Frequently asked questions

How do you determine how much light is needed for a lighting application?
The determination of light levels is based on the function of the product. The IES (Illuminating Engineering Society of North America) – publishes lighting design and illumination standards for many indoor and outdoor applications. Solas Ray engineers can help you determine the exact specifications for your fixture’s light output based on its function and lighting standards.

What is glare and why is that important?
Glare is a visual sensation caused by excessive and uncontrolled brightness. It can be disabling or simply uncomfortable. It is subjective, and sensitivity to glare can vary widely. Older people are usually more sensitive to glare due to the aging characteristics of the eye. Disability glare is the reduction in visibility caused by intense light sources in the field of view, while discomfort glare is the sensation of annoyance or even pain induced by overly bright light sources. Reducing glare is an effective way to improve lighting components.

What does Dark-sky compliant mean?
There are lighting requirements in certain parts of the USA that restrict the amount of light that can go upward at night. The general theory behind these restrictions lies in the belief that light going upward serves no practical benefit. There are nocturnal animals that need the darkness in order to survive. Energy spent on light that goes upward is wasted energy, in that there is nothing illuminated by upward light. In larger communities uncontrolled upward light can build to a point where it creates a haze that obscures the night – some refer to it as light pollution. In summary, dark-sky compliant lighting protects wildlife, cuts energy waste and stops night light pollution.

What is light pollution and how do I avoid it?
The great increase in the number of people living in urban areas has resulted in a rapid increase in urban sky glow at night due to outdoor lighting. The sky glow that adversely affects the environment and restricts astronomical observation is called light pollution, for it is wasted light that does nothing to increase night time safety, utility or security. Such wasted light only serves to produce glare, and wastes energy, money and natural resources. A good means of eliminating light pollution is to use lighting products that provide glare control, and do not allow upward wasted light at night.

What does optical design do for a lighting product?
Optics direct the light where it is wanted and only where it is wanted, thus reducing the amount of LED’s required for the fixture. In most applications we recommend the use of optical treatments for LEDs. “Treatments” is a term we use to describe things that change the light, such as lenses and reflectors. The cost of the optical treatment is usually far less than the additional LED’s that are required with no optical treatments. Costs for optical devices vary with the complexity of the optics. In certain cases off-the-shelf optical lenses can be utilized, greatly reducing the cost of molds or tooling for optical lenses.

Why is heat build-up and thermal engineering important for lights?
With LEDs there is far less heat than with an incandescent light source, but LEDs still generate heat. An LED has to stay within a specific temperature range in order to last for 50,000+ hours. Just 20 degrees Centigrade hotter than the upper limit for 5 hours can reduce an LEDs life by half. With high output LEDs the heat is controlled with a heat sink (a device, usually made out of aluminum that drains the heat from the LED) located directly under the LED or by placing the LEDs on metal housings designed to dissipate the heat generated by the LEDs. These sinks and housings are carefully designed by thermal engineers to keep the LEDs in safe temperature ranges.

Lifetimes – How long will different light sources really last?
LED life expectancies can vary. Premature LED failures are often due to overheating. When an LED gets too hot, it will reduce the life of the LED exponentially, much as excess heat will harm a computer. An optimally engineered high output LED fixture will utilize heat sinks to dissipate the heat the LED generates, thus prolonging the life of the LED. Additionally, the electronic drivers of the LED must be engineered so as not to overpower the LED, which can also create more heat and cause early failure of the LED.

What kind of energy savings can I expect with LEDs?
The savings depends on the light source that the LEDs are being compared with. In many cases the energy savings can be up to 50% or more for an LED light fixture.

What is pay-back, and how do I calculate it?
Pay-back refers to the total savings of an energy efficient light source over a period of time. If one were to take the cost of a new light fixture less any energy rebates, and then look at the energy savings it produces, one could add up these savings over several years to calculate the pay-back one would receive over the life of that light. Entered into this calculation should also be the reduced cost of maintenance, replacement parts, etc.

