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***Update – 10/4/09 – I have an improving lighting cost comparison that includes a lighting calculator and includes a residential LED bulb. See the incandescent, CFL, and LED lighting cost comparison and calculator.
In the last few months I’ve heard this statement twice: “I want to conserve energy. I plan on changing out my incandescent bulbs to CFLs as soon as they burn out.”
While thinking of CFLs is a great start, there is no need to wait until your old bulbs burn out. If you do a life-cycle analysis (which I have done below) it makes much more sense to replace the incandescent bulbs immediately! This is not just from a “save the Earth” perspective, but especially a cost savings one.
Based on the cost of electricity at .09 cents/kwh, a regular old 60 watt light bulb would cost you $10.80 over its 2,000 hr life. The 14 watt CFL equivalent’s electricity cost would only be $2.34 over the same 2,000 hrs (plus the CFL will last another 4,000 hrs after that)! The only way it would not make sense for you to immediately change that old bulb is if the CFL cost $8.46 or more, which I can assure you they don’t ( I get mine for around $1.50 a pop). So what are you waiting for?
The figure below displays 3 different scenarios for a 10-year lighting analysis. The light is assumed to stay on for 4 hours a day, 365 days/year, for 10 years. The first case is all incandescent, the second case is all CFL, and the third case is you replace the incandescent after it burns out, and use CFLs after that. As you can see, immediately replacing the regular bulbs with CFLs provides the best payback!
-click on the thumbnail below, then move it around the screen if necessary
The scenarios ignored one thing. How are you heating? If like many people it is winter and you are using electric baseboard heating, the lighting energy use is just part of the heat delivered to your home. I personally believe the radiant heat from an incandescent light is more efficient at warming my body than the convected heat of baseboard heat. I have replaced almost all my incandescents with CFLs but I keep the one next to my reading, tv watching, computer using chair, an incandescent. I also have began to replace some CFLs with solar powered LEDs that I assemble from solar garden lights, leaving the solar panel outside and bulbs inside connected by long wire. I also have installed a switch so these are on only when I want. This appears to work well, and avoids a lot of the mercury waste of the CFLs, CFLs are great when applied [properly but daylighting and LEDs are the true energy champios we need to embrace.
Ed,
I will concede that incandescents do help heating in the winter, but they also help heating in the summer, which most people don’t want! I would like to see if Rocky Mountain Institute or any of the other organizations have done an analysis comparing which saves more energy: using incandescents in winter (helping use less heat) and CFLs all other times, or just using all CFLs. I’m sure this depends on which region of the country you are in, but it would be nice to see several different scenarios.
I did not know that I was questioning your statements but rather I felt I was contributing further knowledge. As to the rightness of my comments I am sure that wherever you have an incandescent bulb shining on your body, that radiant heat is superior to almost any other kind for keeping you comfortably warm at the lowest temperature. This is why heat lamps work so well in the bath, and why even small fake electric fireplaces close to you body allows you to turn down the central heating system. I am always colder than my wife and if I do something like this I can turn down the temperature at least 1 degree and still feel comfortable. Comfort is not a point on a graph. It is a complex set of relationships, including activity, air temperature and humidity, temperature of surfaces in the room, method of delivering heating, air movemenmt, and your own preferences. Of course CFLs are better in all locations in a warmer climate, since they do not add heat. I replace my incandescent bulb with a CFL in the summer. I go back to incandescent in winter. I love studies by Rocky Moiuntyain Institute but I think they would tell you I was correct for my individual case , which is what we all have to be to really save energy. I just believe that if we think for ourselves we will save a lot more than trying to met some average or most often situation. I will always learn from brilliant people like Amory Lovins , but I can hardly expect him to design the best system for me. So when I tweak my own system a little I do it because I am sure, from 60 years of living on this earth and having a fascination with efficient heating systems for the last 30 years, of my decision.
I believe you forget some factors, including life cycle transport from China, recycling etc, see http://www.ceolas.net/#li13x onwards
also full facts re heating see http://www.ceolas.net/#li6x
In general while consumers may benefit from energy refficiency,
it’s hardly for governments to decide:
the energy supply is not a problem,
and emissions can be dealt with, including funding, as also described
on the ceolas.net website
Peter, thanks for the comment, but I was merely doing the cost analysis from a consumer standpoint, not a life-cycle analysis from an environmental standpoint. It all depends on what the consumer cares most about. If it is just saving money then the CFL is the hands down winner. If it just saving the environment, then more analysis needs to be done to look at shipping costs, how the product is manufactured, how it is disposed of, packaging, etc…
Re
“Peter, thanks for the comment, but I was merely doing the cost analysis from a consumer standpoint, not a life-cycle analysis from an environmental standpoint.”
