Programmable thermostats save you money. That’s a no-brainer, right? You’ve seen that advice in books and magazines and on personal-finance blogs — even here at Get Rich Slowly.
Well, it turns out programmable thermostats aren’t the miracle device we’ve believed all along. In fact, sometimes using a programmable thermostat costs more than not having one at all. But the fault doesn’t lie with the thermostat. The trouble, as my father used to say, is the nut behind the wheel.
Theory and practice
In theory, programmable thermostats are a great way to save on home energy costs.
According to the Energy Information Administration, about 42% of home energy costs go to heating and cooling. A lot of these costs come from heating and cooling empty (or unused) spaces, including heating and cooling while people are asleep. In plain English: People spend a lot to heat and cool their homes, and they’re not good about turning things off when they’re not needed.
In fact, some folks think it uses more energy (and thus costs more) to turn the thermostat down at night and then re-heat the following day. They’re wrong. A 1978 research paper (“Energy Savings through Thermostat Setbacks” by Nelson and MacArthur) confirmed basic physics. On average, if you turn the thermostat down by one degree Fahrenheit for eight hours every night, you’ll use about 1% less energy. (So, if you turn the temperature down by 10 degrees every night, you’ll use about 10% less energy.) But note that you’ll see less savings in milder climates (the bigger the difference between indoor and outdoor temperatures, the more you save by adjusting the thermostat) and with electric heat.
Based on this, it makes sense that a programmable thermostat could reduce energy usage. You simply program the thermostat to warm (or cool) your home when you’re actually there; when you’re away (or asleep), the thermostat switches off. As is often the case, though, practice is different than theory.
The main problem is that people don’t use programmable thermostats the way they’re intended. Someone might keep the home cool during the day, for instance, but crank the heat above room temperature at night. But even when used properly, programmable thermostats may not offer a cost savings.
Where’s the savings?
An Environmental Protection Agency (EPA) document from 2004 describing the Energy Star programmable thermostats specification [PDF] summarizes the research into their efficacy:
Consumers are often advised that installing a programmable thermostat can save them anywhere from 10 to 30% on the space heating and cooling portion of their energy bills. While reliant on proper use of the programmable thermostat, such savings are easily true in theory; however, there needs to be more field-tested data to better substantiate savings claims. Analyses from recent field studies have suggested that programmable thermostats may be achieving considerably lower savings than their estimated potential.
How much lower? In 2007, RLW Analytics prepared a report for GasNetworks, a New England-based energy company. “Validating the Impact of Programmable Thermostats” [PDF] found that using an Energy Star-certified programmable thermostat produced an average savings of about “6.2% of total household annual natural gas consumption”. Those who installed programmable thermostats into older heating systems (in other words, those who didn’t install a new heating system at the same time) saved an average of 6.8%.
And that study painted the rosiest picture of programmable thermostats.
In 2000, the Energy Center of Wisconsin published a report entitled “Programmable Thermostats Gone Berserk? Taking a Social Perspective on Space Heating in Wisconsin” [PDF]. The study found, in part, that:
Despite the emphasis that has been placed on the use of programmable thermostats to reduce thermostat setpoints and so save heating energy, respondents with programmable thermostats report thermostat setpoints that are not substantially different from those of respondents with manual thermostats.
[...]
These details and the conclusions above lead us to suspect that the aggregate savings that can be expected from the installation of programmable thermostats in residential housing is probably quite modest.
Elsewhere, it’s worse. Sometimes those with programmable thermostats use more energy. In 2008-2009, Florida Power & Light conducted a study of 400 homes with programmable thermostats [PDF]. Turns out that those who programmed their thermostats actually used 12% more cooling energy than those who did not.
Sure, those who programmed the thermostat used less energy when they weren’t around; however, they tended to set the thermostat much lower for the times they were home. As a result, the folks who did nothing saved more energy.
Why is there a discrepancy between the theoretical and actual savings with programmable thermostats? Because the proposed savings were, in actuality, theoretical. That is, they were based on computer models and not on real-world experience. Now that there’s enough real-world data, it’s clear that programmable thermostats have only a minimal impact on energy consumption. As in other areas of personal finance, it’s human behavior that make the most difference.
The bottom line
In May 2009, the EPA suspended Energy Star certification for programmable thermostats [PDF], writing:
EPA has been unable to confirm any improvement in terms of the savings delivered by programmable thermostats and has no credible basis for continuing to extend the current Energy Star specification.
Programmable thermostats can reduce energy consumption — if they’re used right. But so can regular thermostats. What does make a difference on your heating and cooling costs? According to the Wisconsin study I mentioned earlier, your attitude toward conservation makes a big difference in energy consumption.
