- Author
-
Murdoch, J. B.
- Title
- Simplified Procedure for Calculating the Direct Components of Contrast Rendition Factor and Equivalent Sphere Illumination.
- Coporate
- National Bureau of Standards, Washington, DC
- Sponsor
- Energy Research and Development Administration, Washington,
- Report
-
NBSIR 77-1303
November 1977
- Distribution
- Available from National Technical Information Service
- Keywords
-
interior lighting; commercial lighting; contrast; illuminance; computation; shadows
- Identifiers
- contrast rendition factor; equivalent sphere illumination
- Abstract
- A procedure is presented which enables the user to compute the direct components of contrast rendition factor (CRF) and equivalent sphere illumination (ESI) for an interior lighting design with the aid of a card-programmable hand calculator. The underlying theory and equations of CRF and ESI are discussed, including a consideration of body shadow, intensity distribution curve interpolations, bidirectional luminance factor approximating equations and Inverse Square approximations. The procedure is designed so that the user is a participant in the computations as they progress and thus is able to modify a lighting design in 'midstream' to improve CRF or ESI. A set of user instructions is included with the calculator programs.