Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
All EnergyPlus sizing calculations will include internal gains, solar gains, thermal mass, etc. unless the user inputs remove them. For example, all of the SizingPeriod:DesignDay objects for heating which are in the ddy files bundled with the weather files have zero sun and constant outdoor temperature for the WinterDesignDay. Also, internal gain schedules should be zero for day type "WinterDesignDay". These inputs effectively remove all of the above from the heating sizing calculations. For cooling sizing, you want all of these items to be included.
With ideal loads, run the design days only, and take the peak loads from there. See SimulationControl "Run Simulation for Sizing Periods". The system "coil" loads are reported as output variable "Ideal Loads Supply Air * ".
If you want EnergyPlus to do system-level sizing, then you'll need to add a full HVAC system with appropriate Sizing:System inputs.
