Research suggests that occupants are best satisfied in an office with lit desktops and vertical surfaces, some daylight, and a moderate degree of lighting variation (non-uniformity).

Office lighting designers create a satisfactory lit environment by strategically using light sources and room surfaces to provide and distribute light:

• Establish illuminance levels and uniformity appropriate for the office tasks;
• Design ambient light (daylight and electric light) to illuminate the vertical and horizontal surfaces;
• Design task lighting to illuminate particular task surfaces that need high illuminances;
• Design accent lighting to fill shadows, provide areas of visual interest and relaxation, and create some lighting variation;
• Create surface characteristics, workstation design, and computer placement to enhance light distribution and avoid glare.

After a 4-year study, the COPE researchers have compiled design strategies from the COPE study, the Illuminating Engineering Society of North America (IESNA), the Chartered Institution of Building Services Engineers (CIBSE), Canada Occupational Safety and Health Regulations (COSHR), and other authoritative sources.

Elements of Open-plan Office Lighting

When creating the open-plan office luminous environment, designers work with a number of light sources.

• Luminaires: prismatic-lensed, parabolic-louvred, indirect, direct/indirect, task, accent
• Windows and skylights

Lighting designers must also consider the elements that affect light distribution.

• Partition (partial-height screen) height and location
• Surface reflectances and specularity
• Workstation size
• Computer screen type and orientation

These surfaces can alter a lighting design significantly. Creating open-plan office lighting without considering the furniture results in a flawed design. Quality open-plan office lighting systems are planned for each cubicle as well as the whole space.

The following design suggestions will help readers understand the process of lighting design, and the role of each office element.

Light Levels and Locations

The first step in selecting lighting levels is to consider what occupants will be doing and where they will do it, and, then, to choose the required illuminance. The many recommendations on illuminance can provide guidance concerning the appropriate levels for different activities.

The following charts list illuminance recommendations relevant for offices. These values appear in documents from IESNA, CIBSE, the New Buildings Institute's Advanced Lighting Guidelines, and COSHR. Overall, these recommendations are relatively similar; however, there are some differences worth noting. For instance, ambient illuminance levels and locations are not the same across all organizations. In some cases, the illuminance measurement is taken on a horizontal plane and in others it is taken on a vertical plane.

Most organizations and lighting professionals agree that good office lighting design may be achieved with relatively low ambient light levels and supplementary higher task illuminance. The Advanced Lighting Guidelines (2001 Edition) and Code for interior lighting state that ambient lighting should provide one third of the necessary task illuminance ^[1].

Most of the recommendations are for illuminance on horizontal surfaces. However, in modern offices, vertical illuminance is also important. Workers spend a high proportion of their time doing 'head-up' tasks, such as reading a computer screen, meaning that they see vertical surfaces most often. When implementing the desired illuminances, whether task or ambient, ensure that some light falls on vertical surfaces.

IESNA recommendations for illuminance ^[2]


CIBSE recommendations for illuminance ^[3]

Lighting for Offices (1993), which references CIBSE Code for interior lighting, recommends 300-500 lx for offices with computer screens ^[4].


Canada Occupational Safety and Health Regulations on Lighting ^[5]

Light levels should be verified in the completed, furnished room. Illuminance is often calculated in empty spaces, which can provide an inaccurate assessment of the light that will actually reach each surface. Partitions can reduce light levels by about 30% to 35% ^[6] compared to a room with no furniture. Have the designer model the luminaire system in a furnished room with the expected daylight availability.

Daylighting and Windows

The second step in creating a lighting system is to choose the light sources that will create the desired illuminances. Daylight is an excellent source of energy-efficient, flicker-free light that can reveal subtle colour differences. No building can be lit by daylight alone because daylight is not reliable (weather, time of day, time of year, etc), and it generally does not reach all areas in a building. However, good office design can allow daylight into the first and second rows of cubicle offices away from the façade, providing potential energy savings and occupant satisfaction with light and view. Daylight availability and design should be created before the electric lighting design, so that electric light can supplement the illuminance provided by daylight.

To make best use of daylight design, designers should aim to use diffuse daylight from windows and skylights, while avoiding direct sunlight. Façade geometry, glazing type, shading device, and the position of occupants and tasks determine the success of a daylighting design.

