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


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.

It’s hard to think of a downside to fully natural indoor daylight – without heat or sunburn-causing UV – that doesn’t even need to use electricity.

At present there are a couple of significant shortcomings to this promising technology: the price, and the distance limit. Though cost-effective, currently-available plastic optical fibers impose a limit on transmission distance of thirty to fifty feet. Thus the benefit of optical lighting could not go beyond the one or two top floors of office buildings. At present, therefore, one- and two-storey, flat-roofed retail commercial structures are seen as having the most to gain from hybrid lighting. And there are many such buildings in every city and town.

The HSL 3000 is scheduled for release early in 2007, and is initially priced at about $8,000 USD. Even at this price the savings in energy costs are expected to offset the purchase price over time. And this price is expected come down in the usual way, as volume of sales goes up.
Though skylights are a valid option for building owners, in some cases the architecture may not permit these to be added later. Water tanks or other structures on the roof may interfere with placing the opening in the most desirable or useful location. Citing research showing that sales increase by up to forty percent in stores with natural light from skylights, Sunlight Direct’s founders believe that retailers would indeed gain more than just the saving in electricity costs from installing fiber-optic collectors. Infra-red blocking skylights are not cheap either, and entail risks such as leaks or breakage. Optical-fiber lighting offers greater flexibility of location, and ease of moving the light fixtures, should the office be rearranged.

Optical Fiber Research Continues
Dr. Earl forecasts that ongoing research on the plastic fibers will increase the carrying distance of visible light by 300%. Equipped with these hypothetical new fibers, therefore, as many as six top floors of an office or other tall building could be served with direct natural light from roof installations. Using the more pricey but longer-range glass optical fibers, this distance is already possible. However, because glass fibers cost more and are difficult to work with, using them would likely limit the market to companies with very deep pockets, or to politically- or militarily-strategic windowless or underground establishments.

Beta Testing
Beta testing of this hybrid unit was opened up as of June 2005. It should be noted that participating in official testing is expensive and involves data collection. Any interested organizations or businesses able to handle the cost, data collection and follow-up reporting are invited to examine the beta-test agreement at Sunlight Direct’s website.

Architectural Integration
Depending on the design and orientation of a building, and the height and location of any surrounding structures, by mounting additional solar collectors on the outside walls of an office or condominium tower, it might be possible to extend hours of effective lighting to more lower floors. . For example, solar collectors might be placed at a south corner, on every floor or every second floor depending on size. From that corner they can track the sun as it moves from SE through South to SW, which would cover the hottest part of the day and until late afternoon when most people leave for the day. And on an office tower of which the SW corner is shaded by another building, morning to mid-afternoon exposure could be captured from an SE corner.
On a residential building solar collector units might be mounted at a south-west corner to take advantage of noon to evening light. Or in a condominium building, early-rising residents might choose to have either first half of the day from a SE placement, and late risers might choose the afternoon sunlight feed. Though windows are normally provided for living-rooms, in very few buildings have the architects provided a window for the kitchen, where natural light would be appreciated for breakfast or supper preparation.
In the future, we might even see buildings designed specifically with more un-shaded roof areas at different heights to make the best use of fiber-optic indoor lighting. The area served by a single HSL 3000 is about 1000 square feet. Though many small and mid-sized homes would get by with a single collector, more units would be needed on large buildings. At current pricing, this combined cost might cause many buyers to hesitate. However, as more capability, greater carrying distance, more options  and lower costs come together, the benefits may outweigh the costs.

Hybrid Systems vs. Manual Control
People already notice when outside light is diminishing and routinely turn on artificial lights as required, or for romantic purposes someone might want to let the light die down naturally. Fluorescent-hybrid lighting is not as necessary or affordable for homes or apartments. Eliminating the more complex circuitry and automatic artificial-light-intensity sensors and controllers should lower the price somewhat. A simple fiber-optic light system would suffice for a budget-conscious homeowner.

On the products page of Sun-Direct’s website, a simplified version of the solar light collector, without sensors and automatic level adjustments, is represented as suitable only for research. When asked whether the company might consider offering a simplified optical-fiber lighting setup such as this for households, Dr. Earl mentioned that it’s not only homeowners who are interested in a manually-controlled version, and not merely for financial reasons.
Some commercial building occupants have indicated a preference for a non-automatic system. These people prefer natural light that blends with the quality of light outdoors whether it is overcast or bright. “It gives a connection to the outside environment that is very pleasing,” Dr. Earl comments. “I think a simplified, lower-cost system makes a lot of sense, and would be possible.”

