I thought that it saved money and energy to leave the thermostat at one temp... like 68 degrees... all the time as opposed to turning it up or down.
Yeah whatever. How many thermostat's do you have in your apartment? I'm betting one, the same number that I have in my 2 story house. I can guarantee you that when I raise my thermostat up a few degrees, ALL of the air in my house doesn't get raised that much before the thermostat shuts the heat off.
There are a lot of variables in a topic like this one.
bingo.
Final answer: it depends. on how cold it gets outside, on the efficency of your home, thermal mass effects, and assorted other things.
As a general rule though, for most homes, if you're going to be gone for more than 4 hours, you will save energy by setting it back 8-10 degrees.
OK
The fact is that you aren't saving anything as it gets back to temp, if you go lower it has to burn more to get it back to your regular temp and heat the mass and so on. Where it saves the money is for every hr it runs maintaining the lower temp, because the closer it is to the temp outside the less the differental loss
and less the furnace runs.
I would think and from my exp using a programble thermostat and It would take quit a while to get it from 45 back up to 70? ours goes down to 64 at night cause of the kids and kicks in bout an hr to 70 for when we are at home. The last 3 mornings at -33C is still was only back up to 66 after 1 1/2 hrs.
We also set it to kick out about 1/2 hr before we go to bed to increase the time at the lower temp.
The fact is that you aren't saving anything as it gets back to temp, if you go lower it has to burn more to get it back to your regular temp and heat the mass and so on. Where it saves the money is for every hr it runs maintaining the lower temp, because the closer it is to the temp outside the less the differental loss
and less the furnace runs.
I would think and from my exp using a programble thermostat and It would take quit a while to get it from 45 back up to 70? ours goes down to 64 at night cause of the kids and kicks in bout an hr to 70 for when we are at home. The last 3 mornings at -33C is still was only back up to 66 after 1 1/2 hrs.
We also set it to kick out about 1/2 hr before we go to bed to increase the time at the lower temp.
I'm no expert, but I've put some thought into it, and I'm pretty sure you would *have* to determine this on a case by case basis.
The blanket statements don't take all the variables into account - especially things like how well insulated your house is to begin with, etc.
If you have a gas furnace, it's actually probably pretty easy - you have a gas meter you can read, right?
Pick two days where the conditions are approximately the same. Use a 24 hour period - record your gas usage for the first 24 hours doing it one way, then for the 2nd 24 hours immediately switch to the other technique. See what your actual energy consumption was. (And don't use any other appliances that use gas)
I wish I could do something similar, but there's no way for me to get much of an equivalent here in south florida - I could watch the electric meter but there are way too many other variables over the course of 2 days... with gas you could probably pretty easily live without the other gas appliances in the name of science.
The blanket statements don't take all the variables into account - especially things like how well insulated your house is to begin with, etc.
If you have a gas furnace, it's actually probably pretty easy - you have a gas meter you can read, right?
Pick two days where the conditions are approximately the same. Use a 24 hour period - record your gas usage for the first 24 hours doing it one way, then for the 2nd 24 hours immediately switch to the other technique. See what your actual energy consumption was. (And don't use any other appliances that use gas)
I wish I could do something similar, but there's no way for me to get much of an equivalent here in south florida - I could watch the electric meter but there are way too many other variables over the course of 2 days... with gas you could probably pretty easily live without the other gas appliances in the name of science.
Kelemvor
Lifer
- May 23, 2002
- 16,928
- 8
- 81
Originally posted by: KarenMarie
I thought that it saved money and energy to leave the thermostat at one temp... like 68 degrees... all the time as opposed to turning it up or down.
Assuming you aren't kidding, that's actually the opposite. That's why all new furnaces come with EnergyStart Programmable Thermostats. Why heat the house if you aren't in it or are sleeping. THe only point of contention is how much to turn it back. I wouldn't go back past 55 or 60.
Do an experiment. TIme the intervals the heater/AC is on and off with the temperature you like to have your house. Time the events for an hour or so to get a good average. Then the next day set it to a level you think will keep it from wasting energy while you are gone. Endure the adverse temps for a while to measure the intervals again. Then set it to the desired temp and time how long it has to run to bring it to the temp you like it. A little math and you should be able to see if turning the heater way down or the AC temps way up really save you any energy. You can even test different settings and come up with the best settings for efficiency to keep the house the way you want it. I did this and now I know exactly how to set my climate controls in the house.
Okay,
hmm Neither really matter here in a South Texas winter. I think we were below 60 about 5 days this winter so far . . . But for electric heat It's cheaper just to set the temp where you want it and leave it all the time for me 60' Winter and 78' Summer (It get's hot here) If we're gone for an extended vacation we do drop it as low as our thermostat goes about 55', so different answers from different folks all over the country.
Austin Energy
Looks like I got it dead on for Summer but I must be warm blooded cause I set it way to cold for the Winter.