- If you’re motivated to save energy (for whatever reason), you’re more likely to use less energy. In this case, a programmable thermostat makes no difference.
- If you don’t care about saving energy, you’re likely to use more energy. Again, a programmable thermostat won’t change this.
Programmable thermostats can save money — not just in theory — buit only if they’re used correctly. Pick your set points based on your household’s habits, and then leave them there. Don’t fuss with the thermostat. The following is a typical energy-efficient program:
- During the winter, set your thermostat for 68°F (20°C) while you’re awake, and set it lower for when you’re away or asleep.
- During the summer, set your thermostat for 78°F (26°C) while you’re home, and turn it off when you’re away.
- Better yet, heat (and cool) individual rooms instead of the entire house. If you tend to spend a lot of time in just one or two rooms, you can save a lot of money by using a space heater or a room-sized air conditioner.
Our thermostat is programmed for 65 when we’re home and 58 when we’re away or asleep. It kicks on about an hour before we wake or arrive home. (We don’t have a cooling system, so the thermostat doesn’t get used from June to October.)
After all these words, the bottom line is common sense: Whether you use a programmable thermostat or not, if you turn down the heat (or turn off the air conditioning) when you don’t need it, you’ll save money.
Footnote: This post was inspired by a discussion at The Simple Dollar, in which “Lurker Carl” pointed out that programmable thermostats have come under fire. His comment prompted me to spend three hours researching this stuff and another two hours writing up my findings.
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I know that sometimes new and interesting content is hard to generate and I appreciate all the work that JD does, but I really can’t read another article on a financial blog about programmable thermostats.
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I know you said last week that nobody would be interested in this article, but take heart- I am! We have electric heat throughout our house, unfortunately, and we pay a fortune in utilities because of it.
We’re willing to try nearly anything and everything to get the bill down, and we’ve had more success with some than with others. Similar to the conclusions presented here, our programmable thermostats seem to be a wash. Not saving much, but not any worse off either.
Can I ask what the theory behind turning the temperature down when you’re asleep is? We’ve programmed our thermostats to do so (frankly) just because we’ve been told it’s a good way to save money and we’ll “never notice”. We’re seriously considering turfing that advice- we DO notice, and I wake up in the middle of the night freezing!
I can’t wait for spring to come back…
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We just installed a new furnace, and the installer told us *not* to program different temps day and night. He said it cost more to bring the temp back up in the morning, than it would to maintain the temp during the night (thermal mass?).
And this in a Minnesota winter! I’m highly skeptical, so I’ll be checking my next gas bill very closely.
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The revelations in this article are no surprise; they’re yet another example of some level of “rebound theory.”
“Sure, those who programmed the thermostat used less energy when they weren’t around; however, they tended to set the thermostat much lower for the times they were home.”
This type of thing happens all the time for those who think they are going to “go green.” Recycling your bottles? Great, no reason to worry about drinking only bottled water. Drive a Prius? No problem taking longer road trips on the weekends. Live in the city and walk to work to save on gas? Wonderful, now you have extra money to fly halfway around the world for responsible eco-travel. People eventually spend their money one way or another, and there’s practically nothing you can spend money on or give it away to that doesn’t ultimately require energy. Even giving the saved money to some wonderful non-profit to help poor women in under-developed countries means that those poor women are now going to be able to purchase more milk or meat or refrigeration.
And even someone, somehow truly succeeds at using less energy, which is extremely rare, the best he can hope to do is simply lower the energy commodity costs for everyone else, and the usage of other people will easily make up for his sacrifice. Energy efficiency is great, but it never results in anyone using less energy. More energy is ultimately consumed as a result. One way or another.
Anyway, as for thermostats: the amount of energy you’ll consume to heat or cool your house is the amount of energy needed to replace the lost heat (or cool air). If you lived in a perfect thermos, you’d only have to pay to heat the house once per year, at the beginning of winter. So what you’re paying for is heat transfer. Heat transfer is what you’re worried about, so think in those terms. In simple terms, the amount of heat transferred is determined by multiplying three factors: (temperature difference b/w hot and cold) * (area for transfer–size of your house and roof) * (coefficient for transfer–how well insulated is your house).
Re: programming the thermostate, the term we’re playing with is the first one; the temp. difference. If, for a few hours each day, your thermostat is set for 55 instead of 68, and the outside air is 32, perhaps, then the amount of heat transfer, which is linearly proportional to (55-32=23) vs (68-32=36) is (36-23=13…13/36) = 36% lower rate of heat transfer during that eight-hour period.