What is total cost of ownership and how do I calculate it?
The Total Cost of Ownership is the only true calculation of the cost savings provided by a light fixture, and it often is a comparison of the cost savings for two different light fixtures. The Total Cost of Ownership includes energy savings, Maintenance Labor, Replacement Parts, Tax Benefits and other factors. Solas Ray can help with the creation of an accurate calculation of the Total Cost of Ownership.

What is the right white colored LED for my needs?
Any “white” light source has a color, from orange to yellow to blue. This is measured on a Kelvin scale. A yellowish light (low Kelvin) is considered a warm white and a bluish light (high Kelvin) is considered a cool white. LED’s come in the whole spectrum of “white” colors.

How bright can LEDs get now and where will they be in 3-5 years?
New LEDs are being released several times a year, each one brighter than the last, and this trend is expected to continue for the next 10 years. Single LEDs are tiny light sources, about the size of this o. LEDs are being combined together into multi-chip LEDs, to make an LED light far brighter – in some cases over 40,000 lumens. The more light you want, the more LEDs you use.

What is the most efficient light source in terms of lumens per watt?
In terms of lumens produced per watt of electricity the LEDs are the most efficient light source. LEDs are far above the 100 lumens per watt range currently, and are expected to pass the 200 lumens per watt level before the end of 2015.

What light source will last the longest?
There are many LED and Induction Fluorescent light sources that routinely exceed 50,000 hour life spans, with many approaching the 100,000 hour range.

What does bulb maintenance really cost?
Bulb replacement costs depend on the fixture and the equipment needed. In some cases on streets with commercial lighting, a special multi-operator crew equipped with a “boom arm” or “cherry-picker,” plus a lane flasher behind it can create a bulb change cost over $250, not including the cost of the bulb. Two year life spans or less for older bulbs can really add up the maintenance costs when compared to newer lights that can exceed 10 years before bulb replacement.

What is the Solas Ray plug-n-play Light Bullet?
Solas Ray has created an innovative new LED light module called the “Light Bullet.” It has an LED, lens and plug on a threaded heat sink that can be easily plugged in and screwed into, or removed from a Solas Ray fixture. This compares to other LED products, where – in the event of an LED failure, the LED cannot be replaced without replacing the whole board.

What is lumen depreciation, and why is that important?
Every light source starts out at a certain level of lumen output, and over time, that output will decline or depreciate. With LEDs the life expectancy is determined by when the light drops to 70% of the initial lumens. This is important because some light sources claim longer life expectancies but fail to tell you that they drop over half their light output over that time. Other light sources define the life as when the bulb burns out, or drops 100%.

Why are there so many kinds of LEDs and why is there such a difference in cost?
LEDs have a wide range of quality and light output. Some include special thermal features that help keep the LED cooler. There are others that have been pre-sorted to get very close color matches to other LEDs. Others come in groups with 5 colors (RGBWA – red, green, blue, white and amber) that can combine to create every different color. Other LEDs can be much more efficient in terms of lumens per watt. Cost is usually a factor that determines special features, color, brightness, quality or power efficiency. There are larger, more established LED companies with higher quality that charge more for their LEDs, but have a good track record of reliability and standing behind their products. They also provide accurate technical data that allows the lighting engineer to obtain the expected performance from the LED. There are literally thousands of new LED companies, many located overseas, with very cheap pricing, and no real track record to consider. We have tried these sources and recommend utilizing an LED from an established manufacturer even though the cost may be higher. With LEDs, the old adage rings true – you get what you pay for.

Can I really trust cheaper Asian sourced LEDs for quality?
There are some well established and very reputable Asian sources for LEDs. But there are many new arrivals coming onto the market every day, and there can be a great difference between what they claim their products do and what is measured in the lab. Jim Brodrick, the solid-state lighting (SSL) portfolio manager in the DOE’s Office of Energy Efficiency and Renewable Energy recommends caution in the selection of Solid State Lighting components. He has started the CALIPER Report, and every quarter his Department selects a range of LED products and tests them, comparing the lab tests to the product literature.

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