(of course my Thermostat is wacky and it constantly stays at 65 on heat when I set it to 60) hmm. . .
hmm Neither really matter here in a South Texas winter. I think we were below 60 about 5 days this winter so far . . . But for electric heat It's cheaper just to set the temp where you want it and leave it all the time for me 60' Winter and 78' Summer (It get's hot here) If we're gone for an extended vacation we do drop it as low as our thermostat goes about 55', so different answers from different folks all over the country.
Austin Energy
Looks like I got it dead on for Summer but I must be warm blooded cause I set it way to cold for the Winter.
(of course my Thermostat is wacky and it constantly stays at 65 on heat when I set it to 60) hmm. . .
Yea, but your pipes aren't all located at the thermostat.
If you set it to maintain 45 degrees at the thermostat, you could easily be at risk to freeze a pipe in a crawlspace or such.
This tip was actually on my utility bill a few months back, albeit for summer use of the air conditioner but the general principal is the same, but I still don't understand why it would work, intuitively
when no one is home, doors arent being opened and such, so there is much less heat loss than when you are home, so setting it to 65 instead of say 40 will not cause it to run THAT much more, and when you get home, it only takes but a few minutes to heat it up to 70 from 65 as opposed to a few hours from 40. i rarely use the heater anyway, my apartment stays a constant 70-72 all throughout winter (4 guys, 4 computers, big TV, only one side exposed to environment, and we are beneath another apartment = great insulation)
TheLonelyPhoenix
Diamond Member
- Feb 15, 2004
- 5,594
- 1
- 0
Exactly.
Heating pipes aren't always close to your water pipes. Add in the paper-mache insulation that complexes like to use to save money, and voila: broken pipe and several hundred dollars of repairs.
Originally posted by: flot
I'm no expert, but I've put some thought into it, and I'm pretty sure you would *have* to determine this on a case by case basis.
The blanket statements don't take all the variables into account - especially things like how well insulated your house is to begin with, etc.
If you have a gas furnace, it's actually probably pretty easy - you have a gas meter you can read, right?
Pick two days where the conditions are approximately the same. Use a 24 hour period - record your gas usage for the first 24 hours doing it one way, then for the 2nd 24 hours immediately switch to the other technique. See what your actual energy consumption was. (And don't use any other appliances that use gas)
I wish I could do something similar, but there's no way for me to get much of an equivalent here in south florida - I could watch the electric meter but there are way too many other variables over the course of 2 days... with gas you could probably pretty easily live without the other gas appliances in the name of science.
the variables basically adjust the time you have to leave it lower before the numbers start to work in your favor...for most homes that don't have a heat pump, it's roughly four hours.
If you have a heat pump, setting it back is almost never a good idea.
Originally posted by: Dubb
Originally posted by: flot
I'm no expert, but I've put some thought into it, and I'm pretty sure you would *have* to determine this on a case by case basis.
The blanket statements don't take all the variables into account - especially things like how well insulated your house is to begin with, etc.
If you have a gas furnace, it's actually probably pretty easy - you have a gas meter you can read, right?
Pick two days where the conditions are approximately the same. Use a 24 hour period - record your gas usage for the first 24 hours doing it one way, then for the 2nd 24 hours immediately switch to the other technique. See what your actual energy consumption was. (And don't use any other appliances that use gas)
I wish I could do something similar, but there's no way for me to get much of an equivalent here in south florida - I could watch the electric meter but there are way too many other variables over the course of 2 days... with gas you could probably pretty easily live without the other gas appliances in the name of science.
the variables basically adjust the time you have to leave it lower before the numbers start to work in your favor...for most homes that don't have a heat pump, it's roughly four hours.
If you have a heat pump, setting it back is almost never a good idea.
If you have a heat pump, in the winter, I wonder if it might almost be a good idea to set the thermostat higher during the day? Particularly if you could pump it into some nice thermal mass like a concrete floor slab.
shilala
Lifer
- Oct 5, 2004
- 11,437
- 1
- 76
The payoff cutoff is 10 degrees. After that the cost of reclaiming the lost heat mass is greater than the savings. Department stores, restaurants, and homes with night setback thermostats are never set at a difference greater than 10 degrees. Optimum is 6 to 8 degrees.
If you're going on vacation, set back to 55 degrees. If you're going away for a weekend, set back 10 degrees.
You can save by setting the thermostat back that 6 degrees when you're out of the house (at work) too.
Mine has 4 time periods a day and 7 days. Some have less periods and less options.
I set mine back 8 degrees at night and 6 degrees during the day when we are all gone. The heat comes up automatically before we get home and goes down automatically shortly before we go to bed.
We can just bump a button if we happen to be home during one of the setback periods and it goes into occupied mode.
They save a lot of money if they're used properly.
If you're going on vacation, set back to 55 degrees. If you're going away for a weekend, set back 10 degrees.
You can save by setting the thermostat back that 6 degrees when you're out of the house (at work) too.
