You may get better results to your question if you start
with a new subject/thread.
Schedules are used for many things in EnergyPlus: indication of building
occupancy, when the lights are turned on, when the HVAC system operates,
etc.
Each schedule ultimately has a "day type". There are
twelve day types allowed for each schedule. Valid days of the week
(Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday) can be
entered as well as Holiday, SummerDesignDay, WinterDesignDay, CustomDay1,
CustomDay2. These day types are then used during the simulation
where a day type is indicated (weather files, sizing periods)
The SizingPeriod:* objects are designed to be used with the autosizing
feature for equipment or for early runs in your project to minimize run
time.
SummerDesignDay is used for the cooling day type. WinterDesignDay
is used for the heating day type. This allows a schedule that can be used
for sizing and later for general runs without change.
The purpose of SummerDesignDay is to allow you to specify special
schedules that are used only in the sizing calulation. For instance, I
use the normal week day schedules for occupancy, lights, equip etc but
I use flat (no set back or set up) schedules for the zone
thermostats.
Recommend that you read carefully, the SizingPeriod:*, SimulationControl,
Design Objects section, and Schedules objects in the IO
Ref.