Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.1

Inquiry

Full Spectrum Lighting Intent To provide a high quality light for the work environment that will also help to reduce the effects of the physical and psychological symptoms associated with Seasonal Affective Disorder (SAD), a condition brought on by lack of sunlight experienced during winter months in high northern climates. Design Approach The design approach was simple. Instead of using standards 32-watt T8 fluorescent lamps in many of the facility light fixtures, we chose to install 32-watt, full-spectrum lamps. The full-spectrum lamp is typically fluorescent and is defined as having spectral emissions in all parts of the visible spectrum and in the near UV, with a correlated color temperature of 5000 K and a color rendering index level of 90 or above. Although full-spectrum lamps are not as photopically bright, or intense, as standard fluorescent lamps, they are perceived as being brighter due to the broad range of the spectrum of light they emit. Studies show they are vital in the treatment of SAD disorders due to their quality of mimicking natural daylight. Research over the last decade has proven that full-spectrum lamps have a very significant, positive effect on humans both physiologically and psychologically. And though more expensive than standard lamps, they are still economical to operate, being comparable in size, wattage and hour rating to todays standard, energy-efficient fluorescent lamps. Although not commercially well known, Tsunami Warning Center employees were already familiar with the (perceived) brightness of full-spectrum lamps. National Oceanographic and Atmospheric Association (NOAA) project managers were open to installing the lamps in fixtures of all rooms of the new facility that are to be frequently occupied by employees. The Eyes and Full-spectrum Lamps The cones of the eyes are the retinal receptors that mediate photopic vision. They dominate the retinal response when the light level is high and provide the basis for the perception of color. The rods are the receptors that control the retina during scotopic vision, in low-illuminance settings, with dark-adapted eyes. At these lower levels, there is no basis for perceiving differences in hues. Pupil size also plays an important role in the quality of vision, small pupils providing better acuity and added depth perception. Conventional lighting design practice has been "colorblind" focusing on the brightness of a task and ignoring color quality. This is reflected in the standard measurements of lux and lumens used throughout design. Considering only photopic vision, the greater the detail required by a task, the greater the level of light intensity is brought to a design. When considered at all, color output of the lamps involved has been chosen for culturally-accepted, psychological effects. In general, lamps are mostly chosen for their efficiency (lumen output produced per watt); and the yellow-green ban, is the most efficient light to generate. Little, if any, consideration is given to light distortion caused by the concentration of light in this and other narrow spectrums that many lamps provide. Recent light studies have proven that the rods of the retina have as much to do with seeing well as do the cones1. Scientists are now beginning to understand that color temperatures, especially the higher color temperatures on the white and blue side of the spectrum, also affect the rods and pupil size. By including these colors in lamp illuminance, scientists are able to decrease the size of the pupil, providing better vision with less lumens. The perceived level of light is greater; and because there is less brightness, there is less glare on a task. In fact, studies have determined that broad or full-spectrum lamps provide the best visual acuity for high detail tasks2. These factors may also contribute to the reason why studies indicate that people suffer less fatigue working under full-spectrum lights than under conventional fluorescent lights3. Seasonal Affective Disorder and Full-spectrum Lights Due to the long, dark winters in Alaska, light quality is at a premium. As night grows longer and longer, many people fall victim to Seasonal Affective Disorder (SAD), commonly known as the winter blues. While somewhat an annoyance in the lower states, it can be very serious in Alaska, affecting up to 15% of the population. Symptoms include lower energy, hypersomnia, overeating, and craving of carbohydrates. There is convincing evidence that exposing people to bright light, or daylight-mimicking light, is very effective in treating against SAD4. Light travels through the retina of the eye and affects the part of the hypothalamus believed to be involved in running our biological clock. The hypothalamus is a complex part of the brain that plays a vital role in reproduction, thirst, hunger, satiation, temperature, emotions, sleep patterns and depression. The light also affects the tiny pineal gland that secretes the hormone melatonin. Studies continue on how melatonin affects humans, but it is thought that it regulates behavioral changes in animals. It is the bright light, or that imitating sunlight, which is the most effective in treating SAD4. Sunlight is very intense electromagnetic energy in a continuous spectrum of colors from the short, invisible, ultraviolet light through blue, green, yellow, and into infrared. Incandescent lamps are very good at imitating sunlight, but they are very inefficient, producing a low intensity light as well as one that is heavily infrared. People can be burned by its infrared radiation. Fluorescent lamps are more intense and far more economical than incandescent lamps. They can be purchased in a variety of dominant areas of the spectrum. Many fluorescent lamps are taunted as being full-spectrum, though most are heavy in the yellow-green portion of the light spectrum, the wavelengths to which the eye are most sensitive. However, conventional fluorescent lamps do not include the near-UV wavelength of the sun. It is this wavelength that advocates claim is the most beneficial to our health and whose absorption into the skin is also the main stimulus for the synthesis of the D hormone, essential to the absorption of calcium for skeletal development5. Though caution must be taken to avoid shining high intensity UV into the eyes to prevent damage, the percent of UV exposure in a full-spectrum lamp at light levels appropriate for general and task lighting is considered acceptable by today\'s standards6. True full-spectrum fluorescent lamps contain this near-UV radiation, the widest spectrum of visible light technically possible at this time in a fluorescent, minus the damaging infrared wavelength. These are the lamps we have specified for the new NOAA facility. Two of the more successful varieties are Vita-Lite by DuraTest, and ParaLite. Conclusion While the full-spectrum lamp itself is more expensive than conventional fluorescent lamps, it appears that its benefits exceed the extra cost. Most brands are rated to last as long as standard fluorescent lamps V between 20,000 and 30,000 hours. And they are comparable in size and wattage to todays standard, energy-efficient fluorescent lamps. Although their photopic lumen output is slightly lower than conventional fluorescent lamps, their color rendition and correlated color temperature are higher, mimicking natural sunlight. The wide spectrum of visible and near UV light emitted by full-spectrum lamps is taunted as being highly effective in the treatment and prevention of SAD. Ongoing studies hope to prove they have other additional benefits. This scotopically-enhanced light allows people to see better and actually gives them the impression that the light is brighter than other fluorescent lamps that have greater lumen output. They are the best artificial lamps under which to perform detail work. They reduce worker fatigue. If conventional lighting design practice were to change to consider the effect of the color spectrum of the lamp as well as its light intensity, it is possible that recommended lighting levels might even be able to be reduced in the future, resulting in further energy savings. Given the recent increases in health care costs, it would be advantageous to see additional studies carried out to determine the overall effects full-spectrum light may have on the health and productivity of students and workers.