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How to save electricity on lighting

Last Update: September 2015

Lighting is one of the easiest areas to save in. You can start saving a whopping 70-90% right away by simply screwing in new LED or CFL lights.  And if you're concerned about mercury from CFL bulbs breaking, you can either use a CFL that has a plastic cover, or use an LED bulb instead.

Environmental Defense has the best explanation of what's wrong with regular light bulbs:

"Though we call them light bulbs, traditional incandescent bulbs are actually small heaters that give off a little bit of light—something you know if you've ever touched a bulb that's been on for a while.  These bulbs were technological wonders when they were patented in 1880, but today they are inefficient dinosaurs.  They waste energy and money, and they are responsible for millions of tons of global warming pollution."
Light Bulb Cost Calculator    (energy + initial & replacement bulbs)
Your electric rate:  
Five-Year Cost
Wattage
(original)
Number
of bulbs

Hours on
per day

Standard
CFL
LED

$  $  $ 

$  $  $ 

$  $  $ 

$  $  $ 
  Total
See  the calculator assumptions.
$  $  $ 
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There are other easy ways to save money on lighting besides switching bulbs, like putting lights on timers or motion sensors, and just being more diligent about turning off lights you're not using.  A single 100-watt bulb left on continuously will run you $12 a month (assuming 16¢/kWh).

That's the short summary on saving energy on your lighting.  Below are the details, as well as several other money-saving tips.


Use LED or CFL lights.

You have two choices to replace your old-school, energy-guzzling lights:  LED or CFL.  They're both good choices, produce very good light, are direct screw-in replacements for your current bulbs, and save tons of energy.  I recommend LED's which are superior in most ways, but note that only some of them can be used in totally enclosed fixtures, and they'll cost a little more up front (though you'll make that back and more with the energy savings).

If you've heard the scare-mongering about mercury in CFLs, relax.  The median exposure for a broken CFL is 0.07 mcg, while six ounces of Albacore tuna has 48 mcg—700 times as much. (See this paper by LBL scientists for more.)  And of course, you can always use a CFL that has a plastic cover, or use an LED light.

Here's a table showing the difference between the different kind of light bulbs:

Incandescent vs. CFL vs. LED

Incandescent
CFL
LED
Cost
  Cost over 25,000 hours (bulbs + electricity)
$246
$66
$42
  Cost for one 60-watt equivalent bulb
$0.37
$1.24
$1.99
  Cost over 25,000 hours (bulbs only)
$6
$6
$2
  Cost over 25,000 hours (electricity only)
$240
$60
$40
Life
  Life (in hours) 1500 5000 25,000
  Life reduced by cycling on/off A wee bit
A little bit
Not at all
  Light output over its life Constant ~70% of initial brightness
by end of life (30% drop)
Applications
  Dimmable
All models
Some models
  Can be used in enclosed fixtures All models Some models
Rare models
  Good in freezing temperatures
All models
Rare models
All models
Characteristics
  Light quality
Excellent Excellent Excellent
  Time needed to get fully bright
Instant
~1 minute
(some models are instant)
Instant
  Heat generated (source, source 2)
A lot
A little A little
  Toxic mercury
No
Barely
No
  How breakable
Fragile
Fragile
Strong
  Watts for 1600 lumens 100 25 16
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When shopping for lights, you'll probably want to choose warm white or soft white, which is the kind with the pleasing yellowish tint.  By contrast, cold white is the harsh bluish light.  The color temperature (often printed on the package) tells you exactly how warm or cold the light is.  Warm is 2700-3000k, and cold is 3600-5500k.

Lumens-to-Watts Converter
Lumens
Incandescent
Watts
CFL
Watts
LED Watts
250
25
7
4
450
40
11
6
800
60
15
10
1100
75
21
12
1600
100
27
16
Yes, manufacturers fudge their numbers, and comparing apples-to-apples is difficult anyway because different bulbs send light in different directions.  But for practical purposes, this table is usually accurate enough. And despite some claims that LEDs require just as many watts as CFLs to output the same amount of light, my own test showed an 8w LED to be comparable to a 13w CFL.

Many online retailers don't bother to tell you how bright their LED lights are in watt-equivalents.  A rule of thumb is to just multiply the LED wattage by 5 or 6.  So if you're looking at a 10-watt LED, it's a 50- to 60-watt equivalent.  I also recommend checking the lumens, which is a measure of brightness.  The table at right shows how many lumens you should be looking for depending on what kind of light you're buying. 

When buying CFLs, make sure they either have the Energy Star logo or come with a warranty.  The cheaper CFLs can burn out really fast.  I have a separate page which covers CFL's in more detail, including the real story behind the mercury warnings.

Halogen lights are similar to traditional incandescents, except they use 20-30% less energy.  They're definitely inferior to CFLs and LEDs which use 73-84% less energy, but if for some reason you can't stand CFLs or LEDs, then halogens are an option.

 

The Light Bulb Ban

Legislation passed in 2007 required light bulbs to meet a minimum efficiency standard, which effectively banned old-school incandescent bulbs.

