It's come to my attention that there's some unit confusion in the LEED Treatment of District Thermal Energy Guide where DES virtual rates are calculated.

The Guide includes equations on page 14 in units of MBTU but doesn't clarify the meaning of "MBTU". The Canadian equivalent of this Guide is CaGBC's "The LEED Canada 2009 Interpretation Guide for District Energy Systems (DES)". The Canadian version uses similar equations (but the steam and hot water conversions notably don't have an electricity term). But while the equations look the same, they use MMBTU as the units. They do take the extra step to note: MMBtu = 1 million Btu.

MBTU commonly means mega or "M" BTU (x10^6) or 1 million BTU. But it sometimes means "M" for mille or Roman numerals M, which is (x10^3) 1 thousand BTU. Using this latter notation MM is 1 thousand, thousand (x10^3 x10^3) or 1 million.

My interpretation is that the USGBC's DES equations mean MBTU = 1 million BTU.

I know that was stressing a lot of people out. And with that said, let's all go metric.