Energy Efficient Lighting

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The incandescent light bulb is one of the inventions that has impacted our lives most. Before Thomas Edison’s discovery of electricity in 1879, it was pointless staying up after sundown. Before the emergence of the modern day light bulb, kerosene lamps provided not only poor lighting but poor air quality. When electricity was new, there was little thought for efficiency or environmental issues related to electric power, so the first light bulbs were inefficient. The light bulbs in your home today may be as they were a hundred years ago, but lighting technologies have changed.

CFL bulbs use less power and last much longer than standard bulbs

The incandescent lamp and its cousins provide light by heating a small coil, called the filament, inside a glass bulb. As the metal is heated, it glows until it becomes white. The filament glows in various stages, called incandescence. If the supplied power is reduced (for example, with a dimmer switch) the filament heats up less and the bulb is dimmer, glowing yellow or even a dull red. At end of life, part of the metal filament vaporizes (with the associated white sparks and popping sound), breaking the current’s flow through the bulb. This, in turn, stops the remains of the filament from heating and effectively extinguishes the bulb.

To make a bulb glow brightly requires lots of energy to heat the filament. The common light bulb wastes 90% of its energy in generating heat, while only 10% is actually converted into the light you want. Such a waste!

Even worse is that the waste heat warms the house and causes more load on your air-conditioning. Traditional light bulbs are a double whammy on cost: low energy efficiency with high operating cost and increased cost through greater use of air conditioning. We can even calculate the rough amount of waste heat: if you assume it’s a warm evening in summer with fifteen 100W lights switched on, the waste heat is:

15 bulbs x 100 W x 90% heat loss = 1,350 W of heat loss

That heat loss is equivalent to the output of a big electrical space heater. One could argue that this can warm the house in winter: perhaps, but the electricity required to do so will make it the most expensive heating system in the country! It’s also difficult to control without a thermostat on all your house lights. Even if you have an off-grid system to generate your electricity, the waste is still huge. What, then, would be better for cost and energy savings?

Today, there are many alternative lighting technologies, including halogen, mercury vapor, semiconductor-LED, halide, sodium and fluorescent. Different technologies offer differing efficiencies for different applications. The best, most popular technologies are the ones for home applications. 

Let’s pause to consider semiconductor or LED lighting. LED lights are most commonly installed in vehicles or high-efficiency flashlights. But, even today, LED lighting is only half as efficient as compact fluorescent technology . Bulb color quality is also very bad for the home. The main reason for its continued existence is a longer lifetime and lower energy consumption when compared to standard light bulbs.