White LED Hybrid Lighting
One other option is being considered. Numerous homeowners have contacted Sunlight Direct to propose that fiber optics be hybridized with white LED lighting. These LEDs are being widely touted for their long life, very low power need (one half to one watt), and non-toxicity. Unlike incandescent vacuum bulbs which are illuminated by a tungsten filament made white-hot by the electrical current, all fluorescents – “full spectrum” or not – contain mercury vapour which is essential to create the glow. When a tube is broken, this mercury escapes into the room. For the same fifteen to twenty-three watts needed for one “energy-saving” fluorescent screw-in spiral light, several LED fixtures could operate day and night on energy collected by a small solar panel.
Although a single LED is small, a Fresnel lens can spread its light outward. Or several LEDs can be mounted in the same fixture, angled in different directions for more diffused lighting. Again, as long as the power comes from the sun, the LEDs need not be automatically controlled in co-ordination with the daily sunlight cycle. Instead, people will want to have a choice of either always-on hallway and bathroom lights, or track lighting and other fixtures that are switched for manual control – or perhaps some of each. All LED fixtures should be designed so that more can be wired in as new requirements arise.
Sunlight Direct has proposed another joint project to Oak Ridge Laboratories to develop a hybrid system with white LEDs. If funding is approved, this will be underway later in 2005. Even if a homeowner does not opt for fiber-optic collector at this time, being able to install white-LED fixtures wired to a solar panel would be a welcome interim choice. It would be ideal if such off-grid lighting linked to a solar panel were designed to be integrated with the fiber-optic light at a later date when the price comes down.

Installation and Fire Safety
The company originally planned to offer units with do-it-yourself installation, expecting the price to be initially about $5000. Those who are technically adept would not blink an eye at this, but some less-than-handy homeowners are likely to hesitate. Given that the visual light from even one fiber is capable of boiling water, there might be a fire hazard from broken fibers if the work is incorrectly or carelessly done, or if a later home renovator were to cut across the installed fibers. This risk would be expected to be more serious once connecting IR fibers to a water-heating system is involved.
Even if homeowners were to install this system “at own risk”, the company’s reputation would still be affected if the system does not function as it should due to errors made by incompetent installers (either oneself or others). Further, litigation would inevitably arise if fires were to occur. In answer to a question about providing instructions and perhaps certification courses to train technicians in the proper handling of Sunlight Direct products, Dr. Earl said that the future Canadian partners would be responsible for installations. Similar arrangements are being negotiated with American companies as well.
Although Sunlight Direct has not specified the cost of installation – other than to imply that it would involve extra money you would not be paying if doing it yourself – having professionals do the work would obviously add to the price of the system. Basing a rough guess on the rates charged by other professional trades, this could amount to an additional $1000 or more, depending on the size of the house and the number of areas to be lighted. But the safety factor may make this worth the extra cost.
Rather than installation cost, it is the fire-safety issue that is delaying release of the home systems until 2008.
“Our biggest concern about the residential systems is that [they need] to be installed properly to ensure safe and optimal operation (or at least this is true given the current HSL design). We are trying to modify the current design to actually eliminate some of these concerns by having inherent safety features built in.”
These changes include modifying the mirror so that it focuses sunlight only when aligned to the sun within five degrees, avoiding excess concentration of heat. It is not clear why five degrees would be significant. Enclosing the vulnerable fibers in a fireproof conduit might be more to the point. The company’s researchers are also working on a “breaker” that would automatically stop the sunlight from being brought in if an optical fiber were to be broken. If it can be reliably implemented, an automatic breaker would be a worthwhile fail-safe against inadvertent damage to the fiber-optic lines.

