Key Terms

Acrylic Prismatic Lens
The least expensive and most typical lens, used on both lay-in and surface mounted fixtures.

CRI
Color Rendition Index

Full Spectrum
Fluorescent lamp with a color temperature of 5,000 Kelvin or higher, with a CRI of 90 or better.

Indirect light
Light that is reflected, often from the ceiling.

Lay-in Fixture  
Fixture that is recessed into a ceiling grid.

Pendant Fixture
Light fixture that is suspended below the ceiling.

T-8 Lamp
Energy efficient 1inch (8/8 inch) diameter fluorescent lamp.

T-12 Lamp
Older style 1 ½ inch (12/8 inch) diameter fluorescent lamp.

 

Lighting the Learning Environment
Randall Fielding

“We want plenty of windows and full spectrum lighting - not those cold fluorescents.” This is a request I hear frequently from teachers while planning learning environments. While the benefits of full spectrum lamps remain inconclusive, there is a good deal of consensus on the value of daylight and quality lighting design.

The Daylight Standard:
Daylight has long been the standard measure for lighting quality. Studies by Kuller and Lindsten (1992), and the Heschong Mahone Group (1999), demonstrate a positive correlation between day lighting and academic performance. Daylight gives off a continuous spectrum of all light wavelengths, including blue, red and green, appearing as a bright white. Daylight is the standard for color quality in lighting, with a Color Rendering Index (CRI) of 100. Daylight is free – the most energy efficient source of illumination.
       In contrast, fluorescent lamps give off a discontinuous spectrum - a flickering light, with spikes of color. Most fluorescent lamps operate at 3,000 K (warmer) to 4,100 K (cooler), with a CRI from the low 50’s to 86. While fluorescent light fixtures with electronic ballasts and T-8 lamps (one inch diameter) provide an efficient utilization of electricity, they cannot be compared to daylight, since most electric power relies on fossil fuels or nuclear power. While natural illumination from windows and skylights is a preferred standard, most learning environments will require supplemental electric lighting.

The Wired Learning Space:
The movement towards learning spaces developed for notebook computers allows for tremendous flexibility in the configuration of teams and individual learner stations. This flexibility can pose a challenge in lighting design. Ideally, light from an overhead source will be directed from a learner’s right or left, minimizing glare or “veiling reflections.” Light directed from the front or behind can reflect off of computer screens or glossy pages into the learner’s eyes, causing eyestrain. Light directed from the left or right bounces off a page or screen to the side, rather than in the learner’s eyes. In a flexible environment, where team and individual seating arrangements change often, a directional light source produces poor results. One popular solution is to provide indirect lighting, with most of the light reflected off of the ceiling from pendant-mounted fixtures. Pendant fixtures are typically mounted 18 inches to 24 inches below the ceiling; requiring ceiling heights of nine foot six inches or more. These fixtures may include a portion of direct or filtered down light. Since light is reflected, an efficient installation requires 80% reflectivity for ceiling materials and 65% reflective paint for major walls.

Lighting Controls, Accent & Task Light 
Indirect lighting, while uniform, can also be monotonous, lacking shadow and contrast. Accent lighting on display areas or white boards enlivens a space. Recessed cove lights or pendant mounted directional fluorescents provide accent and task lighting efficiently. Location of lighting controls near presentation areas allows presenters to reduce the light level during media presentations, and increase them for speaking and discussion.
       Switching of selected rows of fixtures allows for a more efficient use of lighting resources. For example, fixtures running adjacent to a window wall can be switched separately; during most seasons and times of the day, these fixtures are not needed – illumination will be provided by daylight. Another switching option involves multiple ballasts; with a 3-lamp fixture, one may turn on one row of lamps, two rows of lamps or all three. During a media presentation, one row of lamps will be adequate for note taking, with minimal distraction from the presentation. During active team collaboration or discussion, all three rows of lamps are desirable.

Laboratory Lighting in Higher Education
Photo labs, life sciences and hi tech environments involved in the development of microchips may find that ultraviolet rays contribute to unwanted chemical reactions and bacterial growth. The same radiation can have beneficial effects in the absorption of vitamin D, thus the term the “sunshine vitamin.” Ultraviolet filtering lenses, sometime referred to as “yellow” lenses, filter out both the blue and ultraviolet spectrum.

