Forum discussion
CS-2009 EAp2: Minimum Energy Performance
Dear all,
We have a school campus project (LEED NC MB) in Shanghai. The cooling source is from central cooling plant and the heating source is from Municipal steam. We want to use option 2 according to the DES guideline.
My question is how to model the heating source in baseline and proposed model. Both steam meter or hot water boiler? If use hot water boiler, how to determine the average efficiency?
Waiting for your feedback.
Best regards
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
March 13, 2015 - 9:42 am
How you model this is explained in the DESv2. The baseline is according to Appendix G. It depends on the size of the project whether it will be a boiler or not. Steam or hot water depends on what the district heating delivers to you. If you convert steam to hot water then the baseline does that too. The proposed is a virtual plant which accounts for the upstream systems. The efficiency calculation is addressed in section 2.4.1.2.1.
Shenhao Li
Atkins7 thumbs up
March 16, 2015 - 10:14 pm
Thank you for your response, but we still have some confusion. If central boilers are used for heat source, we can model the average efficiency of the upstream system. But the heat source is Municipal steam, we can't get the municipal boiler's information. We just know the stream project use. So how to calculate the average efficiency of upsteam system? Can we use steam meter for both Baseline and Designcase?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
March 17, 2015 - 9:31 am
If you can't get the actual information from the municipal system then you use the default efficiencies in section 2.4.1.2.3.
Using the steam meter sounds like DESv2 Option 1.
Shenhao Li
Atkins7 thumbs up
March 17, 2015 - 10:48 pm
Thank you Marcus! So we have to use natural gas for both Baseline and Proposed case although there are no natural gas used in project. The efficiency of Baseline boiler is 82% and virtual boiler is 70%, it seems unfair for these kinds of projects. T_T
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
March 18, 2015 - 10:13 am
See Section 2.4.2.2 which indicates that the fuel mix you use in your model should match the actual upstream DES fuel mix. If the fuel mix cannot be determined then it appears that gas would be used as a default. See Appendix C in DESv2.
You do pay a penalty for hooking up to an inefficient plant. They are assumed to be relatively inefficient unless shown to be otherwise. This is a conservative approach. You can always use option 1 to avoid this penalty.