The fact that you have to heat it back up when you get home is inconsequential. It’s perfectly balanced out by the fact that for a few hours after you left, the heat didn’t have to run at all while it drifted down from 68 to 55.
The problem, of course, is in real life, now the homeowner says “I’m saving all this money, now I can turn the temp up to 72 when I’m home. Or, we can justify adding on that bonus room.”
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We live in Houston, TX and our specific neighborhood doesn’t have gas lines, so we are electric all the way.
Our programmable thermostat saves us a ton because we would never remember to turn up the temp every single day when we go to work….we have it auto set to 80 on work days, 75 on work afternoons when we get home, and 72 while we sleep (I like to hibernate). Our electric bills are always between $80-$160 (summer), which is STELLAR for our area. LOVE my programmable thermostat.
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Kate (2) who wrote “We have electric heat throughout our house, unfortunately, and we pay a fortune in utilities because of it.”
I don’t know where you live or how much property you have, but you should Google “outdoor wood boiler.” I don’t have one, because we have natural gas and it’s terribly cheap, but otherwise I’d look into it. It’s like a little shed-style woodstove that you put out in the yard. You throw in any sort of wood that you can get your hands on; it absolutely does not have to be split firewood. It heats a closed loop of water that flows into your house and across the air handler (in your basement?). They say they’re over 90% efficient.
I’ve seen one video-testimonial where a family in the upper Midwest is playing in a steaming swimming pool that’s surrounded by a snow-covered ground; all from the cheap heat of a wood boiler.
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“the installer told us *not* to program different temps day and night. He said it cost more to bring the temp back up in the morning, than it would to maintain the temp during the night (thermal mass?).”
The installer has no idea what he’s talking about. By this logic, you should never turn off your oven. Just keep it at a constant 350F. Otherwise, it costs too much to pre-heat it every time you want to bake cookies.
See the explanation in my previous post. The money you spend bringing the house back up to the comfortable temperature is perfectly balanced by the money you save letting it drift down.
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Programmable thermostats idiot proof the process. We are as diligent as any in our energy savings (to the point we write about it) but even still, on the non-programmable thermostat in our sun room (baseboard heaters – eek!) I still forget to turn it down some evenings and I pay for it in electric billing.
http://www.genywealth.com/programable-themrostat-savings
Good article there about a careful analysis of GenY’s bills one year to the next.
If you are able to 100% guarantee you will never forget to turn the heat up or down as needed these devices make no sense – but no one is infallible and eventually you’ll forget.
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I live in Austin, TX, where summer temperatures usually soar above 100 degrees, and it has always been for me an accepted fact that turning off the a/c during the day would use more energy than just turning it down a little, which makes sense to me: depending on the size of the house, cooling it from 90 or higher to a comfortable temperature could take several hours of continuous a/c. Can you point to any information detailing the most efficient use of programmable thermostats in hot climates?
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J.D.’s note: Imagine how painful it was to WRITE yet another article on programmable thermostats! Yet I like to think this one is very different than anything else that’s out there…
I’m with you, JD. And while I’ll agree that this article is different than the others concerning programmable thermostats, it’s just a matter of oversaturation. It’s almost like how the health media changes their stance on eggs every couple years — they’re good for you, so here are loads of articles about how good eggs are; oh wait, now they’re bad, cue the negative articles about eggs. It’s not a matter of content in this case. The subject of the article is already tired and will certainly make readers, especially readers who have followed the finance blog circuit for a while, a little bit weary.
Regardless, keep up the good work on this blog. GRS is the only finance blog I keep up with anymore as many of the others have really lost steam.
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This is right on the money: “If you’re motivated to save energy (for whatever reason), you’re more likely to use less energy. In this case, a programmable thermostat makes no difference.
If you don’t care about saving energy, you’re likely to use more energy. Again, a programmable thermostat won’t change this.”
We have a programmable thermostat but as my husband is home during the day we cannot use it to acheive cost savings by setting it lower during the day. We kept fiddling with the temperatures and time frames but ended up settling on setting it around 64 during winter, and 79 during summer, 24/7. We tried setting it lower during the night at winter but our children sometimes throw their covers off during the night. This is the best balance between cost and comfort in our house.
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Great article! I must have missed all the internet discussion on programmable thermostats, because all that comes to mind is Funny About Money about a year ago complaining that her electric bill went up when she installed one. It’s nice to see that she’s not just crazy.
We do have a programmable thermostat– in the winter it’s nice to get up to a warm house and I am really bad at remembering to turn the a/c down when we leave the house in the summer. I do manually adjust it, generally warmer in the summer and cooler in the winter. The problem is that our sensor is in one of the rooms of the house that heats differently based on sunlight compared to the rest of the house (despite our best efforts to crepe mrytle the heck out of the window area in front), so on sunny days the a/c goes too high and on cloudy days too low (similarly for the heat).
