Wednesday, 23 September 2009

Lamp Guide

Now that the market is being flooded with such a confusing profusion of different lamps to replace the incandescent bulb, it is more difficult than ever to find the right lamp for the right place.

Swedish national TV consumer program Plus last week tried to sort it out with the help of Kalle Hashmi at the Swedish Energy Agency, STEM. [1] My translation of his unusually informed and balanced recommendations:
* In closed luminaires it is not advisable to use CFLs as they get too hot which shortens their life. Where you have very short burning time, such as in a closet or the bathroom, the lamp life will shorten significantly if you turn it on and off a lot. In such a situation you could preferably choose a halogen lamp.

* If temperatures are too low [= outdoors in northern winters] the [CFL] lamp does not perform at its best. The lamp is made to function best in 25 degrees [C]. In such a situation we think the best option is to use an induction lamp. Very expensive but on the other hand it lasts 100 000 hours.

* When you get older, 60+, you need more light to be able to see, and our ability to distinguish colours and contrasts diminishes. Then we need to choose a light that solves all three problems.

* When it comes to contrast, for example, it is usually limited to reading text, black on white. Then you need to choose a CFL with higher effect, e.g. 15W and you can use a correlated colour temperature around 4000K, but only for reading.

* When in a situation where colour rendition is very important, where you need to match colours, then it is very important to use a mains voltage halogen lamp because it has much better colour rendering capacity. It can be a situation like cooking, where all colours seem matte to the eyes. So what an elderly person perceives as 'brown' may actually be burnt. With halogen you see better.

* CFLs are not the answer to all our prayers. When it comes to colour rendering they are not as good, and they also contain mercury. LEDs will be the dominating technique, but it's better to replace low voltage spotlights with LED spotlights than replacing standard bulbs for general lighting.



My comments: Good advice all of it, except for the recommendation to use cool-white CFL for reading. Some research suggests that contrast decreases rather than increases with higher correlated colour temperature (blueness) and that certain blue wavelenghts may harm rather than help in cases of macular degeneration. [2] The small traces of UV which some naked CFL tubes emit may at close range may also worsen cataracts and skin conditions. [3] If you sit closer than 30 cm for more than an hour per day, the the British Health Procection Agency recommend that you use a covered CFL with an extra outer bulb. [4]

I would instead recommend frosted incandescent or halogen for reading, as clear bulbs tend to give disturbing light patterns on the page and most LEDs are either too dim or too directional. Unfortunately, thanks to the European Commission, that's no longer an option.

Replacing spotlights with LED is a better idea as LEDs are already directional by nature and perform better as reflector lights than as omnidirectional light trapped in a bulb - if you don't mind the slightly lower light quality and paler colours which can be seen clearly in this comparison between 'warm-white' & 'daylight' LED and incandescent downlights [5]:


More tips:

* For those who prefer a daylight-simulating light despite the lower contrast, white LEDs are naturally cool-white and need no special phosphor mix like CFLs, or neodymium filter like incandescents, to achieve a daylight look. Daylight lamps usually look best in the daytime. At night the cold light can look and feel more unnatural when contrasted against the dark, as we humans are traditionally used to fire light at night (though cultural and individual preferences may vary).

* Where warm-white incandescent type light with perfect colour rendering is needed, there exists no replacement other than halogen. No CFL or LED has that special sunny feel and warm glow which makes colours come alive. The next best thing after halogen would probably be metal halide HID reflector lamps, but they're usually too bright to be used at home and require special luminaires.

* In traditional environments with antique furniture and art, CFLs and LEDs tend to look particularly out of place, whereas they may look acceptable with more contemporary designs, even if a bit dull.

* CFL and LED have zero romance factor when it comes to mood lighting of your dinner table, cosy corner or favorite restaurant, whereas halogen or incandescent spots on dimmers will complement candle light and create an attractive, romantic and relaxing atmosphere. More so the warmer, the dimmer, the lower down in the room, and the more directional & narrow-beamed the lighting is.

* Around children, I'd use only LEDs or incandescent lamps (preferably frosted in all open luminaires, if EU hadn't banned them, and clear in enclosed & shaded luminaires). CFLs contain mercury and can break, whereas clear halogen lamps can get too hot, bright and glaring.

* For night-lights, I would use LED. Even if you only save 6 watts per lamp, they're usually on all night, every night.

* Any coloured lights, e.g. Christmas lights, signal lights in cars and traffic signals, stage lighting etc. can be replaced by LEDs. LEDs come already coloured and are often ideal due to their smallness and lack of excess heat. Using top quality incandescent light only to filter out most of it with a colored filter is truly a waste! Except in cold climates where the heat helps melt the snow on traffic signals.

More photo comparisons between different lamp types can be found here:
http://snarkish.com/cgi-bin/forums/ikonboard.cgi?act=ST;f=12;t=10654
http://www.popsci.com/environment/article/2009-09/better-energy-efficient-light-bulb http://www.hamhelpdesk.com/?p=914#more-914
http://apathyball.blogspot.com/2009/09/led-tints.html

TreeHugger CFL guide:
Be Careful When You Shop For Compact Fluorescents

Lighting design tips:
GE Lighting Style
Philips Lighting for the Home
Philips Lighting Design tool

References:
1. Plus, SVT, 17 sep 2009 http://svtplay.se/t/102796/plus
2. Artificial Lighting and the Blue Light Hazard
3. SCENIHR: Light Sensitivity
4. HPA - Emissions from compact fluorescent laights
5. Picture from http://www.ezdiyelectricity.com/?p=735

11 comments:

  1. This is great
    The more you think you know, the less you know
    (another version of what lights to use and where
    http://www.ceolas.net/#li8x)

    I like the photo on the right best... incandescent it turns out, of course...

