The template requires data be entered for both Ez and Ev. From what I read in ASHRAE 62.1-2007 Ez is not related to your Vot if you have a multi-zone system. In additional unless your population density varies then Vot is basically the sum of Vbz (Vou) divided by Ev so you end up with Vou/Ev.

The problem I'm having is that the template is calculating Voz by dividing Vbz by Ez (Vbz/Ez = Voz) and then calculating Voz by dividing Voz by Ev (Voz/Ev = Vot) to obtain Vot for the zone. From what I read in ASHRAE 62.1-2007 and calculated using the 62MzCalc.xls spreadsheet, the second equation is not correct.

Has anyone else had this issue? I've tried contacting the USGBC, but have not been able to talk with anyone that understands the actual equations from ASHRAE 62.1-2007.