Lighting professionals can recommend techniques that will provide maximum daylight in the room. Software, like Lightswitch Wizard, can help evaluate daylight and recommend good techniques, and organizations, such as the Daylighting Collaborative are excellent resources for information on daylighting techniques: www.daylighting.org.

Exterior Design, Zoning, Façade, and Building Design
Ideal daylighting designs are created when the building, façade, and lighting design develop concurrently so that all elements are built to increase daylight penetration and distribution. This is possible for new buildings or major renovations, but less feasible in existing buildings. Here are a few points to consider when consulting a professional during building design.

• Choose a façade orientation that receives a limited amount of direct sunlight. North and east facing façades are preferable because the angles of the sun are not likely to cause direct glare; south and west façades are susceptible to glare.
• Consider the glazing transmittance. A visual transmittance of 60-70% in the upper (clerestory) window area is required to allow for sufficient daylight to penetrate to the second row workstations ^[7]. However, such high visual transmittances should be avoided for the lower see-through window area to prevent glare. The Daylighting Collaborative recommends visual transmittances of 18-25% for the see-through area ^[8]. To resolve this contradictory situation, designers can either use two different glazing types for upper and lower window areas, or employ a versatile glare protection device, like a split blind system or a devise that closes from below. (Photo of a split blind system below in Shading and Distribution Devices.)
• Investigate shading devices like louvres, light shelves, and other façade designs that can redirect daylight and offer protection from glare.
• Match the upper edge of the window as near to the ceiling height as possible so that daylight can penetrate deeply into the room.
• Make pavements and low roofs reflective to increase the amount of light that comes from below.
• Use trees as shading devices because they block direct sunlight. Deciduous trees offer more shade in the summer and allow more light in the winter.

Shading and Distribution Devices
Most office designers have to work with existing buildings and have no input into façade design. They have to use remedial devices to make the best use of the available daylight. Effective, adjustable, user-friendly shading devices can be added to an office to allow users to benefit from daylight, while excluding direct sun and the resultant glare problems.

• Use blind systems to block direct sunlight and heat gain, while allowing diffuse light to enter the building. Blinds can be interior or exterior, fixed or retractable, and manually or automatically controlled. Slat or baffle spacing, number, and orientation (vertical or horizontal) should be designed to block common sunlight angles, therefore avoiding glare. The slats should also have a matte texture and a high reflectance.
• Provide shades, curtains, or other items to allow occupants to control daylight. Opaque shades will block light completely; more transparent shades will diffuse the intensity of direct light. Consider creative solutions.

Note: While daylight and windows are excellent light sources, they can also cause ventilation and thermal problems. Windows can be cold or heat sources, which can affect occupant thermal comfort and ventilation cooling loads. Well-designed shading, internally ventilated windows, spectrally selective low-emissivity glazings, and low U- value glazing assemblies can reduce thermal problems. Consideration should be given to the thermal impact of daylight design and ventilation professionals (building operators and HVAC designers) should be consulted. Please refer to COPE VENTILATION for more information about ventilation and thermal comfort.

Electric Lighting

Even with an excellent daylighting system, electric light must be provided to maintain the desired illuminance levels under all circumstances. The choice of lighting system depends on the illuminance levels needed in the office, the location of the surfaces on which most tasks are performed, the desired energy savings, and the budget.

Luminaires
Generally, luminaires that provide the right amount of light on the task surface, while avoiding glare, are successful.

Note: The type and placement of light fixtures can affect sound propagation and speech privacy in the office. Please refer to COPE ACOUSTICS.

