A dim glow from before the lightbulb Conspiracy

There's a story here about a lightbulb that's been going for over a hundred years. It was made before the lightbulb consortium got together and demanded that lightbulbs have a limited lifetime, to guarantee their ongoing sales. 

It's something of a miracle that LEDs have seen light in the market. A victory of technology over control capitalism. A victory for the consumers over the manufacturers. Perhaps a victory for the energy conservationists over generators, but that may depend on the Jevons paradox.

You can listen on 99% invisible.

Sensor lights

One of the problems we came up with in the one-year evaluation was the light in the under-floor store room.

We put a regular ceiling light with a sensor on it, and the problem is that you have to crawl into the middle of the room for it to switch on, since the ceiling is only about 1.4 metres high so the cone of the sensor's sensitivity doesn't spread very wide. My idea of a solution was to move it closer to the door, which should be relatively straightforward.

Their first suggestion was just to put a light switch on it. Since this is a fluorescent tube and it's in a store room, where it could be left on for a day or two, this seems a pretty good place for a sensor.
That night when I put the kids to bed, I noticed that the light was still on in the machine room, where we had been during the visit. This is one of the few places we have a light switch and if the door had been closed, it would have been on for the rest of the month, until next time to clean the filters.
Another option is fitting an external sensor to the light, to switch it on. A further complication with the room is that it has two entrances, around 3 metres apart, so it would be tricky to get one sensor sensing activity in both places. There are sensors for yard lights that react to movement up to 10 metres away, so this should be possible.

The sensor itself sticks down in the middle of the light, which is round with a round fluorescent tube inside. It's not designed to be adjusted, as are most of the other sensors I bought, but I do have a screwdriver.

I was sure to switch off the lights at the breaker when I was doing this. Any kids reading, get a grown-up to help you do this as you might fall off the stool trying to reach the master switches.
The sensor assembly could easily be disassembled from the bracket and the wire was stiff enough to hold it pointing in any direction, so the first thing I tried was putting the plastic cover over it, to see if the sensor could see through it.

At first this seemed successful. After I put the breaker back on, with the lighting-up duration set to the minimum of 5 seconds, when the kids went in from the kitchen the light went on, then they waited for it to go off and went in from the living room and it went on, then they didn't move and it went on again, then they got as far away from the room as possible and it went on again, then again just after it switched off 5 seconds later. Then again, and again regardless of any human activity.
I guessed that the lights were heating up the inside of the cover when they were on, then the parts inside the cover would cool rapidly, which the sensor registered as a movement of heat, therefore switching it off again. So I took the cover off, and it seems to be better. I toyed with making a bigger hole in the cover, but for the moment it's just there with the cover off, working relatively well.

New LED strip light

I just saw this for 2,180 yen. Is it a no-brainer to buy, or would I be another sucker?

We have four fluorescent lights in the house. Fluorescent tubes are cheaper to buy than LEDs for the moment, although they use more electricity and don't last as long. We used fluorescent tubes in three store rooms in the house. We seldom use these, perhaps once or twice a month for the ones upstairs, so the electricity usage is tiny, and the difference in lifetime is insignificant. The underfloor storage is more marginal as we use this more. 

The other fluorescent tube was ready-installed in the bathroom sink and mirror unit. This is used a few times every day and is often left on. There are four advantages to switching it to LED: Lower electricity costs, no need for replacement, instant switch on, and less heat in the summer. 

In terms of electricity usage, we're comparing 9 watts for the LED with 20 watts for a 20-watt fluorescent tube. If we use it for two hours a day, which may be a bit generous, the difference will be around 600 Watt hours per month. At an average 20 yen per kWh, that's around 12 yen per month. Those yens are certainly going to add up, but will take almost 7 years to reach 1000 yen. In a living room or kitchen, and more so in shops or offices, the payback in electricity cost is going to be much shorter. 

I always scratch my head in wonder when I go to the local electrical appliance shop and see the LEDs being promoted and on offer, but looking up at the ceiling there is row upon row of fluorescent tube. Perhaps they get a special deal from the electricity company as they do so much to boost their business!