Mine has 4 time periods a day and 7 days. Some have less periods and less options.
I set mine back 8 degrees at night and 6 degrees during the day when we are all gone. The heat comes up automatically before we get home and goes down automatically shortly before we go to bed.
We can just bump a button if we happen to be home during one of the setback periods and it goes into occupied mode.
They save a lot of money if they're used properly.
This is very informative - from the DOE webpage linked by tellsek:
"A common misconception associated with thermostats is that a furnace works harder than normal to warm the space back to a comfortable temperature after the thermostat has been set back, resulting in little or no savings. This misconception has been dispelled by years of research and numerous studies. The fuel required to reheat a building to a comfortable temperature is roughly equal to the fuel saved as the building drops to the lower temperature. You save fuel between the time that the temperature stabilizes at the lower level and the next time heat is needed. So, the longer your house remains at the lower temperature, the more energy you save.
In the winter, significant savings can be obtained by manually or automatically reducing your thermostat's temperature setting for as little as four hours per day. These savings can be attributed to a building's heat loss in the winter, which depends greatly on the difference between the inside and outside temperatures. For example, if you set the temperature back on your thermostat for an entire night, your energy savings will be substantial. By turning your thermostat back 10° to 15° for 8 hours, you can save about 5% to 15% a year on your heating bill?a savings of as much as 1% for each degree if the setback period is eight hours long. The percentage of savings from setback is greater for buildings in milder climates than for those in more severe climates."
1. It doesn't say how much set back is optimal
2. But it does say amount of savings from temp setback reduces as climate gets colder.
Btw, from what I read, same rules do not apply to forced air furnace and heat pump. So let's assume we're talking about furnace.
"A common misconception associated with thermostats is that a furnace works harder than normal to warm the space back to a comfortable temperature after the thermostat has been set back, resulting in little or no savings. This misconception has been dispelled by years of research and numerous studies. The fuel required to reheat a building to a comfortable temperature is roughly equal to the fuel saved as the building drops to the lower temperature. You save fuel between the time that the temperature stabilizes at the lower level and the next time heat is needed. So, the longer your house remains at the lower temperature, the more energy you save.
In the winter, significant savings can be obtained by manually or automatically reducing your thermostat's temperature setting for as little as four hours per day. These savings can be attributed to a building's heat loss in the winter, which depends greatly on the difference between the inside and outside temperatures. For example, if you set the temperature back on your thermostat for an entire night, your energy savings will be substantial. By turning your thermostat back 10° to 15° for 8 hours, you can save about 5% to 15% a year on your heating bill?a savings of as much as 1% for each degree if the setback period is eight hours long. The percentage of savings from setback is greater for buildings in milder climates than for those in more severe climates."
1. It doesn't say how much set back is optimal
2. But it does say amount of savings from temp setback reduces as climate gets colder.
Btw, from what I read, same rules do not apply to forced air furnace and heat pump. So let's assume we're talking about furnace.
Air conditioner (which is like heat pump except pumping direction reversed) and forced air furnace don't always share the same principles as they work in totally different ways. So tips good for AC or heat pump may not work for furnace.
I agree, the cost stvings will be lost by having to expend more natural gas to heat up everthing else besides the air.
That seems to be another misconception. From here
"Many people continue to believe that it takes significantly more electricity to turn on a fluorescent lamp than to operate the lamp for long periods. Modern fluorescent lamps, however, use little starting energy. Turning them off actually helps them last longer and lowers lighting energy costs. Researchers at the U.S. Naval Civil Engineering Laboratory have found that a fluorescent lamp?s initial "start surge" lasts only 1/120 of a second. The entire starting current for two-tube rapid-start luminaries lasts less than one second before it stabilizes. Consequently, Navy engineers assert that turning the lamps off for only one second saves the energy required to turn them back on.
Not only does turning off fluorescent lights reduce lamp replacement costs, it also reduces electric bills. For example turning off a single one-tube light for only one-half hour a day can save about $3 in energy over the life of the lamp. In fact, the money saved by this routine is typically more than the price of a new lamp.
In short, you should turn off lights in your office or a room in your home when you leave, even if you leave for only a few minutes."
Kelemvor
Lifer
- May 23, 2002
- 16,928
- 8
- 81
The quotes you posted here and the ones above are great. They state exactly what a lot of people hav esaid. But unfortunately some people will never believe the facts and will only believe what they want or what they know as fact from decades ago.
Anyhow, back to thermostats...
If you want to do a test, here's a real easy one.
Lots of newer thermostats have a setting on them wher eyou can view the amount of time the furnace actually runs during the day. Get one of those, and play with the settings. You will see that if you set it back during the day while at work and at night while sleeping, the furnace will run less and therfore be saving you money...
Now obviously there are exceptions if your house in incredibly poorly insultated, if you have crappy windows, etc.... but for most people, these are the facts.
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