Springtime is upon us. The birds are chirping, the flowers are blooming and our thoughts naturally turn towards light bulbs. Okay, maybe not naturally, but this is the best time of year to think about your lighting. By this point in time we probably all know that LED bulbs are the best, but many of us are still dragging our feet on installing them. Maybe you’re just waiting for your old incandescent bulbs to burn out before replacing them? Patience is often a virtue, but waiting to replace incandescent bulbs is just burning money. Air conditioning season is just around the corner so spring is the time to replace incandescent bulbs with LEDs.
How Much Better are LEDs?
Way Less Heat
This depends on what type of bulb you’re comparing them to. A 60 Watt incandescent bulb uses 60 Watts of energy to make somewhere between 550 and 850 lumens of light. A cheap modern LED bulb can produce 800 lumens using just 9 Watts of power. So what happens to the extra 51 Watts of electricity that the incandescent bulb consumes? It basically all turns into heat. You can think of a 60 Watt incandescent as a 9 Watt LED with a 51 Watt heater attached to it. Put 4 of these in a lamp and you’re got your own personal 200 Watt heater that incidentally blasts out a couple thousand lumens of light. Fill a house with incandescent bulbs and you start adding thousands of watts of heat to it. In the winter this isn’t so bad, except heat rises it generally makes more sense to install heaters along the floor instead of in the ceiling. In the summer, though, when heat needs to be removed from a house, incandescent bulbs really increase the amount an AC has to run.
Incandescent bulbs generally last a pitifully short amount of time. They’re usually rated at around 1,000 hours before they burn out. Even the worst LEDs are rated near 10,000 hours, the ones I linked above are rated at 20,000 hours and some go as high as 30,000. Sure, a few dud LEDs may burn out sooner but unless you have frequent power surges most will last this long. Incandescents only cost around 80 cents per bulb so they might seem like a decent deal compared a fancy color changing wifi LED bulb for $32 but they just cannot touch a $2 cheap LED bulb that lasts 10 to 30 times longer. Dimmable or oddly shaped LEDs can cost more, but they can still be found for under $5 bulb. If you like going to physical stores check out Lowe’s and Ace, they often have LED bulbs discounted somewhere between $1 and $3 per bulb1. Even without taking into account the lower energy costs, LEDs are now just plain cheaper per year of use, and when you factor in power the difference is massive.
Compact fluorescent light bulbs come far closer to LEDs in terms of efficiency. You can find CFLs that produce 850 lumens of light using just 13 Watts of electricity, though older ones may use more. In the best case, a CFL is like having an LED with a 4 Watt heater attached to it. This is a lot better than the 51 Watt heater you get with an incandescent. But CFLs fall down in other departments. They often take a few moments to warm up to full brightness, while LEDs turn on almost immediately. CFLs generally render color worse than LEDs and incandescents. And CFLs sometimes flicker. The worst thing about CFLs is that they have a tiny amount of mercury in them so you have to be careful if you shatter a bulb. LEDs, on the other hand, have no mercury and their bulbs are just light diffusers. You can shatter the diffuser and the bulb itself will just keep working. CFLs were a good bridge technology, but if you’re buying bulbs now you should definitely get LEDs over CFLs. Whether you should replace existing CFLs with LEDs right now takes a bit more math that I’ll get into below.
The only thing that can really challenge the LEDs of today are the LEDs of tomorrow. In 2017 the best LED bulbs for sale produce close to 100 lumens per watt. These are still turning over 80% of the electricity they use into heat. For a 9 W LED this is over 7 Watts of heat waste. Some might read that and think that this hurts the comparison with other bulbs, but that’s a misconception. A 13 Watt CFL is like an LED with a 4 Watt heater attached to it; that means it produces about 11 Watts of heat total, and similarly a 60 W incandescent is producing about 58 W of heat total. Of course the 7 Watts of waste heat from an LED could still be improved upon. In 2014 researchers made an LED that produced over 300 lumens per watt in the lab. Packaging this in a bulb with an AC to DC transformer will drop its efficiency, but it should still be well over 200 lumens per Watt so you could have a 4 or 5 Watt LED replace current 9 Watt bulbs. Unfortunately this technology is still not cost effective, but the possibility is there and as time goes on LEDs will surely get more efficient. The question is how long it will take for this improved tech to hit the market. LEDs are already so cheap and efficient that buyers aren’t really drooling over another 4 Watt improvement so it may take a while. The smart choice is to replace all your bulbs with LEDs today and revisit the issue every 5 to 10 years.