In terms of replacement, I can pick up a regular 20 Watt tube for around 100 yen, which, relative to the price of the LED is free. The lifetime of an LED is not twenty times longer. Even if it were, the lifetime of the fluorescent tube is still going to be a few years. They are rated with a lifetime of around 9,000 hours. This is 10 times longer than incandescent bulbs, so switching from incandescent to fluorescent is a no-brainer. LEDs are about five times longer again. In the case of our house, the fluorescent tube should last over ten years. That's a theoretical figure, but one practical bit of evidence is a house my parents built twenty years ago, which used all compact fluorescents. It was eight years before they had to change a bulb.

So after a couple of replacements, LEDs are likely to be cheaper than fluorescent tubes as the economics of their inherently lower resource use take over. So in terms of replacement, getting the LED and replacing it now is going to save perhaps a couple of hundred yen in ten years time. Of course, in ten years, fluorescent tubes may have been banned and there may be no choice, since another issue is the pollution from the production and disposal of the fluorescent tube. 

If I had the choice of buying a fluorescent tube or an LED tube for this, then I would go for the LED. This is not really a direct financial cost in my pocket now, but a more general trend of picking the pocket of the planet, and increasing the problems and shortages that our children and grand children will face. Having said this, LEDs are not made out of sunshine and rainwater, and have their own range of dirtily-mined precious metals and toxic chemicals, but there are undoubtedly going to be less of them. The choice is whether to carry on using a tube I already have, or replacing it.

The instant switch on is not a major issue as everyone has lived in Japan for quite a while and is used to that flicker. The summer heat is also marginal. It's brighter in the summer so we use it less, and it is only putting out an extra 10 watts. 

So, for now there is no need to spend 2,000 yen. When the bulb goes, it's going to be sensible to replace it with an LED. Until then, or unless LED-style tubes get to be much cheaper, or threaten going off the market as everyone is installing LED light units, I can put away my wallet. 

The logic of light switches

Here's an example from our bathroom. This is the wall inside the changing room.  The bathroom itself is beyond, through the door. As is typical of Japanese bathrooms, it is a wet room with a drained floor, so the whole room can be used as a shower rather than having to shower in the bath, worrying about splashing water on the carpet, as you often have to do in the UK.

The switch itself is on the left as you come into the changing room, then the door to the bathroom is beyond that, also on the left. One of the switches is for the light in the changing room, the other for the light in the bathroom. Which one is which?

Yes, I thought so too. I suppose when there are lights to the left and right and switches to the left and right, it's obvious that the switch on the right is for the light on the right. Like the ones below, custom-built for our low-voltage tension lights.

Actually those switches are vertically aligned too. They were going to be to the left and right though, corresponding to the two arrays of lights on the left and right of the room.

Anyway, when the switches are vertically aligned, it seems intuitive to me that the top switch is for further away, and the bottom switch is for nearer. So for these switches, the top one should be for the bathroom and the bottom one for the changing room. Don't you think so?

In fact, they are the other way around, and I still sometimes get them wrong. Maybe that's just me, or it's some fundamental difference between western and eastern visual grammar. Or maybe the switches were just connected at random.

Things IV. Power sockets at the top of the stairs.

Doesn't this look a really silly place for a power socket?

Especially when there's lots of space on the other side.

It's an invitation to make a trip wire. Shouldn't this be illegal? Like having a door opening onto a staircase, it is inviting danger. There's another one further down the steps too. What was he thinking? Fair enough having as many sockets as you can, but do you need them where there is a chance of sending somebody tumbling down the stairs and being electrocuted? It was on the drawings and I should have picked it up.

I think the reason it is there is because he wanted to put a power socket with a built in nightlight there. Something that would automatically come on when it got dark so that you can see where the steps are. A very clever invention, apart from the rather obvious fact that you don't necessarily want a socket where you want a light. I suppose they are a good way of making sure that you're using electricity all the time, even if it is just a watt or two. I can just imagine how it was invented by some old fart who had inherited a big electrical company from his dad, and came up with the brain wave when he got home drunk one evening. The next morning, when he told everyone else about his wonderful idea, they all went "yes boss, that's a wonderful idea," massaging his ego and nursing their hangovers.

