Hi
I am doing the energy modelling for district cooling plant which is consists of chiller room, pump room, thermal energy storage tank room & small office within it using option2. I would be required two clarification for this type of building.
1. The chiller & pump would be available within the project intended to server for many building around the project proposed for LEED.In this case how the equipment load or connected load of chiller & pump could be considered in the energy modeling. If I consider the total chiller & pump load, then acheiving 14% is not at all possible. Shall i consider 25% as the process load?
2. Based on the building total conditional area sq.ft, the system 6: Packaged Varaibale Air Volume with parallel fan powered boxes needs to be considered for the baseline case. However considering the major area of the building with chiller & pump room, whether any other system like packaged single zone (constant volume) could be considered for the baseline case?
Thanks & Regards
Ramesh Narayanan
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
May 21, 2013 - 10:03 am
1. Never arbitrarily set the process load to 25%. Always model what is present in the building. One way to do this would be to include all the equipment as a process load, establish a reasonable baseline and then attempt to claim savings based on the plant being installed. Not sure how else to approach it. Have you checked the LEED Interpretations?
2. If any of the exceptions in G3.1.1 apply then you may be able to use an alternative system.
Melissa Crowe
Sr Energy EngineerCMTA Inc
1 thumbs up
May 21, 2013 - 10:21 am
If the plant is in the building then, if you use the 2009 DES Guide with the Option 2 path then the plant equipment is "Upstream". I just did a CHP plant building where 98% of floor space is associated with the plant. There is a small office. I had very little process energy. I had a lot of savings mostly due to lighting. I will let you know if the review takes exception to the lack of process energy.
I also did not model the proposed ventilation for the mechanical spaces per the design, as I consider the HVAC system as designed as integral to the plant processed. So I modeled fans, cooling and heating auto sized same as Appendix G base case. Don't know if that last bit will fly. Any opinions?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
May 21, 2013 - 10:44 am
Under DES Option 2 you need to account for the upstream equipment. The central plant is the headwaters! Sounds like you ignored the central plant equipment and did not even model the project as designed which violates Table G3.1-1 Proposed. Will be interesting to see if either one flies.
I am not certain the best way to do this - anyone done one and had it accepted?
Melissa Crowe
Sr Energy EngineerCMTA Inc
1 thumbs up
May 21, 2013 - 11:47 am
Marcus - I guess my explaination was not clear. For the record, we did model the CHP, as upstream equipment, but only inculded the portion of the plant energy associated with the heat used in the building and therefore only used the electricity generated when using the thermal energy (tracking thermal). Since the equipment is in the building distribution losses are negilgible. The violation may be in not modeling the actual fans.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
May 21, 2013 - 12:14 pm
Did you model the CHP equipment as a load in the associated spaces? Not only are you required to model the systems as designed but you must model the process loads as designed too (Table G3.1-1 Proposed (a)). This does get very difficult as the DES was written for a project served by a DES/CHP not necessarily housing one.
If you model the whole plant, treat most of it as process, and try to claim some savings related to process as an exceptional calculation, I could see how this would work within the rules.
Melissa Crowe
Sr Energy EngineerCMTA Inc
1 thumbs up
May 21, 2013 - 4:29 pm
There is no way we can get process energy savings if we did it that way. This is for a hospital and the actual plant process energy is 2 orders of magnitude greater than the CUP building energy [including lighting, HVAC and office (200 SF) equipment]. I did not include the thermal loads for the plant. Only lighting. We submitted a CIR and based on the answer I believe that we treat the equipment as upstream and therefore not in the building. I noted the lack of process energy and they did not take exception. This was/is indeed tricky,...we will see.
Ramesh Narayanan
95 thumbs up
May 22, 2013 - 7:04 am
Thanks for all your response.
1. The plant room within the building having the chiller & pump for 45000 TR (since district cooling plant which would serve the whole development around that). But the TR requirement for the particular would be around 500 TR only. In this case how much process load should consider for the plant or pump room. For small office area, i could consider 2 w/sq.ft as a miscellaneous load. But for plant & pump room what would be the appropriate process load?
2. Kindly advise on the system selection since the inside temperature. operating hours etc. would be differ between plant room & office area.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
May 22, 2013 - 9:07 am
Fundamentally you need to know how best to approach this situation. I would suggest that you look through the LEED Interpretations to see if there is any help there. If not I would submit an Interpretation to GBCI with a thorough explanation of how you think it should be done. Sounds like Melissa has done so but the project has not yet been reviewed.