Turning down the home thermostat

[specialk]

So I have the old style, unprogrammable thermostat. My schedule is too crazy for the programmable type.

At night I turn it down 10 degrees, for about 8 hours, until I get back up. Does doing this save money or is the savings being eaten up every morning when I bring the house back up to normal temp. It's a 1,000 sq. ft. house, split level.

My brain tells me I'm saving money but I've never seen a study done that shows it to be true. Any heating/energy experts out there want to set me straight? Thanks!

[Armitage]

I wouldn't want to be your wood furniture or guitars...

[Brewmaster]

When I was living up North I always had the thermostat at 68 degrees during the winter and 78 during the summer. I do the same thing down here. My electric and gas bills were always less than everybody else in spite of the fact I had a much larger house.

I think the key is maintaining a consistent temperature. If you are not sure, compare consumption year over year and see what the difference is.

[MCChris]

I equate it to a car engine: Burns more gas accelerating to speed than it does cruising at a constant speed.

[ArnieZ]

I think there is a lot of information out there that shows a 10 degree differential for several hours saves money.

We have been using 68/58 for years. I personally prefer it cooler for sleeping. I think humidity has a bigger effect on the guitars than temp, if it's not extrreme. I have had no problems with any of my guitars, I do keep them in there cases though.

ArnieZ

[veatch]

I ain't no HVAC guy, but my understanding is that anything more than a 4 degree swing is actually hard on the HVAC system. I have nothing to back that up other than the recommendations i have received from more than one HVAC person.

Back in the day, i used to do a 10 degree swing and i think i did save money. But, at the end of the day, i simply got tired of everything in the house being cold. I'd sit on the couch - cold. I'd crawl in bed - cold. Sit on the floor - cold. Toilet - don't even ask.

The furnace can get the air in the house back up to 68 pretty quickly, but all of the cold solids will keep cooling the air making the need for the furnace to kick back on happen more frequently until everything stabilizes. In the mean time, everything is ... cold.

At this time, i'm with Brewie - 68 in the Winter, 78 in the Summer.

I do turn down to 64 when gone for a week or a long weekend, but that is pretty rare.

[tommy p]

I had my entire system replaced a few years ago. I asked that very question to the 4 different companies I got estimates from and every one said to find a temperature you're comfortable with, then "set it and forget it".

Edited to add: And I still didn't listen, but I don't change mine drastically. I set my to drop 5 degrees when I'm at work and a couple when I'm asleep and my bill is very reasonable.

[doody]

I had an "Energy audit" done a couple years ago to qualify my house for rebates from my energy company.(insulation, windows, furnace, etc) The guy doing the audit say no more than 4 degrees. Bigger swings just make the furnace run harder/longer to catch up. Mine goes down to 64 at night and when I'm at work,68 when I'm home and awake. My "smart thermostat" will actually bump up to 66 first, then to 68. In the summer I just leave it at 78 and forget about it.

On a side note, my energy company(Alliant energy) will rebate the money for buying an electronic "smart thermostat".

[HSB0531]

I've alway done no more than a 6 degree swing.

The bigger the house, the longer it will take to get back up to normal. And the bigger the change, the more energy you will use.

I worked at a music store that used to turn the heat off at the end of the day.

It took until 4:00 pm the next day to get back up to normal temps.

[specialk]

Thank you, gents.

It looks like a 5 degree lowering at night from now on.

[jwhitcomb3]

Depends on the system. If you have an older heating system where the heater is either full on or full off, then a big temperature swing can be inefficient. I had a newer Trane furnace that had four burners, but had modes where it only turned on two of them. It would keep the house closer to your comfort zone, rather than swinging between too hot and too cold. Combine that with different fan speeds and a smart computer controlled thermostat, and you can save a bunch of fuel.

Do you have hot air, hot water, or something else?

-Jonathan

[specialk]

Do you have hot air, hot water, or something else?

-Jonathan

I have a natural gas furnace, so it's hot air. It's an older furnace, probably 15 years old, but I'm a renter so I ain't buying a new one! It's either on or off.

[RecRm Rocker]

I work for Siemens Industries, Building Technologies division.

Keep in mind these settings are for commercial, office, school settings most likely with central boiler and chiller systems. But to answer the questions. default terminal unit settings are as follows.

Day Cooling 74

Day Heating 70

Night Cooling 84

Night Heating 65

These settings assume unoccupied spaces at night. Also are targeted at energy savings.

[gregc]

I settled on leaving the bedroom floor at 65. The living area swings 65/68, depending on occupancy. Seems reasonable.

[Uncle Thor's Hamer]

Thermodynamics tells us that the bigger the temperature difference between inside and out, the more energy is lost through the walls/roof. It is a linear relationship just like electronics Ohms Law E=IR.

Humidity has a big effect on how comfortable the air is, with experts claiming that too dry feels colder. We live in a dry climate, with inside air in the winter running in the single digits for humidity. I run two humidifiers, putting about 6 or 8 gallons of water per day into the air when it is really cold outside.

In theory, turning the thermostat way down at night or when you are away should save money. But I think that it doesn't really work that way because we feel the cold objects in the room and turn the heat up even higher than we normally would. So we waste more energy when we are home, making up for whatever we may have saved at night.

[Armitage]

For the difference, I'd rather be comfortable.

[BillW]

There seems to be a scientific opinion on this:

Ask A specialist - programmable thermostats

looks like the key is 4hours or more reduced:

"Some people mistakenly believe that the energy savings from lowering the thermostat for a few hours are offset by the expense involved in reheating the house. Tests show that lowering your thermostat setting daily for intervals of four or more hours will reduce costs.

"

[DaveH]

On the older systems you would benefit from lowering temps more with a gas furnace than you would a heat pump....gas heats the air pretty quickly, whereas a heat pump system will kick in the strip heaters in your air handler to try to catch up, and those are big power consumers. If the heat pump is left running the strips are not generally being called on to help heat (I don't know if this is true in really cold climates...I'm in the south). The new high efficiency/high SEER two-stage heat pumps and variable speed blowers are fantastic, the difference in comfort level and operating costs beat the hell out of even a 10 year old system.

[specialk]

There seems to be a scientific opinion on this:

Ask A specialist - programmable thermostats

looks like the key is 4hours or more reduced:

"Some people mistakenly believe that the energy savings from lowering the thermostat for a few hours are offset by the expense involved in reheating the house. Tests show that lowering your thermostat setting daily for intervals of four or more hours will reduce costs.

"

Thank you for this, BillW! exactly what I was looking for.

If we leave for work or when we go to bed, we drop the thermostat. But if it's just for a few hours we don't. So I guess we were doing it right all along. Only now it's just a five degree drop, not ten degrees as before.

The HFC and its members rock as always!