Written by: Laurel Kruke, Sustainability Manager with Pierce Energy Planning
Lighting is a huge part of energy efficiency – turning your lights off can save a lot of money on electric bills. According to the APS Energy Efficiency Guide for K-12 Schools, indoor lights account for about 33% of the energy use in a school – that’s more than equipment, computers, exterior lighting, and motors combined! I did a couple calculations, and by reducing the amount of time overhead lights are on in a typical classroom by 25% (for example, 6 hours a day instead of 8 hours a day), a school can save between $1,000-$2,000 a year!
While turning lights off is a great way to save energy, so is replacing older lightbulbs with more energy efficient lightbulbs. Most people have heard the terms incandescent, CFL, and LED, but it’s not always obvious which is best for consumers, and which one is the most energy efficient. Today, I’d like to share some information about the different types of lightbulbs. Here is a great video from the Department of Energy about different lighting choices. NPR has also put out a helpful comparison guide to the different kinds of lightbulbs – see that guide here.
Incandescent lights are the traditional lightbulbs that were developed by Thomas Edison. These lightbulbs give off a lot of heat, as well as provide light. According to the Department of Energy, 90% of the energy used to power an incandescent lightbulb is used up on the heat that’s produced – that’s a lot of waste! In 2007, congress passed a law that addressed many fuel efficiency standards and energy conservation topics, one of those being improved appliance and lighting standards. To comply with that law, in 2014, the U.S. discontinued the production of traditional incandescent lightbulbs. Their replacement is an energy-saving incandescent halogen light, which uses halogen gas to help produce light more efficiently, as well as protect the filament in the bulb itself.
Compact fluorescent lights (CFLs) are a more energy-efficient option than the incandescent halogen bulbs. They tend to use 65-75% less energy than their incandescent counterparts, and also last quite a bit longer. CFLs used to usually come in long, tube-like fixtures; these tubes have been redesigned into the curly-cue shape that you can now find at the store. CFLs also generally used to give off a bluish-white light, rather than the soft white light of an incandescent – this made them less popular at first with residential consumers who did not like the look and feel of the light the bulbs gave off. CFL technology has improved, however, so the color-spectrum of the bulb more closely resembles that of an incandescent. One drawback of CFL bulbs is that they contain very small amounts of mercury, so at their end of their life, they need to be specially recycled rather than just thrown out in the trash.
A third type of lightbulb is the light emitting diode (LED). These are the most energy efficient bulbs on the market; compared to an incandescent bulb, a LED bulb can use more than 75% less energy, and last 25 times longer – this means a lot of energy (and maintenance) savings over their lifetime! Not only does an LED use less energy, but it also gives off less heat, so indirectly saves on costs to cool down spaces that are heated by extraneous lighting heat loss. LEDs have historically been used in things like emergency exit signs, computer monitors, and televisions, and are just more recently being used in the residential and lighting fixture market. LED lights tend to be more expensive than their incandescent and CFL counterparts. However, over the past few years, demand has increased and technology has improved, so the price of LEDs is becoming more reasonable. Plus, the savings over time can be significant, and make up for the up-front costs!
Consider buying LEDs next time you need to replace a lightbulb. But remember, turning your lights off when you’re not using them or when you leave a room is the best way to lower your energy usage!