I'm modeling a district heating system according to option 2 of “Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction”. In the proposed model I'm going to model a virtual on-site hot water boiler, according to Table 4 of the document. Since the real district heating is fueled by agricultural crops, I can consider it as renewable energy (see page 15 of “Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction”).
For the baseline model I have to consider System 7 (according to Table G3.1.1A of ASHRAE 90.1).
What fuel shall I consider in the baseline model?
Since in the real plant there is a system (another district system) that is fueled by natural gas and that can be considered a backup system, shall I model natural gas for the baseline model? The use of natural gas is very common in Italy (I would say, it's the “standard solution”).
Best Regards
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
August 12, 2015 - 10:43 am
The modeling rules say that you will need to use the same rate for district heating in both models. Assuming the district system fuels are qualified renewables you can clearly count them toward EAc2. The question is if you can count them also under EAp2/EAc1. Since these renewables have a cost associated with them and the metric for EAp2/EAc1 is cost one could easily make the case that they should not count.
I would try one of two options. Submit the "savings" related to comparing this DES rate to the natural gas rate as an exceptional calculation making the case that this is a valid comparison in your situation. Alternatively you could look at this document -http://www.usgbc.org/resources/treatment-scandinavian-district-energy-sy... - which has been approved for European projects and allows a fossil fuel baseline.