Bulb Basics

Some light bulbs are more efficient than others, and each renders color slightly differently. For example, compact-fluorescent bulbs emit near-white light, have long lifetimes, and are very energy efficient, whereas incandescent (tungsten-filament) bulbs create a warm cast, burn out much more frequently, and use lots of electricity for the amount of light they produce.

When choosing a bulb, first determine how much light you need for your application, then find the most appropriate bulb for that need. Look for the lumen rating — not just the wattage — on the packaging. Bear in mind that some types, like incandescent and mercury-vapor bulbs, may have low initial cost but use a great deal of electricity. In fact, as this table shows, in dusk-to-dawn applications a single outdoor lighting fixture can cost more to operate per year than cost to buy!

To get a better idea of what your outdoor fixtures cost to operate, check out this handy "Lighting Cost Calculator".

• ¹ Lumens are mean output values over the lifetime of the bulb. ²Dusk-to-dawn values are based on an average use of 11¼ hours per day (4,100 hours per year). ³ Motion-sensor values are based on six 5-minute-long cycles per night; the long warm-up time of some bulbs preclude their use in motion-sensor applications. Costs (per year) are based on actual wattage used and electricity costing $0.10 per kilowatt-hour.