Enclosed Office Applications

Last Update: February 14, 2011
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Enclosed Office Design

Lighting uniformity, glare control, daylighting and visual comfort are high priorities for all office environments. The perception of natural color and appropriate facial modeling contribute to effective worker interactions. Vertical illuminance on wall and partitions enhances the impression of brightness in the environment. The lighting should be interesting without creating distractions such as shadows, high contrast, or sudden changes in light levels.

Each of the following modules show alternative energy effective lighting designs for enclosed or private offices of three different sizes: small, medium and large (executive). These are only a sampling of valid approaches, but each adheres to the following goals for enclosed office lighting:

  • Task lighting may be separate from the ambient lighting for the room, but both systems shall be within the control of the occupant.  A local task light at the desk should be made available for all workers who desire it. 
  • Glass partitions, with some privacy accommodation, should be provided between private and open-plan offices, so that light and views can be shared. Adjacent office circulation may not need dedicated luminaires if illuminance can be allowed to spill from the offices.
  • If offices are located along perimeter window walls consider orienting and zoning the electric lighting to take advantage of daylight harvesting.
  • Private offices should always include separate task lights or separately controlled ceiling lighting. Individual lighting preferences vary widely, and many occupants will choose to work only with daylight, or only with task lights. This personal control not only saves energy, but contributes to worker satisfaction.
  • Locate computer screens perpendicular to the window wall, to avoid high contrast and reflected glare.
  • In offices without perimeter windows, the electric light should be designed to illuminate ceiling and vertical surfaces to increase the occupant’s sense of brightness in the space.
  • Light-colored finishes should be used to better utilize lighting energy and create a visually comfortable space. 
  • Overhead bins and shelves may cause shadows that create excessive contrast. Consider mitigating these shadows with local lighting or wide-distribution ambient luminaires.
  • In large private offices, visual interest can be created by accenting walls and art work or introducing decorative luminaires with energy efficient sources.
  • An educational program should be in place to educate users of the functions and abilities of the lighting control system.

Enclosed offices utilize daylight quite effectively, since the window or skylight not only provides task light, but also distributes ambient light onto the walls and ceilings. In offices 15’ or narrower, daylight can be the primary source throughout much of the day, with local task lighting providing supplementation as needed. Proper sun control should be designed to prevent excessive heat gain and glare. Individual office occupants will usually control their own interior shading to meet their needs. However, since private offices are often vacant, automated blinds will provide better thermal control, since uncomfortable heat gain can occur while the occupant is not in the office, requiring additional cooling when they return.
Maintenance Issues

  • Linear fluorescent lamps, especially 4’ long high performance (“super”) T-8 lamps and ballast systems, are the most efficient source for ambient office lighting. These systems have very long rated lives and are readily available through distribution. It is best to design with the fewest different lamp types possible to minimize stocking and replacement errors. Luminaires should be cleaned on a regular basis to avoid loss of light from dirty surfaces.

Controls for Private or Enclosed Offices

Vacancy Sensors
Due to single or low occupancy, the greatest savings in energy consumption in enclosed offices is achieved through the use of vacancy sensors. Electric lighting should require manual-on operation, turning lights off when the space is vacant. Single occupant offices can usually be fitted with a wall-box combination switch and infra-red sensor. Consider a ceiling-mounted sensor and separate wall switch for a multiple-occupant enclosed office, to accommodate obstructions from files or partial-height partitions.

Daylight Dimming or Switching
In enclosed offices with windows, there will be many times during the day when the daylight will be sufficient. The use of a “vacancy sensor”, (a sensor with manual-on, auto-off operations), reduces energy consumption by preventing the lights from coming on automatically during daylight hours. Greater savings are available through the use of vacancy sensors in conjunction with photosensors that can be set to prevent the electric lighting from turning on when daylighting levels are sufficient, but this requires careful calibration. Finally, dimming ballasts and photosensors can be used to dim luminaires. By zoning the luminaires separately, those near the window should dim before those on the interior. Dimming ballasts can also accommodate demand reduction.

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