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Energy Myths
August 31, 2011
Some of our energy experts answer some common questions...
If I turn my heat or air off or down while I'm gone, does it use more energy to heat it up or cool it down when I get home than it would if I left it running the whole day?
If you are going to be away for more than four hours, it is beneficial to turn your HVAC system off or set the thermostat back. If the system is working properly, it will not work any harder re-cooling the home. We recommend 78 degrees in the summertime and 68 degrees in the wintertime when the home is occupied.
Does a computer use energy when it is in the sleep mode?
There are 4 basic types of computer power management, or "sleep" features on Windows PCs:
"System standby" Drops monitor and computer power use down to 1-3 watts each Wakes up in seconds Saves $25-75 per PC annually
"System hibernates" Drops monitor and computer power use down to 1-3 watts each Wakes up in 20+ seconds Saves work in the event of power loss Saves $25-75 per PC annually
"Turn off monitor" Drops monitor power use down to 1-3 W Wakes in seconds or less Saves half as much as system standby or hibernate: about $10-40
"Turn off hard disks" Saves very little energy
Do appliances use energy when they are plugged in?
The U.S. Department of Energy tells us that not only do appliances continue to draw electricity while the products are turned off, but in the average home nearly 75% of all electricity used to power electronics is consumed by products that are switched off.
VCRs, televisions, stereos, computers, and kitchen appliances all use energy while not in use. You may have noticed how a cell phone recharger can be warm even when not attached to a phone. The best way to prevent unnecessary energy expenditures is to do a clean sweep of your home. Here at the office, weve gotten into the routine of unplugging our water cooler at night. The process is a bit of a hassle at first, but hassle quickly turns into painless habit.
Tips for saving:
Use power strips to turn off TVs and stereos. Youll save the energy equivalent of a 100-watt light bulb that is always on.
Unplug chargers (think cell phones and iPods) when not in use. Only 5% of the power drawn by a cell phone charger is used to charge the phone. The other 95% is wasted when it is left plugged into the wall.
Which uses more energy, a microwave or conventional oven? How much more or less?
Microwave ovens use much less energy than conventional ovens, so they can save you some pocket change. Lets assume you are paying 8 cents a kilowatt-hour for your electricity. If you run a medium-size (1,000-watt) microwave at high power for 15 minutes, you'd spend 2 cents. A typical electric oven run at 350 degrees for one hour would cost you 18 cents. Do that every day, and you save yourself $60 a year with the microwave. More significantly, by keeping the kitchen cool in summer, a microwave may reduce your air conditioning costs.
How much energy does an electric car use and how much does it cost, generally, to run them?
In layman's terms, an electric car is like running an electric clothes dyer. Typically it will cost about a dollar a day or more specifically about $.02 (cents) per mile in equivalent fuel cost compared to $.20 (cents) per mile for a gas vehicle getting 20 mpg and fuel costing $4.00 per gallon. Additional benefit is that we have very few cost and generally minimal adjustments for electricity, so you can be assured that you wont have to deal with wild, weekly fluctuations in your fuel cost for the vehicle.
If I turn my heat or air off or down while I'm gone, does it use more energy to heat it up or cool it down when I get home than it would if I left it running the whole day?
If you are going to be away for more than four hours, it is beneficial to turn your HVAC system off or set the thermostat back. If the system is working properly, it will not work any harder re-cooling the home. We recommend 78 degrees in the summertime and 68 degrees in the wintertime when the home is occupied.
Does a computer use energy when it is in the sleep mode?
There are 4 basic types of computer power management, or "sleep" features on Windows PCs:
"System standby" Drops monitor and computer power use down to 1-3 watts each Wakes up in seconds Saves $25-75 per PC annually
"System hibernates" Drops monitor and computer power use down to 1-3 watts each Wakes up in 20+ seconds Saves work in the event of power loss Saves $25-75 per PC annually
"Turn off monitor" Drops monitor power use down to 1-3 W Wakes in seconds or less Saves half as much as system standby or hibernate: about $10-40
"Turn off hard disks" Saves very little energy
Do appliances use energy when they are plugged in?
The U.S. Department of Energy tells us that not only do appliances continue to draw electricity while the products are turned off, but in the average home nearly 75% of all electricity used to power electronics is consumed by products that are switched off.
VCRs, televisions, stereos, computers, and kitchen appliances all use energy while not in use. You may have noticed how a cell phone recharger can be warm even when not attached to a phone. The best way to prevent unnecessary energy expenditures is to do a clean sweep of your home. Here at the office, weve gotten into the routine of unplugging our water cooler at night. The process is a bit of a hassle at first, but hassle quickly turns into painless habit.
Tips for saving:
Use power strips to turn off TVs and stereos. Youll save the energy equivalent of a 100-watt light bulb that is always on.
Unplug chargers (think cell phones and iPods) when not in use. Only 5% of the power drawn by a cell phone charger is used to charge the phone. The other 95% is wasted when it is left plugged into the wall.
Which uses more energy, a microwave or conventional oven? How much more or less?
Microwave ovens use much less energy than conventional ovens, so they can save you some pocket change. Lets assume you are paying 8 cents a kilowatt-hour for your electricity. If you run a medium-size (1,000-watt) microwave at high power for 15 minutes, you'd spend 2 cents. A typical electric oven run at 350 degrees for one hour would cost you 18 cents. Do that every day, and you save yourself $60 a year with the microwave. More significantly, by keeping the kitchen cool in summer, a microwave may reduce your air conditioning costs.
How much energy does an electric car use and how much does it cost, generally, to run them?
In layman's terms, an electric car is like running an electric clothes dyer. Typically it will cost about a dollar a day or more specifically about $.02 (cents) per mile in equivalent fuel cost compared to $.20 (cents) per mile for a gas vehicle getting 20 mpg and fuel costing $4.00 per gallon. Additional benefit is that we have very few cost and generally minimal adjustments for electricity, so you can be assured that you wont have to deal with wild, weekly fluctuations in your fuel cost for the vehicle.
Memphis, TN 38103