Generally we set at 82 in the summer and 68 in the winter. We’ve got a great system of ceiling fans.
I make the big bucks so that I’m never hot or cold no matter what’s going on outside. Seriously. Scarlett O’Hara moment and everything. “I will never be too hot again!”
And yes, this is far different than any other programmable thermostat article I’ve read.
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I’m surprised anyone thought that programmable thermostats were some kind of miracle device.
They are just a simple timer – similar to the type you might install on your Christmas lights so you don’t have to manually turn them on and off.
That study by Florida Power and Light doesn’t make any sense:
Sure, those who programmed the thermostat used less energy when they weren’t around; however, they tended to set the thermostat much lower for the times they were home. As a result, the folks who did nothing saved more energy.
This is like saying that fuel-efficient cars don’t save gas because their owners tend to drive faster than owners of other cars. They are mixing two different variables in their test.
Changing your temperature setting based on house usage will save money – and as SPF noted, automating that procedure makes it easier for the house owner and will ensure they don’t forget.
Even if you only save 1% of your heating/cooling expense, the device should pay for itself in a few years.
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@Coley- nice idea, but it’s unfortunately illegal in our area. Too urban. Not surprising considering our yard is about 50 square feet!
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Its good to see a post explaining that programmable thermostats are not always right for everyone.
My fiance and I work erratic schedules and are not home too frequently during some parts of the week, so we tend to only heat rooms we are in when we are in them, and keep slippers and blankets around the house to use until the room warms up. A programmable thermostat would certainly do us more harm than good.
At the same time, my mom’s household has central heating and everyone there tends to be on a pretty consistent schedule, so a programmable thermostat would help them a lot if they avoid the pitfalls mentioned in the article.
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I can’t believe this hasn’t been mentioned yet, especially that it wasn’t in the article itself.
It is NOT better to use a programmable thermostat in the SUMMER. With air conditioning, the energy used to lower the temperature is far greater than that to maintain it at a temperature. So in the summer, you should pick a temperature, and keep it there, day and night, all summer long.
In the winter, the standard logic of cooler at night and when you’re away, and normal when you are home and awake, is sound. Adjust to your personal preferences obviously.
I’ve heard this advice from countless HVAC workers, friends, and family, and I’ve tested it myself for many years. You will have cheaper bills in the summer/hot climates if you maintain one temperature constantly than if you regularly bring the temperature down and let it go back up.
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I finally switched to a programmable thermostat but haven’t really noticed a decrease in my energy bill (perhaps because the price keeps going up?).
68 degrees is fine in the winter and then we have A/C kick on at 74 degrees in the summer.
You must be freezing with the house at 65 degrees, and I don’t think I have a blanket on my bed warm enough for me to handle 58 degrees at night
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Blankets will not do for cold temperatures at night. Find a quilt (online)that has box construction. That is: a top and bottom and vertical walls of the fabric inside forming compartments with the spaces filled with insulation. Duck or goose down is expensive and can cause allergic reaction. Buy synthetic-fill quilts. At least one vendor in New England also sells blankets like this that are only a quarter-inch or so thick that can help. Insulating blanket for the cool part of summer nights, add a suitable quilt in colder seasons. Note that a quilt intended for very cold conditions can be too warm. Pick the temperature rating carefully. I have done well with a sleeping bag (40 degree F rating) opened out and used as a quilt. Had the sleeping bag, did not want to spend money on a quilt. When the sleeping bag wore out, I bought a quilt.
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We don’t have AC, just a window unit in the bedroom for sleeping. But for winter, we definitely use the thermostat. It can get well below zero here and the gas bills are high even for an apartment (close to $300 even using heat cautiously).
The main way I use it is to have it set to turn itself down several times throughout the day. This way if I leave and forget and leave it up (at 68-72) it will turn itself back down to 58. At night it’s 55.
I’ve seen a difference of over $100/month doing that, and using a space heater in just one room, compared to keeping the whole place warm.
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JD I am surprised that you did not speak to the new trend in climate control, where you sign over control of your thermostat back to the power company. They reduce your power usage when energy costs are higher and reallocate it to you when the costs have stablized again. How does this compare to a self-controlled thermostat? I believe you are allowed to program in limits as well e.g. I don’t want my house above 80 in Summer.
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I installed a newer programmable thermostat last year. It has definitely made the house more comfortable and I believe it has saved some money.
We had a much colder winter than usual here in New Jersey and found ourselves running the heater much more than last year. All-in-all the bills came out to about the same as last year – even with a rate increase.
