General Discussion?

I have to wonder if turning your heat down when you leave home really saves much …if anything as the heater runs that much harder to get it back up to temp. I realize theres probably some math involved here and an ideal temperature range…

Ok i didnt get that quite right. Say your just gone over night or you turn it down when you go to bed. It runs that much harder when you turn it back up. Im thinking the fuel saved is very little if any

It depends on how long you’ll be turning it down for…Just the morning when you go to work…it’s NOT worth it…But if you leave for a few days then it’s worth it.

Copy that. I should have given it a little more thought

I used to keep the heat set at a constant temperature in winter. For the last few years I’ve been lowering the thermostat by five degrees when I leave for work, when I go to bed at night, and if I go away for a weekend.

My heat bills have been lower since I started reducing the temperature. My utility allows me to track my usage online, and I can clearly see the savings from year to year.

I’m sure there are situations in which the results might vary, but I save money, and use less energy, by lowering the thermostat when I’m not home.

It will vary depending on many factors including the insulation type and amount and insulation as well as the energy source (gas, oil or electric) etc.

However I believe you are going to find that turning it down will 98.7% of the time prove out to be cheaper.

The math will require knowing a lot about the local weather, construction of the house, the energy used inside the home (like TV, hot water, lights etc as well as the situation of the house, the wind and outside temperatures, number of people in the house type of windows etc.

There have been several experimental homes in my area and they all have reported an overall savings by turning down the heat (or increasing the temperature for cooling).  

The issue is energy in vs energy out.  Allowing the home to get colder when you are away or sleeping, reduces the heat needed.  Electric is really straight forward as there is no loss due to working the electric harder for part of the day and less for another part.  The harder part of the calculation is with power sources that may be more or less efficient when working at higher outputs.   

 Doing those calculations are about as hard as doing calculations for cars.  It can get complex.

We have a programmable thermostat which lowers the temperature at 10 pm and resets it again at 6am.

The general formula is Q=RxdeltaT, Delta T being T1-T2, so as you can see the heat required to heat the house is directly proportional to the temperature difference between ambient and you house.

If, in the winter it is 0F, and your house it 78F, setting it back to 68F will save Rx (78-68)/78 or 10/78=12.8% over that 8 hour period. If you go on vacation and have no sensitive house plants, you can permanently set back the thermostat and save money continuously.


Agree, that setting it back and then cranking it up again a few hours later does not save a lot. Also, if it’s +50 degrees out, the setting back does not save a lot.

I agree with the others, as a general rule it’ll help. Of the things you can control, the heat loss depends largely on the difference in temp, inside-outside (also on insulation and air infiltration). So, if you’re not addinng insulation or sealing windows, the biggest savings will come from turning down the termostat. That said, I wouldn’t bother for less than 8 hours or so.

You will save money if you set it down overnight or if you set it down when you go to work. And the lower you can stand the temperature when you are home, the more money you will save. We run the temperature at 67F when we are home and set it down to 55F when we are out.

Thats what i had in question. Your heater warming the house from 55 back up to 67…is it worth it as the heater work harder to bring the temp back up. If your going to be gone a week i can see it but overnight i have to question it

Overnight’s worth it.

I go for insulation (walls,windows,doors) as being a much larger factor as to how much energy is needed to keep one comfortable. I am out of the “leave the computer ,lights,TV whatever on, because it costs more to turn in on again” club also. It costs more to leave them on than turn them off when you are gone.

This year we decided to do the turn the thermostat down whenever not home to save money. 1 degree net difference heating/cooling from the energy bill last year but a higher energy cost and usage via the bill. I have a friend with a similar sf house, high efficiency furnace, he upgraded windows and insulation. We kept ours at a constant 72, he was 65 max and 58 when he was not home. Our bills were never more than $15 apart. Sure my 1918 house has plastic on the windows, no insulation in the walls, but it is double brick construction and r 24 blown in the attic. I hear the 40 year old furnace every time it kicks on, not real loud but I tend to listen how many cycles per hour. I had a heater tune up guy who missed his, that was the same as ours. He got the new high efficiency, said he did not save much money over our 70s era honeywell with a lifetime guarantee on the heat exchanger, but really missed the blast of warm air as the new ones are a constant temp. I think if you could live with a constant 68 degrees that would be the best.

Reminds me of a joke, this general discussion.
Wal Mart manager to greeter who was chronically late.
What would happen if you showed up late at your last job?
They would say General, would you like a cup of coffee?

The heater never ever works “harder.” It’s either on or off. The thermostat is a temperature controlled on/off switch, nothing more.

I agree !

The better insulated the house, the more effective it is. Houses that depend upon their mass to retain heat, stone and log, less so. Poorly insulated houses allow the internal mass to cool down and it becomes less energy efficient, with the shorter time. It’s really difficult to generalized without having an energy audit and heat loss evaluation done on your house as to the most efficient way. But “old school” has it right IMO. Tighten and insulate the house before you begin to experiment too much.

I got another…
While discussing ways to keep warm when turning the thermostat down, one fellow says to the other; "Did you hear about the new corduroy covered pillows they just came out with. "
The other fellow says, “No I haven’t, should I ?” To which the first fellow said; “you should have by now, they’re making ‘headlines’ you know.”
(grand children approved)

You’re right that the difference between the two, cooling off and heating back up, completely counteracts the other.
Once you’ve cooled to the new set temperature you’ll still see the same time span between the heat and non-heat cycle for temperature maintanence to the set temp.
If you can just get used to and learn to live with the lower temp ( wear more clothes and some good ol’ slippers ) then you might notice the savings of the first cool down but -> temperature maintainence <- is still the kicker here.

The savings comes when you can extend that time period between cylcles AND to use all heat produced to max efficiecy.

Insulation, caulking, draft elimination, high efficiency furnace or other heat source and a long list of other ‘tricks of the trade’ are the ony real way to save on the heating bill.

That is correct, that the furnace does not run at all while the house is cooling down and that savings is canceled when the house (and its contents plus the wallboard) is warmed back up again. In the meantime, while the inside temp is lower than normal, the temperature differential between outside and inside is less so during that time, the furnace does not need to work as hard because heat loss to the outside will be less.

Setback thermostats have been around for well over a decade and I have never heard a negative word about using them to their capabilities. I would not bother with a setback period of less than about 6 hours (my personal preference) and not more than two setbacks per day; one while at work and another while sleeping.