LED Recessed Lighting Guide - Downlights

LED Recessed Lighting Guide - Downlights

Polar Ray Admin

In the United States alone there are well over 700 million downlights installed in residential and commercial buildings. Representing less than 1% of all these lights are LED downlights. If all those existing non-LED downlights were replaced with LED units, the overall energy savings would be over 2.5 billion dollars per year. LED downlights are available in numerous designs with numerous lighting characteristics and can be used in so many places for so many different lighting applications that choosing the best product for an intended application can be quite daunting. Although they are mostly offered in the traditional round configuration, square units are also available. There are recessed, flush fitting and surface mount applications, in differing finishes with trim ring options, and some have gimbals that can be rotated to direct the light to the desired area. The units themselves are all designed with some sort of neat connection device that allows for quick and easy installation in nearly any standard junction box configuration. In addition to all the various physical design characteristics of the lighting units, there are the performance metrics of the lights themselves to consider, e.g., the color temperature (CCT: Kelvin rating; 4000 K, etc.), the color rendering index (CRI), lumen output, wattage (W), efficacy (lm/W), and all the rest. Today, with LED lighting, there are soooo many choices that one didn’t have to make – actually, couldn’t make - with incandescent and even fluorescent lighting. Actually, once all the possibilities are understood, the beauty of the technology is that it is so diverse in its lighting potentials that the correct decision can make an important impact on the potential of the final lighting results.

The following information can help in understanding the different options and assist in making an educated decision. The discussion will explain metrics (measured properties) that are associated with LED lighting, as the metrics of LED lighting are important factors to understand in considering lighting needs (and wants). The options which consumers are now given, thanks to the numerous metrics of LED lighting, are options which were not available, thus not considered with incandescent lighting. Fluorescent lighting, unlike incandescent lighting, does offer some choice in metrics, as they are available in different color temperature (CCT) designations. However, the general household fluorescent lighting can exhibit either too much magenta or greenish rendering in their color, and that affects the CRI rating, which is another potentially important metric that was not previously considered but is in the discussion, along with other standard LED metrics – all, which are important to understand in the selection process. It should also be noted that the LED technology is developing new metrics as new methods of evaluating the light sources are being established. In fact, there are currently numerous developments in the field which are being implemented and if they reach widespread industry acceptance, they may replace current metrics. There are also metrics which are not covered here as they are not always listed by manufacturers, or they are beyond the scope of this writing.


WATTAGE - Input and Output; not the same with LED luminaries

OK, we’re going to start with what is quite likely the most commonly known term in artificial lighting. The wattage designation of LED lighting does not really mean the same as the term does when associated with incandescent lighting. Incandescent lighting, in reality, has no real advertised metrics other than wattage ratings. Although lumen ratings are generally listed on the packaging for incandescent bulbs, not many consumers pay attention to those, or even know or care what they mean or that they exist. Those wattage ratings of incandescent lights are not only tied to the amount of energy consumed but to the expected output of light – as the wattage increases, so does the light output. Although the term was seldom to never considered in the incandescent technology, lumen output is the visible, end result of wattage differences in the form of the light output. In LED technology, the wattage listing is basically a standard of comparison to the well-known incandescent light’s output. The wattage output listing for LED lighting is the close equivalent to what an incandescent light of that wattage would produce. The phrase “close equivalent” is about the best that can be applied when it comes to comparing incandescent lights to LED lighting, as the ability to produce different properties/metrics within the LED technology is a groundbreaking element of the field. As is probably understood by most consumers, the wattage output “comparison” of LED lighting is not a characteristic that is associated with the wattage consumed, which, with LEDs, is much less than a comparably rated incandescent luminary, e.g., a 60 watt (equivalent) LED light consumes around 9 watts . The wattage callout for the LED products is a listing that allows the consuming public to have a reference for the expected light output.


