Many countries are phasing out incandescent light bulbs. For example, in the European Union, various types of classic light bulbs have been removed from the market in the last years.

The claim is that this process will help reduce overall electrical energy consumption:

By enforcing the regulation of switching to energy saving bulbs, EU citizens will save close to 40 TWh (roughly the electrictity consumption of Romania, or of 11 million European households, or the equivalent of the yearly output of 10 power stations of 500 megawatts) and will lead to a reduction of about 15 million tons of CO2 emission per year.

Critics say that the switch to CFLs won't conserve energy for various reasons, two of the most prominent being that CFLs take substantially more energy to manufacture and that households will require more heating:

An International Association for Energy-Efficient Lighting (IAEEL) study conducted in Denmark, explored some carbon footprint factors, but not all, showing it took 1.8 Kwh of electricity to assemble a CFL compared to 0.11 Kwh to assemble an incandescent bulb. [...] The study did not include the fact that a CFL is much heavier and is more dangerous to handle, and will thus cost more to package, to ship, and to sell. [...] This research also did not calculate the energy required to safely dispose of a CFL and reclaim the mercury. [...]

Because they burn cooler, they cause home heating costs to rise. "Lighting regulations (banning incandescent lights) will increase GHG emissions in Hydro’s service territory by 45,000 tons due to cross effects of a switch to cool-burning bulbs,” explained a BC Hydro spokesperson in 2009 Vancouver Sun article.

Is there any hard data that shows a measurable effect on the overall energy consumption in countries or regions that have already started the phase-out a few years ago? Or is it to early to get statistically significant measurements?

Related questions:

  • Welcome to Skeptics!. It would improve this question if you could cite some of the critics. – Oddthinking Nov 1 '13 at 14:38
  • 1
    @Oddthinking: Thanks for the welcome and the hint. I've added a citation for the criticism. – Heinzi Nov 1 '13 at 16:14
  • 1
    Although the linked claim and most of the body of the question focus on CFLs, the bolded question at the end does not mention them. Should answers to this question include LEDs and statistics about the uptake of them in comparison to CFLs or would you prefer the narrower claim just about incandescents and CFLs, ignoring LEDs? – Ladadadada Nov 1 '13 at 19:18
  • @Ladadadada: Basically, my question is whether the light bulb phase-out is effective w.r.t. energy saving or not, i.e., I was hoping for an answer along the lines of "In country X, there has been a x% decrease in energy consumption in the last years which can be statistically traced back to the phase-out, because ..." CFLs are just an example, since they are commonly used in both arguments supporting and criticizing the claim. – Heinzi Nov 2 '13 at 2:31
  • 3
    The heating argument is a total loser from simple physics.. resistive heating is the least energy efficient form of heating in use, and you have to cool that heat during the summer. – dmckee Nov 2 '13 at 2:58

A very simplistic calculation shows that the initial energy input is quickly paid back. The cited numbers show a manufacturing energy difference of 1.8 - .11 = 1.69 kW-hr = 1690 W-hrs. A CFL with a light output equivalent to a 75 W incandescent bulb typically uses about 20 W, or about 50 W less than the incandescent. 1690 w-hrs divided by 50 watts = 34 hours. So within the first week or two, the initial energy cost has been paid back.

A more detailed study requires a life-cycle analysis that takes manufacturing, transportation, and use into consideration. Fortunately, there is one available. It concludes that the initial extra energy cost to produce CFLs and LEDs is made up very quickly, and they ending up being far better in the long run from an energy use point of view.

The key results of this analysis indicate that the average life-cycle energy consumption of LED lamps and CFLs are similar, at approximately 3,900 MJ per functional unit (20 million lumen- hours). This is about one quarter of the incandescent lamp energy consumption—15,100 MJ per functional unit.

The heating impacts are a bit misleading. True, during heating periods the waste heat from light bulbs helps warm the building a little, and if not there it must be made up for with other sources. Light bulbs are fairly efficient heaters, but not quite as efficient as a small electric heater that doesn't "waste" any energy by producing light, and not nearly as efficient as a heat pump. So using an electric resistance heater to make up the difference would have no impact at all on carbon emissions or electric consumption, and using a heat pump would produce a net reduction in electric use and carbon emissions. If heat from light-bulbs was important for heating houses, we would leave our lights on all the time.