Full-Spectrum Lamps and Polarized Diffusers
Light from the sun is polarized by the atmosphere, resulting in reduced glare and the blue color of the sky. Polarizing lenses are available to filter fluorescent lamps. These chemically treated acrylic lenses, combined with full spectrum lamps, can achieve artificial illumination with the spectral energy distribution and light polarization characteristics of natural daylight. “The lighting has been found to match natural daylight so closely that one cannot tell the difference between the artificial illumination and any light entering the windows. There is none of the eyestrain and fatigue typical of conventional cool-white illumination, which dives fluorescent lamps with core coil ballasts in unpublicized fixtures.” (Karpen, 1991
      
A full-spectrum lamp is generally defined as a lamp having a Color-Rendering Index (CRI) of 90 or above and a color temperature of 5,000 degrees Kelvin or above. Full-spectrum lamps and polarized lenses are more costly, and have not been widely accepted commercially. In the last decade, high efficiency electronic ballasts with reduced flicker and lamps with improved color rendering have become readily available. T-8 Lamps with a color temperature of 3,000 to 4,200 K are available with a CRI as high as 86. One study concluded that there was little consistent difference between conventional lamps with a good CRI and full spectrum lamps with a polarizing diffuser (Veitch, 1994).

Cost Factors & Efficiency
Lighting quality is closely linked to fixture costs. Lay in fixtures with acrylic prismatic lenses are cost as little as $35 for a four foot fixture, and are generally considered to provide the poorest quality of light, with the highest glare. A similar fixture with a parabolic louver produces less glare, and can be purchased for as little as $50. A steel pendant mounted fixture that produces indirect, reflected light starts at about $80. A steel pendant fixture with a mix of up light and down light starts at about $140. Extruded aluminum pendants, producing a much straighter line when installed in a line may cost even more. While installation costs are lower for pendant fixtures, the overall cost is still typically higher.
      
According to Tom Lyman, Director of Lighting Design at the Princeton, New Jersey-based firm CUH2A, when overall efficiency is considered, an installation of steel indirect pendants will outperform lay in fixtures and result in a superior lighting quality. The efficiency of a lay in fixture is in the 50% to 70% range. The efficiency of a pendant indirect is in the 70% to 85% range. The efficiency of a bi-directional pendant, with both up and down light is in the 80 – 95% range.

Conclusions
Utilize day lighting wherever possible, providing windows on one or two walls; where window walls are limited, utilize skylights. For all but northern exposures, provide overhangs or blinds to allow for control of direct light.
      
Provide ceilings at nine foot six inches or higher. Provide a combination of pendant direct/indirect fixtures for general illumination and linear strips of accent light along display areas and white boards along one or two walls. With breakout or learning alcoves, provide a unique directional pendant that focuses light on the center of the discussion area. If the budget does not allow for this, provide indirect lighting in least a portion of the learning spaces, such as technology-rich areas or collaborative common areas.
        Consider making the study of light a curriculum elective. Numerous study programs have been developed around the study of water and air quality. Sunlight is an essential element in life, and warrants the same attention as water and air quality. The physics of light and the effects of lighting on behavior are rich sources of study.

Randall Fielding is an educational planner, architect and the editor of Design Share. He can be reached at fielding@designshare.com

References:

Heschong Mahone Group. 1999. “Daylighting in Schools: An Investigation into the Relationship Between Daylighting and Human Performance.” Pacific Gas and Electric Company Report, on Behalf of the California Board for Energy Efficiency Third Party Program. (August 20), pp. 24-29. http://www.pge.com/pec/daylight/valid.html

Karpen, Daniel. 1991. “Full-Spectrum Polarized Tackles Computer Screen Glare.” AIP Facilities (March/April), pp. 35-38

Kuller, R and Lindsten, C. 1992. “Health and Behavior of Children in Classrooms with and without Windows.” Journal of Environmental Psychology (12), pp. 305 - 317

Veitch, Jennifer A. and McColl, Shelley L. 1994. "Full-Spectrum Fluorescent Lighting Effects on People: A Critical Review.” National Research Institute in Construction, Ottawa, ON K1A OR6 IRC Report No. 659, (June), pp. 53-100 http://www.nrc.ca/irc/fulltext/ir659/contents.html

Lighting Designers and Engineers Interviewed:

Tom Lyman, Director of Lighting Design, CUH2A, a Princeton, New Jersey firm specializing in higher education facilities.  tlyman@cuh2a.com

Wilson Dau,  Manager, Applications Engineering Department, > Ledalite Architectural Products, Langley, British Columbia, wdau@ledalite.com, www.ledalite.com

William Boland, Lighting Designer, Fletcher Thompson, Inc, a Connecticut-based firm specializing in higher education facilities  bboland@ftae.com

Lily del Berrios, Director, Education Studio, an Atlanta-based form specializing in higher education facilities. lilb@sizemorefloyd.com

David Black, Design Principal, Flad Associates, a Madison, Wisconsin-based firm specializing inn higher education facilities. David_balck@fald.com

Myron Kaplan, CEO, Polarized Lighting International, a Tarzana, California-based manufacturer, specializing in polarized lenses.  myronkahn@aol.com , http://www.polarizedighting.com

Additional Information On-line:

The National Clearinghouse on Educational facilities, a leading indexer of educational planning issues. http://www.edfacilities.org/rl/lighting.cfm

 

www.designshare.com  |  June, 2000