Why is Spring the Time to Switch Bulbs?
With the warmth of spring upon us we start to be able to shut down our furnaces. If the weather is right it can be a blissful time of open windows where no heating or AC is needed. But, soon we know that the heat of summer will be upon us. When the heat from our old incandescent and CFL bulbs will have to be removed by our AC systems. In the winter we could live with having heat lamps on in our houses because we were heating them anyways. But as summer comes on we need to get our lighting to tip top efficiency.
How Much are People Saving with LEDs?
How Much Does Energy Cost
To figure out how much money can be saved, first we need to know how much energy costs. Energy is sold in kilowatt hours (kWh), which is equivalent to using 1,000 Watts of energy for an hour. For example, if you ran ten 100 Watt light bulbs they would be consuming 10×100=1,000 Watts of energy. If you had them all turned on for 1 hour you would have used 1,000 Watt hours of energy, aka 1 kWh. How much a kWh costs depends on a lot of things. The average cost per kWh in the US was a bit over 12 cents in January 2017. It was just under 12 cents in 2011 so it’s been remarkably stable over the past few years.
The price individuals pay can vary a lot based on other factors. Where you live can make a big difference. Hawaii had the highest average price for a U.S. state in January 2017 at over 28 cents, while Louisiana had the lowest at just under 8 cents. Utilities are also rolling out time of use rates where you pay more for electricity during peak usage times and less at others. My current plan with APS charges me 24 cents per kWh I use between noon and 7 pm but only 6 cents for each kWh I use during the rest of the day. All of this means that it’s complicated to figure out exactly how much money reducing your energy usage really saves you. Here I’ll just put in a naive 12 cents per kWh and call it a day. If you want more detail I encourage you to rerun these calculations for your own utility’s rates and put the results in the comments below.
There are two big ways that LEDs save you money. First, they use less energy to produce the same amount of light. Compared to a 60 Watt incandescent, a 9W LED is saving you 51 watts. That means every 20 hours you run that LED instead of the incandescent you save a bit over 1 kWh just in powering it. To save the $2 cost of a bulb you need to run it for 327 hours ($2 / $0.12 per kWh × 1000 Watts per kW / 51 Watts = 327 hours). If you use the bulb for an hour each day it will pay back in under a year; if you use it for 4 hours a day it’ll take less than 3 months. Of course if you spend more, say a fancy dimmable flood LED for $5, it will take longer (5/.12×1000/51=816 hours), but even that is far less than the 10,000 or more hours the bulbs are rated to last. Oh, and we haven’t even looked at the cost of AC yet.
So, how much does AC cost you? Well, similar to kWh’s this can vary a lot. The main factor it depends upon is how efficient the AC unit is and this is rated by something called the Seasonal Energy Efficiency Ratio (SEER). Dividing SEER by 3.8 gives roughly how many Watts of heat the AC can remove using 1 Watt of electricity. I say ‘roughly’ here because there are many factors that can move this a little, like outside temperature, humidity, etc. Still, the 3.8 division is a pretty good approximation so we’ll run with it. A fancy modern 22.8 SEER heat pump can pull 22.8/3.8=6 Watts of heat out using just 1 Watt of electricity. That means to pull out the extra 51 Watts of heat that an incandescent is dumping into a house would take 8.5 Watts of electricity using this heat pump. This extra 8.5 Watts adds to the 51 Watts of electricity you are already saving to cut your payback time even further. Now the payback math is 2/.12×1000/(51+8.5)=280 hours. The bulb now pays for itself in just 70 days if used for 4 hours a day.
Of course the above numbers were run using a top of the line AC unit. Unfortunately, most ACs in the US are far less efficient. In 2012 the average SEER value of AC equipment in the USA was calculated to be equal to a sad 2.85. This is because there are still a ton of old inefficient ACs out there. A single Watt of electricity in a SEER 2.85 AC will only remove 2.85/3.8=0.75 Watts of heat. It’ll take 51/.75=68 Watts of electricity for this old AC to suck out the 51 watts of extra waste heat the incandescent bulb is adding. 68 watts is 7.5 times as much power as the LED bulb itself consumes! That means the payback goes to 2/.12×1000/(51+68)=140 hours. If you have the bulb on for 4 hours a day while running this old AC it will pay for itself in just 35 days! After that you start saving nearly $2/month every month you run your AC and use the bulb. Of course you should replace your AC to make it more efficient, but that’s a big endeavor. If you have an old, inefficient AC and there is a single incandescent bulb in your house you need to go buy an LED replacement for it right now; your wallet will thank you. You can even use the immediate energy savings from this bulb to help sock away cash for your expensive AC upgrade in the future.