Also, in the case of our house, it's even more ridiculous as there is a sensor light in the ceiling above the stairs so the lights come on automatically when you walk near them. I told him I didn't want his stupid nightlight power sockets, but he left the sockets in exactly the same place.

Another fossil of a silly decision, carelessly missed in my checking of details, exposed in the house for all to see but few to notice.

Lights in the bedroom

For a start, the main purpose of a bedroom is sleeping, so you have to wonder exactly what the light is for. We're going to get some bedside lights, so we can read before going to sleep. These can be fitted on, or beside, the bed. It seems foolish to permanently fit bedside lights as we may realise the bed is not in exactly the right place.

The room has a window very high on the north wall, so it should get plenty of light in the daytime. So the most likely situation in which we will really need lights is if we get up very early in the morning and need to choose which clothes to wear. There are a couple of built in wardrobes along the west wall, probably opposite where the bed will be along the east wall. The door comes in at the south east corner of the room and sliding doors along the north open into the walk-in closet. The a walk-in closet in the back has its own lights anyway, so even in the scenario of getting up really early, we may not need much light. 

The ceiling is diagonal, underneath the solar roof, but there is a horizontal part in the middle where a beam runs east-west, and a couple of ventilation ducts run alongside it. This seems like a good place to fit some lights. There are several options, below. In each
case, I'd like to choose LEDs, although in view of how little it seems this light will be used, I'm not entirely sure. In a very short time, I suspect fluorescents will look rather silly in a low-energy house.

1. A duct rail with spot lights on
2. Universal downlights that can point in different directions
3. A single, variable light in the middle of the ceiling
4. Regular downlights
5. Double LED spotlights
6. An LED strip light, running east west
7. Single LED spotlights

I started off thinking 1. The duct rail seems like a good idea, as you can move the lights back and forth and twist them around to illuminate what needs illuminating. They seem pretty expensive though, at least for LEDs. You have to get the rail, of course--5,000 yen for a 4m Toshiba rail--and any light fitting that is reasonably priced (under 2 or 3,000 yen) has "bulb not included". Maybe I'm being stupid, and I'm probably not being economical, but I have a problem with any fitting that is designed to exchange LEDs, in a country where the life expectancy of LEDs is longer than that of houses. There are, of course, some existing fittings that LED bulbs can be retrofitted into, but three lights is probably going to end up around 20,000 yen. There are some reasonable duct rail fittings for E26 bulbs, for under 2,000 yen, then with a bit of shopping around, it looks like there are LED bulbs to fit in them for 2 or 3,000 yen each for 5 or 6 watts, corresponding to a 50 or 60 watt incandescents. If the house is delayed much longer, the bulbs are likely to become even cheaper.

The architect's first plan had a row of down lights, two with universal joints to the west, to illuminate the wardrobes, and two fixed to the east. When I started looking at prices, I noticed how expensive the universal down lights were. The cheapest fixed downlight I could find with a built in LED was 3,650 yen. This was 5 watts, corresponding to a 40 watt incandescent, with a CRI of 70. For higher wattage and better colour referencing, they get more expensive. The cheapest with a universal joint was 8,620 yen. In terms of design, uniformity seems like a good idea, so if we need the lights on the west side to move around, then having a row of three of the same lights will look least offensive. Not that people are going to be spending much time looking at the ceiling. Three of these will come in over 20,000 yen.

So by the time we've made these allowances, we could just get one of the central ceiling lights that we're putting into the living room and the Japanese room downstairs. These follow the simplicity of a "traditional" Japanese ceiling light, that is stuck to the middle of
the ceiling, usually with a pull-cord dangling from it. They have two or three circular fluorescents, and a mini night light, so if you pull the cord it toggles between being on at full brightness with all the lights lit, to partially on, to just a night light. We have a couple in our house and converted them several years ago to being low-energy by taking out one of the circular fluorescents. Actually, we just didn't replace one of the tubes when it stopped working. It's still perfectly bright enough. Anyway, a year or so ago, I think Sharp brought out an LED ceiling light that looks like one of these ceiling lights, but is filled with
LEDs of different colours. It has no pull cord, instead sporting a remote control which can vary the brightness and the colour. They started retailing around 70,000 yen, and have been followed by other manufactures, and I've recently found a Toshiba light for 20,000 yen. The advantage of these lights is that they are very flexible and can fill the room with the right colour and amount of light for the circumstances. They have remote controls so, although the manufacturers recommend you add a wall switch, you don't really need one and can fit a holder for the remote control wherever you like on the wall. I think this won't look so good on the bedroom ceiling though.

