Energy Efficiency of Different Lighting Types

Lighting is another key factor in green energy renewable systems. Imagine not having light? Pretty impossible to imagine life without it! Conventional lights (filament, halogen, etc) use a lot of energy to create very little light. Most energy output from these lighting types are in the region of 70%, or more, heat output. That leaves very little energy spent on actual usable light!! So for alternative systems, particularly solar, we need a very efficient lighting type. A lighting system in the region of 90% efficiency should be the minimum anyone should look at. Obviously everything in this world has an attached price, so be prepared to pay for your efficiency. The good news is that over the past five years alone, energy efficient lighting has radically reduced in cost. This means that everyone has the option of choice! Let's face it, the main reason most people want to go alternative is not to save the environment like the perpetual advertising, although that is a spin-off, most just want to save some money in a world where prices only go up and income stays the same.

Now the question comes in, “it's only a few lights! They don't use that much, do they?”.

Simple answer, YES, they do use quite a bit of your monthly bill. 25% of the average home's electricity budget is spent on lighting inefficient light bulbs (halogens, incandescent, etc). A typical light bulb will cost 5 to 10 times its own cost in electricity during its relatively short lifetime.

There are however alternatives such as Fluorescent lighting, Compact Fluorescent Lights (CFL's), LED's, Quartz-Halogen, and many more!!

Each lighting type has it's own advantages as well as disadvantages, although in the long run, any of these options is100 times better that your standard lighting at the least (aka less money on the electricity bill!). I have put togethor some of the more popular lighting forms with their efficiencies, advantages, disadvantages, etc.

Feel free to leave a comment about what your thoughts are or if you just have an energy saving tip to do with lighting!

IMPORTANT: The standard way of rating lighting efficiency is in lumens per watt, and this figure accounts for all of the light produced by a bulb. This rating does not necessarily reflect how much usable light is thrown on your work area. The reflector and fixture will have a large effect on this.

Incandescent Light Bulb

They give out a lot more heat than light (between 2 – 4% percent of energy is converted to light). Amory Lovins of the Rocky Mountain Institute calculated that replacing a 75 watt incandescent lightbulb with an 18 watt compact fluorescent (that gives the same amount of light) would, over the lifespan of the new bulb, prevent the emission of about 1 ton of carbon dioxide and 8 kilograms of sulpher dioxide into the atmosphere, plus a huge savings on electricity cost.

Compact Fluorescent Lights (CFL's)

CFL's are miniature versions of full-sized strip fluorescent lighting and fit straight into the light fitting (just like the incandescent does). They come both as screw and bayonet types as well as in many different shapes and sizes. CFL's bulbs are around four times as efficent as incandescent light bulbs and last up to 10 times longer. 22 Watt CFL, therefore, will offer the same amount of light as a 100 Watt incandescent bulb and will last for around five years. Using an 18 Watt CFL in place of a 75 Watt standard light bulb will save over 500 kWh over its lifetime offering savings of around £25 - far in excess of the initial cost of the CFL - and will prevent half a ton of CO2 being pumped into the atmosphere by power stations.

The main disadvantage of CFL's is that they contain 4mg of Mercury, a highly toxic substance to humans as well as to the environment.

Tip: the life of a CFL is greatly reduced when used in applications where the light is frequently switched on and off. Also, some are unsuitable for use with dimmer switches.

11 Watt CFL = 60 Watt Incandescent bulb

20 Watt CFL = 100 Watt Incandescent bulb

Standard AC Fluorescent Lights

These really are a very good, energy efficient method of area lighting, and are widely available. They are the most efficient room light available.

The main disadvantage is that some people find the small flicker irritating (most new designs these days have very advanced ballasts, so flicker really only affects the old ones).

LED Lights

The current operational life of current LED lamps is 100,000 hours. That is equal to 11 years of continuous operation (most incandescent lights have a maximum of 5000 hours)!! LEDs have a 80% and higher energy efficiency (the other 20% or so is lost as heat).In money terms; if a 100 Watt incandescent light bulb is used for 1 year, with an electrical cost of 10 cents per kilowatt hour, $88 will be spent on electricity costs. Of the $88 expense, $70 will have been used to heat the room (not light the room!). If an 80% efficient LED bulb had been used, the electricity would be $23 per year, there would be a cost savings of $65. Realistically though, the cost savings would be much higher as most incandescent bulbs blow out within a year and require replacements, whereas LED light can be used easily for a decade without burning out.

The only disadvantage is that the cost of buying LED light bulbs is quite a bit more than your standard light. Although in the long run it becomes much cheaper (as the LED light could last up to 25 years with normal usage).

Quartz-halogen Light

These bulbs are about 15% more efficient than the standard incandescents, but are available in 12 volt versions (normally used for downlight applications). They also fit in most standard light sockets. These quartz lights last almost 3 times longer than incandescents.

So here's the condensed info in a nutshell:

• 32 watt fluorescent -85 to 95 lumens/watt

• Standard cool white fluorescent - 60-65 lumens/watt

• Compact fluorescent - low 30's to low 60's lumens per watt, usually 48-60

• Tubular halogen - 20 lumens/watt
• LED (white) – 50 to 60 lumens/watt (Manufacturers have reported new white LED's that are approaching the 80+ lumens/watt. Research labs have also reported efficiencies as high as 250 lumens/watt as of 2010)

• Standard 100 watt incandescent - 17 lumens/watt

If you have any suggestions, tips, or comments, please feel free to post them below!

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