Hello again,
We now have the 62MZ spreadsheet working (thanks again!), but a few more questions have come up as our ME works through it. Can anyone provide some insight on these?
1. If we are analyzing a constant volume system serving a large arena seating area, do we enter only one zone for the entire area served?
2. Under the section, Inputs for Operating Condition Analyzed, there are no instructions for the pull down menu codes for “Air distribution type at conditions analyzed”. Where can we find the definitions for these codes?
3. If many different ventilation systems are being analyzed, is it best to create a new file for each unit?
Thank you!
Julia Weatherby
PresidentWeatherby Design & Co. Engineers
94 thumbs up
February 13, 2014 - 1:02 pm
Christina-
1. The "MZ" in 62MZ means multi-zone, so it isn't normally used for single zone constant volume systems (just for multi-zone recirculating systems). A simple excel spreadsheet or even just filling in the table in the LEED form should work fine for a constant volume single zone system serving a large arena seating area. It might work to just put in one zone in the 62MZ calculator, but I think it requires a minimum of 2 zones.
2. If you have the USGBC LEED version of the 62MZ calculator, there should be a button to click on the Vot calculation spreadsheet that says "Show Codes for Ez". These can also be found in Table 6.2 of ASHRAE 62.1-2007 or the 62.1-2007 users manual. The most commonly used is CSCRH: Ceiling supply of warm air 15degF or more above space temperature and ceiling return. This gives an Ez value of 0.8.
Note that in the Directions tab of the USGBC 62MZ calculator, it states:
"LEED Documentation: If the value for Ez is different than 0.8, the narrative should describe the value used, and provide a brief justification for that value."
3. Yes, it generally works best to create a separate file for each ventilation system.