Saturday, September 25, 2010

Simple Ways to Save Money with LED Bulbs

The most common is to use compact fluorescent low energy lamps (or the larger 'strip' fluorescent light fittings, for commercial buildings or where their appearance is acceptable). A rapidly growing alternative is to use LED low energy lamps, although these are still not bright enough for many applications, unless you are prepared to pay a lot more money. If you still insist on using incandescent bulbs (many of which are being phased out in some countries), energy usage can be reduced using dimmer switches.

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Compact Fluorescent Lamps
Many people have already switched to these, but there is still considerable resistance to their use, mainly because some people still base their opinions of them on early examples. They have improved considerably and I would like to counter some of the most common prejudices:

1. They are not made with fittings that fit my lamps. Compact fluorescents are now made to fit nearly all kind of fittings (except the very small halogen capsule bulbs - fittings taking these bulbs are best avoided). There are 'retro-fit' ones, which replace ordinary incandescent or halogen lamps, and ones fitting dedicated compact fluorescent fittings. These have bases that conventional bulbs will not fit, and are commonly found in new builds.

2. They take a long time to come on. We are used to incandescent bulbs, which reach full brightness in a fraction of a second. It is true that they do take a few seconds to reach full brightness, but certainly not a few minutes, as early ones did. I have tested current examples by Philips, Osram, GE, Megaman and others, and found that while the first time they are used they may take a longer time to 'warm up', after that they reach full brightness in a few seconds. In most applications, does this matter?

3. They are very big or very dim. The brightness of the lamp depends largely on the length and thickness of tube. By various ingenious methods of cramming longer lengths into smaller spaces the bulbs have got brighter and smaller. These include 'U' tubes, spirals and other shapes. While it is still true that an incandescent lamp giving the same amount of light can always be made smaller, this is often not important. A lampshade of sufficient size will hide the bulb. and if you are buying a new light fitting, always ask yourself or your retailer whether it will look good with low energy bulbs. In fact low energy bulbs should automatically be supplied with most new fittings these days.

4. They look ugly. Do they? I contend that some people think this because for many decades, we have got used to the look of incandescent lamps. If the positions were reversed, I imagine that so would these opinions.
5.Incandescent lamps contribute more to heating. This is true (in fact the reason they are so inefficient is that they give out about 85% of their energy as heat, not light). But do we buy lamps to provide heat or light? Do we want this heat in warm weather when we may want light? Do we want the majority of this heat near the ceiling of a room, where most lamps will be?

6. Compact fluorescents contain hazardous mercury. This is also true, as do longer 'strip' fluorescents. We are talking about tiny amounts though, and when they are disposed of leave them intact when giving to the refuse disposal people. Do not smash them, and they will provide no danger.

7. Compact fluorescents affect certain conditions, causing headaches, nausea, etc. This can be a problem with a very few people. Controlled tests have shown it is somewhat exaggerated, as the psychological effect of people expecting this, because they have been told about it, makes them think they are experiencing it. Remember that offices having banks of flourescent fittings, where many people work, function in the same way. Some people say they experience no ill effects with these, but do not like compact fluorescents. I do not understand this. There are however a very few conditions that are worsened by them, and if you are affected, I do not know of any way around this, other than not using them.

8. The 'whiteness' of the light they give doesn't look right. The 'colour' of the light depends of the colour temperature, and they now come in a big range of colour temperatures. The higher this is, the more blue the light (nearer to natural sunlight). Choose one that suits you - some people prefer 'warm white' at the lower end of the scale, while others prefer a 'cool white' or higher. Here is a list of approx. colour temps for different types of light: 2700K to 3000K - warm white (sometimes given the colour code 827 to 830) 3500K - white (colour code 835) 4000K - cool white (colour code 840) 6000K - daylight lamps or craft lamps (colour code 860) 8000K - sky white (colour code 880) As a means of comparison, most incandescant bulbs have a colour temperature of about 2800K and halogens of about 3000K. Natural daylight can be anything between 4000 and 10000K. All the above range is available in various types of fluorescents although you will pay more at the higher end of the scale.

9. Compact fluorescents cannot be dimmed. This is true of most of them, but there are now compact fluorescents that are dimmable. There are two types. One of them is used with a dimmer switch, used the same as with a convential lamp. The second can be dimmed from a normal light switch, so even a dimmer switch does not have to be fitted.

Savings in cost and CO2 emissions using compact fluorescents are made using the following assumptions: (a) the cost of one unit of electricity (1kWh) is 12p in UK prices. (b) the cost of one retro-fit cfl is 42p - this is a Megaman 'My Planet' 15W lamp, taken from the author's website. Some other lamps are more expensive, but this is a basic cfl, suitable for most applications. The cost of an equivalent incandescent bulb is 39p. (c) the lifetime of the bulb is 10000 hours (compared with 1000 hours for the average incandescent). Again there are longer and shorter lifetimes of both types, but these are typical values. (d) the energy consumption of a cfl is one-fifth that of an incandescent for the same light output. (e) the bulb is used for an average of 4 hours a day.

LED energy saving lamps
These are an order of magitude more efficient than compact fluorescents. Advances in these have been made in recent years, so that a greater selection of fittings and brighter light is now available, but bright ones for normal practical lighting are still very expensive. Moderately priced ones are useful for low level decorative or emergency lighting. There is no extra cost for coloured ones, and colour changing ones are becoming increasingly popular for special effects. Whereas cfls use about one-fifth of the electricity of incandescent lamps, some LEDs use one-tenth to one-fifteenth. I would particularly consider using them as GU10 halogen replacements, providing bright light is not needed. A reasonably priced GU10 replacement LED will give the equivalent of 20W of light, but only use about 1.5W electricity.

Dimmer switches
Where all else fails, an incandescent lamp run below its rated wattage on a dimmer switch will save electricity and increase the lifetime of the lamp. I am often asked if running a lamp at, say, half power using a dimmer switch saves half the running cost. The answer is more or less yes (a very little power is lost in the dimmer switch, but this is negligible). Thus it makes good sense to run lamps more dimly on dimmer switches, except on occasions when the brightest light is needed.

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