Another option is to just put a row of regular downlights east to west. If they send out a 55 degree beam it should cover all of the floor and most of the wardrobe, except possibly the top right and top left corners. These lights should be bright enough and would look good. This solution would come in a little under 20,000 yen.

It would also be possible to put a double spotlight bracket on the ceiling, pointing to the wardrobes. One of these is available from Odelic for 11,000 yen, but I'm not completely sure it comes with bulbs. There's another from Koizumi for 15,000 yen, also with exchangeable bulbs, I think included. If we put a double spot to the west, then for aesthetic balance we should put another double spot to the east. This solution would also come in a little over 20,000 yen.

Another option is LED strip lighting. This should be an economical option as strip PCBs with LEDs added every few centimetres are cheap, however one problem is the fittings. There are some from Neo blue 1.2 metres long for 13,860 yen. These run on 24 volts DC, so a transformer is necessary. It would be easy to dim them, but I don't think dimming is a high priority for this room. Either we want it light or dark. There are some 100 volt strips from Mini Bee for around 10,000 yen for 90 cm. There's also a 590 mm strip from Noatek for 2,700. Most of these cost around 1000 yen per watt of LED. There's a 420mm strip for 1750 yen that is about half that, but
it is 12V and needs a power supply. All of these are manufactured outside Japan. Another problem with these is how bright they will be. This kind of lighting seems to work very well inside cabinets, for corridor lighting or for ambient lighting, and it will certainly stop the room from being dark. It may not be bright enough to help choosing clothes. As the light comes in strips, it could run along the edge of the horizontal bit of ceiling and would be practically invisible when not on. This kind of lighting fits the lines and spaces of buildings and the manufacturing processes of LEDs, but at the moment it doesn't fit into the imaginations of architects, the mindsets of electricians or into the spaces in the market.

Option 7 is then single bracket spotlights, arranged in a row from west to east. Three would probably be enough, if they are wide-beam. Again we're limited by the range and cost of spotlights, which seem to start at 7 or 8,000 yen with bulbs built in or included.

After the first round, I think we can eliminate 2, 3 and 6. The more I look at it, the better the duct rail of spot lights seems. It will probably come out cheapest, and has the advantage that if it's not bright enough, we can get another couple of fittings to put in there, or replace the bulbs with higher wattage ones, notwithstanding my earlier comments about the irreplaceability of non-replaceable LEDs. There are some 12 watt bulbs for 7,500 yen and 16 watts for 8,200 yen. Those prices will probably halve in the next year.

Low cost and high flexibility. So I'm back at my original idea and it seems like I've been wasting my time prevaricating and writing this. I hope it wasn't a waste of time to read it!

Don't be LED astray... search, and you will find the light!

For the past couple of years I've been searching for decent lights to put in the house. I don't have particularly difficult requirements: energy efficiency, low cost and aesthetic pleasance.

LEDs seem to best meet these requirements, but one obvious problem is the timing. Just in the two years of planning, LEDs have gone from monochromes that the Chinese were adding to disposable toys onto the shelves of shops to replace incandescent bulbs and into traffic lights and a whole range of applications. Certainly they have been in camping shops for a while. This is an area where people have always paid a premium for light weight and a long lifetime. LEDs remain far from standard in domestic electrical installation, but I'm sure this will change in the next five years.

Since their invention in 1962, efficiency and light output of LEDs has been increasing exponentially, roughly following Moore's law, which predicts a doubling every 36 months, which has been renamed Haitz's law for the LED. The costs of materials are probably already below those for incandescents or fluorescents, and it's only a matter of time before the other costs of the industrial infrastructure are accommodated, and prices can come down. As of summer 2011, I'm still set to pay an early adopter tax.

