Meeting EAp2 in Zone 1 without A/C?

Katrina In a nut shell (not that easy) you need a software that can give you results for temperature and humidity (or wet bulb temp) for the occupied spaces of the project without HVAC. In some software you need to assume an HVAC system with no capacity (zero heating and cooling). This will give you what and how many hours of the year your project is within the comfort window of ASHRAE standard 55. Once you know that information, you model the project with the Baseline HVAC system. After that you subtract the energy usage, in the second run, that are directly related to the hours you already know the project will meet comfort conditions with only natural ventilation. This in turn will give you (possibly) a much lower total assumed energy usage for the proposed HVAC system (BASELINE HVAC - HOURS INSIDE COMFORT ZONE) than your BASELINE PROJECT. You will need hourly reports of: zone space dry and wet bulb temperature or relative humidity, energy related to the HVAC system (fans, compressors, pumps, heat rejection, etc.), to be able to only take into consideration the hours the project would've required conditioning, and to justify the calculations to the GBCI. That is as simplistic as I can explain the process. GOOD LUCK

The Advanced Energy Modeling Guide for LEED has a summary of the acceptable procedure for claiming savings for natural ventilation in the appendix.

Jorge, Has GBCI accepted the method you describe before?