Therm-o-STAT!

October 26, 2011 8:04 PM

What are the major benefits of a programmable thermostat, how big a deal is the new Nest thermostat, and how much might I expect to save with either one over a non-programmable digital thermostat?

I just bought a new house in the Midwestern U.S. (all four seasons!). It has central air and heat, which I've never lived with before except in dinky apartments. It also has a digital thermostat, which I've never lived with before ever.

The current thermostat is not programmable.

I like the ease and repeatability of setting the same temperature whenever I want, and seeing how close the current temperature is to where I'd like it to be. I can see the advantages of being able to program a thermostat to heat or cool my house automatically before I get home from work or when I'm asleep.

Am I missing any other major benefits of a programmable thermostat? Assuming I often forget to adjust the thermostat before I leave for work or go to bed, is there any way to estimate what I might be able to save using a programmable one? Are the benefits of the recently-announced Nest thermostat (http://www.nest.com) -- "learning" your habits, automatically adjusting when it doesn't sense your presence, connection with the Web to grab outside temp, and ability to adjust over the Web -- worth the premium?

(And all of that notwithstanding, I would probably see a better return on my money by replacing the still-original wood frame and sash windows, right?)

posted by brentajones to home & garden (21 answers total)

You can save around 10% a year on your heating and cooling bills by simply turning your thermostat back 10°–15° for eight hours : energysavers.gov
posted by crunchland at 8:15 PM on October 26, 2011

(I should have also added that when we had a new furnace and AC installed in our house last year, the techs suggested that using the programmable thermostat would save energy and money, but to have it work harder than a 5° swing might be counterproductive in the long run, forcing the system to work overtime to adjust the temperature back and forth.)
posted by crunchland at 8:27 PM on October 26, 2011

(And all of that notwithstanding, I would probably see a better return on my money by replacing the still-original wood frame and sash windows, right?)

I doubt that. You can buy a programmable thermostat for less than $50, and you might save 10% of your energy costs. New windows will cost a lot more than that for not much more savings.
posted by Forktine at 8:34 PM on October 26, 2011 [2 favorites]

I haven't even checked out the nest yet, but we have a Filtrete programmable digital thermostat which we can control from the internet. Yes! I set a program for my usual schedule, but if I decide to come home early one day and want to turn the heat up before I get home I can do that from my computer! If I get too hot while sipping my cocoa on the couch, I just pick up my laptop and change the thermometer! (I know, that's really lazy, but it's pretty cool!)

I don't regret it. I could live without it, for sure, but I like it a lot. I think it saves me money because it never forgets to turn down the temperature once I set it, but I forget on my own way too often.
posted by LilBit at 9:14 PM on October 26, 2011 [1 favorite]

The Nest has some great pedigree behind it. The lovely thing is that you don't need to program it per se, you just need to practise using your thermostat cleverly for a week or two. It also uses things like weather reports to estimate what the temperature should be.

Ultimately, it's a high-end product, and an unproven one at this point. But if it lives up to it's claims, then it sounds like a good investment.

If I were in your situation, I'd probably either stick with what I've got or buy a cheap programmable one for now. Wait and hear what the feedback it like on the Nest after it launches. I really hope it's something special.
posted by Magnakai at 9:21 PM on October 26, 2011

The nest materials say you can save 20% of your heating/cooling costs, which are 50% of your total energy costs, so their numbers add up to the energysavers.gov numbers.

The ROI on a $250 thermostat that promises to get the programming right for you and to also have a wireless interface depends on what 10% of your energy costs are. If you are in Texas and paying $300/month for air conditioning, you'll be in the black quickly.

Two of my friends have already pre-ordered. I'm waiting until after grad school...
posted by Mad_Carew at 9:41 PM on October 26, 2011

I would probably see a better return on my money by replacing the still-original wood frame and sash windows, right?

No. Generally speaking window replacements are a lot of cost for very little actual energy savings in most cases. I have a local electricity coop here in Vermont and they do a lot of efficiency stuff for people and this is their mantra: do not replace windows until you have done things like insulated around your foundation/basement and attic. I'm a dorky Yankee and so I just set the thermostat to 55 when I go to bed and put on a hat, but programmable stuff is especially useful if

1. you have a family esp. children who you don't want messing around with the thermostat but who might keep different hours from you
2. you have a zone system where parts of the house are heated and cooled differently and you'd like some general settings to be constant and not have to remember multiple settings for multiple places.
3. you keep super regular hours and it can just have the house warm when you wake up and cools down when you go to bed. I have a place I stay regularly with programmable thermostats and it's sort of great to be all "oh hey the house is chilly, must be bedtime..." In my own life I have an erratic schedule and this doesn't solve as many problems for me.