Functionality vs. Aesthetics Trade-Off
Other issues may arise as homeowners consider whether to invest in fiber optic lighting. The presence of shade trees tall enough to overhang the roof can block reception of light in the mirrors. Dr. Earl agrees that trees are a valuable addition to landscaping, and strongly endorses their environmental contribution of restoring oxygen to the air and preventing heat buildup in the home receiving this natural shade.
However, he emphasizes that although a mounting system can be devised to place the collector at the peak of the roof and up to six feet above it, some landscaping changes may be essential. For example, nearby trees may have to be pruned, preferably by a competent arborist. Also, it would be necessary to calculate the angle of the sun, as the length of the cast shadow will increase later in the fall and winter when the sun is lower in the sky. In the case of deciduous trees, this factor is less important since in most of Canada and the northern states, this type of tree sheds its foliage by the end of October or early November, and the thin upper twigs won’t cast significant shadows. For several weeks before and after the winter solstice, the sun is too low in the sky to provide much energy anyway.
Some homeowners may not like the utilitarian look of the mirror on the roof, though most people don’t worry about the appearance of satellite TV receivers. Dr. Earl says that about 50% of people are very worried about how something looks, and the other half of the population doesn’t care at all. Sunlight Direct is considering various sculptural modifications of their product to appeal to the esthetes in the market. Presumably, solar collectors could be created with decorative themes like those used for weathervanes, or in abstract shapes. Designer solar collectors could even be licensed to third-party companies, and marketed to high-end consumers and social climbers.
However, fussing over the look of the system seems frivolous. Personally speaking, I would not care to spend extra to have anything other than the bottom-line scientific hardware on the roof. Others have water-pipe arrays and satellite dishes, so why not a bare-bones sunlight collector? If fortunate enough to be able to afford solar direct lighting, why would anyone hide the energy-saving technology? At least some environmentalists might consider it a badge of honour to display a sunlight-collector mirror – alongside their solar panel and perhaps a home-made windmill.
Everyone will be better off if even ten percent of homes and commercial buildings are outfitted with HSL systems, due to relieving stress on the grid at peak times. As the quality of optical fibers improves, and unit costs come down, we should expect to see wider adoption of non-electrical sunlight systems.
Book-ends of the Visible Spectrum: Infrared and Ultraviolet
Being able to use the non-visible portions of sunlight is highly desirable, but still in conceptual stages. Among the challenges that remain is the need for optical fibers to be optimized to carry IR and UV wavelengths. The one must withstand extra heat, and the other must resist the molecular breakdown that high-energy UV light causes to many types of materials as well as to DNA. There are UV-resistant plastics, such as those used to protect artwork from fading. However, their transmission qualities are not yet at the level required for Sunlight Direct’s proposed applications. The company is working with Oak Ridge National Laboratories to improve the transmissive qualities of plastic fibers for each of three main the types of sunlight energy.

INFRARED: Cream or Sugar in Your Solar Coffee?
In the Discovery Channel report, Melissa Lapsa, Program Manager of Solar Energy Technologies at Oak Ridge National Laboratories, waxes enthusiastic about the possibility of water heating using IR from sunlight. No wonder. The first experience that Sunlight Direct had with the impressive potential of sunlight for heating water involved idly dipping a single optical fiber – which was “emitting only concentrated visible sunlight” – into a mug full of coffee. Duncan Earl says, “The coffee was boiling within minutes!” With captured and selected IR light, the effect would be expected to be even more dramatic.
“When people see this effect in person, they really get a feeling for the enormous amount of power available in sunlight. And if you’re into totally natural coffee brewing…” Dr. Earl lets this thought hang tantalizingly in the air to stimulate imagination. If something is already in the works, he’s not letting on – yet.