We are also out of the house for the entire day. We have it set to 60 when we are not home, 65 when we are home, and 62 when we are sleeping. It may sound cold, but it’s quite comfortable. I mean I can’t lounge around the house in shorts, but long pants and a long sleeve shirt works just fine. When we are cold some days, we just turn it up!
It all takes some getting use to. I also found that having the right window treatments can help keep the hot air in.
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“It is NOT better to use a programmable thermostat in the SUMMER. With air conditioning, the energy used to lower the temperature is far greater than that to maintain it at a temperature.”
Alex, can you explain this? I’m a mechanical engineer, with an educational and career focus in thermodynamics, and this just doesn’t make any sense to me. It’s just not correct.
Here’s the only caveat I can imagine–if, somehow based on the schedule of your energy usage, your utility is charging a higher rate for electricity during certain times of the day, and your higher use coincides with that time, then the higher cost might outweigh the benefits. But you still would not be using more energy.
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I’d like to also add: KNOW YOUR HEATING SYSTEM! I tried to follow the conventional wisdom of programming the thermostat to a lower temp in winter while away and ended up paying a HUGE gas bill ($500 for one month!) and nearly burning out my boiler pumps.
This may work for people with forced air heat, but I have a boiler and radiant heat in the floors of the basement and first floor of my house. I programmed the thermostat to a temp considerably lower (about 10 degrees less) and when I got home I’d find the boiler working like crazy to try to heat the house up. In the five hours it was set to be at a higher temp in the evening, the boiler pumps would run constantly and it would never get to the programmed temp.
I had the HVAC company come out on a service call to fix what I thought was a malfunctioning boiler and was told that I should not program my thermostat this way. The concrete basement floors cooled down fast, and it took a huge amount of energy and time to heat them back up again, which was why my boiler pumps were running continuously and never catching up. Unless I somehow have the basement switched to it’s own heating zone, I will always run into this problem in my house. So…no huge temp changes in winter in my home! I do have it programmed to be a few degrees cooler at night, but that is the extent of my thermostat programming these days.
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@ Kate – We live in Illinois and also have electric heat. Our electric bill was getting close to $450 in the coldest months of the year…this was after we had set our theromostat to 55, closed off some of our rooms that we don’t use (including the entire upstairs). So, we purchased a wood-burning stove and my husband started chopping wood. He’s had no problem finding free sources of wood; many people want him to clean up dead trees, etc. Our bills are cut in half. Yes, it’s more work, but this is what has worked for us. Perhaps it can work for you, too?
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How many people these days go without AC? Maybe it’s because I live further north (southern Minnesota), but I do not use AC. I didn’t when I lived in Oregon, Washington, or Michigan. Yes, it gets hot in my apartment. When it did so, I use fans and opened/closed windows judiciously. I have been known to sleep with a fan pointing directly at my body. A few times a summer, if it’s really blisteringly hot, I might spend the hours from 1-5 in a public library or other air conditioned space. But, for the most part, I try to stay in the natural heat. I’m cold all winter, so I really do enjoy being warm for a change.
Also, I’ve spent plenty of time in countries without electricity. They build their houses to take advantage of cross-breezes and natural cooling. Why do we no longer build like that in the southern US? It just seems to me like AC it a really expensive item that could be significantly reduced with other, simpler technologies.
And, more on topic, I have to say that I do like programmable thermostats. Mostly, I appreciate not having to think about turning the temp down before going to bed. I don’t have a programmable now, and I’ve spent many a night sweltering in bed because it just gets too warm for me.
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I was looking forward to this post when J.D. first mentioned it. I’ve had programmable thermostats for years and find them really helpful.
What most people miss (and that is alluded to in his article but not stated directly), is that a programmable thermostat is just one piece of an energy-efficient lifestyle.
My thermostat is part of a package that includes dense packed insulation, a high-efficiency furnace, an on-demand, high-efficiency water heater, a clothes line, a small house, lots of sweaters and warm socks, etc., etc., etc.,
But @Coley #4 makes a great point that conservation doesn’t decrease overall usage of energy. We need a whole new way of thinking about energy usage which includes some really painful discussions about why one part of the world is using the vast part of the world’s resources.
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Brrrr. Setting the thermostat to 68 EVER would lower my heating bills (Ok, the heat is off when I’m not home…but still). No thanks anyway.
Like Nicole said. Being comfortable now is important to me.
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Actually this is the most useful article on the subject imho.
I don’t have one but have been feeling guilty about it LOL.
