Architectural lighting design is a field within architecture, interior design, and electrical engineering that is concerned with the design of lighting systems, including natural light, electric light, or both, to serve human needs.
The design process takes account of:
- the kind of human activity for which lighting is to be provided.
- the amount of light required.
- the color of the light as it may affect the views of particular objects and the environment as a whole.
- the distribution of light within the space to be lighted, whether indoor or outdoor.
- the effect of the lightened system itself on the user.
Lighting designers are often specialists who must understand the physics of light production and distribution, the physiology and psychology of light perception by humans, the anatomy of the human eye, and the response of the rods and cones to light.
For simple installations, hand-calculations based on tabular data can be used to provide an acceptable lighting design. More critical or optimized designs now routinely use mathematical modeling on a computer.
Based on the positions and mounting heights of the fixtures, and their photometric characteristics, the proposed lighting layout can be checked for uniformity and quantity of illumination. For larger projects or those with irregular floor plans, lighting design software can be used. Each fixture has its location entered, and the reflectance of walls, ceiling, and floors can be entered. The computer program will then produce a set of contour charts overlaid on the project floor plan, showing the light level to be expected at the working height. More advanced programs can include the effect of light from windows or skylights, allowing further optimization of the operating cost of the lighting installation. The amount of daylight received in an internal space can typically be analyzed by undertaking a daylight factor calculation.
The Zonal Cavity Method is used as a basis for both hand, tabulated, and computer calculations. This method uses the reflectance coefficients of room surfaces to model the contribution to useful illumination at the working level of the room due to light reflected from the walls and the ceiling. Simplified photometric values are usually given by fixture manufacturers for use in this method.