The big thing, to my mind, about the nest is that you could buy literally six programmable thermostats for what one of those costs. So you might want to try life with a generic $40 programmable thermostat first and see if the savings seem like it would be worth the extra widget cost [or get one for a home office and take it as a tax writeoff]
posted by jessamyn at 10:22 PM on October 26, 2011

get a cheap programmable - you are going to have 3 settings in the winter: home, sleep, out. those are pretty predictable. Other times - like going away for the weekend you'll just override the settings or reprogram.
posted by any major dude at 10:41 PM on October 26, 2011

A programmable one is certainly worth it unless you always remember to turn it down whenever you leave or go to sleep. They're cheap, and I bet you'll be surprised at how expensive gas or electric is for a house -- even if you only save two or three percent per month, the savings will add up (at $150 per month three percent would net you $67.50 after the first year, more than enough for a cheap programmable).

I have a programmable one, and I've about decided to get the Nest. My schedule is irregular enough that I suspect it could pay for itself in a few years, even if it doesn't quite live up to the hype, and it looks like it'll be fun to play with.
posted by vorfeed at 10:42 PM on October 26, 2011

Get a regular programmable thermostat. As a nerd, I really wanted to love the Nest system - and I think it is a step toward better technology for climate control - but in terms of a standard heating cooling system it doesn't add that much value beyond a normal programmed schedule.

In a "normal" house, you have one system (or one zone), and it literally does one of three things - Heat, Off, or Cool. There is no variance in intensity, temperature, location, etc. It blows out hot or cold air until the set temperature is reached, and turns off. The Nest multiple zone sensors are great, but most likely will be used more for sensing whether people are home than for temp (which they do as well). But no matter what, the Nest will still just turn it to Heat, Off, or Cool for the entire house.

If your schedule is irregular, the Nest might make a little bit more sense. Or if you're like me, the gadget factor makes the Nest even more tempting. I wouldn't ever actually do anything to my thermostat remotely, but its fun to think I might.

If you leave the house every morning between 8-9 am, arrive home 5-6 pm, and go to bed 11-12, a normal programmable thermostat will do everything you need. Weekday versus weekend schedules, all of it.
posted by shinynewnick at 10:50 PM on October 26, 2011 [1 favorite]

We've got a programmable thermostat which, while not a Nest, is pretty decent, easy to install, and well-regarded. (And $52.) We only use it for heat, and while it's not set-and-forget, it doesn't require a huge amount of manual overriding through the winter. (OTOH, I love what the Nest is aiming to do -- it's much more compelling household ubicomp than the internet fridge. And even the best $50 programmable thermostats right now are plain clunky.)

nthing no need to junk the windows.
posted by holgate at 11:02 PM on October 26, 2011

I would probably see a better return on my money by replacing the still-original wood frame and sash windows, right?

Window-replacement companies -- makers and installers -- love to tout the savings, but a lot of data shows that many replacement windows are themselves replaced or repaired before the ROI. You can usually achieve nearly as good energy savings for a significantly smaller investment in rebuilding your existing windows.

Windows are an easy, visible win, and you may want to replace them for other reasons (tilt-ins on upper stories are convenient to clean), but energy savings -- despite seeming significant against other options -- only come after a very large investment. FYI.

By comparison, you can get a basic programmable thermostat for as little as $20 (though $50 is a better price point), and immediately see many times that in return.

I am really loving the Nest UI and overall approach, but I'll wait and see until I have the money they've proven their worth versus regular programmables before I'll make that big an investment.