However we have a fairly well insulated house and tend to keep the heat quite low. Then we get cold and kick it up for a while but are careful to lower it again because it makes the nights unbearable if we leave it on downstairs. And upstairs? It’s mostly on OFF except if it feels chilly when we go up – then we leave it on for an hour or so and shut it – otherwise we wake up gasping LOL.
So I think I am better off reacting to our bodies here, rather than heating it even if it’s not necessary . . .
Thanks JD!
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I have a programmable thermostat — and I don’t believe it has saved me any money. Why?
1) Different members of this household are home/not home at different, erratic times of the day, making it impossible to simply program the thermostat to be “off” from, say, 9am – 5pm.
2) Even when the thermostat is off from 9 – 5, its freezing indoors when we come home … causing us to crank the heat.
3) Gaps around the windows, doors and even in the outlets, which let cold air blow into the house, make a much bigger difference. A $10 bottle of caulk and some $10 weather-stripping can fix these leaks and create much bigger savings.
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Insulate, Insulate, Insulate,esp the attic, seal up the cracks around the foundation and windows with foam, this will keep the heated air/cool air in the house which should lower the amount of time the furnace/air conditioner is running thereby saving $
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I actively tweaking our thermostat settings for over a year now and I’ve notices a big difference in our bills. biggest savings appears to be in not running at all when we are not home (8-10 hours a day). we used to subscribe to the theory of maintaining the temp all day but once we abandoned that we started to see a real savings. Peak month bills were always $400+ before we got aggressive in our programming. our highest bill over the winter was $368, and that was over the coldest period of one of the worst winters on record in the Northeast.
If there is a period of time where everyone is out of the house you can really see a savings using a programmable thermostat. Just set it to turn on a little while before you get home and you will barely notice that you weren’t heating or cooling the place all day.
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Just out of curiosity how does the use of ceiling fans play into this? I understand that ceiling fans use electricity but they can also cool down the room I’m in vs the whole house. Reversible fans, theoretically, distribute heat more evenly or quickly.
I also understand that the motor from ceiling fans create their own heat.
Just curious.
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I live in a cold climate, so we spend a lot on home heating and nothing on air conditioning. Like everyone, we would like to consume less energy and see a reduction in our heating bills. If a programmable thermostat would help us do that, we would consider it.
A bigger problem for us is that the fee structure of our gas bills offers a disincentive to save energy. My most recent gas bill was $200, of which only $104 is the actual cost of natural gas. The other $96 are fees and taxes that don’t go away if we reduce energy consumption. Even if we cut gas consumption by 50% (an unrealistic goal) our gas bill for the month would only go down by 25%.
I suppose this gripe isn’t directly relevant to the topic of programmable thermostats, but I wish our utility company would structure the bills differently so folks who are environmentally responsible could actually realize some savings.
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“how does the use of ceiling fans play into this?”
They’re wonderful in the summer, and somewhat nice to have in the winter.
Your body is 98 degrees, and it’s constantly generating heat, so you need to transfer that heat away from your body. The temperature of your surroundings is an important variable in this equation, but it’s only one variable. Equally important is the effectiveness of your surroundings at transferring the heat off of your skin. Water is much more effective than air at pulling heat off of your body, so you can cool off in an 80-degree swimming pool, but you might be uncomfortable in an 80-degree house. Dry air is better at drying your skin’s perspiration, and the phase change from water to vapor of the sweat on your skin has a tremendous cooling effect–it takes a lot of heat, just like on the stove, to turn water into vapor. That’s partly why dry air feels more comfortable (cooler in the summer) than humid air.
Similarly, air moving across your skin pulls more heat from your skin (through forced convection) than air that’s relatively stagnant. So, in the summer, a ceiling fan that keeps the air moving rapidly around the room (and across you) can make an 80-degree room feel much more comfortable than a room at the same temperature with no fan. Maybe you’d have to turn the thermostat down to 76 for the same effect without the fan. You’re adding a wind-chill factor.
The small amount of electricity that the fan uses pales in comparison to the cooling effect that it has on you (as well as the fact that moving more of the air across the walls and windows inevitably raises the amount of heat transferred through those–losing some of your “coolness”), but that’s still negligible.
So, the fans are great when you’re in the room, but turn them off, or maybe just to low, when you’re not–they don’t cool the room, they only cool people (and animals).
In the winter, depending on the specifics of your house, you might like having the fan on low, possibly in the reverse direction. It could help prevent the thermal stratification of having all the warm air up by the ceiling and cold air down on the floor. To that end, it doesn’t really matter what direction the fan is turning–it will mix it either way–but having it blow upwards will reduce the now-undesirable wind-chill effects described above.
In our house, we have ceiling fans intalled in the family room and in every bedroom.
