20161030_efficacy

The focus on efficacy is damaging the lighting industry

Market transformation programs like DLC and Energy Star were initiated to deliver energy-effiency requirements to the industry, but JOHN BURNS of Global Tech LED explains how the energy push can lead to a reduction in light quality.

The DesignLights Consortium (DLC) was formed within the Northeast Energy Efficiency Partnership in 2009. The goal of DLC was to lead the lighting industry toward high-quality, energy-efficient lighting. The organization started qualifying products and the first DLC QPL (Qualified Products List) was publicly released in 2010. Utility companies began to use this qualification as a requirement to award rebates to end users for upgrading to energy-efficient lighting. The US Environmental Protection Agency’s (EPA) Energy Star program is the most popular qualification used in incentive programs, but DLC covers a far broader range of products.For example, Energy Star does not qualify LED-based T8 tubes but DLC does. Most LED product manufacturers seek DLC qualification. Though energy efficiency is obviously a good thing, this perpetually increasing focus is pushing end users in a direction that leaves them with a much lower quality of light

DLC constantly updates and upgrades the requirements for having a product listed on its QPL. The organization released Technical Requirements Version 3.0 in June 2016. One of the most important features of Technical Requirements 3.0 is the introduction of a new classification of high-performing “Premium Products” that have a higher efficacy (lm/W) than the “Standard Products,” which, with many utility companies, results in a larger rebate for choosing a product that is super energy efficient. Recently, the efficacy requirements have been raised even higher with the implementation of Technical Requirements 4.1, which goes into effect in 2017. The problem is that most premium-efficacy LED products must use many more LEDs on their circuit board and thus lose the ability to apply lensing to control the light distribution. This results in terrible implications in the quality of light delivered by these products.

Two main issues arise from lack of customizable light distribution depending on the static distribution of premium-labeled products. If the static light distribution is too wide, more lumens are required to hit the desired light levels, because the uncontrolled light is spilling everywhere and unable to be focused effectively on the application. On the other hand, if the static light distribution is too tight, hotspots occur under the uncontrolled light sources, and more light sources are required to create an even distribution.

Using premium-efficacy products with no light distribution control can result in: 1) the need for increased lighting overall, which 2) increases site wattage, and 3) means a higher cost for the lighting end products. This leads to nearly the same overall energy usage on a site as employing the slightly lower-efficacy products that feature custom light-distribution control. The end user ends up paying more and getting a lower-quality light distribution. Compare an example of high-power (standard rebate, 200W, 95 lm/W) and mid-power (premium rebate, 200W, <110 lm/W) lighting products used in a parking lot. All variables, including wattage, are the same except for the light source being used. The conformity of the controlled high-power system with Type V optics will be far superior to the conformity of the mid-power system without optical control. The difference in average illumination on the ground is nominal – 3.61 fc for the high-power system and 3.85 fc for the mid-power system. The max/min fc for the high-power system in our example is 4.65 with smoother light distribution, versus max/min 66.71 for the mid-power system. The extra light from the higher-output, mid-power LED system spills and turns into light pollution due to the lack of optical control.

This situation does not only apply to outdoor lighting but also indoor lighting. In high-ceiling applications, secondary optical lensing allows you to focus the light more efficiently to the floor. With DLC incentives designed for lm/W, the consumer will choose a fixture that delivers less light to the floor than a luminaire with the optics in order to obtain the greater rebate.

In effect, the DLC is spreading the fallacious idea that efficacy is the best way to judge the performance of an LED luminaire with very little focus on control and conformity of the light distribution – which does not end up benefiting the end user. And it provides no incentive for lighting manufacturers to focus on delivering quality light distribution.

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