All in all, a programmable is probably your biggest, easiest win in terms of any energy efficiency, so go get one right away. Another one is switching to CFL bulbs, at least where you have hard-to-reach fixtures or lights are left on for long periods. (LEDs promise at least as much in electricity savings, but are a bigger up-front investment as yet.) Next, if you don't have a new fridge, replace that (although ROI here can be in the 18-36 month range). Finally, look at your vampire appliances like TVs and DVRs that draw power 24/7. For your next steps, I would ask your utility or municipality if they can offer you a free/inexpensive energy audit, which would tell you what your specific house needs the most.
posted by dhartung at 12:47 AM on October 27, 2011

Here in Arizona, a programmable thermostat is a must-have. Peak energy costs go from 6.1 cents/kWh to 24.5 cents/kWh from 12-7p for me. During the summer, you can imagine that this is absolutely brutal running a 3 or 4kWh AC unit.

So I bought a $60 Hunter 7-day programmable thermostat. (This one.) Lets me set up four zones, one for each day. Has a vacation hold mode (set number of days to stay at a single temperature, absolutely awesome to not come home to a sweltering house), and temporarily overriding a program is reverted as the next time period is hit.

For $60, I can also click the "energy" button to see how long it's been running in the past day, week, last week, or total.

This was the very first thing I bought as I moved in. My parents didn't have one in their huge, two story house and their electric bills would hit $400 in the summer sometimes. They replaced their two thermostats immediately after I got mine.

At the end of the day, I manage to keep the AC basically off during the peak energy hours (and a little before, when I leave the house) and get it turning back on to cool things back down only in the last half hour of peak, since my schedule allows that. This saves me literally hundreds of dollars every summer, because it's brutal out here. (We hit 118° in July. Seriously.)

Don't know if Nest is all that amazing. It sounds like a lot of fun, and a really nice looking device, but at the end of the day, it took me exactly 10 minutes to program my thermostat. It doesn't have activity sensors to automatically set to away mode if I'm not here, but frankly, I'd be concerned with Nest making me uncomfortable because it can't see me, among other issues. For $250, I'd wait and see.

Definitely buying one of those Filtrete $99 Wifi thermos for the cottage, though. So glad they're down in price enough!
posted by disillusioned at 2:24 AM on October 27, 2011

I never remembered to turn down the heat (and I was only keeping it on 64 - I was a bachelor and I can wear a sweater in my house!) in the winter, and was paying 300/mo for my winter gas bills.

I switched to a programmable unit - knock it down to 52 during the day, 56 when I'm sleeping - and even with rate increases, it's about 180/mo.
posted by notsnot at 4:22 AM on October 27, 2011

You might want to see if your local utility has a program similar to one in my area. Basically, they gave us a free programmable thermostat that we can program over the internet, installed it, gave us $80 for signing up and $80 each year for participating. In return, on critical demand days in the summer, they can remotely adjust the cycling on our compressor (the fan will still run). They say that it's only a few days a year and that it's during normal business hours, and that during an event, we can call to opt out. My boyfriend and I have been in the program for years and we've never actually noticed it happening.
posted by amarynth at 5:05 AM on October 27, 2011

I'd add that in addition to the savings (which for us were real, and very nice to see on the bill), I have found a programmable thermostat to be a really nice luxury. It means the house is warm when I wake up, rather than having to go down the hall in the cold, turn up the heat, and then sit around and shiver for a while waiting for things to heat up. And the same when I get home from work -- I come home to a warm house in the winter, and a cool house in the summer. For the frugal among us, it's nice to never have that mid-day realization of "oh shit, I forgot to turn the thermostat back down!"

So while the savings are great, I'd say that the lifestyle bonus is at least as large. Now that I've lived with a programmable for a few years, I'd be reluctant to switch back to a regular one. It took a while and some experimenting to get the settings right for our schedules, but once you get it locked in you don't have to think about it at all.

I did replace some windows, but not with any expectation of ever making that money back on HVAC costs. I have found that the biggest benefit is in the summer -- the new low-e glass blocks huge amounts of heat compared to my old single pane windows, so the sun can stream in on a summer day without making you feel like you are in a sauna. So while I'd say the thermostat is about 50/50 savings and luxury, I'd call the new windows 100% luxury. It makes my life considerably nicer, but without any noticeable savings in my utility bills.
posted by Forktine at 5:09 AM on October 27, 2011

If you want to see if better windows would help, try using some of that tape-on shrinky plastic for the windows. It does a pretty good job of emulating an extra pane of glass for not too much money. (And for summer time, they make a window film that blocks radiant heat coming in. I don't know whether it saves money, but it really made a difference in comfort.)