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Great read. Training and educating will only make a difference in the way these devices are used. Unfortunately, as high as the cost of energy is, it needs to go higher for more people to take action to consume less and save their money own money. Thanks, Hunter.
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In my experience the programmable thermostat does save some money on gas/heat in the winter. We leave the temp down at 60 during the day while we’re at work and from midnight to 5 am.
The one issue we have had is that we are freezing going to bed at night and layer more blankets on the bed in order to fall asleep. Then at 5 am you wake up covered in sweat because it is 70 in the house and that many blankets is far too many. This also happens on weekends when you try and sleep in.
I find this particularly annoying because I also can’t use a down comforter because my husband is allergic and down comforters are usually the solution to variable temperatures because they breathe better than anything else.
So, I’m not sure the small cost savings is worth losing sleep over like we do.
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@ #2 Kate, I think “never notice” is overstated, but to compensate, you use more blankets in the winter. Alternatively, you could use a room heater in your bedroom, or as I recently discovered the wonders of electric blankets/mattress pads! They auto-shut off in 3 – 10 hrs, so you’re not burning extra power when you don’t need to. Compared to my room heater which runs at 1500 W, I think my electric blanket is at 400 W.
Major plus points for not getting into a cold bed!
I live in the NE, and lower it to 55 at night, and 60 when I’m around the house. I definitely am wearing sweats & slippers around the house. If I’m going to be in a particular room for a while, I use a room heater.
In the summer, the AC doesn’t kick in until the house gets to 86, and I lower it to 80 when I get home in the evening, but 76 at night. My bedrooms are on the 3rd floor, so they get toasty, and require extra cooling.
I’m pretty energy conscious, so the programmable thermostat is my backup, if I’m not paying attention. It catches times I adjust the temperature so it’s comfortable for guests, but forget to set it back to my norm.
I have 3 floors, approx 2k sq ft, and electric everything, living the in the NE. My worst winter usage is around 1300 kWh, and my worst summer is 730 kWh. My best is in the fall, at 270 kWh.
(Thought kWh might be more helpful, I’m not sure how much energy prices vary around the country..)
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It does not take more energy to raise (or lower) the temperature of something to a given temperature than it does to maintain it there.
Get a glass of water out of the fridge (or soda, or your favorite beverage) and put a thermometer in it. Every time the temperature rises above 38 degrees, add more ice. Keep the glass below 38 degrees for eight hours. Count how many ice cubes you use.
Then, get a glass of room temperature water and add ice until it cools to 38 degrees. Count how many ice cubes you used.
Guess which glass used more ice (and therefore, energy from your freezer), the one that you kept cool all day, or the one that you just cooled down when you needed it?
You can do basically the same experiment with coffee if you want to test it for hot things, but it works exactly the same way.
This argument is ridiculous and anyone who parrots it back to you is just regurgitating something they heard somewhere else and has never really thought about it, let alone tested it.
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It seems odd that this is completely contradictory to what I was taught in college Physics. Laws of thermodynamics say that it takes MUCH more energy to change the temperature of something than it does to maintain that temperature.
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Obviously it takes less energy to maintain a temperature than to change the temperature, you don’t need a degree in thermodynamics to tell you that. That is not the issue. We are talking about the difference in energy usage between maintaining a specific temperature for an extended period of time vs changing the air temperature by the amount of temperature change that would have occurred over that maintenance period.
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JD’s article is correct- programmable thermostat’s aren’t all that. Especially if you live in a 100-year old, drafty house with a moody furnace.
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My summer thermostat program is a little different than the recommended, but it works for me –
In the early morning (5-7am), my thermostat is set to cool the house to 70 degrees (with windows open at night to help the cooling). The outside is cooler before dawn, so it takes less energy to pump the heat out. And my electricity company charges less for electricity in the night than during the heat of the afternoon.
The thermostat then turns to 78 degrees for the rest of the day, which it generally doesn’t reach until late in the afternoon or early evening.
I found this costs less for me than running the AC all day to keep it at 78 degrees constantly.
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I added a programmable thermostat and after comparing the first two months this year versus last year, I saved more than $16 and $40, respectively. It saves when one is away at work but also in the middle of the night. I set the temp lower once every one is asleep, since everybody is under the sheets.
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I definitely think our programmable thermostat helps save us money. We do the colder during the day, and after 10pm (60 degrees) and warmer even we wake up and come home in the evening (68). We have a very old home with single pane windows which we shrink wrap every year (doesn’t look bad if you do it right). Abd we use 2 down comforters on our bed. This year during the coldest month our bil was about 30% lower than last year because I keep the temp down below 70. During the summer we use a swamp cooler because it is very dry here. Its extremely cheap to run o about $20 a month. If you live someplace dry, consider one
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They are only worth it if you use them for the purpose they have been designed. Like Lindsay said above, you have to set them up right to reap the rewards. Also, if your house isn’t well insulated you are wasting your time.
