Friday, June 3, 2011

Does constantly changing the thermostat temperature 2-3 degrees affect electricity usage?

Would changing the thermostat back up and down 2-3 degrees affect electricity usage rather than keeping it at one temperature. For example, my roomates like to change the thermostat around 2 degrees lower at night then change it up again in the day.





I always thought this would cause the AC to work harder to maintain the temperature, thus leading to a high electricity bill.|||The rule of thumb is that you can save about 3% on your heating bill for every degree that you set back your thermostat|||yes


we did a 2 yr study on changing the temp at night and turning it back up in the am, with a programmable thermostat,


we dropped the temp 5 deg at night, then back to 70 at day time


for 1 yr then we removed the programmable one and went to a standard thermostat, and left it at 69 deg 24/7


we saved over $1,000 a yr on the electric and fuel bill with the standard thermostat.|||Ultimately depends on the time of year. I%26#039;m assuming we%26#039;re talking about the summer because you said AC. If you turn the thermostat higher during the day (when its hotter), then the AC unit will work less often, thus saving you energy. At the night when it%26#039;s cooler, even though the AC thermostat has been lowered, the AC unit doesn%26#039;t have to compete with the sun%26#039;s direct heat which makes it cheaper to operate.|||Any time you set your thermostat down you save money. Anytime you raise you thermostat it is costing you money.





If you set it down 2 degs you are saving money. If you set it back up to the original setting you will be right back where you started if you hadn%26#039;t set it down. You save money during the time it is set down and you spend the same money during the time it is set back to the original setting. A net saving.





People so think otherwise have never sat down and done the math.|||adjusting your thermostat 2-3 will only save you money.


adjusting it 10+ is where your theory baffles many. but it still saves money...





the lower the thermostat the more money you will save no matter how much you change it.|||It is all relative . So it all averages out.|||when it goes lower it saves you money that is what you are suppose to do 5degrees is better|||When you ask, %26quot;Does constantly changing the thermostat....affect electricity usage?%26quot;, the answer is %26quot;Yes, it saves electricity usage.%26quot; Any time you turn something off, you save, and raising the AC thermostat setting will turn the AC off for longer periods of time. You cannot save more than when the unit is off.


However, when you ask, %26quot;Does changing the thermostat cause the AC to work harder to maintain the temperature?%26quot;, again the answer is %26quot;Yes, it will be harder to maintain the desired temp.%26quot; This is where most people think that the catch up time causes the unit to run more and therefore use more electricity. When outside temps are changing, it is harder to illustrate my next point and make comparisons. So, first, consider the following.


Let%26#039;s say that the outside temp maintains an outside temp of 100 degrees F. Let%26#039;s also say that the AC in question is able to cool the house to 78 degrees F, and no lower, as long as the outside temp maintains 100 deg. F. If I keep my thermostat at 77 degrees, my AC will run 24/7, and will never turn off. If I raise my thermostat two or three degrees, my AC will enjoy SOME off time, and therefore save SOME electricity. As the thermostat setting is lowered, longer run times will be required of the AC to maintain the lower temp.


The above scenario is almost exactly the way it has been where I live. When the outside temp is approx. 95 to 100, the inside temp of my house would never get below 78 degrees. When my wife and I leave home in the morning, if we keep the thermostat at 72 degrees, the house would be at 78 when I got home in the early afternoon. At night when the outside temp lowers to 70 or 75 degrees, there obviously will be a point when the thermostat will be satisfied and turn off the AC. However the lower the thermostat setting, again the longer the AC will run. I thought that if I kept the AC on all day with the thermostat setting as low as 72, that%26#039;s the temp I would enjoy when I got home. My AC was never going to be able to reach that temp anyway.





Notice the following quote from Michael Bluejay%26#039;s website:





%26quot;It%26#039;s a myth that leaving the AC on while you%26#039;re away at work uses less energy than turning it on when you get home. Here%26#039;s why:





Heat goes to where it%26#039;s not. That%26#039;s why heat from outside goes into your cooler home. With the AC off, at some point your house will be so hot it can%26#039;t absorb any more heat. When you come home and turn the AC on, the AC removes all that heat.





But if the AC is on when you%26#039;re gone, then you%26#039;ve turned your house into a heat magnet. But keeping it artificially cool, there%26#039;s no limit to the amount of heat it can absorb. It can always absorb more heat. And your AC has to remove that heat constantly. Your AC kicks in and removes some of that heat, then the house is cooler so it sucks in more heat from outside, so your AC kicks in again and removes that heat, and so on.





This means that throughout the day, your house has absorbed way more than one houseful of heat. And your AC had to remove it all. By contrast, with the AC off all day, then it has to remove just one houseful of heat when you come home and turn it on.





Let%26#039;s say you leave the AC off, and your house absorbs 20k BTU%26#039;s of heat and then stops, because that%26#039;s all it can absorb.





Now let%26#039;s say that you have the AC running instead. The house absorbs 5k BTU%26#039;s of heat, so the AC kicks in and removes it. Then it absorbs another 5k BTU%26#039;s, and your AC kicks in and removes that. Repeat that process several times during the day.





The actual numbers will vary, and I haven%26#039;t tested this to see exactly how much the penalty for leaving the AC on during the day is, but there is zero question that running the AC all the time uses more energy than turning it on when you get home. This is not a gray area, it%26#039;s simple physics, and no person with any knowledge of this subject disputes it. Running the AC when you%26#039;re not home wastes energy, period.%26quot;





I hope this helps.

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