Future Visions: Practical Applications for the Sun’s Heat
Assuming the development of the new IR-conducting plastic, it’s hard not to fantasize about a kitchen console with heat-tolerant optical rods of various thicknesses depending on the volume to be heated. Ensconced in ceramic sockets for safety when not in use, these could be inserted into anything that requires to be boiled. Such a futuristic setup might include a solar coffee-maker. And perhaps the deluxe model Sun-Chef console would have a built-in polymer oven such as the one avant-garde Chicago Chef Homaro Cantu (of the Moto Restaurant) demonstrated on the Canadian Discovery Channel recently.
This simple appliance uses no heating element or flame, only the ability of the walls to retain heat by – in the reverse of what Sunlight Direct needs to develop for its water heater and this hypothetical cooker – totally blocking IR transmission. Before insertion into this modern version of the Fireless Cooker – using conventional heat in the televised demonstration, but with fiber optic sunlight in this proposed merger of two technologies – fish, rice and other foods are brought to a boil. They cook perfectly in the sealed polymer box with only the enclosed steam – no drying out or burning on.
With the sun’s power focused, a lot of daytime food preparation could be done without fuel. This would be particularly of value in the sunbelt and tropical regions. When the need to burn wood or other fuel to cook dinner is eliminated, forests would be preserved and replanted – a great side-benefit not listed previously. And because forests are “nature’s refrigerator”, some relief of excess heat may occur in these regions. I hope we can look forward to extensive use of this technology in developing nations, perhaps with assistance of a charity similar to the one that has helped install many bio-gas pits. Though installing these household methane digesters along with tree-planting has already made some difference in soil retention, that system does still use heat-emitting combustion of the methane for cooking.
Early designs of the hybrid system included thermal photovoltaic cells to take advantage of the IR energy that is not currently being used by the HSL 3000. This idea was abandoned due to the cost of these cells and the low power output, but might be revisited if the cost comes down. This might become an add-on in future. If so, the basic system should be designed so that additional features can be simply plugged in without having to re-tool or to modify the already-installed solar collector.

Infrared Water Heating: Competing Systems
In Canada the savings that could arise from sun-heating water would be very significant. Possibly in reaction to serious contaminated-water scares of recent years , the Canadian government has imposed a minimum temperature of 140 degrees Fahrenheit for water heaters. Turning down the water heater – formerly suggested as a dodge to save energy – is now frowned upon for health reasons. The concern is that, at too low a temperature, the hot-water tank may actually incubate bacteria. New water heaters sold in Canada, therefore, must have a pre-set temperature of 140°F, as well as – to prevent scalding – a mixing valve which adds enough cold water back into the heated water as is drawn out of the tank to ensure safety.
Duncan Earl does not know of any similar regulation in the United States, However, he states that IR water heating would bring modest savings: “If we can utilize the currently unused IR component for heating water, that could provide an additional saving to the home owner (around $100/year in the U.S.).” In Canada that saving could be much higher. Given that a hot-water tank is a significant percentage of one’s electricity bill, being able to use sunlight for this purpose for at least several hours out of the twenty-four will obviously save on energy costs.
In an effort to meet the famous “One-Tonne Challenge”, some Canadians are spending $6000 or more to have arrays of pipes installed on the roof, connected to a heat exchanger in a pre-heater additional tank. Heated by the sun, the fluid in these pipes transfers heat to this secondary tank’s water, which then feeds into the standard hot-water tank. Interviewed on the Canadian Weather Channel (Ref.), an owner of this Solarco system said that when he takes a shower with the solar-heated water, the temperature in the pre-heat tank would drop to 15 or 20 degrees Celsius initially. But then it would rebound to 40 Celsius within an hour or less depending on the sunlight’s intensity.

Simpler Design Advantage – If Industry Co-operates
Solarco’s price for its extra-tank system, and the complications of snow-load on a roof with this added array of structures are not its only drawback. The system requires electricity to run a pump to keep the heated fluid moving through the exchanger and back up to the roof. In contrast, Sun Direct completely avoids this additional use of electricity because the sun will deliver its heat to the water tank through optical fibers without our help. Incorporating IR heating of water into a system that also provides light would make the Sunlight Direct product financially competitive and perhaps more attractive. It might amount to a double-whammy “two-tonne” saving, in Canadian parlance.
Though the idea has been proposed that water heaters could be mounted on the roof to compensate for the short transmission distance, in general houses are not designed to take that kind of load in the attic. Since it would be very expensive to bring the structure up to code to support that extra weight, the better option is to wait for the development of IR transmission fibers. Dr. Earl states that the IR light could be “pumped to a basement water-heater and, with a little bit of modification to the water heater, made to work with the captured sunlight.” This of course depends on whether the hot-water tank can be modified. Many people rent water heaters, and permission to do so would have to be obtained from the contracting company.
Modification to plumbing that a householder owns would not void the agreement with the rental company in the same way as modifying the actual tank or any of its components. The alternative would be a specialized pre-heat tank to be added upstream from the rented heater, similar to the Solarco setup. That, however, is likely to raise the price too much. Would feeding some IR fiber-optic lines into the water heater’s intake pipe be sufficiently effective? Some further experiments might help the company find a workaround for this. Personally, I would like to see water heaters sold “IR-ready” from the factory.

