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Forestfen used to say that she had heard it was more energy efficient to keep the air conditioner or heater on a constant setting, or to only change it by a few degrees at night or when we were not at home, rather than turning it all the way off.
That never made sense to me from an energy perspective.
I did some web searches and sent her the following info.
http://michaelbluejay.com/electricity/cooling.html
(See the section "It's a myth that leaving the AC on while you're away at work uses less energy than turning it on when you get home. ")
http://www.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12720
The above page also says it uses less electricity to turn the thermostat
up in the daytime than to keep the a/c on all day. However it also mentions something
about heat pumps, which I didn't pay much attention to at the time, as we don't have heat pumps:
"But when a heat pump is in its heating mode, setting back its thermostat can cause the unit to operate inefficiently, thereby canceling out any savings achieved by lowering the temperature setting. Maintaining a moderate setting is the most cost-effective practice. Recently, however, some companies have begun selling specially designed programmable thermostats for heat pumps, which make setting back the thermostat cost effective. These thermostats typically use special algorithms to minimize the use of backup electric resistance heat systems."
While doing those web-searches, I also came across some posts by people who said they worked in the HVAC business, and that it was cheaper to keep the A/C set to a constant temperature all day, but they did not give any proof. The only reasonable thing I read, was that the a/c has to work harder (the motor has to stay on for longer) to cool the house down by a large amount, whereas if it is on all the time, it only comes on in shorter bursts all day long (the overall time it is on would be longer, but each individual time it was running would be shorter). Since the a/c has to stay on for a longer period in order to cool the house initially, it may wear out sooner and have to be replaced sooner. So you do not save electricity by keeping it on, but you may extend the life of the a/c unit. I am not sure if that is true though.
On television this week, I heard someone mention something about heat pumps and
heat strips in regards to energy efficiency. So I did another websearch, and
found this:
http://www.jea.com/about/pub/downloads/HeatPumpStripHeatManagement.pdf
So, if you have a heat pump as opposed to a gas-powered heater, then it may be true that turning the thermostat down and up by large jumps will cause the unit to operate less efficiently than otherwise. It may switch over to using the electric-powered heat strips rather than the heat pump, to achieve the large change in temperature. However, as mentioned on the previous page, it depends on the unit.
That never made sense to me from an energy perspective.
I did some web searches and sent her the following info.
http://michaelbluejay.com/electricity/cooling.html
(See the section "It's a myth that leaving the AC on while you're away at work uses less energy than turning it on when you get home. ")
http://www.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12720
The above page also says it uses less electricity to turn the thermostat
up in the daytime than to keep the a/c on all day. However it also mentions something
about heat pumps, which I didn't pay much attention to at the time, as we don't have heat pumps:
"But when a heat pump is in its heating mode, setting back its thermostat can cause the unit to operate inefficiently, thereby canceling out any savings achieved by lowering the temperature setting. Maintaining a moderate setting is the most cost-effective practice. Recently, however, some companies have begun selling specially designed programmable thermostats for heat pumps, which make setting back the thermostat cost effective. These thermostats typically use special algorithms to minimize the use of backup electric resistance heat systems."
While doing those web-searches, I also came across some posts by people who said they worked in the HVAC business, and that it was cheaper to keep the A/C set to a constant temperature all day, but they did not give any proof. The only reasonable thing I read, was that the a/c has to work harder (the motor has to stay on for longer) to cool the house down by a large amount, whereas if it is on all the time, it only comes on in shorter bursts all day long (the overall time it is on would be longer, but each individual time it was running would be shorter). Since the a/c has to stay on for a longer period in order to cool the house initially, it may wear out sooner and have to be replaced sooner. So you do not save electricity by keeping it on, but you may extend the life of the a/c unit. I am not sure if that is true though.
On television this week, I heard someone mention something about heat pumps and
heat strips in regards to energy efficiency. So I did another websearch, and
found this:
http://www.jea.com/about/pub/downloads/HeatPumpStripHeatManagement.pdf
So, if you have a heat pump as opposed to a gas-powered heater, then it may be true that turning the thermostat down and up by large jumps will cause the unit to operate less efficiently than otherwise. It may switch over to using the electric-powered heat strips rather than the heat pump, to achieve the large change in temperature. However, as mentioned on the previous page, it depends on the unit.