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NC-v4 EAc2:Optimize energy performance

Energy Model - Proposed Building Heating Loads in Hawaii

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Sachin Shah
Director of Design Build Division
Dorvin D Leis
LEEDuser Basic Member
1 thumbs up

Aloha-

We are currently modeling a building in Trace 700, located on Oahu, Hawaii.  The proposed building consists of a water-cooled chilled water system with hot water reheat in select rooms throughout the facility.  Our system type within Trace is VAV Reheat (30% minimum).

My understanding is that the proposed building must be modeled with a heating system whether or not a heating system actually exists in the building.  However, it is extremely rare that a building in this location would require a heating system (even reheat is somewhat uncommon).  

Our current strategy is to model the rooms that have reheat with a "typical" thermostat setting of 75 cooling/68 heating, and rooms without a reheat coil set to 75 cooling/50 heating to more accurately model the actual usage in the building.

Do any of you have experience with a similar strategy or have suggestions for an alternative approach?

Thanks in advance.

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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Mon, 11/19/2018 - 14:41

Technically you are required to model a heating system. It sounds like the building actually does have a heating system, so it would make it hard to justify not including one in the baseline. What is your baseline system type? That said there is a common work around this issue which you have outlined, just set the temperatures so the heating system never comes on. So knowing this work around it is kind of ridiculous to make someone model a heating system, especially one that does not exist. You can explain this to the reviewer in a narrative and it will usually be accepted. Why do you need to model the rooms without reheat with a 50 heating set point? There is no heating system in those areas, correct? When you run the proposed model does any space heating energy show up in the results? You are probably on the right path but your approach will require you to provide a thorough explanation to the reviewer.
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Sachin Shah
Director of Design Build Division
Dorvin D Leis
LEEDuser Basic Member
1 thumbs up

Mon, 11/19/2018 - 20:06

Thanks for your reply.  Our issue was regarding the heating system in the proposed design, rather than the baseline.  Sorry - I guess I wasn't totally clear with my question but you seemed to touch on the main issue, regardless.   Really we were wondering if, in a climate such as Hawaii, that the USGBC reviewers would accept a model in which the proposed design has a "heating system" that is designed to never kick on (by setting the thermostat to a very low setpoint - in our case, 50F) for areas that will not have a heating coil.   Based on what you said, it sounds like we may just need to provide a narrative explaining the system. Thanks again for the input!
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Anurag Ghosh
Assistant Sustainability Manager
L&T Construction
LEEDuser Basic Member
2 thumbs up

Mon, 02/03/2025 - 02:01

Hi Sachin, I was just going through your post as we are working on an identical scenario in a project. We have monsoon reheat in some of our zones in a project which I believe can only be adjusted in energy model using the heating setpoints and RH balancing. i dont see any further options in the model I would like to know whether the adjustments of heating setpoints did fetch you any heating energy in the proposed model. I am sorry I might be a little late to ask you in this thread but appreciate your reply on this.

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