A Guide for Simulating Natural Light

A Guide for Simulating Natural Light
in Interior Environments to Maximize the Quality of Working Life

VITA-LITE -- SHOWN TO ENHANCE THE WORK ENVIRONMENT In a survey conducted to determine the impact of Vita-Lite in the workplace, three user-dimensions were examined: (a) evaluation of work environment; (b) evaluation of work task; (c) evaluation of how subjects felt.

The results show that subjects felt more relaxed and less fatigued with Viita-Lite than cool white, with higher eye comfort. Subjects perceived Vita-Lite as significantly more pleasant, natural, bright, and stimulating. Additionally, they rated their seeing tasks as more distinct under Vita-Lite, and their work tasks as easier and more satisfying.

ENVIRONMENTAL IMPROVEMENT WITH POSITIVE IMPACT Vita-Lite Energizes the Interior Environment - Natural light energizes the environment for people. They generally feel better, are more alert, see better and perform better. The mechanisms for these positive responses to natural light are not completely known. Many of our customers tell us that Vita-Lite produces similar responses in the ambience and acceptance of the lighted environment.

FIXTURES FOR VITA-LITE Vita-Lite is available in all conventional fluorescent sizes and will provide exceptional color and color rendering in all types of fixtures. For maximum effectiveness of Vita-Lite lamps use the new high efficiency open type fixtures (with energy saving features and improved glare control), fixtures with open ("egg crate") louvers, or fixtures with ultraviolet transmitting diffusers... ideally K-S-H Utran Panels.


  • Blend with natural light from windows and skylights
  • Reveal detail and color accurately. Improve seeabllity
  • Render warm, and cool environments equally well
  • Help improve the performance and productivity of people
Vita-Lite is the only patented (U.S. Patent #3,670,193) general-purpose fluorescent lamp that simulates natural daylight. This simulation is a major asset toward creating the perfect interior lighted environment. No other general-purpose lamp can provide the lighting benefits provided by Vita-Lite.

Vita-Lite was developed and is manufactured by Duro-Test Corporation, America's largest exclusive manufacturer of light sources, including incandescent, fluorescent and H.I.D. lamps.

VITA-LITE PROVIDES ENVIRONMENTAL DESIGN FREEDOM (1) True Natural Spectrum, Color Temperature, Color Rendering Natural light has the unique spectrum, which includes a balance of ultraviolet and visible radiation. The whitest natural light is characterized by a color temperature of about 5000K + and a perfect color rendering index of 100. In lighting, natural daylight is the reference standard for all high color temperature and high color rendering index (CRI) lamps. It also is the design standard for the spectrum of Vita-Lite. A general-purpose fluorescent lamp, Vita-Lite, with its color temperature of 5500K and CRI of 91, is the closest simulation of both the ultraviolet and visible spectrum of natural light.

The simulation of natural light means that for the first time environmental lighting with Vita-Lite can blend perfectly with natural light from windows and skylights -- an important consideration with today's increased use of natural light for energy conservation. This visual system does not have to adapt to a new spectrum, color temperature or color rendering when one goes from outdoors or a naturally lighted environment to an indoor environment lighted with Vita-Lite. Interior colors are true, and details are rendered accurately with Vita-Lite as with natural light. Therefore, it is an excellent source for color and shade matching.

(2) Renders Both Cool and Warm Environments With natural light, cool or warm environments can be created by choosing the appropriate surface coverings and furnishings because the natural light spectrum is balanced and complete with all colors properly represented.

In the past, architects and designers had to associate cool or warm furnishings with cool or warm fluorescent lamps. Because of the spectral deficiencies of these lamps, one had to compensate for the poor color rendering. But spectrally-balanced Vita-Lite allows design color freedom.

In addition, the ultraviolet spectrum from natural light or Vita-Lite causes optical brighteners (used in papers and fabrics) to increase black and white contrast and color discrimination. Black and white tasks are more distinct and sharp. Colors appear more vivid.

Vita-Lite does away with the need to take clothing or articles to the window to see their true color. Vita-Lite maximizes what the architect and designer has created. After all, color is the property of the reflected light from a surface, and the source of the reflected light is the light source. It's right if it's Vita-Lite.

VITA-LITE COMBINES PEOPLE CONSERVATION WITH ENERGY CONSERVATION Double Savings - Since Vita-Lite provides both improved quality lighting plus the additional benefits of how people feel in an improved environment, the result is both people and energy conservation.

While electrical energy conservation for lighting is one of today's major concerns in building renovation and construction, people conservation is even more important and cost effective. For example, compare the average people cost per square foot of office space at $1 50 to that of $1 .25 for lighting cost. With almost 80% of the lighting cost being energy costs, increasing the productivity of people 1% is equivalent to an increase of 135% for lighting energy conservation.

We believe this gain can be achieved with the use of Vita-Lite because Vita-Lite increases seeability and improves the work environment. And since Vita-Lite is available in all typical fluorescent wattages and lengths, including Watt-Savers, you can, for the first time, specify for the best of both worlds: people and energy conservation.

SEEABILITY OVER FOOTCANDLES The complete and balanced spectrum of a 40-watt Vita-Lite lamp produces fewer lumens than the predominantly yellow-green cool white fluorescent (2180 vs. 3150), but those Vita-Lite lumens are more powerful and energetic for visual and physical activities. We use the word "seeability" to describe the human factors effects in Vita-Lite spectrum and lumen output. "Seeability" is a non-technical term, which describes how well the eye sees. It includes the ability to define form, which is a primary function of the eye, but it also includes color discrimination, color rendering and influences on physical activity. In reality, the reaction of the body is greatly influenced by these and other factors, which make up seeability. Footcandle level, while a measurement of light quantity, is not the indicator of real seeability.

The concept that the footcandle or lumen does not adequately define light for visual acuity is well documented. Light from high-color rendering lamps such as Vita-Lite provides enhanced seeability and visual effectiveness even at lower footcandle levels than is obtained with standard high-lumen-output lamps such as cool white. Vita-Lite lamps can be specified and substituted in installations using conventional lamps on a one-for-one basis and still improve seeability.

Any task that is adequately lighted with cool white or warm white will have improved seeability under Vita-Lite. Vita-Lite is then the ideal replacement for cool white or any other fluorescent lamp, wherever they are used.

In calculating the number of lamps required for task and area lighting (using the recommended illumination levels in the Illuminating Engineering Society Handbook Applications Volume, 1981) simply use lamp data for cool white lamps and then substitute them with Vita-Lite lamps in the lighting system. This technique provides a lighting system with the same installed wattage and with enhanced seeability.

SPECIFYING VITA-LITE To specify Vita-Lite, use this table:

Vita-Lite or equal light sources shall simulate the full visible and balanced ultraviolet spectrum of natural light for use in general indoor illumination as follows:

Correlated Color Temperature: 5500K
Color Rendering Index: 90 or greater
Near Ultraviolet Radiation: (UVA, 320-380nm) 254 +/- 51uw/lumen
Middle Ultraviolet Radiation: 15 +/- 4 uw/lumen
Near UV/Middle UV Ratio: 11 - 28