• Prismatic-lensed luminaires are generally not recommended for open- plan offices because they create reflected glare in computer screens and on desktops. However, special low-glare lenses and computer placement in relation to luminaires may be an acceptable arrangement. Prismatic-lensed luminaires have an advantage over parabolic-louvred luminaires because they illuminate walls and ceilings as well as the desktop.
• Parabolic-louvred luminaires are designed to reduce glare in computer screens, and preferentially illuminate the desktop, and are therefore popular for open-plan offices. However, because the light is directed sharply downward, they do not illuminate vertical surfaces or ceilings, creating dark ceilings and sharp scallop shadows on the walls. Vertical illuminance can be increased by using semi-specular or white louvres; by placing parabolic- louvred luminaires near the walls; by reflecting light towards the ceiling with light-coloured surfaces; and by using accent lighting.
• Luminaires with an indirect component are a good choice in open-plan offices because they provide relatively uniform light, reduce glare and shadows, and illuminate vertical surfaces and ceilings. Many occupants prefer indirect or direct/indirect light fixtures, and indirect lighting is highly recommended for offices with intensive computer use.
  However, indirect systems can be expensive, can be difficult to reconfigure with cubicle reconfiguration, and require reasonably high ceilings. Indirect lights can also make the ceiling into a glare source if the illuminance is too high. Please consult the Avoiding Glare section.
• Well-placed wall washing and accent lighting can help create a pleasant scene and avoid distinct shadows on the walls and ceilings. Accent lighting should be subtle: it can help to illuminate vertical surfaces, create luminance variation, and highlight areas of visual interest, such as art work, architectural features, emergency exits, etc.
• Task lighting can be used to provide high illuminances on a task surface so that ambient lighting can be kept comparatively low. Under-shelf task lamps can fill shadows caused by partition-hung storage units, and desktop task lights can place high illuminance on a particular area of the desk.
  Occupants generally prefer articulated task lights because they can direct light as needed. Office Lighting states that task luminaires need to be high enough to prevent shadowing (height should be ½ the width of the task surface), aimed from the side of a task, and shielded from the occupant ^[9].

Lamps and Ballasts

Lamp (bulb) choice is connected to luminaire type because luminaires are designed for specific lamp types. The light output and efficacy (light output per input power) of the lamp greatly affects illuminance and system energy efficiency. Given the desired light distribution, select the most efficient lamp for the chosen luminaire, but be aware that high output lamps may be too bright for comfort.

• Fluorescent lamps are highly efficient, silent, light weight, and, when used with electronic ballasts, do not cause flicker problems. These lamps are recommended for office lighting because they are energy efficient and relatively low cost.
• Compact Fluorescent lamps (CFL) are smaller and more energy efficient for the same given light output as standard filament lamps. They are an excellent alternative to incandescent or halogen lamps because they can provide significant energy savings. A CFL can provide the same light output as an incandescent lamp, using only ¼ the energy. It will also last ten times longer, more than justifying the extra cost.
• Tungsten-halogen lamps provide good colour and are small in size. They are recommended for spotlighting, but should be used with caution because they generate heat. They are relatively inefficient compared to fluorescent lamps.
• Incandescent lamps are the least efficient lamps and should be replaced by CFL, where possible.
• For fluorescent or high-intensity discharge lamps, pay attention to the colour properties of the lamp. Choose a correlated colour temperature (CCT) that is suitable for the space, taking into account the colours in the space and the daylight availability. (If daylight is high, a higher CCT — cooler colour — may blend well.) The colour appearance of light may also be important when indirect luminaires are used because the lamp colour is easily visible on the white or off-white ceiling.
• With fluorescent or high-intensity discharge lamps, choose lamps with appropriate colour rendering abilities. Electric lights provide a constant colour spectrum, but do not necessarily exhibit high colour quality. The tone and subtleties of the colour may not be absolutely true. Lights with a Colour Rendering Index (CRI) of 90 are required for colour identification and matching. CRI 70 is sufficient for office settings, though CRI 80 gives a pleasant appearance to skin tone and surfaces. ^[10]

For discharge lamps, ballasting and control gear must be compatible with the lamp because they start, control, and stop the power flow to the lamp.

• Use electronic ballasts, not magnetic ones. The ballast in a fluorescent lighting system controls the electric arc across the lamp. There are two ballast technologies, known as "magnetic" and "electronic". Magnetic ballasts have been associated with negative effects on occupants such as headache and reduced visual performance because the light output of the lamp varies 120 times per second with magnetic ballasting. Most people cannot report perceiving this flicker, but the nervous system can detect it. Electronic ballasts operate at a much higher frequency, so high that the nervous system cannot detect flicker, and there are none of the associated negative effects. They also use around 20% less energy than magnetic ballasts. However, they are more expensive.

Lighting Controls

Controls ensure light is on when, where, and at the level that it is needed. Controls can increase the usability of daylight, reduce the amount of electric light used, provide energy savings, and allow occupants to set their preferred light levels.

Switching systems, dimming systems, photo sensors, and occupancy detectors allow users or automatic systems to turn off and dim unnecessary electric light.

