Using the 62MZ calculator

Christina, I've been able to use the macros on PC's but never on a Mac. I'm not sure what the issue might be in this case. What about using the form calculator instead? For the demand control ventilation, I would still set up the calculations and testing to reflect the scenario where the potentially critical zones are fully occupied and the fans and outside air dampers are set to the lowest point (worst case condition typically in the heating season). Also, if the CO2 sensors are located in the return duct, the review team will likely request justification for how those sensors are accurately accounting for the CO2 in the breathing space of the occupied spaces.

Christina- On a PC, sometimes if the security level for macros is set to high or very high then even enabling macros will not allow them all to run. I would think you would get a warning message about that though, so that might not be the problem. Your ME on the PC could try downloading a fresh copy (or a copy from a different source) of the spreadsheet and trying again, making sure the security setting under macros is set to medium. Also try the help troubleshooting menu for macros from within Excel. As Ben wrote, demand control ventilation does not necessarily come into play for the ventilation rate spreadsheet. You can use the design ventilation values for the spreadsheet, ignoring the demand control ventilation. Then the demand control ventilation is added as part of the control system.