By Dwayne Kula
May 26, 2017: Many consumers are still wondering how many LED watts they will need to replace an existing light fixture. And many of the vendors are all too willing to respond with the watts of their product that they think will work. The problem is selling LED by watts is extremely misleading. Education is power, so let us educate you into asking the right questions and understanding the proper way to shop for LED.
First and foremost, when you replace an existing light, you have to make sure the solution you are recommending will produce enough light to make the replacement properly. The amount of light each bulb or fixture produces is called lumens, and the collective sum of all lumens in an area is a measurement called foot candles, or lux. So a good solution is always a conversation about foot candles, and the lights have lumens that make the foot candles. The measurement of watts is measurement of the amount of energy the light consumes to produce the lumens.
Forget about watts when buying LED lights
But it’s not that simple. There is an even bigger discussion, and it is known as efficacy, or how efficient a light is producing the lumens. The more efficient a light is, the less watts it consumes to make the lumens. In the world of LED, efficacy is different, and sometimes, dramatically different for each fixture or ‘bulb’. Today, efficacies can reach as high as 200 lumens/watt, although this is rare to find and still an expensive solution. However, it is not hard to find product that is 130-150 lumens/watt in today’s marketplace. And here is why selling LED by watts is misleading.
Let’s hypothetically say there is a customer who wants to retrofit an existing Area Light in their parking lot. The area light is equipped with a 400 watt Metal Halide bulb. Pretty standard. The customer calls up one of our competitors who claims they have a 135W retrofit kit that will do the job. Looking closer, that kit produces 13,164 lumens. Not bad, that solution would work. That same customer then calls us and asks us for the price on our 135W retrofit kit. He is already asking the wrong question.
That customer is not aware of the more important factor, efficacy. The competitors retrofit kits’ efficacy is 97 lumens/watt. So when they call us, and we dig a little deeper into their needs, we discover that they are trying to replace 400W Metal Halide, and we know that 13,000-16,000 lumens is about right, based on previous experience. However, our retrofit kits are extremely efficient, running at an efficacy of 150 lumens/watt. So our 105 watt retrofit kit produces 15,776 lumens, about 2,612 lumens more than the competitor’s product, and consumes 30 less watts per kit. If we wanted to level the playing field even more, we could dial down our kit to 87.76 watts to produce the same amount of light as theirs. That’s a savings of over 47 watts per kit.
So understanding efficacy is paramount in determining your best efficient solution for replacing your existing fixtures. Both these lights are designed to run for a very long time, and both are warranted for 10 years, but one will cost you a lot more to operate over that same 10 year period. Here’s the math.
Let’s assume .12 kw/h cost and running 12 hours a night, 365 days a year. Our retrofit kit would consume 384 kw and the competitors would consume 591 kw. Over a year, ours would cost you $46.12 to run, and theirs would cost you $70.96. Over 10 years, their light would cost you an additional $248.40 to run. If you had 100 lights, that’s an additional $24,480.00.
So that everyone is on the same page, both lights are producing the same amount of light, 13,164 lumens.
But the story doesn’t end there. In the world of lighting there is something known as being DesignLights Consortium Listed (DLC). DLC is a performance standard that each light must pass. Some lights have passed the more stringent DLC Premium Qualification, which is a category for the higher efficiency LED Products on the market today. While some companies product qualify under the less efficient DLC Standard program.
Here is the second way a less efficient light can hurt your pocket book. Rebates are typically larger for lights that are DLC Premium Qualified than they are for lights that are DLC Standard Qualified. So at time of purchase, you are paying more for less efficient lights. A good thing to remember though is this; rebates are in complete control of the utility companies. What they offer, how much they offer, if they offer, and what products qualify is completely up to them. So it does vary. But in the short time DLC Premium has been in existence, we have seen a dramatic difference in the rebate amounts between the DLC Premium and DLC Standard classifications.
In summary, when purchasing LED, we suggest the following approach
Determine how many foot candles you need to light up your area.
- Ask the vendor how many lumens it would take per fixture to meet the foot candle requirements
- Ask them what the efficacy, or lumens/watt is of their fixtures
- Ask them if their lights are DLC Premium, DLC Standard or not qualified
- Ask them if they can assist you with the rebates
- Ask them what their warranties are.
Know what you are buying and ask the right questions next time you inquire about LED lighting fixtures. This way, you will better be able to analyze the best option for your business, instead of going in blind.
Lastly, be sure to bookmark this page for future references, you won’t want to forget this!
Author’s Bio: Dwayne Kula is President and owner of MyLEDLightingGuide.com. Dwayne has started MyLEDLightingGuide.com in 2008 dedicated to helping and educating our customers to make the decision when it comes to converting over to LED. Their client base included large utility companies, military bases and fortune 500 companies. http://www.myledlightingguide.com/