But: light also comes from manufactured sources, and therein lies the problems.
The wrong kind of artificial light can make students irritable in school, reduce production among factory workers, and make office workers sluggish and prone to error.
Scientific studies show that not getting enough light can interfere with calcium absorption in the body and contribute to brittle bones. Low levels of outdoor light and ineffective artificial light indoors can also lead to Seasonal Affective Disorder (SAD) and winter blues.
The light that some scientists consider a super nutrient is full spectrum light, which comes from the sun or is simulated from specially designed full spectrum fluorescent tubes and high spectrum bulbs.
Normal incandescent and halogen bulbs, as well as most fluorescent tubes, produce an overabundance of yellow and orange wavelengths.
These are hard on the human nervous system.
The glare produced by these lights is very hard and irritating on the eyes. 2) Kelvin Heat Rating. Natural outdoor light has a CRI of 100 and a Kelvin rating of 7500 degrees Kelvin.
Although there are no legal guidelines, 5000 degrees Kelvin and 90 CRI (or above) is considered full spectrum.
In comparison, standard cool white fluorescent has a CRI of 68 while warm white fluorescent is 56 CRI.
Standard incandescent bulbs have a 40 CRI.
Under natural light or full spectrum, that duplicates natural light, there is better visual acuity and increased production and accuracy.
Students and office workers experience far less fatigue and chance of error.
Absenteeism due to illness is decreased and people generally have more energy.
When Data Control of Kansas City redesigned their facility using full spectrum light they experienced a savings of $235,000 annually from reduced computer errors by the employees who were entering the data.
Gannett News Service
December 2, 1994 Author: Ken Miller
Washington - In 1986, the U.S. Postal Service selected the main post office in Reno, Nev., for lighting improvements that would make the sprawling mail facility a "minimum energy user."
Immediately, the post office's energy savings hit $50,000 a year, enough to pay for the $300,000 renovation in just six years. But then something unexpected happened:
Reno's mail sorters instantly rose from mediocre performance rankings to become the most productive sorters in the western states.
Their improved productivity alone was worth nearly $500,000 a year - more than the cost of the new lights.
In Seattle, aircraft manufacturer Boeing joined the Environmental Protection Agency's "Green Lights" program by installing energy-efficient lighting in more than 1 million square feet of its assembly plant.
As expected, lighting costs fell 90 percent, enough savings to cover the renovation in just two years.
But here, too, something unexpected happened:
Assembly workers suddenly could see much more clearly. Up and down the line, quality of workmanship increased and flaws were being detected early, when they could be easily repaired.
In both cases, plant managers implemented energy-saving projects as a way to trim costs. But, as in other cases around the country, improved conditions led to a windfall increase in worker performance.
"There are a lot of stories like this out there,"' said Joseph Romm, an energy-efficiency specialist at the Energy Department. "I think this is the tip of the iceberg."
Romm joined William Browning of the nonprofit Rocky Mountain Institute on Thursday in releasing an RMI report, "Greening the Building and the Bottom Line"
The two joined architectural and government energy specialists in touting what looms as the new trend in corporate environmental policies. By weaving "green" improvements into their buildings, from skylights to better heating and cooling and more natural lighting, companies not only are slashing utility costs but also are becoming more competitive wit the help of a more productive work force.
"This is very new stuff," said Romm, author of "Lean and Clean Management: How to boost Profits and Productivity by Reducing Pollution."
"It's just a matter of exposing people to it."
Browning told the story of Wal-Mart, which in June 1993 opened a prototype "Eco-Mart" in Lawrence, Kansas, with the help of RMI.
That store was built with environmentally friendly materials, landscaped with local plants, and when possible, uses energy and water-saving devices.
Because the original costs were higher for the Eco-Mart store, Wal-Mart cut back on the more expensive skylights that allow natural lighting.
But soon a trend developed:
Not only were employees spending more time in the naturally lighted half of the store; cash register sales there were nearly twice as high as in the artificially lighted areas.
"Creating an energy-efficient environment is as critical to their business as any investments they are making," said Romm, citing the case of Lockheed Missiles and Space Co.'s "Building 157" in Sunnyvale, Calif.
Lockheed's architects built a building in 1983 that used half the energy of a typical building its size, but the unique design and interior environment had a hidden benefit.
Worker absenteeism fell 15 percent, and productivity rose 15 percent. While the building was more expensive, savings from less absenteeism alone covered the extra cost.
"We knew energy efficiency was good for the economy and good for the environment," said Christine Ervin, former director of the Oregon Department of Energy and now assistant secretary for energy efficiency at DOE.
"Now, for the first time, we have documentation on the kinds of benefits that boost labor productivity."
Lighting is critical when considering productivity, energy costs.
Interior lighting - a seemingly simple element can impact worker productivity and safety, ultimately affecting quality control and output.
In industries in which color selection or fine detail is critical, lighting becomes even more important to accuracy.
Also: since lighting can consume up to 20 percent of a facility's energy costs, it pays to consider what happens when you flip that switch.
What do I to consider when choosing a bulb?
Color temperature or chromaticity refers to the color appearance of the light that comes from a light source.
It's an important performance characteristic to assess when evaluating lamps because a lamp's chromaticity creates the mood of the space you are lighting and can thus influence buying behavior or work performance.
Also referred to as Correlated Color Temperature (CCT), the apparent color of a light source is measured in Kelvin or "K".
Imagining a piece of iron (a horseshoe, for instance) in a fire can help you visualize color temperature in lamp types designated as "warm" or "cool."
At first the iron becomes "red-hot." Red is the color of light being generated by the metal at a certain temperature. Continuing to heat the metal makes it"white-hot," and heating it further would cause it to become "blue-hot" like flash bulbs or stars).
In describing color temperatures, a low color temperature corresponds to "warm" or a red-yellow appearance like incandescent lamps at 2700 Kelvin.