Flickering lights? Damn those dumb dimmers!

Mark from Yamagata writes:

Dear Sir
After reading the latest doses of your blog, I have a question for you. We have LED down lights in a number of rooms, and at a certain brightness they flicker, usually only intermittently. We have been told this is an irresolvable issue, a clash of LED vs dimming technology Comments?

LEDs are diodes. Diodes are semiconductors and this means that sometimes they conduct and sometimes they don't. A regular diode will conduct if you send electricity one way, but not if you send it the other. As their full name "light emitting diodes" suggest, LEDs emit light if you send current through them one way. I heard a company in Korea is developing diodes that will light up whichever way you send current through, which is a good idea in the world of AC power supply.

Anyway, there's a threshhold, usually 2 or 3 volts, at which they'll turn on. Since they are diodes and conventionally it only matters whether they pass electricity or not, on or off has traditionally been sufficient for conventional LED uses on displays. LEDs will produce more light with more current, but only above a voltage threshhold, and if there is too much current, the diode will start melting.

Dimmers traditionally work as variably resistors, so the more you turn them, the lower the resistance gets, and the less voltage there is across the dimmer and the more voltage there is going through the light. Conventional Edison-style incandescent lights also work like resistors, so the current is proportional to the voltage (as I'm sure you can remember from Ohm's law) and the amount of heat and light increase accordingly. This kind of old fashioned dimmer may work with light emitting diodes. Alternatively, it might work really badly as the LED will not turn on until the voltage is high enough, and may not dim the light; just turn it on or off.

The problem with resistors is that the current going through them is turning into heat all the time. More recent dimmers work by rapidly switching the electricity on and off. You can see more here on how stuff works dot com. The AC comes in as a sine wave, and each time the sine wave crosses the zero volt line, then switch a little later. If you're only dimming the lights a little, they will switch on very quickly. If you're dimming a lot, they will switch on just before the voltage goes to zero again. This kind of dimmer should work well with an LED as it will switch it on for a shorter or longer part of the cycle.

LEDs use direct current (DC), not alternating current (AC) so within an LED "light bulb" there may a row of LEDs adding up to 100V, and a ring of diodes known as a wheatstone bridge which sends the input AC voltage in the right direction so that one output is always positive and the other is always negative. Or they may have a step down transformer inside them. AC-DC power adaptors usually work by switching the AC to a much higher frequency, then converting it to DC. They may just be switching the voltage off when it's at the top of the sine wave, and far higher than is needed.

The flickering problem with the LEDs may be caused by a number of things. It could be that at a certain level, the voltage is close to the threshold for the LEDs to come on, so they are switching on some cycles and not switching on other cycles. Anything switching on and off 50 or 100 times a second is going to appear to be on all the time. Depending whether it's a US-based system or a UK based system, TVs change their pictures 25 or 30 times a second without appearing to flicker, but if you get down to about ten times a second, it's going to be obviously flickering. Apparently, this is known as the flicker fusion threshold.

By the way, the difference between the 25 frames per second in the US and 30 frames per second in the UK depends, in turn, on whether the voltage is at 50 Hz or 60 Hz. The eastern half of Japan is 50 Hz while the western half is 60 Hz, apparently because in each half generators were introduced from the US and Europe respectively. This means that Japanese electrical appliance are generally made to work at either frequency, which has probably been an advantage in their international marketing. However, I digress.

Another possible cause of the problem is that there are two systems both chopping away at a sine wave, and there is some interference going on, resulting in a lower frequency flickering. If this is the case, and the LED lights have their own devices for chopping 100V AC into lower voltage DC, it may be that an old style variable resistor dimmer would work better.
I asked Mark for more details and found that the "certain brightness" at which they flicker was usually at about two points on the dimmer scale, say 1/3 and 2/3, but not exactly the same for each light, and the nature of the intermittent flickering was that they flicker for a few seconds, then stop, then flicker for a few seconds again, then stop, and so on.

