Simulation tab on Model Options dialog and General tab on Simulation Options dialog.
Select the start and end days for the simulation, or select a typical period using the links on the Info panel:
Annual simulation - all 365 days of the year.
Summer design week - a week identified by the weather data translator as being the hottest of the year.
Summer typical week - a week identified by the weather data translator as being typical of the summer.
All summer - simulate the whole summer (as identified by the weather data translator).
Winter design week - a week identified by the weather data translator as being the coldest of the year.
Winter typical week - a week identified by the weather data translator as being typical of the winter.
All winter - simulate the whole winter (as identified by the weather data translator).
The above typical simulation periods are derived from the Statistics data from the currently selected Hourly weather data.