A new electrical lighting and daylighting simulation analysis environment is developed to help designers assess optimal design configurations and operating strategies for electrical lighting fixtures in order to reduce energy use. In this paper, two applications of the simulation environment are presented to optimize the electrical lighting circuiting layouts design and the location of desks within daylight spaces. The results from these applications illustrate how the simulation environment and optimal daylight-base lighting controls can help building and lighting engineers and green building consultants improve the design of lighting and daylighting systems in order to construct and operate high energy performance buildings. (C) 2012 Elsevier B.V. All rights reserved.