More than 150 years ago, a product was introduced that would forever change how people used energy in their homes and offices – it was the light bulb. The invention revolutionized the way buildings were designed, kick started new businesses, and lengthened the average workday. It also triggered new energy breakthroughs – from electric motors to power plants.
Lighting has come a long way since Thomas Edison patented the first incandescent light bulb back in 1879, and more advancements continue to be made by the day. These advancements LED to the invention of the first visible spectrum LED by Nick Holonyak back in 1962 as he was working for General Electric.
No doubt about it, LEDs have come a long way since they were first introduced into the market. New LEDs are more affordable and consume less energy than their older counterparts. They also have longer lifespans.
If you’ve been using traditional lights – and you’re tired of their high energy consumption, low light output, and short lifespans – and you’ve decided it’s time to convert to LED lighting, you’ve come to the right place.
There are several things you should consider when selecting the best LED replacements for your conventional lighting systems. We’ve covered them all in this post to ensure you don’t experience buyer’s remorse after you buy LEDs.
Let’s get started.
First, Understand the Difference between Lumens and Wattage
One of the mistakes people have made since LEDs were first introduced is buying them according to their watts. Watts have nothing to do with the amount of light a LED bulb produces.
Let’s give you a little example.
You’re feeling hungry so you decide to go to the grocery store to buy some bananas. Once you get there, you decide that you also need some milk to take with your cereal the next morning. So, you buy 2 pounds of bananas and 1 gallon of milk.
“What has this got to do with watts and lumens?” You’re asking
Our point is, when buying LEDs, lumens are what you should be looking at, not the watts (wattage).
Lumens are to LEDs what pounds are to fruits. Lumens measure the total amount of visible light a light source produces. They are the most important thing in determining light output.
So, are watts important? Absolutely
Watts measure the amount of electricity a light bulb draws. They also tell you how efficient a bulb is –together with lumens.
This brings us to lumens per watt (luminous efficacy).
When you look at the lumens per watt, you are able to know the efficiency of a LED bulb. Luminous efficacy measures the lumens a light source produces for each electricity watt it consumes.
Calculate the Light at the Source and the Delivered Light
We’ll get a bit technical now, but not too technical because we know we may lose you at some point. Let’s talk a little about lumens, luxes, and foot candles .
Lumens measure the amount of light produced at the source of the light.
A lux is a metric measurement that measures luminous flux per unit area. It is equivalent to 1 lumen per square meter and is used to measure the intensity of light that passes through or hits a specific surface.
A foot candle is an imperial measurement and measures how bright the light is 1 foot away from a light source.
1 foot candle is equal to 10.764 luxes (approximately 10 times the equivalent lux measurement)
1 lux is equal to 0.09 foot candles.
What are we getting at?
As light spreads out across a surface, it becomes less intense. LEDs distribute lumens more efficiently and can yield more foot candles and luxes than traditional light bulbs, something most applications require.
LEDs are directional lights, they emit light in a specific direction hence their light output is much better. Traditional lights are omnidirectional, which means they discharge light in all directions – they don’t focus it in one place.
Let’s say you have metal halide bulbs in your parking lot fixtures and each is supposed to emit 18,000 lumens. However, they emit light all over the place (360°) because HID lights are omnidirectional, so the electrician has to put a reflector in each fixture to reflect the light back and deliver it to the parking lot below. During the reflective process, up to 30% lumens are lost.
But because LEDs are directional lights, you can use LEDs that produce 12,000 lumens in each parking lot fixture and the light they produce will be better than that produced by the more powerful metal halide bulbs. In addition, some LEDs are usually lensed to ensure all the light they discharge is directed to a particular surface.
Look At the Efficiency of the LEDs
These days, LED manufacturers are a dime a dozen so the market is flooded with LEDs of varying efficiencies. Some LEDs emit 70 lumens per watt while others emit 200 lumens per watt. This is another reason why you shouldn’t look at the watts when choosing LED replacements for your traditional lighting systems.
One manufacturer may say that their 150W LED light replaces a 450W metal halide light while another may say that their 250W LED replaces a 450W metal halide. A particular LED wattage cannot replace all conventional lights of a particular wattage. This is the main reason why utility companies find it hard to create general rebate programs for LED conversions.
Consider Light Degradation
One of the biggest upsides of LEDs is that they never lose more than 30% of their initial lumens throughout their entire lifetimes. The same cannot be said for traditional lighting technologies as their light output quickly decreases from the minute they are switched on. These lights suffer from serious lumen degradation.
Let’s say you use metal halide lamps in your warehouse. When the bulbs were new, they may have produced 30,000 lumens, which is very good. But because these lights tend to lose their lumens pretty fast, they may only produce 15,000 lumens by the time they get to half of their lifespans. If you think that’s bad, brace yourself for this: their energy consumption will never go down no matter how many lumens they lose. Now that’s pretty bad.
If you bought the metal halides 2 years ago, they could be 40% less bright than they were when they were first installed. But if the light they emit is sufficient for your space, you may want to get LEDs with a lower light output – not corresponding versions of the metal halides. The light they produce will be adequate for your space. Depending on your setting, this could be an opportunity to not only decrease your power consumption but to also lower the number of fixtures needed to provide the same level of illumination.