VRP vs 62MZCalc

Robert, I find the form v4 online tool to be more straight forward and have an easier lay out. However, on projects with a large amount of zones (50+) the online tool tends to get bogged down (3-5 seconds to make any changes). In those cases I find using the 62MZCalc saves time.

The v4 PDF calculator seems to give inconsistent results. Try changing diversity factor (D) back and forth a few times. At least on the sample template it doesn't work. That is enough for me to warn against using the tool. What I saw happening was after changing D I could change Ez to any value (0.5 or 1.2) and the required outdoor intake flow (Vot) would not change. If I changed occupancy categories back and forth The Vot would change but when the occupancy categories came back to the starting point the Vot would still be the same locked numbers. Although it has a few problems, the 62MZCalc should be used for this analysis. One problem I found with the 62MZCalc tool is that it does not include ventilation rates from the normative appendices, namely health care (Appendix E). Normative means required. Health Care has the most strict ventilation rate per square foot, people plus area, even though area is Zero. I've had to explain to the LEED reviewers a few times that the combined ventilation rate was more strict than anything listed in Table 6-1. The default review comment is use the closest type of space. There isn't a closest type in Table 6-1. Trying to do what the reviewer wanted could result in under-ventilating a health care project. Somehow that would have meet the review requirements but potentially not the 62.1 requirements. The 62MZCalc tool also has the following two errors. They occur in the 2004 and 2007 versions of the tools. The rates were originally added by 2004 Addenda b, and are correct in the 2007 standard, but not in the tool. University and College Laboratories: The default occupancy density should be 25 not 17. Laundry Rooms within Dwelling Units: The default occupancy density should be 10 not 17. In both cases the 17 value is the combined outdoor air rate, cfm/person. The v4 LEED tool does have the above two problems corrected. Health Care can be added to the LEED Tool as space type other. With the 62MZCalc tool you can't add any new space types.