The old days of selecting light bulbs by watts are over. Let’s learn how to select the right LED bulbs by using lumens. It’s not so hard.
Step 1. Understand Watts
Watts are a measure of energy consumption. When we pay our electric bill, we pay for the number of watts we use. A 60-watt bulb consumes 60 watts of energy. Since we used 60-watt incandescent bulbs for so many years, we associated a certain level of brightness with 60 watts. But we can’t do that anymore, since modern LED technology produces more light while using fewer watts. Instead, we need to use a measurement for visible light energy: lumens.
Step 2. Understand Lumens
A lumen is a measure of visible light energy. More lumens equals a brighter light. All lighting manufacturers are starting to tell us how many lumens are produced for each of their lighting products. We see these lumen numbers on the Lighting Facts labels found on all new LED bulb packages. It will take a while for us to get used to using lumens instead of watts, but it’s important in order to make the best lighting choices.
Step 3. Understand Efficacy (Lumens/Watt)
Now that we understand watts and lumens, we can use both terms to come up with lumens per watt or “efficacy.” Sometimes the term “luminous efficacy” is used. This is a measure of how well a light source converts energy (watts) into light (lumens). The old technology of tungsten incandescent bulbs only had an efficacy of about 15 lumens/watt; LED technology can produce about 60 lumens/watt. In other words, LEDs are about 4 times more efficient at producing light than incandescent bulbs. This 4:1 ratio is a rough guide of how to calculate which LED bulb to use when replacing an incandescent bulb.
For example, if you need to replace a 60-watt incandescent bulb with an LED bulb, then divide 60 watts by 4 to get 15 watts – that will be a good estimate. But we should note that efficacy varies wildly from manufacturer to manufacturer, so you should check the Lighting Facts label and try to match lumens. Also, a label will sometimes tell you that an LED bulb has an equivalent brightness – but sometimes it doesn’t. Refer to the charts below for a ready reference. Finally, note that all VOLT® LED bulbs for landscape lighting have the incandescent or halogen equivalent wattage displayed on each of their product pages. We make the switch-over to LED easy.
Lumens for Light Source Watts
|Lumens||Incandescent Watts||LED Watts|
|Light Source||Luminous Efficacy (Lumens/Watt)|