DAYSIM is a simulation engine meaning that it consists of a series of command line programs that carry out the different simulation steps described above. DAYSIM users may choose from a variety of Graphical User Interfaces which call DAYSIM from within Rhinoceros, SketchUp and Ecotect. For more information please click on the images below and or refer to a plug-in comparison chart. Expert users and software developers may refer to the DAYSIM API.