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I thought this was all fairly obvious. My wife likes the temperature how she likes the temperature. Whether the thermostat is manual or programmable doesn’t affect that. If you have trouble remembering to adjust a thermostat when you leave the house, it will save you money. If you don’t, then it’s an unnecessary upgrade and waste of money. Just train yourself to pay attention to the thermostat and it’s a non-issue.
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I’ve always been interested in installing a programmable thermostat, but I living in Phoenix the recommended temps never apply to me. If I kept my house at 78 in the summer, my electric bill would be enormous. I usually keep it at 82 while at home. When I worked full time, I would turn it up to 85 during the day, but now I’m home with the kids and we need to keep cool too! I’d just love to find some good recommendations for my area.
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I think this post is pretty good. We have a regular thermostat and it works pretty well. It’s set to 68 degree now because we just had a baby and want to make sure it’s comfortable for him. Previously we just have it turned off until it gets to low 60s, then we set it to 65.
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In winter, I turn my furnace on when the temps dip into the 40s and below. Even then, I set it at 60. Otherwise, the furnace is completely off. We wear sweaters during the day and sleep under goose down quilts at night.
In summer, the A/C is set at 80 and only when we absolutely have to have it on. We belong to the electric company’s summer savings program which means that our electric bills are really low in exchange for the electric company’s ability to shut down our A/C and recycle our power elsewhere to fill consumer demand on extremely hot days. In that case, we shove a swamp cooler into a window and turn it on.
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We have a programbable thermostat – but make the changes manually – which for us – ABSOLUTELY SAVES MONEY!
We turn it down – when we are not going to be in a part of the house and Turn it up – when we will be in a part of a house.
Thus for us, using a programable thermostat – correctly – would cost us money!
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I’m glad I read this because I’ll no longer worry about not having an automatic thermostat.
During the winter we turn it up to 62 when we get out of bed, turn it down to 52 when we go to sleep. There may be some variances in case of illness, metabolic changes, etc (if we don’t work out in the morning we heat it up higher for about an hour).
In the past we just set the heating at 68 day at night. The new system has saved us 20% during the coldest month and probably 50% in the not-so-cold months. And yes, I’m glad I’m saving equally or probably more than if we had a programmable thing.
Anyway, the best policy is to listen to Jimmy Carter and wear a sweater.
(But now summer is coming so this isn’t so timely. We have a swamp cooler instead of refrigerated air –it’s the desert– so the thermostat will now sleep until November.)
@ Bonnie — this might be the horror to you, but we put up reflective insulation on some windows during the summer. It lowers our indoor temperature by about 12 degrees. I just bought a roll of aluminum/bubble insulation and cut it to the shape of the window wells. Tuck it in, conceal it behind closed blinds, & voila, nobody needs to know. We keep north windows open for air flow but insulate the west and south where the evil rays come from. These windows happen to face the backyard & alleyway so they are not a public eyesore.
There are more upscale products out there, solar screens and awnings and window films and what not– and the price can vary a lot depending on what you want.
If you can keep the sun rays from burning the inside of your home on the cheap you’ll save tons. If you can keep them from burning inside your home regardless of price, your quality of life will likely improve. I work at home and can’t work well when it’s too warm– I get sleepy.
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@El Nerdo – I’ve done similar things in the past. I currently have a very militant HOA and they would freak if I tried it now. We’ve looked into the more HOA-acceptable options like sun screens, but they are expensive and my husband doesn’t like them. We have excellent shutters that keep the house pretty dark in the summer. They help a lot! But when it’s 110+ outside, there’s only so much you can do. If my highest electric bill in the summer is under $400/month, then I count it as a successful year.
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@2 Kate:
“Can I ask what the theory behind turning the temperature down when you’re asleep is?”
I completely agree, and it seems like a bunch of people who’ve posted on here have the same issue. I can go to bed comfortably, but I wake up hot in the summer or cold in the winter, and sometimes I wake up in the middle of the night because of it. In the winter I would definitely trade being warm in the evening for being warm at night. In the summer… well, I hate the heat. I would trade ANYTHING for not being hot.
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As someone who bought a home with a heat pump for the first time we found out that turning down the thermostat at night when it is really cold outside can actually cost you more money. That’s b/c when the temp outside is below a certain point the auxiliary heat has to kick in and the system is very inefficient.
So while I do think programmable thermostats are great it can be more important to understand your heating/cooling system first.
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