Well, if you did read http://www.ceolas.net/#li13x onwards it’s clearly from a consumer standpoint,
including why the savings arguments don’t hold up.
Lifecycle only starts at http://ceolas.net/#li16x !
….continued…..
…continued… (think there’s a spam block on links, understandable enough!)
“If it is just saving money then the CFL is the hands down winner.”
No, that’s not true, the power factor argument alone (as discussed on other lighting posts here) halves the advantage,
added to lifespan issues etc as on http://ceolas.net/#li15x, heat factor as discussed http://www.ceolas.net/#li6x is in several studies in temperate climates halving the advantage again, and so on… cutting dowwn the advantage all the time.
Typically 3% of total energy usage is saved by a switchover of all lights
http://ceolas.net/#li171x
hardly a hands down reason for a switch – I have no reason to favour one figure over another, but so many sources question the “status quo” that it at least should be open to question
…continued….
…continued….
Many like yourself see it as a challenge to save energy, fair enough – and interesting site here too, just exploring it more now
-as long as it’s an individual decision by the paying consumer, not subject to regulation by politicians…
Society doesn’t need to force people to save:
See the “Why all energy efficiency regulation is wrong” from http://ceolas.net/#cc1x onwards
and summary of why light bulb bans are wrong http://ceolas.net/#li01x
In short, energy supply is not a problem, emissions can be dealt with directly as described on the website (light bulbs don’t give out any gases!) and consumers can consider cost savings against all the usage advantages that inefficient products have, or noone would buy them…
Peter, I’m getting ready to go to the Pub (by the way, isn’t it pretty late in Ireland right now), so I’ll have to give you a more detailed analysis later, but one point:
You say society doesn’t need to force people to save, but I dont know that this is true. Society doesn’t pay the true cost of Electricity because externalities are not taken into account. Does the power company pay for the Emissions that I have to breathe in? Does the power company pay for the mountain that was destroyed to get at the precious coal?
Society pays for these externalities, not the power company, so the true cost is not passed on to the user. This is the argument for Energy Efficiency Regulation.
But, I will say that I am generally against forcing people to buy CFLs….
I agree completely about emissions,
in fact that is the point I make on that website…
Basically,
Markets can deal with energy depletion since the price rises anyway and encourages switching to renewable or (long-lasting) nuclear energy
I have taken out the emission section on my site cause I am rewriting it in view of the current House Bill, but the main point is that
markets can’t deal with emissions because there is no incentive
to cut back on them – cap and trade is a (wrongly) artificial; way to create a market in them.
So political intervention is certainly necessary, if we accept the climate change problem(what used to be called “global warming” except it sounded too good!).
That’s why direct action via renewable energy development and spread in new grid systems as well as CCS (carbon capture and storage, ie put simply “cleaning up coal”) solutions should be explored.
That’s dealing with the problem.
Banning inefficient products (via efficiency legislation) is not.
Does your light bulb give out any gases?
There you go!
In fact, any consumption cutback -if really needed- is achieved by fossil fuel price rise with mitigating action for consumers as explained, and/or efficiency based product taxation giving the double whammy of lowering related emissions and of funding emission reduction more than remaining product use causes them.
Taxation is still not a good idea for many reasons but it is better for all concerned -and for emission reduction- than bans, if direct action (emission-free energy spread / CCS solutions) is felt to take too long.
An extensive study was recently published in the July/August 2009 Home Energy Magazine. It closely examines the effects of the amount of heating load offset by the use of incandescents. It looks at heating degree days and length of season for many US and Canadian cities and also considers types of heating systems and how insulation levels, equipment condition and efficiency factor into the outcome. As summarized: “If [after examining data] there is any question as to whether a CFL conversion will save energy, it means that either the heating system needs to be repaired or replaced, or the insulation needs to be upgraded, or both. Once these things are done, the CFL conversion will save energy. If the climate is so mild that heating and insulation upgrades are not cost effective, a CFL conversion will almost certainly save energy even without them.”
Go to http://www.homeenergy.org to read the full article.
Thanks for the great comment!
