There is indeed some related research on the effects of roof reflectance on air temperatures near rooftop condensing units. See:
Regards, Craig Wray
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Saturday, July 19, 2014 10:38
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Rooftop outdoor air temperatures
Dear Forum,
I have had clients in the past who refused to place HVAC equipment on the roof in Dallas, Texas because they knew the near-roof temperatures were much warmer than the temperature farther away. The situations have been for large, black roofs which get very warm in the summer.
I have not thought about that much for energy models other than defining high SRI roofing materials. Yesterday, however, I was talking to an infrared thermal imaging professional who says that he has measured roof temperatures that were 100F / 56C higher(!) than the nominal outdoor temperature. If that is true, then all of my energy calculations for rooftop equipment are WRONG � not a happy thought forr someone who wants results that are realistic.
The resulting questions to the most knowledgeable modeling community in the world (as far as I can tell) are:
· Are you aware of research which has measured or characterized near-roof temperatures?
· Do you have a modeling practice that accounts for the near-roof impact on outdoor air intakes or roof-mounted chillers, condensing units or cooling towers?
Thanks in advance for your insights!
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]
Sent: Friday, July 18, 2014 3:37 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Curve Fit Tool
Thank you very much for you help
Kind Regards,
Felipe Durán
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Posted by: Craig Wray <cpwray@xxxxxxx>
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