Daylighting is a beneficial design strategy since
it may provide energy savings and contribute to a
more sustainable design. In recent studies,
daylighting has also been shown to increase staff and
student productivity and to decrease absenteeism.
The consulting engineer is often faced with the
dilemma of how to design a daylighted building.
What tools are available to predict the amount of
daylighting? What are the design limitations and
parameters? How much time is required? How does
the data compare to the “real world”?
The purpose of this paper is to answer these
questions and provide useful information for the
design of daylighted areas with the assistance of
software-based simulation. A survey was made of
the available software programs for the calibrated
modeling of light scattered in enclosed spaces. These
software packages used algorithms based on either
total radiosity (flux transfer) computations or
physically accurate ray tracing. A summary of this
survey along with the selection criteria used in
selecting a software program are presented.
“Radiance”, a reverse ray tracing method
software package, was chosen for use in the
simulations. An existing school was modeled with
the Radiance software and predictions of daylighting
contributions were compared with actual data taken
at the site location.
The use of daylighting also requires a highly
specialized lighting system. This system incorporates
the use of controllable ballasts and lighting sensors to
maximize the daylighting contribution to the overall
required illumination. Some design criteria for this
system is also discussed