• Controls can be manual or automatic. Manual controls should be user- friendly and easily accessible so that occupants will use them. Automatic controls may be programmed based on time of day, daylight availability, or occupancy. When programming these controls, tasks and occupant preferences should be considered. A manual override switch should also be included.
• Perimeter luminaires, close to windows and skylights, can be placed on separate circuits from the interior luminaires so that they can be dimmed or turned off completely when daylight is adequate.
• Photo sensors and manual dimming switches allow users or building managers to turn down the electric lighting when enough daylight is available. Photo sensors depend on a photocell that reads the illuminance at a given point and, based on the reading, relays a message to turn up, down, or off the electric lighting in the area.
• Blinds and shades can also be controlled. Automatic controls can be programmed to retract or lower blinds and change the slat angle during the day to reduce direct sunlight. They can also be set to raise the blinds at specific times of the day (lunch, evening). This control system allows users to lower the blinds when glare is a problem, but does not require them to raise the blinds when glare is not an issue.
• Individual controls can increase occupant satisfaction by allowing users to meet their individual preferences. Systems with individual controls in each workstation are most satisfactory.

Lighting Design Maintenance

All lighting systems must be maintained for them to remain functional and successful. Anytime there is a renovation, significant occupant turnover in the office, or a change in technology, equipment or tasks, the lighting design should be reconsidered because the light distribution and the needs of the occupants might have changed.

Lighting designs also require some regular maintenance to ensure that each element is functioning as expected.

• All control systems need to be calibrated periodically so that they continue to work as expected.
• Lamps need to be maintained during the life of the lighting installation. Dirt build-up, illuminance loss, or colour shift can reduce the lamp's output and effectiveness over time. Scheduled group re-lamping based on manufacturers' rated lamp life can save labour costs and provide an opportunity for regular cleaning.
• Daylight design is aided by clean windows and shading devices (blinds, lightshelves, etc.); therefore, establish a regular cleaning schedule.

Uniformity

In open-plan offices, the lighting system performance can be greatly affected by the partitions and modular furniture. These elements in a large, open room can inhibit even light distribution by casting shadows. Designers must use techniques to provide relatively uniform lighting on task surfaces so that occupants can work comfortably. According to CIBSE, uniformity is achieved by ensuring that the minimum illuminance on a task surface is at least 0.8 times the average on the task surface ^[11].

Over the entire office, a balance between uniform and variable lighting is needed. Luminance variation will increase visual interest and reveal the space accurately. Complete uniformity creates a flat, unrealistic scene.

IESNA RP-1-1993, a document authored by the IESNA, recommends ratios shown in Table. ^[12] The ratios refer to surface luminances.

Some areas can exceed the recommended uniformity ratios to highlight areas of visual interest or of visual importance. However, any departure from uniformity ratios should serve a purpose.

To avoid excess non-uniformity in open-plan offices, avoid all lighting that creates arbitrary distinct patterns (scallops, patches, harsh striations without a lighting purpose), high brightness, and noticeable shadows.

• Use luminaires appropriately. Misaligned wall-luminaire grids, indirect luminaires with low ceilings, and misused accent lights can create areas of excessive contrast.
• Use many closely spaced luminaires at lower output. Widely spaced luminaires create excessive non-uniformity. The manufacturer's recommended spacing may not be appropriate for an open-plan office when the effects of partitions (reducing light levels and uniformity) are present. If possible, have the lighting designer model the space with obstacles in it.
• Consider luminaires with an indirect component.
• Use accent lighting carefully to reduce meaningless shadow patterns on walls, partitions, or the ceiling. Accent lighting can also be used to highlight areas of visual importance.
• Place luminaires close to the walls to illuminate walls if accent lighting is not used. IESNA recommends placing luminaires approximately 1 m (3ft) from the wall ^[13].
• Reduce partition height and increase workstation size.
• Make office surfaces light-coloured, so that they are reflective. (Do not use specular or glossy surfaces because they can result in glare problems.)

Room and Surface Characteristics
Office surfaces play an important role in distributing or blocking the light that is provided from either electric or natural sources. Surface characteristics are especially important for indirect or direct/indirect lighting installations and for offices in which daylight plays a major role.

Using light colours does not mean that all colours need to be the same. Colour variation is important to create visual interest and to suit user preference. A monochromatic high-reflectance cubicle, while light, is uninteresting and unsatisfactory.

Note: When increasing reflectances in the office, designers should make sure that recommended illuminance levels and recommended luminance ratios are not exceeded.

Ceiling:
The ceiling is the largest unobstructed plane in an office and is therefore very important for light distribution.

