DAYSIM has been developed at Harvard University, the National Research Council Canada and the Fraunhofer Institute for Solar Energy Systems. The overall development of DAYSIM has been coordinated by Christoph Reinhart since 1998. Individual simulation modules within DAYSIM were developed by the following individuals:

2010: A new DAYSIM subprogram called gen_dgp_profile was developed by Jan Wienold to conduct annual glare simulations within DAYSIM based on the daylight glare probability concept.

2010: DAYSIM becomes part of the DIVA plug-in for Rhinoceros that was developed by Kera Lagios, Jeffrey Niemasz, Alstan Jakubiec and Christoph Reinhart

2010: Two independent DAYSIM plug-ins for Google SketchUp were developed by Thomas Bleicher and Josh Kjenner.

2006: A link between Ecotect and DAYSIM was created by Andrew Marsh and documented in a ‘Getting Started’ document by Guido Petinelli.

2003: A modified version of the RADIANCE program rtrace that calculates a set of daylight coefficients using either the traditional RADIANCE approach or Roland Schregle PhotonMap forward raytracer was programmed by Augustinus Topor at the Fraunhofer Institute for Solar Energy Systems.

2003: An early version of DAYSIM's graphical user interface was programmed in JAVA at the National Research Council Canada by the Prashant Jois, Melissa Morrison and Christoph Reinhart.

2002: The manual lighting control model Lightswitch and the stochastic user occupancy model were developed by Christoph Reinhart at the National Research Council Canada.

1999 – 2001: The DAYSIM subprogram to model the short-time step dynamics on indoor illuminance was developed and implemented by Oliver Walkenhorst at the Fraunhofer Institute for Solar Energy Systems.

1997 -2001: DAYSIM's dynamic daylight simulation module to simulate annual illuminance profiles was developed and implemented by Christoph Reinhart at the Fraunhofer Institute for Solar Energy Systems.