According to www.biggreenswitch.co.uk, around 10-15% of every household’s energy usage is for lighting. This usage can be dramatically reduced by swapping traditional bulbs (known as incandescent bulbs) for energy-efficient bulbs.
Whenever a bulb needs replacing, always swap it for an energy-efficient bulb. But the sooner you change, the better – so it pays to swap even before your old bulbs blow.
Energy-efficient bulbs are no longer the large and cumbersome objects they once were. You can now buy them in a variety of shapes and sizes to fit almost all light and lamp fittings/shades.
Most also now come on as fast as standard bulbs and provide the same quality and level of lighting as a normal bulb - both common complaints about low energy bulbs in the past. Low energy light bulbs use up to 80% less energy than a traditional incandescent bulb while still emitting the same level of lighting.
This is because the old incandescent bulbs waste up to 90% of their energy through heat being emitted by the bulb rather than light. The low-energy bulbs also last up to 10-12 times longer than traditional bulbs so, although the initial shelf price of the low energy bulbs may be higher than traditional bulbs, they more than pay for themselves over their lifetime.
Bulb disposal: Please remember to dispose of your used low energy light bulbs safely and correctly. Similar to other items such as used batteries or printer cartridges, CFL bulbs can contain materials which may be harmful to the environment if simply placed in your normal waste bin and sent to landfill. Always take care to dispose of your bulbs at a suitable recycling facility. Home Depot recently started a CFL recycling program and you can read about it here:
Here is a spreadsheet showing the cost savings you could achieve by switching from standard incandescent light bulbs to either Compact Flourescent or LED light bulbs. The comparison is based on $.23 per KWh but you will need to plug in your actual current cost for electricity which I think is closer to $.13 per KWh in the Boston area http://www.productdose.com
Here is a simple Compact Fluorescent Light (CFL) Energy Savings Calculator that will show just the energy savings that you can expect to achieve if you switch over to CFL from incandescent. It does not factor in the cost of the bulbs but it is helpful to know that the cost is dropping all the time and currently is about $3 for a CFL that is equivalent to a 75 watt incandescent bulb.