    Thank you also for the note about clear lights throwing odd reflections on pages etc:
    This is very true, I just checked - having just used frosted in reading lamps, I was not aware of it, it's actually very noticeable.
    Being more or less point source lights it makes sense.
    Quickly bought some more candle lights...
    had been a bit relaxed about it, thinking "well can just stick in clear lights instead".

    And all this nonsense,
    because the ruling political clowns in Europe can't/won't deal with the emissions themselves,
    and/or stick a tax on light bulbs to give them the state income the governments all say they need
    (last year 2 billion - yes, 2 billion - incandescent light bulb sales in the EU, as in the USA).

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  2. I've stocked up on 40W frosted lamps for reading, and use a frosted 30W IR halogen energy saver for detailed desk jobs. I find that standard E27 bulbs work best at close range.

    For ceiling lights I use reflector lamps which focus the light down to the floor or table where it's needed.

    For mood lighting (which is what I mostly prefer at home) I use wall luminaires with incandescent or halogen reflector lamps, connected to a remote so they're easy to turn off with a single click when I leave the room.

    I love to have many light points at different levels and light intensities in each room, in order to maximise options depending on mood and task.

    Contrary to what some anti-lightbulb lobbyists seem to believe, having many lamps installed does NOT mean using more electricity, as they only use electricity when turned ON.

    Rather, it's easier NOT to over-illuminate if there is the option of dimmer (or dimmable) lamps in the room when you don't need as much light. It's of course not number of luminaires that count, but how many is in use, and for how long.

    Some examples from my home:

    * I have an Art Deco luminaire I only light if I have guests.

    * I have a couple of dim peach lamps I only use when I light a fire, to match the firelight.

    * I have a reflector lamp over the freezer I only light to see what's in it.

    * I have countertop halogen ramps I only use when cooking or washing up.

    * I have ceiling triple-spots I only use when cleaning.

    * I have light tubes I only use around Christmas.

    I'm sure its similar for most people.

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  3. Yes sounds familiar..
    shows the value of variety

    Compare the advice (even if supposed savings were true) of
    "Switch all your lights to CFLs and save lots of money"
    with something like
    "Eat only bananas and save lots of money" :-)

    Also,
    what you say of more lights = not necessarily more energy waste,
    try telling that to some pro-ban politicians...

    The more people that repeat the same thing,
    the more true it is assumed to be
    (clever politicians talking about "saving energy output of Romania" "CFLs lasting 10 times as long and with 80% energy saving" etc)
    Nice simple figures and illustrations are given for journalists and news-repeating bloggers to regurgitate, which they happily and uncritically do.

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  4. Yes, it never ceases to astonish me how few actually bother to check the facts before mistaking a simple PR slogan for truth after it has been repeated enough times.

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  5. I've just read this re "white leds"
    http://gadgetwise.blogs.nytimes.com/2009/09/24/is-this-the-lightbulb-of-the-future/?apage=2#comment-39295

    "Fluorescents (CFLs) produce light by using the phosphors coating the tube to convert UV from excitied mercury vapour to visible light.
    There are different phosphors for different part of the spectrum, which determines the color cast. White LEDs use basically the same process — a far-blue or UV LED covered with phosphors. CFLs and white LEDs produce very similar light. Their light spectrum is “bumpy”, due to the contributions of the different phosphors, whereas incandescent light and sunlight have a smooth spectrum."

    -- white Leds not that great either?

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  6. That's correct. That's why LED light looks more fluorescent than incandescent: because it is.

    But where most "warm-white" CFLs tend to look more or less pink-white, the "warm-white" LEDs I've seen tend to look more yellow, or sometimes even green.

    The GU10 LED spot I tried at home for my Energy Saver Review made the room look just as dull as any CFL would. Only when I switched back to halogen did the warmth return and colours come alive again.

    I've sent for more LEDs now (one Cree) to see if more expensive ones can look better than that. So the jury is still out... just not impressed by what I've seen so far.

    I had hoped the RGB type LEDs would give a better white but the two I've tried didn't even produce a white. Please let me know if you find any that do.

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  7. interesting...
    one would think that rgb combination was the best:
    but that being unwieldy, and in order to give a common look, that they were therefore using CFL-like phosphorence for white output compromise.

    Incidentally, I thought I might be wasting my time stocking up on bulbs in view of new LEDS (like the bulb before you showed) flexibly being able to be adjusted for different color temperatures:
    Color temperatures are of course only part of light quality measurement (conveniently fogotten by CFL daylight extollers)
    but I was assuming (er, hoping) the rendition, the spectrum output, was being solved too...

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  8. "US CFL sales drop sharply"

    http://greeninc.blogs.nytimes.com/2009/09/28/as-cfl-sales-fall-more-incentives-urged/

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  9. Thanks, I just saw someone else mention this article and was about to search for it.

    Should blog about this.

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  10. Removed spam/fake comment posted by jack.

    ReplyDelete