Consider Adding SummerDesignDay and WinterDesignDay Options for ScheduleFixedInterval

[chriswmackey]

This issue came up today and I know we'll have to find a solution for it at some point. Right now, EnergyPlus uses whatever FixedInterval schedule values exist in the schedule on the date of the design day for the sizing calculation. This can result in really unexpected behavior in the sizing calculation if the design day conditions are really different from that in the EPW on that date. There really should be a separate way to specify the values on the design day.

If there's no chance of EnergyPlus adding support for this and this OpenStudio issue doesn't resolve it, I think I'll just find a way to replace the 24 hours of the FixedInterval values with optional user-specified properties for the summer_design_day and winter_design_day. And I guess I'll only do this if I know exactly what the dates of the design day are for a certain simulation.