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Re: [EnergyPlus_Support] Rooftop outdoor air temperature





Dear James,

Thank you for the post. Interesting one near-roof temp.


Sent from my iPhone

On Jul 19, 2014, at 11:07 PM, "Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

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 for someone who wants results that aree 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: Arun <arynum@xxxxxxxxxxx>


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