As a solution I suggested he could just try avoiding the level at which they flicker when he dims them, apologising that this was both obvious and not very helpful as the level at which they flicker is clearly the level he wanted! He went on to say:

We have several types of dimmer down lights. The ones that are flickering have replaceable LED bulbs which are not built into the unit. The second type are unreplaceable (as opposed to irreplaceable--a good English lesson there--and built in. They apparently have 200,000 hours in them which will outlive me (though I think the max is really 40,000). These never flicker. At least not yet.

The life expectancy is usually 40,000 hours, but that's 40 years at 3 hours a day, which I think will probably outlive us anyway! In my opinion, irreplacable lights should be unreplaceable.

The ideal solution for dimming LEDs would seem to be a dimmer power supply that will output the correct voltage and current for a DC LED. This is available, even in Japan, for example here on Rakuten. But in the worst case, there is an LED light bulb screwed into a conventional fitting, connected to a dimmer switch, and the dimmer switch and the electronics inside the bulb are left to fight it out.

LEDs may be an irresolvable clash between electricians and new technology.

You can see more about how diodes work here on how stuff works dot com. The graphs above came from this website.

In praise of shadows... at least if they surround light

Actually, rather than being part of some consumerist conspiracy, the dearth of LED fittings for is probably much less sinister and just a lack of a market among house builders for new lighting. The electrics seem to be the last thing that is thought about in the building process. By this time the consultation process between architect and client has probably dried up and a sketch is handed to an electrician to put fittings in the ceiling in the middle of each room so everywhere is bathed in uniform light. Eat your heart out Jun'ichiro Tanizaki 

I've been reading a translation of his essay, "In Praise of Shadows" (1933) which apparently is required reading for any student of architecture in Japan, although Tanizaki is no architect. Of course architecture contains a great deal more philosophy than anything else, and you don't need to be an architect to know how buildings and spaces work. In Praise of Shadows is a good critique of modernisation and the westernisation of Japan. Tanizaki, who was born in 1886, just after the Meiji Restoration, laments the introduction of electric light into restaurants. He goes off on a crusade to find a deeper appreciation of subtlety and cloudiness in orientals from the colour of their skin to the materials used in their soup bowls and on their sliding doors. 

He wrote that "Japan wastes more electric light than any western country except America." This was in the 1930s; goodness knows what he would have made of the country more recently. He adds that "so benumbed are we nowadays by electric light that we have become utterly insensitive to the evils of excessive illumination." He talks about establishments that are "lit far too extravagently" admitting that "some of this may be necessary to attract customers."  He talks of the waste of lighting before it is dark in the summer, "and worse than the waste is the heat . . . Outside it will be cool, but inside it will be ridiculously hot, and more often than not because of lights too strong or too numerous. Turn some of them off and in no time at all the room is refreshingly cool. Yet curiously neither the guests nor the owner seem to realise this. A room should be brighter in winter, but dimmer in summer; it is then appropriately cool, and does not attract insects. But people will light the lights, then switch on an electric fan to combat the heat. The very thought annoys me." (p 36-37)

If only he were still alive and working as an electrician in Matsumoto.

"Light is used not for reading or writing or sewing," he says later, "but for dispelling the shadows in the farthest corners, and this runs against the basic idea of the Japanese room." So when we're asking what went wrong with Japanese architecture and looking for a culprit, we can add electric lights to aluminium windows in the line up of usual suspects. And I suppose the Japanese obsession with imitating the West. 

Joshua Sowin writes more about Tanizaki's essay here . I've been reading a 1977 translation by Thomas J Harper and Edward G Seidensticker, published by Leete's Island Books of Stony Creek, CT. 

No LEDs on display, but what is on display is being lit by LED...

We went to a few showrooms the other day to look at stuff for the house. We're interested in LEDs, for reasons explained here. One problem is knowing how bright the LEDs will actually be. Everybody used to know what a 60 Watt bulb was like, but to compare incandescents, fluorescents and LEDs, wattage has little meaning, and it's not so helpful to compare different LEDs. Light manufacturers have now started putting lumen values on their products, rather than just wattage, so there is some way of comparing, but the angle at which the light comes out can also be an issue in terms of how bright it is. 