The programmable thermostat will work as well as you program it, and works better (ROI-wise) with older inefficient furnaces and homes. When you are in a situation where a significant portion of your heat dollar is seeping out cracks and going up the chimney, reducing the amount of time the furnace is burning fuel/$ is better. The more air tight the house, and the more efficient the furnace, the less money you will save. Because you are already saving the money in the first place.

Also, it depends on your heating type. Forced air can recover pretty quickly, so you can be pretty precise with your programming. But if you have radiant heat, it can take a long time for the temperature to recover. (Because radiant heat heats the stuff in your house, which then heats you and the air. Also because radiant heat often uses a heat source that isn't as hot as the fire in your furnace.) You might end up in a situation where you need to set the temperature to come on hours ahead of the actual warm-up time, and can set it to turn off earlier.

Another option is using space heaters to augment the main furnace. Even though they tend to cost more to run than the furnace (per BTU), you can benefit if your heating needs are confined to one area at certain times. For example, I like it cool when I go to sleep, but if my room is cold when I wake up, I WILL NOT get out from under the covers. So I put a space heater on a timer to warm up my bedroom in the morning.
posted by gjc at 6:12 AM on October 27, 2011

Spend the extra ten or twenty bucks to get the model with a 5-1-1 schedule.

The cheapest units do all seven days the same, which is dumb. The next class do 5-2, so your house will be warmer on the weekends (when, presumably, you are home). The best ones let you set five days the same, and then two more days on different schedules. This is awesome.

The bestest ones offer up to seven different days, but by then they're close to a hundred bucks and I just couldn't pay that when I had to buy one for each of the threee zones in my house.
posted by wenestvedt at 6:39 AM on October 27, 2011

Hey, I could be you. I just bought a house in Indiana, and on our first trip to Lowe's I got a $25, 5-2 programmable (Honeywell RTH2310.) Here are the things that I really wanted and get from it:

• 4-period weekday: setpoints for when we wake, leave, return, and go to bed;
• An 'Early Start' feature in which it can learn how long it takes to come up to a certain temp and automatically adjust the initial firing/cooling time accordingly;
• Battery backup.

I was drop-jawed by the Nest (and seriously considered pulling the trigger on a pre-order) but ultimately think that I get 80% of its core feature set for 10% of the price. I'll spend the difference on air-sealing my crawlspace, basement and attic. It's all about the ROI, right?
posted by JohnFredra at 8:21 AM on October 27, 2011

crunchfield:

the techs suggested that using the programmable thermostat would save energy and money, but to have it work harder than a 5° swing might be counterproductive in the long run, forcing the system to work overtime to adjust the temperature back and forth

I'm sure they told you this, but it is simply wrong. Not only are there many studies showing otherwise, but you can look at energy usage yourself before and after and clearly see the results.

I'm going to get the Nest. The key feature for me is that it shuts down to conservation mode when it doesn't detect you walking past the motion sensors. I always forget to dial back the thermostat when I'm out for the weekend and the programmable one I have now is set to keep the house warm all weekend despite the fact that I'm often gone all day long Saturday. The idea of one that adjusts without intervention is very appealing, assuming it does it well.
posted by Lame_username at 8:23 AM on October 27, 2011

Yeah, windows are... They're kind of a waste. We replaced the single pane sash windows in our 1928 house the year after we moved in (8 years ago), sold on the promises of lower energy bills that never really materialized. For something like half as much as we paid for the windows we had the siding on our house redone last year because the original composite siding needed to be painted and it was starting to look like hell anyway, so we bit the bullet and had new siding put up.

They put up a fairly minimal amount of pinkboard (1/2? maybe 3/4?) under the foam-backed insulation, taped up the joints, filled in all the window voids and basically did a pretty kickin' job of insulating our house, and the results were immediate and noticeable. The windows? Not so much. I expect we'll end up ripping out the ugly vinyl windows we spent the thick end of a chunk of change on and putting in some nice modern wood-like windows 10 years from now.

More to the point, if you can set up a recording in your DVR, you can probably program a thermostat. The Nest seems to be aiming for a non-technical demographic with a nifty tech-lustable device. I don't know if they'll manage it.
posted by Kyol at 10:47 PM on October 27, 2011