Retrofitting for Infrared Use
In Canada we have two completely different climates to deal with. In winter, there is the need to create and/or hold in heat. And in summer, we have the opposite problem. Since early June of this year (2005), central Canada has had near-tropical conditions with high humidex readings and high UV. During this time, one doesn’t even want lights on in the house because they throw so much heat in addition to light. Therefore, the possibility that sunlight could be piped in without its heat component is greatly appealing in summer.
In winter, however, sunlight is much lower in intensity and the side-effect heat of conventional lights is welcome. Though the sun is lower in the sky at these latitudes, it still provides a significant heating effect, raising daytime temperatures by fifteen to twenty degrees Celsius. When fibers capable of carrying the IR energy are created, a future add-on northern customers might wish for would be the ability to have the IR component of the sun’s light brought indoors not just for water heating but for general warmth as well. Perhaps the homeowners who would gain the most from this add-on would be those who have hot-water radiators instead of forced-air heating.
Those who buy a fiber optic system before the IR features are available need not worry overmuch about the cost of upgrading.
The IR component is relatively easily added. The current model simply redirects the infrared back toward the sun. To use this component of light for water heating, the secondary mirror, valued at about $50, would need to be replaced with one that can direct visible and IR light to different focal points. And then the bundle of IR-transmitting fibers would be installed to bring the infrared energy to the water heater with the required modification. Though the capability already exists to provide this function, IR fibers are still too expensive for the general home market.
As the cost of fuel rises, those who use gas water heaters may be looking for add-ons to help reduce their actual “greenhouse gas emissions” at least during the summer. However, optical-fiber IR water heating technology is more suitably applied to electrical water heaters. A gas-heated tank may require installation of the secondary pre-heating tank.

UV: Air Purification still a long way off
Oak Ridge National Laboratories is also keen to develop the potential applications for UV light. One of its primary uses is as an air purifier, as these wavelengths are able to kill molds and other airborne pathogens. This is a future application, depending on the development of the specific UV-resistant plastic optical fibers able to transmit “deep UV wavelengths” in sufficient strength to have the desired lethal effect on pathogens. At present such fibers are still too expensive for the general market.

Agriculture: Direct Lighting in Greenhouses
Future pharmaceutical research will involve growing plants that produce specific proteins. Being genetically modified, patented, and valued as corporate secrets, they are grown in secure installations that are often windowless. Fiber optic light is the obvious cost-saving solution for providing optimum light balance for growth under such conditions. And for the well-heeled drug industry, using expensive glass fiber optic cables enabling longer transmission distance to underground facilities that are already being used for secure drug production – such as former mines – would not be an obstacle. Plants may utilize a wider range of the sun’s energy, depending on species, and in each case the grower should be able to decide whether to bring in the UV range, and how much of the IR to include or exclude.

UV in Animal Husbandry
Another area yet to be developed is natural lighting in factory farms. Most of these high-density barns have no windows. As living creatures, domestic mammals and birds also benefit from balanced lighting. The UV light kills bacteria, reducing the risk of infections and loss of valuable livestock. That UV light promotes health in animals was demonstrated in a television story about an infant gorilla with a serious infection. The veterinarians of the zoo could not risk toxic anti-bacterial drugs on this rare and precious newborn primate. Wearing customized small goggles to protect its eyes, the fuzzy infant was placed under a bank of powerful UV lights to kill the infection. Since gorillas, even baby ones, have black skin as protection against UV, intense light was necessary to get past this barrier and effect the cure.
Independent researcher John Ott conducted experiments which demonstrated that livestock benefit from the UV wavelengths in moderation. The manager of a livestock operation might be able to improve productivity by controlling levels and type of UV light, depending on the species and age of the animals being reared. When the role of UV light in livestock health was brought to his attention, Dr. Earl expressed interest in the concept and indicated that his company would look into the possibility of designing systems for livestock barns. In addition to the beneficial effects of natural light for the growth and vigour of animals and birds, the producers using fiber-optic sunlight could expect cost savings on their electrical bills.

While hoping for direct sunlight technology to be successfully brought to market, one must be patient. Much research remains to be done to perfect the system, and costs do need to come down for it to be accessible by the majority. Meanwhile, there are steps that all people can take to reduce heat buildup, and to adapt to the changing climate. (Ref)