We saw lots of LEDs in the Bathroom shop, Takara, where they have recently changed all their display lights into 60-watt halogen-style bulbs (around 7 watts) in lighting rails for the displays. They even have extra LED spotlights inside the bathrooms on display, to supplement the standard light fittings inside their bathrooms, which puts aside previous concerns that LEDs aren't bright enough.

We asked them to switch off the fitted lights in one bathroom, and just switch on the two LED spotlights to get an idea of how bright they were. They were certainly bright enough, especially under the relatively large area under the spot, but it was definitely less bright on the ceiling and higher up on the walls. Not very good, for example, if we invite a vampire round for a bath, and they turn into a bat and hang from the ceiling. Or perhaps they would prefer to be in the dark, and even for our vampire friends LEDs may be better. Anyway, as a whole the room seemed less bright, as it contained darkness, but it was bright enough where needed.

They are putting LEDs in one of their display bathrooms next week, and the bathroom we're getting has LED downlights as an option to the standard bracket-lights. This will cost us 39,000 yen extra. Obviously they're charging over the odds for this, but the design is superior, with down-lights rather than bracket lights, and it will claw back some of the cost in electricity bills in the next few decades, and should reduce some extra heat in the summer. It's best to write it off as an early adopter tax. 

In the tile shop they had several larger LED display units on the ceiling, like these from Toshiba. Much bigger units.

We asked about LEDs in the home fittings showroom of Panasonic, the electrical manufacturer, and got a rather blank look. They were using some for lighting their own displays of other fixed furnishings, but it obviously hasn't seriously crossed their minds to try to get people to put them in new houses. 

It seems in these, and many other shops that putting LEDs in makes a great deal of financial sense as they can get the same light output for a lower running cost, both in terms of electricity and bulb replacement. There seems to be much less effort getting them into new builds, although they are probably still working on the loss-leader concept that Gillette developed with their razor blades. Buy an LED fitting and you will have light for the rest of your life.  Buy a normal fitting and you'll be buying light bulbs for the rest of your life. Why get people to buy one thing when you can get them to buy two?

LED light bulb... this should be a contradiction in terms.

Just read is-this-the-ultimate-green-led-light-bulb. And it makes me wonder what's going on. It talks about "solving the problem of uni-directionality in older LED bulbs". I wonder whether Edison was concerned with the "problem" of his lightbulb not having an open flame...

Another thing that doesn't make sense is the idea of a replacable LED bulb.  LEDs have rated lifespans of over 40,000 hours. That's three hours a day for forty years. Form most domestic uses, the only reason for replacing the bulb would be if you wanted to change the fitting and keep the bulb. 

This guy at My LED lighting guide gives a list of eight reasons why LEDs are better than compact fluorescants, and Eternaleds asks if LEDs are brighter than CFLs and finds that no, they aren't really brighter. 

The point is that the light all comes out in the same direction, so if you know what you want to be bright, and can point the light there, then the LED is going to use a lot less power, not because it's producing light more efficiently, which it isn't, but because it's going to the right place.

If there's a chance that you're going to be doing something behind the lightbulb, in that bit of the wall where small dead insects accumulate, and you want to make sure it's not dark there, then CFLs or incandescants are for you. If you don't even want a space there, you should probably consider LEDS. If a light is not going to be used very much, and if you're not sure which part of a large area you're going to be using, then fluorescents will probably do as good a job as LEDs, and currently cost less to buy and fit, although LEDs use less resources and as they work out how to manufacture them in bulk, and once they pay back the retooling costs, LEDs will be cheaper.

A practical example in the house is a store room that may be used a few minutes a day. Rather than putting LEDs all around, we'll just put one fluorescent tube in the middle. This will brighten up the whole room in one go, and should still last a few decades. The other low-energy option would be to have a couple of head torches left on a hook at the entrance and turn a trip to the basement into a caving expedition!

