Hi. We are applying for LEED certification for a building housing a Central Utility Plant (CUP) which supplies district energy to a hospital campus. I'm using Trane TRACE to model the CUP building for EAc1 credit (Option 2). LEED has developed a related document -- "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009" -- but I have found it fairly unclear on how the plant should be modeled.
Following ASHRAE 90.1 Appendix G standards for the baseline model results in a small plant that only meets the cooling and heating loads of the CUP building itself. Our proposed model, by comparison, includes a massive plant that significantly exceeds the CUP building's HVAC loads. This plant, obviously, meets such a small load with less efficiency.
My question is this: If the building seeking LEED certification houses only a District Energy System, how should the plant and loads be modeled? Should the baseline and proposed models include the hospital campus loads? Should the baseline model be sized to meet the campus loads?
Thanks in advance for your assistance.
Marcus ShefferLEED Fellow
7group / Energy Opportunities
5768 thumbs up
September 29, 2010 - 9:40 am
If this project is only housing a DES, you might want to check and make sure your project can meet the Minimum Program Requirements for LEED 2009 first.
Christopher SchaffnerCEO & Founder
The Green Engineer
963 thumbs up
September 29, 2010 - 11:05 am
If the plant is in your building, you model the plant as though it were outside the building. Your model should only have the loads from the building itself.
From Page 7 of the DES guidance:
"When the building housing the thermal energy plant is itself seeking LEED certification, then the project shall treat the DES equipment as “downstream equipment” for the following prerequisites and credits:
• EA prerequisite 1
• EA prerequisite 2
o Mandatory Measures: The district energy equipment shall comply with all mandatory measures from ASHRAE 90.1-2004.
o Prescriptive Method: The district energy equipment shall comply with any applicable prescriptive requirements
o Performance Method: The district energy equipment shall be modeled as upstream equipment, NOT downstream equipment. USGBC recommends that such projects use modeling Option 2 (described below).
• EA prerequisite 3
• EA credit 3
• EA credit 4
• EA credit 5"
4 thumbs up
December 8, 2010 - 7:46 am
Is that not contradictory?
It first states that "the project shall treat the DES equipment as downstream equipment".
Under the Performance Method it says the "district energy equipment shall be modeled as upstream equipment, NOT downstream equipment."
Is "DES equipment" not the same as "district energy equipment"? If not, is "DES equipment" the equipment associated with that building's cooling, lighting, etc and excludes the process energy associated with the chiller and pumping equipment?
Also, if the chiller equipment must be downstream and included in the model what do you use for the base line? Can you use standard efficiency air cooled equipment?
Thanks in advance for any assistance!
93 thumbs up
January 18, 2012 - 2:13 am
We are doing a HC project that has two visually separate buildings, main clinic building and a CUP building, but these two buildings' basements are connected. We are thinking using DES Guidance Performance Option 2 to obtain higher energy scores.
The mechanical rooms and control room are in CUP building's above-grade floors, its basement is a part of the main building's clinical space.
However, we are not sure if we want to certify the CUP buildings. Are we allow to exclude CUP building from the LEED boundary, but still include its basement?
Because it seems that in DES Guidance it allows CUP building not to be certified.
Please help, cheers.
Rajarajan SekarSustainability Engineer
March 14, 2023 - 7:15 am
Is there any conclusion for the same,getting stuck with the similair issue .
Cory DugginEnergy Project Engineer
TLC Engineering Solutions
44 thumbs up
March 14, 2023 - 11:47 am
First, i would look at including the CUP building as a supporting building to the hospital if it is going for certification. Then model them together. If you are just trying to model the CUP building for certification, include any heat loss or gain associated with the DES equipment that is housed in the CUP but not their energy use. The only energy use assocaited with the DES equipment included in the standalone CUP energy model should be the small portion of the DES equipment energy used for conditioning the CUP building. You will need to calculate an annual average efficiency of the DES equipment for use in the CUP model. I'm not 100% certain, but I think the CUP building baseline system would be strictly based on the App. G table, which would likely make it a system 3/4. If you modeled the CUP building as cost neutral purchased energy, the baseline system would become a system 3/4 using CHW and HHW though.