CCT – Correlated Color Temperature; the light’s visible color

Once it is determined what wattage equivalent LED light is wanted, the next logical step in the selection process would be the color temperature. The color temperature is a linear scale measurement of the visible color of the light produced and is measured in degrees, Kelvin (°K) which may sound intimidating but, in reality, is pretty simple. The designations will generally be listed in the ranges of 3000 K through 6000 K, with the lower numbers indicating a warmer light and higher numbers indicating a cooler color of light. Putting examples to the colors; a standard incandescent light bulb burns in the area of 2900 K – a warm color – and the sunlight at noon is in the area of 5600 K – a cool color. Those numbers are basically average color measurements but they lay a foundation for the understanding of the CCT rating that is associated with LEDs. It should be understood that the even though the designations of warm and cool colors are called out in degrees, they do not indicate a temperature (hot or cold), they describe a color. The warmer the color, the more reddish the light source appears, and the cooler the color, the more bluish the light source appears. An interesting side note to all this CCT stuff is that sunlight, as noted above, at noon at ~ 5600°K is not the same as daylight. Daylight is a combination of sunlight and skylight - skylight being the light that is cast upon the earth by the reflected and diffused light from the sky. Skylight is actually rated at a higher temperature than sunlight, being in the range of 12,000-18,000°K. Further, the light associated with shade is also rated higher than sunlight, at ~8000°K, as shadows, which are created by blocked sunlight, are illuminated by skylight. This lighting of the shadows by skylight is the reason that they appear to have a bluish tint in outdoor daylight photos. Actually, this whole CCT thing has ties to photography which, during the beginning of color film manufacturing, assigned the basic Kelvin averages as to make choices for the various emulsions used for different films – daylight, tungsten, etc.


CRI – Color Rendering Index; the colors the light renders

This designation defines the light’s ability to render the accurate color of an object, meaning the ability of the light source to correctly render all the color spectrum frequencies when compared to a perfect reference light source of a similar CCT. The rating is on a scale of 1-100; the higher the number, the greater the accuracy in reproducing the correct colors – 100 being perfect. OK, to make things a bit more confusing (maybe), incandescent sources, technically known as incandescent radiators, have a CRI of 100, as all colors in their spectrums are rendered equally. The same can be said for halogen lamps. Any light source which has a CRI of less than 100 will have Correlated Color Temperatures.  Light sources with a rating of less than 100 CRI become inferior in regard to rendering the correct colors of objects, and as the CRI rating number decreases, so does the color rendering ability. Just for reference in this discussion, tungsten-halogen (aka, quartz) lighting is used in photography because it has a CRI of 100, thus rendering correct colors. Even the best specialized photographic lighting from any other sources, including fluorescent and specialized arc lamps, and, yes, even LEDs can only manage CRI ratings of 90-95. In fact, LED lighting generally falls below 90 CRI, and overall into a range of 70-95, with lighting in the 90-95 CRI range being the best that can be had at this point in time. That being said, LED lighting still leads all other technologies in general overall lighting quality and efficiency.


TM-30 – Color Fidelity; will likely supplant CRI

Here is an example of a new metric which has a likelihood of replacing a currently used metric; that being CRI. This new system is comprised of several related measures and graphics that, when used together are able to evaluate and relate a light source’s color rendering capabilities. TM-30 is a more inclusive testing development to measure the color fidelity of LED products and addresses limitations of the current CRI system. At this point, TM-30 is not a required standard in the industry but it is being utilized to help improve LED light sources. In addition to this new metric, there are numerous others and numerous others proposed, especially in the area of color fidelity. TM-30 utilizes various sub-metrics to increase the accuracy of testing and evaluation of light sources. These sub-metrics are fairly complicated and not necessary for this discussion, especially since the TM-30 procedure is not yet an in-place industry standard. 