But anyway, I wish people would stop talking about LED light bulbs. The whole point of a light bulb is that Edison's elements needed a vacuum, or an inert gas, so that they wouldn't burn away. Rather sensibly, with glass being transparent and easy to blow or suck into bulbs, he put them into a glass bulb. LEDs are semiconductors, typically produced on a flat wafer. They don't need a bulb. It may be a good idea to put a lens in front of them.

Putting LEDs into bulbs is like using a keyboard designed for typewriters over a hundred years ago when you're inputting words into a computer...

Electrics and low-energy lighting

In terms of lighting, there are three factors to efficiency. First is the type of appliances used, second is the way that they are laid out, and third is the way they are used. In terms of appliances, LEDs and compact fluorescents are going to use less energy than incandescents and candles. If the light illuminates what needs illuminating to the degree it needs illuminating, then you will use less energy. Finally, if the lights are switched off when they are not being used, this could make a bigger difference than the first two points.

As well as the obvious energy efficiency benefits of low-energy lighting and energy-efficient electrical appliances, in a highly insulated, airtight house, they will mean a cooler summer. Energy efficiency is a measure of how much energy comes out in the form you want it, for example how much power is coming out of a motor or how much light is coming out of a lamp. For example, the luminous efficiency of a candle is something like 0.04%.  In other words, for 10,000 units of energy, 4 of them will turn to light, and 9,996 will come out as heat. Next time you see somebody using candles and calling themselves green, bear this in mind. The rest of the energy is turning into heat, so inefficient electrical appliances mean more heat in the summer. In the winter, this may not be a bad thing, and in fact having a few lamps with incandescent bulbs will make very good back-up heaters for those really cold winter nights.  

Incandescent lights are over 50 times more efficient than candles. Facilitated by Edison's flair for publicity, that's why people stopped using candles and switched to electric light (image of light bulb coming on above head). They are still only 2%-5% efficient, so of those 10,000 units of energy, around 200 are now coming out as light, 9,800 are coming out as heat. The hotter the filament, the more efficient the light is, so very bright lights, such as projector lights, reach 5%, while most bulbs are around 2%. Halogen bulbs are not much more efficient than incandescents. 

Fluorescents light and LEDs are similar in luminous efficiency, around three times better than incandescents. The best fluorescent seems to be Panasonic's spiral tube, reaching 18% http://panasonic.co.jp/corp/news/official.data/data.dir/jn100609-1/jn100609-1.html. The theoretical limit for LED efficiency is up to 40%, and the most efficient currently being manufactured are around 20% efficient.  So now, 2,000 units of energy are coming out as light, and 8,000 as heat. These "lights" are still working better as heaters than illuminators. http://en.wikipedia.org/wiki/Luminous_efficacy

For reference, the sun has 12% luminous efficiency.

The advantage of LEDs over fluorescents is that the light is all pointing in the same direction, which is often down rather than into fittings, walls or ceilings. This can also be seen as a disadvantage but generally it makes LEDs two or three times more efficient than fluorescents. LEDs are also smaller in size, use fewer materials and are simpler to produce so ultimately should be cheaper to manufacture, and they are likely to take over the market.

This leads onto the design of lighting. Generally speaking European lighting, with spotlights and ambient lighting is more efficient by design, while in Japan gains made by use of energy efficient fluorescents are partly lost because everything is bathed in bright light. Work surfaces, such as desks or kitchen tops, need bright light to be able to read or to distinguish between carrots and fingers on the chopping board.  Ceilings, walls, stairwells and corridors generally don't need as much light, so a design based on efficiency would use modest light in corridors, so we can see where we are going, use some ambient light on walls and ceilings, so we don't feel we are in a cave, and focus bright light around chairs, desks, tables and work tops. Flexibility is needed as we don't know exactly where the desks or chairs will be, so adjustable spot lights seem like a good idea.

One of the energy efficiency features of the Panasonic spiral tube is that it will change its brightness depending how much light is in the room. In bright daylight, it will turn off; dim daylight it will come on weakly and at night it will come on fully. As well as light sensors, use of motion sensors, for example in entrances, storage spaces and toilets, will likely stop lights being left on and save electricity. In terms of design and installation, they should also remove the need for light switches on walls, so may be cheaper. This remains to be seen!