Energy Use: Myths and Facts

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As energy costs continue to rise, consumers are looking for ways to reduce their energy use. Although there are a lot of good ideas out there, there are a lot of misconceptions as well about what is really effective. Here are some of the most common myths and the facts to set you on the right path.


Computers, monitors, and other office equipment will use less energy and last longer if they are left running all of the time.

Fact: Turning equipment off overnight does not shorten its life, and the small surge of power that occurs when some devices are turned on is much smaller than the energy used by running equipment when it is not needed. In fact, leaving computers and other office equipment on overnight and on weekends wastes significant amounts of energy and also adds to the wear and tear on the equipment. In general, turn off equipment you are not using or make sure that energy-saving features on networks or individual machines are enabled. Some office equipment, including printers and scanners, features small transformers that use energy even when the equipment is turned off. Plug all such devices into a power strip so that they can be shut down completely with one flick of the switch.


I should run my HVAC 24/7 to avoid an increased demand charge from the “spike” that occurs when the equipment starts.

Fact: Although turning on HVAC equipment will cause a power spike on the order of fractions of a second, this period is not long enough to have any impact on demand charges. Demand charges are based on the average power used in a facility during 15-minute periods. The spike from turning on such equipment does not last long enough to significantly affect this average. Not only are there no significant demand savings from running HVAC equipment continuously, but there is a significant downside as well. Equipment life can be considerably shortened, and unless the equipment is designed to operate at continuously variable capacities, it likely will not be able to properly match the cooling load and will waste energy and decrease comfort.


When leaving a room for a short period, it’s better to leave lights on than to turn them off.

Fact: For incandescent bulbs, it’s always better to turn the lights off. For fluorescent lights, there are some trade-offs. Fluorescent lights use slightly more energy on start-up, but the light needs to be off for only about a second to make up for that surge. The life of a fluorescent light is also shortened by frequent on-and-off switching. The actual break-even point depends on the cost of the lamp and the local electricity costs and is typically 5 to 15 minutes. However, a good guideline for fluorescent lighting is as follows: unless you’re switching the lights every few minutes, it is generally cost-effective to turn the lights off whenever you leave the room.

Source: © 2007 E Source Companies LLC.