Just as troffers are a staple in the lighting of offices, schools, and other large complexes, downlights play the same role in residential and hospitality settings as well as commercial applications. These lights are used as ambient lighting and focal lighting. The original technology of incandescent, was followed by halogen and, eventually, even CFL (compact fluorescent). The CFLs became fairly popular due to the fact that they were quite a lot more energy efficient than incandescent or halogen. However, they could not generally match the luminaire efficiency of the halogen and incandescent lights.
The downlight lighting was among the first lighting applications in which LED lighting technology became competitive with existing technologies. That was due to the fact that LEDs offered easily available changes which would bring about, not only dollar savings but vastly improved lighting. The fact that LED lighting is directional, plays right into the design of downlights and makes for an improvement upgrade that is well suited their purpose. The efficacy and overall higher quality of light, when compared to all previous technologies, makes for a no-compromise solution for entry into the world of LED lighting.
While the predominant “can” size in the downlighting category has been the 6-inch design, there are certainly many different sizes in both round and square or rectangular. These lights can range in size from two inches to twelve inches and have ratings which begin in the area of a couple hundred lumens and extend to ratings of over 10,000 lumens. The lighting industry has covered both the new and retrofit markets well, and has come up with numerous innovative ways to quickly and easily install these lights in both new and existing applications.
Currently, according to the U.S. Department of Energy (DOE), the industry’s most efficacious downlight is rated at 124 lm/W. There are, currently, about 70 products listed in the DOE documentation that exceed the 150 lm/W level. These lights include roadway lights, industrial lights, troffers, and others. The most efficacious product currently listed by the DOE in their listing of all LED products and their efficacy over time comes in at a rating of 190 lm/W and is (surprisingly – to me, anyway) a T8 lamp. The DOE data indicates that the mean rate for efficacy for all the products listed in the DOE data base has continued to increase at a rate of about 10 lm/W per year.
The minimum efficacy requirement for a downlight to meet Energy Star Rating qualification is 55 lm/W, and for downlight retrofit applications, the standard is 60 lm/W. Over 80% of the downlights and about 90% of the retrofit downlights in the study meet those standards. Of the nearly 2,900 downlights listed in the DOE database, nearly 1,700 (~59%) emit between 500 and 1000 lumens. That amount of light is pretty standard for most any average application in residential and hospitality settings. There are about 33% of the lights that produce between 1,000 and 2,500 lumens, and that is quite typical of the need for commercial applications. At least four dozen of the downlights now listed in the study emit in excess of 4,000 lumens.
Although the downlight category is a huge one and it has shown a good growth in efficacy ratings in the past years, the increase in efficacy of 43%, as a whole, compared to the same statistic associated with LED luminaries as a whole, which is approximately 76%, is fairly low. The fact might be traced to the incredible growth of other categories, such as troffers and other forms which generally exhibit less optical control than is often associated with downlights, which usually have lenses of some sort, thus they are able to exhibit higher efficacy. The fact that there are also differing levels of efficacy needed for different lighting types, downlights, troffers, linear lighting, parking lot/garage, stadium, roadway and large area lighting, etc., to meet light quality needs for the application and qualification thresholds for energy efficiency programs. All those factors certainly contribute to the fact that the downlights currently exhibit a lower mean efficacy than any other major luminaire category except decorative lighting.
In regard to CRI, the downlight category boasts a greater percentage of products (38%) in the 90+ CRI range than any other product in the study. This fact is probably quite likely because the use of downlights is most prevalent in residential and hospitality environments. A majority of downlights and downlight retrofit kits (61% for the group) have a CRI in the 80’s and most in the group have a CRI rating that falls between 80 and 85. A vast majority of the lights list at a CCT of 2700 or 3000k and the reason for that is likely because that comes close to matching halogen lighting, which is normally in the 2800-3000K range. To be qualified for energy Star Rating, lamps must have a CRI of at least 80 and a nominal CCT between 2700 and 6500K. Of the downlights currently listed in the DOE study, more than 95% of those products meet the standards.
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. You can view our LED downlights by clicking here. Thank you for perusing our web site.