In this article we’ll help you estimate how much you can save by switching from incandescent or CFL lights to LEDs. To learn how to choose LEDs or decide if they are right for your home, check out our LED lighting buyer’s guide. And if you’re unsure if LEDs will be the right color, check out our LED color and temperature guide.
But for now, let’s chat dollars and cents and answer one question: how much can you save with LEDs?
The average home with incandescent bulbs uses about 2,000 kWh of electricity per year.
At the national average of $0.10 per kWh, these homeowners spend $215 a year on lighting. By switching to LEDs, you can save around $4,000 over 20 years (the typical lifespan of an LED). As far as energy efficiency projects go, that’s a lot!
To put that in perspective, consider that switching to a heat pump water heater (another great savings opportunity) will save you about $200 per year and $5,000 over its 15-20 year lifespan. And switching to a heat pump (for heating and cooling), can save you as much as $1,000 per year and $15-20k over its lifespan.
If you want to calculate exactly how much you’ll save, you need to base it on everything from your location to how big your house is to what kinds of lights you’re currently using. Here, we’ll walk through some averages and calculations to help you get a more realistic number for your personal use case.
As you can see in the map below, the number of bulbs per house varies depending on where you live. Across the United States, the average number of light bulbs per house ranges from about 50 to 80, according to the Pacific Northwest National Laboratory.
Of course, if your home is bigger than the national average—about 2,000 square feet—then you’ll likely have more bulbs. And vice versa.
And if you want an exact figure, you can count how many bulbs are in your house. But if you’re way over or under the average, it might be time for a lighting redesign to get you closer to what most people are using.
The next factor to consider is how much you use your lights. Here’s a chart with all the data you need to make a good estimate of that.
Note: in the image, HOU stands for hours of use.
As you can see, most homeowners use their lights between 1 and 3 hours per day on average.
People talk about electricity in the home in terms of kilowatt hours (kWh); as in, the average home uses 10,000 kWh of electricity per year. But if you look at a light bulb package, you’ll notice it gives you the energy used in watts (e.g., a 60W bulb). So how do you turn watts into kilowatt hours?
You can use the following equation to calculate the energy used by lighting in your home:
If you’re like me, math might not be your forte. So let’s go over an example to show how that equation works:
Once you have the total yearly electricity use, you can multiply that by your average yearly electricity rate to find how much it costs to light your home. At the national average electricity rate of $0.10, we’re looking at $219 per year spent on lighting ($0.10/kWh * 2,190 kWh = $219).
To get an even more precise estimate of your savings (which honestly, might be overkill), you’ll also want to think about lumens.
For a detailed understanding of watts vs. lumens, take a look at our guide to LED lights. But for our purposes here, just know that although watts and lumens measure different things, the general conversion is 60W incandescent bulb = 800lm LED bulb. So if we’re following the same example as above, here’s what it would look like.
Meaning if you had the national average electricity rate of $0.10 per kWh, you would spend $36.50 per year on electricity for lighting. This gives you a savings of $178.50 from the existing lights—over $6,000 throughout the course of home ownership—just from just the electricity savings.
But that’s not the only savings LEDs can give you.
If you’re replacing compact fluorescent lights (CFL) and not incandescents, the math is different. A CFL bulb with a brightness of 800lm has an energy use of 14W and a lifespan of 8,000 hours. Using the process above (with the assumption that all of the light bulbs in the home are CFLs), the average yearly electricity cost of lighting would be $51.10. Take a look at our guide to LEDs for more information.
Existing light bulbs, called incandescents, last for 1,200 hours on average. That means that if you use your bulb for 2 hours a day, you’d have to replace your bulb every 1.64 years. On average, you’re looking at spending $30 a year just on the light bulbs themselves.
LED light bulbs have lifespans of more like 25,000 hours. If you use it for 2 hours a day, you would only have to replace the LED once every 34.25 years—so basically never.
Over the course of those 34.25 years, you’d have spent over $1,000 on incandescents.
LED lighting is up to 44% more efficient than 4-foot fluorescent tubes, according to a University of Michigan study.
The study compared the costs of six replacement options (one fluorescent and five LED) for linear recessed lighting systems and found that LED products were 18%-44% more efficient than T8 fluorescent lamps.
Lighting is responsible for 11% of electricity use in commercial buildings and residential basements, garages and shops. Linear recessed lighting systems, which are also called linear fixtures or troffer lights, are among the largest opportunities for energy efficiency improvement, given their long operating hours.
The study’s key takeaway is that switching to LEDs can save money and energy and reduce one’s carbon footprint, according to senior study author Greg Keoleian, co-director of the Center for Sustainable Systems at the University of Michigan School for Environment and Sustainability.
Greg Keoleian“It’s definitely better to replace your fluorescent lamps with LEDs rather than replace them with new fluorescent lamps,” Keoleian said. “Our finding is consistent with the U.S. Department of Energy’s indication that LED systems are 25% more energy-efficient than fluorescents.”
LED lamps outperform fluorescent lamps in numerous ways, according to Keoleian. They produce light without flickering, have higher energy efficiency and last longer, which leads to improved ambiance, less maintenance and energy cost savings.
LEDs also offer better dimming performance than fluorescent lamps. They have faster ramp-up to full brightness and are more energy-efficient at low dimming levels. In addition, LEDs do not contain mercury, making them safer for indoor use and at end-of-life.
Keoleian and his team surveyed more than 160 LED replacement options, which included lamp replacements, retrofits and luminaire replacements. A lamp replacement is a change-out of the lamps only and does not require any electrical modification, while a retrofit involves modifying the existing fixture to accommodate a new light source and/or electronics. A luminaire replacement is a full change-out of the lighting system, including the mechanical structure.
The study authors compared the costs of six replacement options:
Among their key findings:
“These findings highlight tradeoffs when deciding between LED options and can help guide commercial building owners and managers who are considering lighting replacement,” said Keoleian, who previously studied the energy and cost savings of replacing incandescent light bulbs with LEDs.
The exact savings depend on lamp costs, electricity rates and labor costs for an electrician if you are retrofitting or replacing the recessed fixture, Keoleian said. The LED options—except where you purchase a whole new lighting system (luminaire)—all result in cost savings over time. A whole new luminaire means a higher life cycle cost because of the higher upfront cost of a new unit.
The results are also applicable to residential buildings where T8 lamps and troffers are commonly used, particularly in workshops, basements and garages, Keoleian said.
The study was published online Nov. 10 in the journal Lighting Research and Technology. Lixi Liu of the Center for Sustainable Systems and the U-M Department of Mechanical Engineering and Geoff Lewis of the Center for Sustainable Systems are co-authors.
The research was supported by the National Science Foundation Graduate Research Fellows Program and the University of Michigan Rackham Merit Fellowship.