scope:

Purpose and Scope

The purpose of this Lighting Science document is to provide the theoretical basis for lighting calculations, to describe how this theory is approximated and used, and to describe how it is embodied in most lighting analysis software. This can provide, from a user's perspective, an understanding of the power and limitations of calculations-however performed-and thus make clear their use in the lighting design process.

These purposes require the presentation of information in the following three general areas.

• The fundamental theories of light transport and interaction with architecture, what form-exact or approximate-the mathematical models of these theories take, and how the models are in turn used in lighting software.

• The geometric, photometric, and physical information that is commonly available as input into a lighting calculation process and how the nature, limits, and uncertainties of this information affect the results.

• The various ways of predicting lighting system performance by assessing and interpreting calculation results and their comparison with anticipated or actual measured results.

In addition, this document explains IES standard calculation procedures, including lumen method coefficients of utilization and glare assessment.