Lighting Design

Indoor Lighting

High-quality, energy-efficient lighting enhances the design and performance of buildings and leads to:

• increased productivity;
• reduced absenteeism; and
• lowered maintenance costs.

Quality indoor lighting is an integrated design process that often including daylighting elements.

Light Levels

Today’s design practices factor in glare, luminance ratios and color rendering, and often feature light levels of 30 footcandles or less (50 footcandles is normal for desk level). With balanced contrast ratios, high color rendering and reduced glare, lower light levels make many visual tasks easier to perform.

Contrast Ratios

Careful attention to contrast ratios and glare reduces eye fatigue and headaches. Poor contrast ratio might be a computer monitor in front of a dark background or glare from direct lighting or a window. To alleviate eyestrain, designers now provide relatively low ambient light supplemented with task lighting. Ambient light is ideal for computer-related work. Task lighting works well for desktop activities.

Controls

• Dimming controls allow individual users to adjust lighting levels to their own needs;
• Occupancy sensors turn lights off when rooms and spaces are unoccupied;
• Photo sensors dim or turn off lights in response to daylight contributions; and
• Lighting control panels integrate with building automation systems to minimize energy use.

Additional Information

• Advanced Lighting Guidelines
• National Lighting Information Program
• Lighting Design Lab

Outdoor Lighting

Proper outdoor lighting design enhances visual performance, minimizes environmental impact and helps improve safety and security. Issues to consider during design: glare, visibility, color, illuminance, luminance and brightness.

Design Considerations

• Use full-cutoff light fixture that emits light below horizontal plane;
• minimize non-target illumination (e.g. ensure up-lighting hits its target on buildings and signs);
• turn off outdoor lighting during low-use periods;
• use well-shielded fixtures; and
• angle floodlight beams low so the beam stays in the design area.

Pitfalls to Avoid

• Glare – streetlights, pedestrian lights, floodlights and bright reflectors;
• Light pollution – light reflecting off dust, water vapor and other particles; and
• Light trespass – excessively bright light that shines in nearby windows.