) to SRI. I am not sure how to convert the tech data to E+ inputs.
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of jeannieboef@xxxxxxxxx
Sent: Saturday, August 24, 2013 10:01 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Cc: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Revisiting SRI modeling and calculations
The online pdf form for heat island roof credit had a conversion built in. I'm sure to have saved a calculator somewhere also. I'll check Monday.
Mit freundlichen Grüßen- Sent from my iPhone (excuse the brevity)
i. A.
Jean Marais
b.i.g. bechtold
Tel. +49 30 6706662-23
On 23.08.2013, at 18:10, Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
I have a calculator developed by Lawrence Berkeley, but have not seen one from LEED (nor can I find it)
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jean Marais
Sent: Friday, August 23, 2013 11:56 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Revisiting SRI modeling and calculations
IMO spot on...solar = whole spectrum, thermal=ir specturm.
LEED has an official calculator to go from SRI to reflectance, i just can't remember where I spotted it.
On 23 August 2013 17:12, Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Dear Forum,
I thought I had this topic (modeling SRI values in E+) well understood, but now I am unsure. Please let me know if the approach below is sound:
· The technical data for a “cool” roof generally notes solar reflectance and solar emittance along with an SRI value
· EnergyPlus’s Material object wants to know thermal absorptance, solar absorptance and visible absorptance (plus other properties)
As far as I can tell,
1. solar absorptance for E+ = 1 - solar reflectance from technical data
2. thermal absorptance for E+ = solar emittance from technical data
3. visible absorptance is anyone’s guess, since it’s not mentioned in the technical data.
Does that sound correct? Thanks in advance!
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653
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