To calculate the virtual rate, DES v2 option 1 2.4.2.1 gives the equation of
$/MBTU of hot water = 1.59*$/MBTU fuel + 3 * $/kWh electricity. This would gives me a really big number. For example, for IL, the state averaged gas is $0.00757/MBTU, Electricity, $0.084/kWh. And hot water would be $ 0.264/MBH. Which is almost 40 times higher than gas price. However, if I replace MBTU to mmBTU, everything looks normal. I wonder if people who wrote DES v2 got confused with MBTU with mmBTU
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
April 14, 2015 - 1:42 pm
The MBTU in the DES is million BTU.
Haojie Wang
Energy ModelerKJWW Engineering
4 thumbs up
April 14, 2015 - 1:45 pm
Thats what I thought too. But I think they should make it very clear next to the equation, as MBTU is actually 1000 BTU in IP system (Though I hate this system since I came from a metric country but contractors here are reluctant to use SI).
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
April 14, 2015 - 1:53 pm
Mixing systems seems to be commonplace here. Everyone seems to use kBTU here to represent 1000. I agree that it makes no sense.