Thanks for the link Janice,
RE
“insulation needs to be upgraded, …Once these things are done, the CFL conversion will save energy”
Actually as I say on my link
with references,
once insulation is upgraded the relative benefit of light bulb heat increases – not decreases – as heat is not escaping through the ceiling etc (remember that room heat substantially rises and comes back down from the ceiling)
Also see bans in low emission states
http://ceolas.net/#li11x
There are of course many factors apart from heat as to why cfls don’t save energy/money
I have recently extensively updated re lifespan, brightness and power factor for example
see
http://www.ceolas.net/#li15x
Hi again there Chris,
To summarize a bit and focus more on the cost related issues, like you said
No doubt CFLs can save energy, but not as much as supposed.
To begin with the simple usage factors:
Lost, broken or malfunctioning expensive bulbs cost more to replace than cheap ones.
Meanwhile, the “expensive to buy but cheap to use” concept tends to lose out,
– in rarely used lamps around the house
– in short stay situations, vacations, second homes etc
Brightness problem of CFLs:
Supposed equivalents are not actually equivalent in brightness, so
higher energy using CFLs needed for adequate brightness.
See recent testing of CFL brightness versus ordinary bulbs:
telegraph.co.uk/news/worldnews/europe/eu/6110547/Energy-saving-light-bulbs-offer-dim-future.html
More, with other links: http://www.ceolas.net/#li15rbx
CFL Lifespan
is lab tested in 3 hour cycles. That does not correspond to real life usage and numerous tests have shown real life type on-off switching reducing lifespan.
Leaving lights on of course also uses up energy, as does the switch-on power surge with CFLs
Also, CFLs get dimmer with age, effectively reducing lifespan
Ceolas.net/#li15sox
Power factor:
Few people know that CFLs typically have a power factor of 0.5 – that means that power stations use up twice as much power than what the CFL rating shows. This has to do with current and voltage phase differences set up when CFLs are used.
Although consumers do not see this on their meters, they will of course have to pay for it on their bills.
This is explained with official links including to US Dept of Energy here:
Ceolas.net/#li15eux
Heat benefit from using ordinary incandescent light bulbs
ceolas.net/#li6x
A little bulb near the ceiling may not seem like much, but
room heat substantially rises to the ceiling (convection) and spreads downwards from there. As shown via the above link with American and Canadian research references, half of more of the supposed switch savings are negated in temperate climates.
Effect on Electricity Bills
Inasmuch that energy use does fall with light bulb and other proposed product efficiency bans,
electricity companies make less money,
and they’ll simply raise the electricity bills to compensate
(not least in USA, power companies often have their own grids with little supply competition)
Energy regulators can hardly deny any such cost covering exercise…
One might add that as Scottish and Cambridge university research shows (as referenced on the website)
energy efficient products effectively mean cheaper energy so people just use the appliances more, leave them on etc.
With CFL lighting that is actually advised anyway (due tom on-off switching reducing lifespan, but of course leaving them on as said in turn uses up energy…
OK thanks again for a nicely put together site.
Learning something every time I use it.
Greetings from open4energy
A most informative discussion and excellent points being made by all.
I live in a small two bedroom apartment and recently replaced all the old incandescent bulbs with latest version Energy Star approved CFL bulbs. I have my opinions on what is best to do, but rather than express them I decided to monitor the energy profiles, before and after, using a Watt-up Smart Circuit 20.
Here is the graph, it compares the two sets of light bulbs, each set being turned on in the same sequence, with 15 seconds between them.
http://open4energy.com/forum/home/lig/energy_saving_light_bulbs_0912102218
The theoretical saving from the bulbs is a little under 75% if I adjust for the bathroom fan which remained unchanged. For those needing exact numbers, the peak load for the incandescent bulbs was 819.7 Watts with Power factor of 99% – while the load for the new CFL’s was 230.6 Watts with Power factor of 79%
I then wondered how this played out in real life. I did a second test, monitoring the actual living energy use on our bedroom/office/bathroom circuit for two days, once with the original bulbs and then again with the new CFL bulbs.
Here is the graph of the four days of data, again monitored using the Wattsup Smart Circuit 20
http://open4energy.com/forum/home/lig/energy_saving_light_bulbs_incandescent_cfl_0912142219
Do note that this includes the energy used by my computer in the home office.
Energy use in the first two days was 4657.6 Watt Hours, and in the second two days was 2400.3 Watt Hours, a reduction of 48.46% And much to my surprise, the Power Factor for the CFL two days was above 80% – I believe that the laptop computer with its mechanical reactive power was creating some compensation on the circuit?
And if the energy data is “boring” the graphs provide way too accurate a record of when I worked on the computer, and when someone needed the bathroom in the night ……