• Increase ceiling reflectance to make the ceiling appear brighter and to distribute daylight. In open-plan offices, the ceiling is often in the field of view and should be light and pleasant, not dark and cave-like. With indirect lights, increased ceiling reflectance improves desktop illuminance and daylight penetration. IESNA recommends that ceilings have 75-90% reflectance ^[14]; IESNA RP-1-1993 recommends 80% or more ^[15]; CIBSE recommends that ceiling reflectance be between 60 and 80% ^[16].
• Use matte ceiling surfaces to reduce veiling reflections and direct glare.
• Avoid excessive ceiling luminances, which cause glare. Please consult the Avoiding Glare section.

Walls:

• Increase surface reflectance. IESNA, both the Lighting Handbook ^[17] and RP- 1-1993 ^[18] suggest a reflectance of 50-70% for walls. CIBSE differentiates between walls with and without windows: walls with windows should have a reflectance of at least 60%; walls without windows should have reflectances between 30% and 70%. ^[19] The CIBSE technique helps to reduce the contrast between the bright window and the adjacent wall; high contrasts can be uncomfortable for occupants.

Partitions and Workstation design:

• Create smaller peripheral workstations to allow daylight to reach the second row workstations. (Smaller workstations increase daylight penetration, but they also reduce uniformity on the desktop. Please refer to Uniformity.)
  
• Use lower partitions. High partitions reduce the amount of light that reaches task surfaces and inhibits daylight penetration. High partitions particularly reduce illuminance with indirect light fixtures. (Low partitions can greatly reduce acoustic and visual privacy. Please refer to COPE ACOUSTICS and COPE WORKSTATION DESIGN.)
  
• Use matte or satin finishes and light coloured surfaces to better distribute light within the cubicle and increase uniformity without creating glare. Dark colours will absorb light and may reduce light levels below the expectation, making the room appear less bright. IESNA RP-1-1993 recommends that furniture have reflectances of 25-40%, and that partitions have a reflectance of 40-70% ^[20]. (The use of light colours should be incorporated with colour design.) Avoid specular surfaces, especially on desktops. They create glare patches in the visual field and can make an adjacent task difficult to look at.
  
  
• Avoid placing high partitions and storage units close to or parallel to the windows to allow daylight to penetrate as far into the office as possible.
• Place occupants who need to communicate with each other (acoustic privacy is less important) in adjacent first and second row offices so that partitions can be kept low for daylight penetration purposes.
• Note: Many of the recommendations for daylight penetration contradict recommendations for visual and acoustic privacy, and spatial density. A balance must be found between these factors and daylight usage. For some occupants, privacy is paramount; for other, daylight availability will be more important. A design with some high and some short partitions might be a compromise between lighting and privacy concerns. In all cases the primary needs of the occupants must be consulted when making compromises. Please refer to COPE ACOUSTICS and COPE WORKSTATION DESIGN for more information on these issues.

Avoiding Glare
Disability and discomfort glare are significant issues in open-plan offices because occupants are affected by distant luminaires that can create direct and reflected glare. These glare problems would be less likely to occur in private offices with full-height walls. The spatial relationship between light sources, a task, and the occupant's eyes (source/task/eye geometry) needs to be designed carefully in open-plan offices.

Glare can be avoided by keeping illuminance levels relatively low, eliminating specular and glossy surfaces, screening light sources, and carefully designing source/task/eye geometry. Remedial technologies, room configuration changes, and lighting system modifications can reduce glare.

Light levels:

• Do not exceed recommended illuminance levels and luminance ratios.
• Reduce ambient illuminance if reflected glare in computers is a problem. Lower light levels are generally preferred where computer work is intensive. CIBSE and IESNA recommend illuminance levels between 300 and 500 lux for offices with computers ^[21]. Choose the lower illuminance for intensive computer work and the higher illuminance if documents are used with computers. Also consider using task lights for documents so that ambient light levels can be kept relatively low.
• Keep luminaire luminances below 100 times the level of the surrounding surfaces ^[22].
• Prevent the ceiling from becoming a glare source when using indirect lighting. CIBSE recommends a ceiling luminance less than 500 cd/m2 with indirect lighting. ^[23] Technics: Solving the Problem of VDT Reflections recommends a maximum ceiling luminance of less than 850 cd/m2 for any 0.6 by 0.6 m area ^[24].