Multiple Bulbs Multiplies Savings
You might be thinking to yourself, savings one to two dollars a month isn’t that big a deal. Well, you’re forgetting that the above math is just for a single bulb. You likely have tons of bulbs in your house. I have 21 recessed can lights in my main living area alone. Replacing these means I’m saving $20 to $40 per month. That’s hundreds of dollars per year in savings. This multiplication also comes into play if you have old dimmer switches that don’t work well with new LED bulbs. A new LED compatible dimmer switch can be had for $24, if it’s controlling 6 bulbs it’ll be paid for in under two years. After that it’ll just keep saving you money for years to come.
CFL Savings Math
For CFLs the savings come a lot slower. The 4 Watts of extra electricity they use compared to LEDs is 12.75 times less than the 51 extra Watts incandescents use. That means that all of their payback times increase by a factor of 12.75 compared to our incandescent math. Paying for a $2 LED with lighting alone will take 327×12.75 = 4166 hours. This is still less than the expected lifetime of the LED bulb, but unless the bulb is on for 12 hours every day it’s going to take years. Factoring in AC savings helps a bit. If you have an old average 2.85 SEER AC it’ll take 1785 hours. This is much better, but it’s long enough that it’ll take more than one summer to pay back. During the heating season you don’t care about removing the waste heat from bulbs so you don’t get this extra savings over those days. This probably puts your payback somewhere between 2,000 and 3,000 hours even factoring in an inefficient AC. It’s still a decent financial return to replace a CFL, but it’s low enough that if money is your main concern you might prefer investing in the stock market instead. You may find the faster turn on times and better color rendering of LEDs to be reason enough to upgrade though. If that’s the case, make sure you dispose of your old CFLs properly.
What to do With the Old Bulbs?
If you love your old incandescents or CFLs and can’t bear to get rid of them, there is an answer. You can simply put in LEDs in spring and then put back the old bulbs in the fall. This is certainly a bit of work and it’s probably easier to just keep the LEDs in year round, but if you must use your old bulbs till they burn out, this is the economical way to do it. Another good use for old incandescents is to make a heat lamp. Just find an old lamp that takes 3-5 bulbs and fill it with incandescents. Put this in a small office near your chair and in the winter you can turn it on to add a bunch of heat and light to that room. I did this when I used to work from home and I was able to set my home thermostat down to 58 °F but keep my small office above 70 °F with the heat of my lamp and computer. If you do this, make sure to shut the door to the office while you’re heating it and throw a draft stopper under the door to seal the heat in the room.
Disposing of older CFLs is a bigger challenge. Because they contain mercury you definitely do not want to just throw them in the trash. If you’re going to throw them away find a CFL recycling bin. Home improvement stores like Lowe’s often have a box for this right at the front entrance. You can also often find CFL recycling directions from your local dump. Another option instead of throwing them out is putting them in less frequently used places. A friend of mine put all my old CFLs to work in his unfinished basement. He had had incandescents down there and wasn’t replacing them because he only used them for an hour every month or two. Now he has CFLs down there so they’re more efficient at no extra cost. This isn’t saving him much, but if he ever accidentally leaves a light on down there it’ll cost a lot less being a 13 Watt CFL instead of a 60 Watt incandescent.
Well after reading all of the above I hope you’re convinced that spring is the time to replace incandescent bulbs with LEDs. Not only do they use far less energy to make light but they dump a lot less heat into your house so your AC doesn’t have to work as hard. If you have an older inefficient AC the savings will pile up really fast. The LED bulbs will generally pay for themselves before the summer is over and after that they just save you money year after year. Each bulb will likely save $50 to $100 over it’s lifetime and if you think of all the bulbs you have in your house the total savings can really add up. LEDs are so cheap now that it even makes sense to replace CFLs with them, though it isn’t as much of a financial slam dunk. It will likely end up taking a few years for an LED to pay for itself when replacing an already efficient CFL. I hope this guide helps and you start saving money by installing LEDs in your house!