Published 22 June 2009.

Update to my earlier CFL article

I see that Consumer NZ has just completed (June 2009) a test of some CFL’s available locally in New Zealand and I am encouraged by some of their results.

You might want to read my original article of April 2009 first: Go to original article.


I claimed that an 18 watt example that I tested produced only 85% of the light of an 60 watt incandescent. Consumer compared 20 watt CFL’s against an 100W incandescent bulb. Some of their CFL’s produced less than 80% of the light of the incandescent, but they did find several CFL’s that gave more light. You have to carefully select brands. Consumer didn't look at the light spectrum for comparison however. CFL’s are ’spiky’ in their light spectrum and they do not have the smooth uniform spectral output of incandescents. Non uniform spectral output can look un-natural.

On-Off switching

I said that CFL’s are not suitable for frequent switching on and off. Consumer gave their CFL’s a switching test of over 6000 cycles. Some did fail, but most did not. This is encouraging and it seems some manufacturers have addressed the problem, but again, you have to get the right brands.

Light output reduces over time

This is where I disagree somewhat with the Consumers protocol. They measured the light output after the 6000 cycle switching test and found all lamps produced nearly as much light as they originally did. In my view a switching test does not make an adequate ‘life’ test for the purposes of measuring light output. CFL’s are fluorescents. The emission will reduce with age and that means it is related to hours of operation and not on/off cycles.

Savings to the household

Consumers have a calculator on their site which works out your household savings if you were to replace your bulbs with CFL’s. I ran their calculator and compared the result to my original estimates. They got about 50% more savings than I calculated using my original assumptions. The main reason for this is that they assume all your original bulbs are 100 watt and that you replace with 20 watt CFL’s. I had a mix of 100 watt, 75 watt and 60 watt bulbs in my scenario. This would make for lower savings. I note that Consumers did not factor in the higher cost of CFL’s to the saving, because of the long life attributed to CFL’s. I think the cost should be factored in, because the life of a CFL may only be twice that of a incandescent, although it may also be five times or more. Furthermore, their recommended CFL brands are the more expensive ones.

Nonetheless, the savings of power consumption achieved for an individual household are significant enough to warrant a replacement plan. Bear in mind that you cannot run standard CFL’s in a dimmer circuit or in unsuitable fittings. If you want a dimmer you must buy a special dimmer unit plus a suitable dimmable CFL. These cost more and will erode some of the potential savings.

Savings to the country

My original article was about comparing the bulb types for the purpose of making national savings. This is different to the goals of the Consumer article, which is focussed on reducing costs to individual households. The main difference is the power factor of CFL’s which can be quite poor. Household electricity meters do not respond to loads with poor power factor but the country has to generate and distribute power accounting for it. This makes the equation look worse than is claimed for CFL’s. The Consumer NZ article did not address CFL power factor.


The Consumer NZ article does give some redress to CFL’s mainly in terms of their light output and reliability. They make it clear that some brands are better. The better ones are somewhat more expensive. I still think they need to be used wisely, and they are still not a universal replacement for incandescents.

Note: I have intentionally omitted detailed results of the Consumer NZ test. It is not my place to make their advice freely available. Go to and locate the article. If you are not a subscriber, you can buy just the article.

From: D.Helmore
24 July 2009


When I am under compact fluorescent light bulbs (CFLs) including the newer more efficient ones even for a short time, I suffer extreme headaches and dizziness which take some time to wear off. I have discussed this with someone at National Radiation Laboratory, Auckland University and my doctor, and their advice is to avoid them as I am obviously allergic to them. That's all very well, but avoiding them is going to become impossible if more people get them. Do you have any answer to this? When I visit people who have them I have to bring my own incandescent bulbs and ask them if I can fit them while I am there, as you can imagine a socially disruptive performance.

From Richard Petty, Pat Booth column, Central Leader, Auckland, 16.7.08:

"A single fluorescent light flickers on and off 100 times a second. While this is not discernible to the human eye, it cases headaches and eyestrain in many people. In offices the fluorescent light fittings contain two or more tubes which operate out of phase. For example: A four tube light fitting will have two tubes "on" and two tubes "off" thereby reducing flicker. Even then some people need an incandescent desk light to overcome the problem of eye strain. More people will suffer headaches and eyestrain as a result of this decision. I wonder how much this suffering will cost in lost work days, doctor visits and medication."

While working as an illustrator at University College London, DSIR and Landcare Research (NZ) I used an incandescent desk light like everybody else doing similar work (like architects or draftsmen/women) because working under neon was impossible for any length of time. I can't imagine anyone doing any sort if work under CFLs, which are much worse than neons.

From Naomi Meltzer, letter to NZ Herald, 19.8.08:

"As an optometrist, I am finding many people struggling to read with so-called energy-saving lights. As we age, we need more light and good-quality lamps for reading. The eco-lamp gives off light horizontally, rather than vertically downwards as an incandescent bulb does, and gives a gloomy and inefficient light. Are we really going to save the planet by struggling with poor-quality light? Who is really benefiting by pushing for this?"

Some people I know have reverted to using incandescent bulbs because they could not read with CFLs, and found them unpleasant in spite of the minimal savings in electricity. They're usually relegated to the porch.

CFLs may be "holistic", whatever that means, but to me they're pure poison, so please don't tell me to get used to them. They're certainly not "environmentally sound" if they cause distress to people. If incandescent bulbs are phased out, I can imagine being unable to go out at night and sitting at home with a candle.

Why are you pushing the introduction of these horrible lights? Is it worth it for the minimal electricity savings? Have you thought about the affect of them on young children? .

From: Axino
20 September 2009


D.Helmore makes some interesting points in his comment to my previous CFL article but I do not agree with some of them. I should add that I have no medical qualifications which would allow me to confirm or refute the veracity of the claims made regarding physiological effects caused by CFL's.

I have performed some further experiments to try and confirm the assertions made by D.Helmore. Go to: More CFL experiments. These are engineering tests that may or may not assist, but cannot support a conclusion of the presence, or not, of physiological effects to humans by CFL's.