It is remarkably easy to waste electricity in our homes. Reducing some of this waste requires replacing inefficient equipment, but much of it can be solved by low- or no-cost changes, or often, just a change in behavior.

Mistake #1: Leaving ceiling fans running

Starting with the simple stuff, an amazing amount of electricity is wasted by just leaving things on when not needed. Ceiling fans are the worst culprits — if you aren’t sitting under a fan, it isn’t doing anything but wasting energy. Turn them off when you leave the room, period. If you’re too lazy to flip a switch, then invest in timers or occupancy sensors that will do it for you.

Mistake #2: Leaving the TV on

TVs run a close second to fans, and since they make a lot more noise, they should be easier to remember to turn off. Far too many people leave multiple TVs on all the time, and truthfully I have no idea why. Are they lonely? I’ve even seen people who leave them on for their pets while they are away. Just turn them off unless you’re watching a show. Also, since they also use energy when they’re off, put TVs on a power strip that you can turn off when you’re not watching to save even more energy.

Mistake #3: Leaving lights on

Along with TVs, we leave on too many lights, both inside and out. If you’re not in a room, you don’t need lights, so turn them off. If you don’t have timers, photocells or motion sensors controlling outside lights, hire a local electrician to install some, and make sure they are programmed so they work properly. No sense having a timer that doesn’t turn a light off during the day.

Mistake #4: Leaving bathroom and HVAC fans running

The last bits of low hanging fruit are bathroom vent and HVAC fans. It’s a good idea to use your bath fan after a shower, but it’s important to turn it off after about 25 or 30 minutes — don’t leave it on all day. And in most cases, it doesn’t make sense to run your HVAC fan full time. It uses a lot of energy, and unless your house and ducts are really well sealed, it brings unwanted hot or cold outside air into your home. Go to your thermostat, look at the “fan” setting, and make sure it is set to “auto” instead of “on.”

Stepping up to things that take a little more effort and may cost a little money, let’s look at hot water, programmable thermostats, and that old favorite that always stirs up big emotions — light bulbs.

Mistake #5: Installing electric water heaters far from bathrooms

Many big homes have electric water heaters far away from bathrooms, and builders usually solve this by installing pumps to circulate the hot water full time around the house. This is convenient for people who like hot water right away, and it does save water since you don’t have to run cold water down the drain waiting for hot water to arrive. But it does waste a lot of energy making hot water that is never used, and it acts like a radiator, heating up your house, something you really don’t want in hot weather. If you can’t move your water heater close to your bathrooms, try swapping out the pump for a demand- or timer-operated model, and, if you can, insulate your hot water lines.

Mistake #6: Opening windows when the HVAC system is running

You don’t always need a programmable thermostat, as long as you turn your manual thermostat up and down so you aren’t heating or cooling your house too much when you’re not there. Programmable thermostats, if they are set properly, can do this for you, saving energy in the process. But all this effort to save energy will be for naught if you open your windows for “fresh air” when the HVAC is running. Don’t do it; it’s just stupid. If the weather’s nice, turn it off and open things up. If it’s too cold or too hot, close the house up tight and turn things back on.

Mistake #7: Not using efficient light bulbs

Finally, look at your light bulbs. I know that there are lots of strong opinions about CFLs and LEDs, but they are way more efficient than incandescent bulbs, prices are coming down, and quality is going up. Give them a shot and don't bust my chops just for mentioning them, OK?

Carl Seville originally wrote this for It is reprinted with permission.

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7 electrical use mistakes that will cost you
Flip a few switches, monitor the air conditioner and check those light bulbs.