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Besides affecting the physical and emotional well-being of the building occupants, a building's interior lighting system is both a dominant consumer of electrical energy and a major source of internal heat. Proper illumination levels depend on the type of work being performed, and on occupant preference.
Recommended illuminance levels for offices range from 30 to 60 footcandles, but the quality of the visual environment can have a substantial impact on the “appropriate” amount of illumination. In well-designed office spaces, with light-colored surfaces, appropriate task lighting, and careful placement of lights and furniture to avoid glare and shadows, much lower illuminance levels are acceptable, and usually even preferred.
Proper placement and orientation of both daylight and occupancy sensors is essential. Placement of controls should take into account furniture placement as much as possible.
| Type of Fluorescent Luminaire
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Description
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Benefits
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Cautions
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Applications
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| Indirect/Direct Linear Luminaire
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Primarily indirect, pendant or wall mounted, T8, T5 or T5HO lamping
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Soft, even illumination, good visual comfort, easily dimmed
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Choose spacing for good ceiling brightness uniformity
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High and low bay areas and classrooms
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| Indirect/Direct Decorative Luminaire
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Typically compact fluorescent or induction lamping
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Significant energy savings, performance comparable to incandescent
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Select diffuser for good brightness uniformity on glowing elements
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Small offices, lobbies, waiting areas, atriums, and corridors
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| Linear Strip Luminaire
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Surface mounted or pendant mounted with or without side reflectors, typically T8 lamping
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Energy-efficient, small size, low-cost, easily dimmed
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Best when concealed
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In coves or wall slots, on top of cabinets, stacks or lockers, and mechanical rooms
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| Task Luminaire
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Linear wall mounted "under shelf" or "arm type"
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Task lighting allows for lower ambient lighting levels
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Provide appropriate task/ambient contrast ratios
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Any task surface (desks,counters, workbenches, etc.)
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| Indirect Recessed Luminaire
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Recessed (light is directed up toward top of housing and reflected back down), typically 2' x 2' or 2' x 4', T8 or CFL biax lamping
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Optimized for fewer lamps than typical recessed lensed troffer luminaires, good visual comfort
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Optimized for fewer lamps than typical recessed lensed troffer luminaires, good visual comfort
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Corridors, open/private offices (can replace standard troffer in many applications)
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| Recessed Wall Washer
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Linear or round can-type, Linear or CFL lamping
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Significant energy savings, performance better than incandescent
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Best when paired or in groups, choose spacings carefully
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Select wall surfaces in many room types
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| Recessed Downlight
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Round can-type, CFL lamping
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Significant energy savings, performance comparable to incandescent
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Does not brighten the ceiling, can create light "scallop" on walls
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Localized infill lighting, often combined with other luminaire types
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| Wall Sconces
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Wall mounted, decorative, CFL lamping
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Significant energy savings, performance comparable to incandescent
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Select diffuser for good brightness uniformity on glowing elements
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Lobbies, corridors, conference rooms, etc.
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The first step in lighting design is to determine the visual needs of the space and identify what type of lighting to use. Lighting types are divided into four categories:
- Ambient Lighting - Ambient lighting systems can be easily integrated with the available day lighting. In a well-designed building, day lighting can offset most or all of the daytime ambient lighting loads.
- Task lighting – used where clearly defined lighting levels are required to complete detailed work, such as paperwork, reading, or bench-top experiments.
- Accent Lighting – used for architectural purposes to add emphasis or focus to a space or to highlight a display.
- Emergency or egress lighting – used to provide a pathway for exiting a building if an emergency arises.
- Safety Lighting-Safety lighting allows people to enter a space , occupy it, and move through or exit it without endangering their physical well-being. Building codes require that potential hazards, circulation areas, entrances, and exits must be illuminated.
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Participants