R9 – Color calculating; red being very important

The R9 metric is a measurement of red rendering in illuminated objects and is a very important property to be aware of. The term, R9, actually refers to the ninth test color, red, within the fourteen base colors utilized in the color rendering testing processes. The importance of R9 in color rendering is quite high since some red can be found in various hues of most processed colors. The ability of a light source to accurately produce the color red is key in the overall accuracy in color rendering properties. The higher the R9 rating, the greater the ability to properly produce the most accurate and vivid colors. The importance of this metric cannot be understated as the correct rendering of the color red in objects is adversely affected by inaccurate rendering of the color red by artificial light. One example of an important place for the correct color rendering would be in a supermarket, where the appearance of many things such as meats, fish, and fruits and vegetables are greatly affected by poor rendering of the color red.


Lumens – lu; the light output amount

This is a pretty easy metric to understand. It simply indicates how much light a lamp puts out. The measurement is the amount of light produced in the area of one square foot, with the light to be measured set at a distance of one foot away. This is an important metric when it comes to replacing existing lighting. Even older technology lighting – incandescent, fluorescent, etc. – lists the lumen output, so one can use the ratings of those to ensure that the LED choice is up to the task of illuminating the area with at least as much as light as the previous lighting provided.


Efficacy – lu/watt; the efficiency factor

This metric is a measurement of how efficiently the product is producing light. Not so much efficiency in terms of energy consumption, but efficiency in terms of the number of watts it takes to produce a particular amount of illumination. The higher this factor, the greater the performance efficiency, and in all reality, it does have a bit to do with energy efficiency because with higher efficacy numbers comes better illumination and the possibility that fewer luminaries may be necessary to illuminate a particular area if lights of higher efficacy are utilized. The efficacy rating of LED lighting has steadily been increasing in recent years. A few years ago, most LED lighting was in the 30-50 lu/watt region. Today, that is quite low and any LED that is not rated at 70 lm/watt or better should not be considered. With LED lighting, the lumens per watt can vary depending on the chips used, the heat sink efficiency, how hard the LED is being driven, and the overall design and construction.


Beam Angle – in degrees; spread of the light

The beam angle is an important specification to be considered when shopping for the correct light to illuminate the area properly. Since LEDs are a point source light, the ability to direct light without all the reflective surfaces which are needed for older technology makes for more efficient lighting. Actually, this metric is just as important to consider as lumens ratings because if the correct beam angle is selected and the lights are spaced correctly, the minimum amount of luminaries will be necessary and the area to be lit will be evenly illuminated.


Center Beam Candle Power – CBCP; central power

Here is a metric that will not come into play in most LED luminaries but is a measurement which could be quite important in lighting that is intended to accent or spotlight an area or object. This property is determined by measuring the light intensity at the center of a beam of light. It certainly is possible for a light to have a high lumen output and a low CBCP, as is the fact with general area lighting which aims to spread light evenly over a wide area. That being the case, it is important to be aware of CBCP in choosing a light which is intended to directly light a specific area with the purpose of drawing attention to it.


Dimming – %; ambiance

Not all LEDs are capable of being dimmed, even then, they are only capable of dimming to a certain percentage of their full light output, e.g., 10%, so, unlike incandescent lights, which can be dimmed to 0%. Using the correct dimmer is quite important and the best way to determine this capability and the correct dimmer type to use is to refer to the factory spec sheets that are posted with each luminary description.


Rated Life – hours and %; they just won’t die

The life rating listing for LEDs indicates the length of time they would be expected to operate before only outputting 70% of the original brightness. With LED products having a life expectancy of 50,000 hours, this indicates that they should be expected to maintain 70% of their original brightness at 50,000 hours. Typically, LEDs do not suddenly burn out as is the case with traditional lighting technology. Instead, LEDs slowly dim over time – a very long time – and when they reach the rated lifetime they still have life in the form of 70% of their original output. To put the 50,000-hour time period into perspective, math says that’s about 5.7 years. So, after being continually energized for 5.7 years, a 50,000-hour rated LED luminary will still be producing light, but it will have lost 30% of its original output. The standard testing procedure for lifetime rating of traditional lighting is based around determining when 50% of the identical test subjects burn out. Since LEDs do not, generally, suddenly burn out, the testing procedure varies in that instrumentation is used to determine the amount of light the test subjects are emitting over a period of time. Both lumens and efficacy are at play here, as the LED ever so slowly loses a bit of both as it ages.