During cooling periods the air conditioner will work less hard if there is less waste heat in the building. The heating and cooling affects may largely offset each other over the long run. To really understand we'd need to know how BC Hydro came up with their numbers. However, I couldn't find any legitimate source for the quote from BC Hydro, though it sure appears on a lot of right-wing internet sites.

  • The reason it might increase GHG emissions is that BC Hydro uses mostly hydro-electric (GHG-free) generators, whereas people use non-electric power for their heating. – ChrisW Nov 1 '13 at 18:59
  • @ChrisW - that's a valid point in Vancouver which has a lot of hydro power available, and low requirements for cooling. Areas which use fossil fuel for power generation or have a higher need for cooling would not see that affect. – Mark Nov 1 '13 at 19:52
  • 2
    "Light bulbs are very efficient heaters" Isn't really correct. They dump a lot of heat, but resistive heating is very inefficient. You get a lot bigger effect for your kilowatt-hour from a heat-pump or even from burning gas directly. – dmckee Nov 2 '13 at 2:59
  • 1
    There is nothing wrong with the simple equations, but the results are theoretical as they make an assumption that nothing else changes. The key question is whether this effect is visible in actual consumption numbers for households or countries. – matt_black Nov 2 '13 at 17:36
  • @dmckee - good point, I revised the wording. Thanks. – Mark Nov 3 '13 at 2:46

In the comments to your question, you ask for percentages.

The total electricity production for Europe is approximately 3,200 TWh:

The savings alleged in the OP are "close to 40 TWh": which is approximately 1% of the total.

The first link above claims to be able to measure small percentage differences:

After a decrease of electricity production in 2011 (-2.2 %), the volume of produced electricity at EU-27 level decreased once again in 2012 by 0.9 % compared to the preceding year.

I wouldn't know how to prove that these savings come from changing light-bulbs. I don't believe that even smart meters know exactly which minor devices (not major appliances) in a home are responsible for what percentage of the home's consumption.

Anyway, 1% is a small percentage.

Households account for 30% of total consumption so that "1% of total consumption" is approximately "3% to 5% of household consumption" -- which is still a pretty small percentage.

The last link tries to answer the question, Is electricity consumption decreasing in the European household sector?, saying,

  • Between 1990 and 2009, the electricity consumption in the household sector in EU-27 grew by 39.0 %, at an average annual rate of 1.7 %. This trend can be explained by rising incomes, higher living standards, a shift towards smaller households and larger dwellings and a growing demand for electrical appliances. In 2009, total household final electricity consumption was 839 TWh (representing 30.9 % of final electricity consumption across a total of almost 200 million households in the EU-27). Between 2005 and 2009, the electricity consumption in the household sector increased by 4.3% and between 2008 and 2009 it increased by 1.6%.
  • In non-EU EEA countries, electricity consumption in the household sector grew by 76.4 % in this period, an average annual growth rate of 3.0 %. Improvements in efficiency of large electrical appliances (leading to a decrease in average specific consumption of 1.5 % per year in the case of refrigerators, freezers, washing machines, dishwashers, TVs and dryers) were to a large extent offset by the use, numbers and size of large appliances as well as a growing number of smaller appliances such as videos and computers (Enerdata et al, 2003). Between 2005 and 2009, electricity consumption in the household sector increased by 13.2%. In 2009, electricity consumption in the household sector increased by 1.1 % compared to 2008.
  • Overall despite the overall increases in electricity consumption in the household sector, just under half of EEA32 countries reported a reduction in consumption as a result of high electricity prices, milder winters and the economic recession, most notable decreases include Malta (-11.6%), Ireland (-6.5 %), Spain (-5.0 %), United Kingdom (-2.6 %), the Netherlands (-2.6 %) and Denmark (-2.4 %).

You can see from the above that there are many factors (other than the type of lightbulb) which affect gross domestic electricity consumption.

  • 2
    A 1% savings each year for 20 years is not an insignificant percentage. – Peter Shor Jun 6 '16 at 14:25

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .