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Cool Light on Hot Days: Fiber Optics Bring the Sun Indoors

Piping in sunlight without using electricity is a win-win proposition for the ecosystem and human society. Both home and business customers anticipate energy savings and a more pleasant indoor environment.

by Mary-Sue Haliburton
Pure Energy Systems News
Copyright © 2005

CANADA

TABLE OF CONTENTS
A. FULL-SPECTRUM LIGHTING
B. THE COST-DISTANCE TRADE-OFF
C. FUTURE DEVELOPMENTS: IR/UV
D. RELATED TECHNOLOGY; ADDITIONAL LINKS

A. FULL-SPECTRUM NATURAL LIGHTING

Latest model of the HSL 3000, mounted on a flat roof.  Dish is 4 feet in diameter, and lights 1000 square feet inside the building, minus the UV rays.  Expected lifetime: 20 years.

The HSL 3000, a hybrid lighting system developed by Sunlight Direct, carries the actual light of the sun indoors. The system’s 48-inch primary mirror concentrates light into a secondary mirror, which strips away the infrared and ultraviolet components, and directs the visible light into the receiver. A tracking system has two motors governed by a GPS microprocessor, which can calculate the position of the sun within half a degree. This enables the mirror to follow the sun across the sky like a sunflower, gathering in maximum light intensity throughout the day. The tracking system itself requires very little power to operate. It could be supported by a small solar cell – equivalent to a 9-volt battery (which would last about a week).

“When come in, in the morning and you’re tired, and you’ve got your coffee in your hand and you’re not quite awake, you like seeing the reddish glow… the same type of light as outside.” Dr. Duncan Earl, CEO of Sunlight Direct, explained the psychological appeal of his company’s hybrid lighting system to the Canadian Discovery-Channel’s host Jay Ingram. (Ref)

People are more comfortable “waking up with the sun” and as the light becomes white they work through the day. “And at the end of the day when there’s a reddish glow, you know it’s time to go home.” Dr. Earl’s eyes twinkled and his face lighted up with a satisfied smile as the camera caught the interior light brightening to noon and fading toward evening russet in the brief time he took to describe this very effect.

It’s a nifty demonstration of his company’s finesse in controlling the intensity and visual temperature of light.


Hybrid Lighting Blends Solar with Conventional

The company may offer several versions.  Some will provide a hybrid with fluorescent bulbs, adjusting the fluorescent depending on the amount of sunlight available. Others may be a stripped-down sunlight-only model.

In the automatic hybrid system, a Daylight Harvesting Sensor detects the continuing increase of sunlight strength in the morning, and accordingly reduces the percentage of fluorescent light. Late in the day, the process is reversed. The computerized controller thereby maintains an ideal level of illumination for office work without anyone having to adjust the settings.

Pure visible light – without the uncomfortable infrared or the damaging ultraviolet – is conducted through the optical fibers into the building. The fibers feed light into an acrylic rod, the non-electrical equivalent of the fluorescent tubes between which it is sandwiched in the commercial hybrid lighting fixture. The sunlight, which would otherwise continue in a straight line, is diffused outward into the room by means of hundreds of tiny scratches on the surface of the rod. One HSL 3000 is capable of lighting approximately 1000 square feet.


Controlling the Sun: Light without the Heat

An estimated 35% of electricity used in the United States is expended on lighting interior spaces in daytime. Ironically, the working day coincides with the hours that the sun is strongly illuminating the whole hemisphere. At 45%, the demand for electricity is even greater in retail businesses. In a striking case of outside-the-box thinking, instead of focusing on trying to generate more electricity to meet the high business-hour demand, the goal for Sunlight Direct is to reduce the need for electricity with fiber-optic lighting.


Many Benefits

Having light without further draining the electrical grid in itself is a great benefit, but there are other advantages as well to natural full-spectrum light, including higher sales in stores, improved moods, and more productive employees.


Not Just for the Sunny South

Although the company’s first focus was on serving the needs of the sun-belt in the southern U.S., since the time this story aired on Canadian television, Sunlight Direct has received many inquiries from the north. Canadians, both business and home-owners, got their message across. Impressed with the level of interest, Sunlight Direct has entered into negotiations with several companies in Canada to create a distribution network.

In Canada, an official program called “The One-Tonne Challenge” has people looking for ways to cut back their use of electrical and combustion energy. The objective is to reduce by one fifth the per-person energy-consumption rate, said to average five metric tonnes of carbon dioxide per year.

Due to low sunlight intensity in winter, direct solar lighting would be practicable for only about half of the year in the north-temperate zone. However, it could still have significant benefits to society at large. Reducing demand lowers the risk of overload on the grid during hot weather.


Blackout “Insurance”

System-wide failures are most likely to occur during the period of peak air-conditioning usage which occurs when the sun is at its brightest. The major blackout of August 2003 showed everyone that the cost of a grid failure is very high. Large numbers of people were laid off from stores, offices and manufacturing plants as businesses and manufacturing were shut down for ten days to two weeks. Both in grocery stores and in homes, fresh and frozen food spoiled and had to be destroyed. Backup generators could not cope with the total shutdown.

Most significant, in this “cashless economy” dependent on debit and credit cards, electronic transactions could not be posted. By noon of the first full day with no electricity, even banks were closing. People arriving a few minutes later were turned away by security guards at the local Toronto-Dominion. Not only were the machines not working; but banks actually do not keep much cash on the premises and had no more to give out even if they were to do the transaction records by hand. Therefore, anyone who had not kept some cash in reserve at home could not buy anything.

Setting up a natural, non-electric lighting system in even ten percent of homes and businesses would be like having blackout-prevention insurance. Another hidden saving would result. Since traditional artificial-light tubes and bulbs emit heat as well as visible light, the use of fiber-optic direct lighting will actually lessen the amount of energy that has to be expended on air conditioning, diminishing the strain on the grid.

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Page posted by SDA July 26, 2005
Last updated July 28, 2005