Luminaires:

• Shield lamps from seated and standing occupants to avoid direct glare, and use luminaire shields that are designed to reduce glare. Desktop and under- shelf task lights, as well as ceiling luminaires, require shields.
• Avoid placing ceiling luminaires in 'offending zones', where the source/task/eye geometry will result in direct or reflected glare. (See diagrams below.)
• Use luminaires with an indirect component to create more diffuse light.
• If using direct luminaires, choose parabolic-louvred luminaires that cut off light at angles likely to cause glare.
• Use accent lighting with direct lighting to fill shadows that may contribute to reflected glare.
• Avoid prismatic luminaires, unless they are very carefully designed; they often cause reflected glare in computer screens.
• Provide shading devices for windows.
• Reduce ceiling-luminaire contrast. With downward lighting, this involves illuminating the ceiling. With indirect lighting, this involves using light- coloured luminaire bodies or luminaires with a direct component so that the ceiling luminaire contrast is not great.

Surfaces:

• Use matte or satin finishes on walls, furniture, and partitions to reduce reflected glare.
• Give tasks a matte finish: avoid glossy paper; use anti-glare coatings; use glare filters on computer screens, or use flat, matte screens.

Source/task/eye geometry:

• Rearrange source/task/eye geometry. The following diagrams demonstrate some typical source/task/eye geometry problems. These problems can be resolved by changing the luminaire configuration or by moving the task. In many cases, rearranging the task orientation is quickest and least expensive way to reduce extremely unsatisfactory glare problems.

• Do not place occupants directly under parabolic fixtures to prevent overhead glare.
• Place computer monitors parallel to light sources, such as windows, to avoid reflected glare.

Considering Computer Screens

Most employees use a computer in the office, and special consideration has to be given to providing light on and around the computer screen and to avoiding glare.

Lighting designers should consider how frequently the computer is used, how it is used, the type of image (negative contrast or positive contrast), and the angular relationship between the user, the screen, and light sources. Vertical illuminance, greater uniformity, and source/task/eye geometry are important.

The following suggestions help create an environment appropriate for computer work:

• Follow recommendations on reducing glare, especially the source/task/eye geometry recommendations. Because computer users work in a heads-up position and can see the ceiling, poor source/task/eye geometry can cause discomfort and result in veiling reflections.
• Keep the computer screens close to vertical. Ergonomic practices generally suggest a tilt angle of 5-15 degrees from vertical ^[25]. Inappropriate tilt angles can maximize reflected glare.
• Increase uniformity. Uniformity should be considered over the computer screen, the keyboard, and reference documents especially. General uniformity also helps to reduce glare in computer screens. Please consult the Uniformity section for suggestions.
• Use flat, matte computer screens. The typical glossy, curved computer screen is highly susceptible to reflected glare.
• Use glare screens, or anti-glare coatings on the computer screens.
• Encourage users to adopt a light background with dark characters on the computer screen. Reflected glare is less obvious in these conditions.
• Use furniture elements to block glare sources, if necessary.

Lighting Consultant

Lighting design is a complex process that involves the function and aesthetic appearance of light, the immediate and long-term costs of the system, energy consumption, and environmental issues.

A lighting consultant is trained to consider all these issues and has the experience needed to create the most satisfactory lit environment within building, environmental, occupant, and budgetary requirements.

Contacting the IESNA or the International Association of Lighting Designers (IALD) is the best way to locate a lighting designer. These organizations can identify and recommend local professionals who provide lighting services.

Lighting Software

There are many lighting programs that can help users design and evaluate lighting systems.

The COPE-ODE tool provides a basic evaluation of user satisfaction with lighting and with the other components of open-plan offices. This program can be accessed over the Web and is available to any user.

Lightswitch Wizard is an online daylighting analysis tool that has been developed by the NRC and by Natural Resources Canada. It supports daylighting-related design decisions in peripheral offices during an early design stage. It offers a comparative analysis of the amount of daylight available in peripheral cubicle offices or private peripheral offices as well as the lighting energy performance of automated lighting controls (occupancy sensors, photocells) compared to standard on/off switches. This program is available over the Web and can be used by any user.

Other software packages are available for more complex calculations of the luminous environment. Every year, an article published in the IESNA magazine "Lighting Design and Application" lists, describes, and reviews various lighting programs.

