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Lifecycle Energy Showdown: CFLs vs LEDs

2 February 2012

Compact fluorescent light bulbs (CFLs) use 75% less electricity than older incandescents, and light emitting diodes (LEDs) use even less – but how does their energy use compare when you take into account their whole lifecycle, from creation to destruction?  A study done by the Green Design Institute at Carnegie Melon University compared the energy use of these three types of light bulbs with production, manufacturing, and end of life included. An LED bulb, or solid-state lighting (SSL) as it is called in this study, takes approximately 15 to 20 kWh to manufacture and will last for 25,000 hours. This is less than 2% of the total energy used in the life cycle of a LED. Your typical CFL takes 2.2 kWh and lasts about 7,000 hours, and a 60 watt incandescent takes only .9k Wh- yet it also only lasts 1,000 hours.

The above graph shows the energy use for 25,000 hours of light- which is the lifetime of a LED bulb. From this it is concluded that for the same number of hours and lumens- the life cycle energy use of CFL and LED are, for all purposes, the same. Yet,within the next three years LED technology is expected to make large improvements in manufacturing and lumens/watts. When this happens LED technology will be much more energy efficient in comparison to CFLs (refer to the last bar in the graph above). This is because the higher lumens/watts, the more energy efficient the bulb is. 

This is an interesting and I think important perspective to consider when thinking about new higher efficiency lighting technology.

Green Institute study article 1   Article 2

7 Comments leave one →
  1. 2 February 2012 10:15 am

    “When this happens CFL technology will be much more energy efficient in comparison to CFLs”

    First “CFL” should be “LED?”

    • 2 February 2012 10:16 am

      Eric, you are FAST!! Thank you for pointing that out…corrected 🙂

  2. Buggar permalink
    2 February 2012 12:16 pm

    Is this a purely academic study? A box of CFLs has a half life of 3-6 months at my house. Many different brands have been tried by the way. They are horrible to use in bathrooms because of the 5 min warm up time. Who wants to leave their bathroom light on all day? I have 60 watt incandescent bulbs that were installed by the builder of my house back in 2005 that are still working. I can’t say that about ANY CFLs I bought then. I mainly use CFLs but hate their cost/reliability, color, and warmup time. My 48″ tube lights in garage and basement are much more reliable. LEDs? I’ll be the first in line when they drop under $10 AND they get the lumens and color quality right. $50 at the store? keep em!

    • 2 February 2012 12:22 pm

      Sorry to hear about your negative experience with CFLs. Are any of the fixtures you’re having issues with dimmable?

    • 3 February 2012 11:10 am

      I’ve heard other people talk about CFL longevity & warmup issues, but I really haven’t had much trouble here. There were definitely some shoddy ones on the market for a while though; if you’re game, maybe do an experiment with a couple new, energy-star certified ones, and see if they’re any better?

      For LEDs – Xcel is subsidizing the Philips 60W LEDs at Home Depot right now, for $15 each (in the twin cities anyway). They are still a little pricey but to my eyes the light output is fantastic, and they should in theory last a very long time.

  3. Auntie K permalink
    17 February 2012 3:54 pm

    Where can I find this Carnegie report to read?

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