  • Jan. 1, 2012: 100-watt bulbs phased out
  • Jan. 1, 2013: 75-99 watt bulbs phased out
  • Jan. 1, 2014: 40-74 watt bulbs phased out
  • <40-watt bulbs not affected by the legislation (source)

Rabid right-wingers frothing about this supposed affront to the free market have failed to notice that the legislation was signed into effect by that notorious socialist, George W. Bush.  And of course, the net result is simply dramatically less energy use (directly translating into less pollution via reduced power plant emissions), and big savings for consumers on their electric bills.  Yeah, what a travesty.


Turn off lights when you're not using them, even for just a few minutes.

The idea that lights use extra electricity to start up is a myth. You'll save electricity every time you turn the lights off, no matter how short the off duration, and whether they're regular lights or fluorescents.

You might have heard that you wear out your lights quicker by cycling them off and on, but that effect is so small it's not worth worrying about, and you can safely turn your lights off every time you leave the room, no matter how short the duration. If you feel you need to obsess over this (as evidenced from all the email I get about the subject) then see my answer about fluorescent cycling costs.

Yes, old-school lights really do waste energy.


Some readers have argued that incandescent lights don't waste energy, because the extra energy they use helps to heat the house, sparing the heater.  They're missing two things.  First, almost nobody uses only heat and not air conditioning.  The extra heat helps in the winter but hurts in the summer (when you're paying for the AC to remove it), so it balances out.  Second, heating with electricity (which is what you get from light bulbs) is more expensive than heating with natural gas or fuel oil.

Use a motion sensor for outside lighting

Exterior security lights automatically shut off after 1-15 minutes, so you're not paying to run them all night. Fixtures start at $20 at home improvement stores like Home Depot. Do not that you can't use CFL's in security lights though, because the fixtures cycle a very small amount of voltage through the lights constantly which makes the CFL's die a lot faster.

Exercise: You buy a security light for $20. The light used to be on all night, for 12 hours each night.  Now it's on for about an hour a night.  You're using two 75-watt bulbs in the fixture.  How long does it take for the security light to pay for itself?  (assume electricity costs 15¢/kWh) (see answer)


Put nightlights on photosensors.

You can get a simple screw-in photosensor for $4.50 ($8.50 for the outdoor version) which will automatically turn your light on at night and off during the day. You just screw the special socket into the existing light socket, then screw the light bulb into the special socket.

Exercise: How long does it take for one of these $4.50 devices (indoor version) to pay for itself, assuming you were using a 60-watt bulb, paying 15¢/kWh for electricity, and saving 12 hours per day of light use? (see answer)
You can also make lamps or other devices go off during the day and turn on at night by using a plug-in light sensor ($6). You plug the appliance into the sensor, and then plug the sensor into the wall. If you're handy with electrical wiring, you can mount a light sensor to a wall (like you'd mount a light switch or electrical outlet). Wire-in sensors are around $10.

Use a motion sensor for interior lighting.

If you can't remember (or can't be bothered) to turn off the lights throughout your house, a motion-sensor switch will shut them off for you automatically. You can buy motion-sensing wall switches for as little as $10 at a home improvement store.

Use the lowest-wattage bulbs for lights that are always on (e.g., stairways).

Replacing 75-watt bulbs with 15-watt bulbs reduces energy usage by 80%.

Replace fluorescent magnetic ballasts with electronic ones.

For long-tube fluorescent lighting (as opposed to screw-in compact fluorescents), an old-style magnetic ballast might use 100W to power two 40W tubes, while an electronic ballast might use only 60W. Also, the electronic ballast eliminates flicker and usually eliminates hum. They also generate less heat, which saves additional money on cooling.

Use LED holiday lights.

LED Christmas lights use 84% less electricity than standard holiday lights (which use 25 watts in a typical 50-bulb strand). LED lights also generate much less heat, so they're less likely to catch your Christmas tree on fire.  Another advantage is that the LED's are virtually indestructible?they don't burn out like normal bulbs (not for about ten years, anyway), and they're not fragile like normal holiday lights.  I actually unsuccessfully tried to crush one by standing on it on a concrete surface. I broke the decorative casing but was unable to break the LED bulb itself?it still lit up just fine when I plugged it back in.

I put a few strands of LED Xmas lights on the ceiling and use it as mood lighting.  (Yeah, I know the packaging says not to use them for permanent installations, but that's just how I roll.)

Inirgee sells a nice variety of LED lights in a variety of colors: 120V holiday light strings, and 12V holiday light strings to be powered from a battery. Notably, most of the products carry a lifetime warranty.

I have a separate page about rewiring Christmas lights to run off batteries.

 

Use solar or LED landscape lighting

Replacing your old landscape lighting with solar or LED can save a fair amount of money.  Don't be fooled into thinking your existing lights are low-energy just because they're "low-voltage".  A low-voltage system uses the same amount of energy as a high-voltage system, since it's the watt-hours you get charged for, not the volts.

Solar lights are great, but absolutely buy a model with a warranty.  Many of the cheap solar landscape lights on the market now last only a year or two before the solar panel wears out and the lights are useless.  Yes, I know the price is really attractive, but don't skip the warranty!


Skylights lose more energy than they save


Skylights save energy on lighting, but they lose more energy from heat entering in summer or escaping in winter.  If I can ever find the time I'll write an article on that subject.


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All advice is given in good faith. We're not responsible for any errors or omissions. Electricity can kill you; if you're not competent to work on your electrical wiring then hire a professional to do it.
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