References:
1: Benya, James, Heschong, Lisa, McGowan, Terry, Miller, Naomi, & Rubenstein, Francis. Advanced Lighting Guidelines. Ed. Jennifer Roberts, 2001, pg. 4-7; Code for Interior Lighting. ed. R. Yarham. London: CIBSE, 1994, pg 137-138.

2: The IESNA Lighting Handbook: Reference and Application. Ed. Rea, Mark S., 9th ed., New York: Illuminating Engineering Society of North America, 2000, pg. 10-13.

3: Code for Interior Lighting. ed. R. Yarham. London: CIBSE, 1994, pg 40; Lighting for Offices pg 42 (750) and pg. 36 (VDTs).

4: Lighting for Offices. Lighting Guide LG7: 1993. Task Group: R.L. Gardner, L.A. Ayscough, E. Maddock, A. Maxwell, B. Wilde. Ed. BW. Coping London: CIBSE, 1993) pg 36.

5: COSHR: Section 6.4 and 6.7; Schedule I and IV; pgs 2, 3, 5, 6, 10.

6: Benya, James, Heschong, Lisa, McGowan, Terry, Miller, Naomi, & Rubenstein, Francis. Advanced Lighting Guidelines. Ed. Jennifer Roberts, 2001, pg. 4-7.

7: Reinhart, C.F. Effects of office design on the annual daylight availability - A simulation study

8: Daylighting Collaborative: www.daylighting.org

9: Littlefair, Paul, Slater, Anthony, Perry, Mike, graves, Hilary, & Jaunzens, Denice. Office lighting. London: Construction Research Communications Ltd with permission of Building Research Establishment Ltd, 2001. pg 14.

10: The IESNA Lighting Handbook: Reference and Application. Ed. Rea, Mark S., 9th ed., New York: Illuminating Engineering Society of North America, 2000, pg 10-4.

11: "Code for Interior Lighting" ed. R. Yarham. London: CIBSE, 1994, pg 29.

12: Kohn, Mitchell B. American National Standard Practice for Office Lighting. ANSI/IESNA RP-1-1993. New York: Illuminating Engineering Society of North America, 1993, pg 3.

13: The IESNA Lighting Handbook: Reference and Application. Ed. Rea, Mark S., 9th ed., New York: Illuminating Engineering Society of North America, 2000, pg 10-9.

14: The IESNA Lighting Handbook: Reference and Application. Ed. Rea, Mark S., 9th ed., New York: Illuminating Engineering Society of North America, 2000, pg 10-6.

15: Kohn, Mitchell B. American National Standard Practice for Office Lighting. ANSI/IESNA RP-1-1993. New York: Illuminating Engineering Society of North America, 1993, pg 2.

16: "Code for Interior Lighting" ed. R. Yarham. London: CIBSE, 1994, pg 31.

17: The IESNA Lighting Handbook: Reference and Application. Ed. Rea, Mark S., 9th ed., New York: Illuminating Engineering Society of North America, 2000, pg 10-6.

18: Kohn, Mitchell B. American National Standard Practice for Office Lighting. ANSI/IESNA RP-1-1993. New York: Illuminating Engineering Society of North America, 1993, pg 2.

19: "Code for Interior Lighting" ed. R. Yarham. London: CIBSE, 1994, pg 31-32.

20: Kohn, Mitchell B. American National Standard Practice for Office Lighting. ANSI/IESNA RP-1-1993. New York: Illuminating Engineering Society of North America, 1993, pg 2.

21: "Lighting for Offices." Lighting Guide LG7: 1993. Task Group: R.L. Gardner, L.A. Ayscough, E. Maddock, A. Maxwell, B. Wilde. Ed. BW. Coping London: CIBSE, 1993), pg 36 ; The IESNA Lighting Handbook: Reference and Application. Ed. Rea, Mark S., 9th ed., New York: Illuminating Engineering Society of North America, 2000, pg. 10-13.

22: The IESNA Lighting Handbook: Reference and Application. Ed. Rea, Mark S., 9th ed., New York: Illuminating Engineering Society of North America, 2000, pg 10-5.

23: "Code for Interior Lighting" ed. R. Yarham. London: CIBSE, 1994, pg 31.

24: Rea, Mark S. Technics: Solving the Problem of VDT Reflections. Progressive Architecture, 1991, v. 10 pg. 35-40.

25: Kohn, Mitchell B. American National Standard Practice for Office Lighting. ANSI/IESNA RP-1-1993. New York: Illuminating Engineering Society of North America, 1993, pg 35.