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Guideline I.5: Quality Lighting
Intent
Electric lighting should be designed to supplement and support the use of daylight as the primary source of light for visual tasks. This is vitally important to achieving environmental, health and economic goals. The integrated design of artificial and natural light must also maintain these lighting quality characteristics and effects: tolerable glare, natural color rendering, and attractive illumination of people for social exchanges.
Required Performance Criteria
Guidelines apply to all projects designated New Buildings and for Major Renovations with lighting replacement in the project scope.
- Newly installed electric lighting must be operable in multiple modes and responsive to both daylight zones and differentiated uses within a given space, such as separating controls for media projection areas from general task areas within a space.
Recommended Performance Criteria
- For general illumination in most space types, attain an average electrical illumination at the work plane of 35 to 50 foot-candles. A minimum of 25 foot-candles is recommended at any point 3 feet or more from a wall.
- Consult the current version of the Illuminating Engineering Society of North America (IESNA) handbook for other recommended light levels.
- Keep contrast ratios in the field of view within the space as seen from the task areas to no greater than 10:1
- Achieve a Color Rendering Index (CRI) for each space type based on recommendations in the current version of the IESNA handbook.
- At a minimum, conduct a point-by-point analysis of horizontal illumination levels at the work plane in each lighting mode for each space.
- Perform computer simulation of the performance characteristics of the electric lighting system in each primary space type. Illumination levels on vertical planes should be evaluated when they have been defined as a task or work area.