Hello all, according to the document “Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction”, for Option1: Virtual District Hot Water Rate [$/MBTU] = Virtual Fuel Rate (in $/MBTU) x 1.59 + + Virtual Electric Rate (in $/kWh) x 3. I don't know the fuel used by the DES central plant, so i have considered only methane (the most common fuel used in Italy) with his national average rate. So that, the Virtual District Hot Water Rate is equal to 0.083 $/kWh, but the reviser thinks that it is lower than expected. Did i make any mistake? The reviser also asks me the efficiency of the district heating plant, but in theory with Option1 this information isn't required, isn't it? Thank you in advance!

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Marcus Sheffer

LEED Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Thu, 10/18/2012 - 14:54

Ciao Fabio, The value does seem low. The formula multiplies kWh x 3 so if you divide 0.083 by 3 it is a very low rate. The formula should result in $/MBTU so perhaps it is a conversion issue? I agree that the efficiency of the plant does not even enter the picture under Option 1.

FABIO VIERO

Head of Sustainability

Manens S.p.A.

LEEDuser Premium Member

16 thumbs up

Thu, 10/18/2012 - 17:42

Ciao Marcus, - Virtual Electric Rate is 0.1415 [eur/kWh] * 1.301 [USD/eur] = 0.184 $/kWh - Virtual Fuel Rate (methane) is 0.39 [eur/m3] * 0.1 [ m3/kWh] * 1.301[USD/eur] = 0.051 $/kWh = 14.9 $/MBTU So Virtual District Hot Water Rate [$/MBTU] = 14.9 * 1.59 + 0.184 *3 = 24.3 $/MBTU = 0.083 $/kWh Where is the mistake? Thank you very very much

Marcus Sheffer

LEED Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Thu, 10/18/2012 - 19:08

Yep seems like unit conversion issues, not a mistake. This rate seemed low for electricity, so perhaps the reviewer is confused about your final conversion of $/MBTU to $/kWh. I know we were. We use BTU as the common metric for fuel comparison, not kWh so perhaps the reviewer was thinking like we were. If you did not already, submit your calculations just like above and stop at $/MBTU. You might want to take the methane directly to BTU. There appears to be 36.3 kBTU/m3. When converting the gas I come to $14.0/MBTU and the difference could be related at least in part to rounding issues. This calculation in the DES is a bit confusing and it would have been a good idea to show the units associated with the 1.59 and 3 used in the calculation. A district hot water rate of $2.40/therm ($24.3/MBTU) is actually very high for the US but I would expect your rates to be higher. Good luck with that pesky reviewer.

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