Location, location - dry, damp, or wet; indoors or out

This is not a metric but is an important property as you certainly wouldn’t want to be installing a dry or damp listed lighting unit in a location that can become wet. Make sure your selection fits the environment it will live in.




The inventory of LED downlights we carry at Polar Ray are of the highest quality, from well-known manufacturers in the LED field. Because LEDs themselves are sensitive to thermal influences and electrical conditions, quality is a factor to be aware of when purchasing any LED luminary. This is especially true for one that is designed as a fixture which might be mounted within a ceiling or wall, such as is the case with downlights. Even the best quality LEDs will perform badly if used in a poorly designed fixture, this can lead to lowered lumen output and shortened life. The old adage of, “you get what you pay for”, is as true in the LED industry as it is in any other.

Below are short descriptions of different categories of downlights. The titles are links which take you to further, in-depth information and images of the many downlights we carry.


Recessed LED Downlights 

The downlights here are 4, 5, and 6-inch diameter recessed downlights which are often referred to as can lights. They are manufactured in numerous configurations which allow easy installation in new or retrofit construction.


Eyeball or Gimbal LED Downlights

These lights are designed to allow the light to be rotated 360° and tilted as much as 35°. These attributes make them ideal for angled ceiling installations, wall wash and highlighting applications, and other settings which might benefit from a light source that can be adjusted to illuminate a particular area, some even allow the choice of a beam width. All are available in configurations which allow easy installation in both new and retrofit applications in residential and commercial applications.


Halo LED Lighting

These recessed lights are available in numerous series designs and some allow the selection of trim rings that best match the décor of the space. The installation system allows for ease of installation in either new or retrofit work. Each light comes with an Edison adapter which allows for easy retrofit in many existing housings.


LED Glimpse Downlights by Lighting Science

As great substitutes for 65 and 75 watt incandescent lights, the versatile design of these downlights allows for ease of installation in 5 and 6-inch housings. The ability of the product to be installed in a junction box with a minimum of 2.5-inch depth makes them useable in areas which cannot accommodate a standard housing.


Sylvania LED Downlights

A highly efficient and affordable line of recessed lighting by a well-known, long-standing lighting company. The designs allow for easy installation in new or existing applications. The 4, 5, or 6-inch downlights can be nicely mixed and matched for varying combinations of physical appearance and light.


Square LED Downlights

Besides being square, which is not the norm for downlights, these lights have a CRI in excess of 90 and an R9 of greater than 50. Those two metrics mean that the lights exhibit the ability to more properly render colors. This new line of downlights allows for new design possibilities which have the potential to compliment the straight lines that normally exist in houses and buildings. They are designed to be easily installed in new or retrofit work with a snap-in connector and a friction clip system.


LED Recessed Housings

This selection of recessed housings for use with LED downlights or LED bulbs in four and six inch sizes. There are two different styles, one which is designed for simple new construction installation and one which is made for easy retrofit installs.


4” Surface Mount Downlights

These are designed to fit in standard 4” J-Boxes, or housings and offer optional designer trims.


6” Surface Mount Downlights

This selection of lights can be retrofitted into 6” recessed downlights or can be mounted in a J-Box as a surface mounted downlight.


High CRI LED Downlights

These downlights all exhibit high CRI index ratings. The selection of styles and designs includes various manufacturers and covers the available selection of downlight designs; round, square, gimbal, different sizes, different trim, and varying available metrics.


We hope you find this guide helpful in your search for just the right downlights. As always, if you have questions in regard to any of your lighting projects, please feel free to call Polar-Ray at 303-494-5773 to speak with a lighting consultant. Thank you for perusing our web site.