Is a programmable thermostat worth the expense?

by RJ

in Random

I wrote this post to answer one question–Is a programmable thermostat worth the expense?

This was my second winter I have lived in my house. The first winter beginning in December of 2009, I neglected to buy and install a programmable thermostat. In November of 2010, looking for ways to lower my gas bill, I decided to make the purchase. The thermostat cost $40. Looking at the installation, average temperature, the historical price of gas, and the gas bills themselves, do programmable thermostats really save you money?

Let’s find out…

Installation

I joke that the only tool I own is a checkbook. In other words, I wasn’t born with the handyman gene. In all honesty, after purchasing the thermostat it sat in my closet for two weeks. I was afraid that if I installed it, I would break something.

It turns out, the installation process was much easier then I thought. It took only 30 minutes.

What I’m trying to say is, if I could install a programmable thermostat, ANYONE can.

Reviewing my Gas Bill

The first step to finding out if a programmable thermostat actually saved me money this winter is to compare gas bills for the winter months of this year and last. 

Gas Bill for Winter 2009/2010

  • December = $98.53
  • January = $102.17
  • February = $211.32
  • Total = $412.02

Gas Bill for Winter 2010/2011

  • December = $41.39
  • January = $121.12
  • February = 121.95
  • Total = $284.46
  • Total Savings = $127.56

What was the Weather Like?

I paid $127.56 less for gas during the three coldest months of the year this year over last year. Was this savings due to the programmable thermostat or was it just due to the weather?

Here are the average temperatures from last winter compared to this winter.

Average Low Temperature in Winter 2009/2010 for:

  • December = 26 degrees
  • January = 20 degrees
  • February = 26 degrees
  • Average = 24 degrees

Average Low Temperature in Winter 2010/2011 for:

  • December = 21 degrees
  • January = 20 degrees
  • February= 25 degrees
  • Average = 22 degrees

Even with a lower average temperature by 2 degrees, my gas bills were still $127.56 lower this year.

The Price of Natural Gas

The next variable I need to look at is the actual price of gas. Was the savings due to the programmable thermostat or from a decrease in the price of natrual gas?

Here is the comparison in cost from this winter to last.

Natural Gas Cost Per Therm

  2009/2010 2010/2011 % Change
December .5563 .4655 -16.3%
January .6751 .4933 -26.9%
February .6481 .5238 -19.2%
Average .6265 .4942 -21.1

What was my Total Savings?

It’s hard to predict the exact savings from installing a programmable thermostat because I don’t know how to measure the impact of temperature changes. Based on my results, I did have considerably lower bills this year. Part of that was due to the price of natural gas decreasing.  The majority came from the only variable that changed this year to last–the programmable thermostat.

By looking at the $40 purchase price of a programmable thermostat as in investment, I’m comfortable saying that I doubled my return in just three months. In other words, an $80 savings. One of the best $40 investments I’ve ever made and one that if you haven’t made yet, you should.

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{ 10 comments… read them below or add one }

John HunterNo Gravatar March 18, 2011 at 10:48 am

Congratulations, I agree, programmable thermostats are great. In addition to the cash savings you also save the environment. People should also consider high efficiency furnaces when they are replacing them – I did it last year and the saving are huge (I am saving over 35%) – mine also has high efficiency AC.

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RJNo Gravatar March 18, 2011 at 12:12 pm

Wow…35%. I don’t use AC much but to just save $80 in a span in three months is well worth it.

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Sustainable PFNo Gravatar March 18, 2011 at 4:57 pm

Great number crunching. These thermostats are no brainers it seems. I’m pretty sure they are part of the building code here in Canada. This is the sort of thing our site discusses a lot – how being green WILL save you green.,

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RJNo Gravatar March 20, 2011 at 1:35 pm

@Sustainable PF – Love the site concept. Looks great.

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ColeyNo Gravatar March 21, 2011 at 7:54 am

If you saved your utility statements (or can access them online), then you could eliminate the variable for the price of natural gas and just look at the units of energy used (ccf, I think–centi-cubic feet?). Besides, the full price fluctuations in natural gas markets doesn’t necessarily get passed on to you immediately.

Additionally, the average LOW temperature probably isn’t as good of a parameter to compare so much as just the average temperature during your evaluated period. Of course, we’d both expect the correlation between the two to be strong.

And finally, your comparison is also assuming relatively constant usage of hot water, the stove, a gas clothes-dryer, possibly; plus, environmentally, sunshine and wind levels–both of which have a much larger impact than most people realize.

There’s a sure path to madness in all of this. Still, I very much enjoyed your post.

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RJNo Gravatar March 21, 2011 at 3:27 pm

Thanks for the comment Cooley. You brought up a lot of good points that I didn’t think about. There sure is a lot of madness to exactly how much I saved. I’ll probably have to do an update next year.

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Funny about MoneyNo Gravatar March 21, 2011 at 10:59 am

Wow! You appear to have done well, although the existence of other natural gas uses does complicate things.

I had exactly the opposite experience: power costs went up after I installed a programmable thermostat; went way down when I replaced it with a nonprogrammable. My house is heated and cooled with electricity, though; water and cooking don’t figure in to the electric bill, making the calculation a little more self-evident.

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RJNo Gravatar March 21, 2011 at 3:24 pm

Interesting. Maybe the change is due to my old obsession with tweaking the temperature. Coley brought up a good point, there are a lot of other variables.

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ColeyNo Gravatar March 22, 2011 at 8:18 am

Funny about money –
This is what I realized yesterday from Get Rich Slowly, and what very well might have happened in your case…

You say “electricity,” which I assume means a heat pump. When your thermostat was maintaining a temperature, your relatively efficient heat pump was doing all of the work. Your programmable thermostat allowed the temperature to drift down, but then it suddenly demanded a comfortably warm house again. Normally, this would be fine, and it would still save you money, except for the fact that when the difference between setpoint and actual temperatures exceeds a certain value (maybe 5 degrees?), the system will activate the auxiliary heater in addition to the heat pump because it assumes that you desire the home to warm up more quickly. The auxiliary heater is electric resistance, which is just about the least efficient you can get. It’s essentially just running a fan across a giant toaster.

So you could tweak your system to not activate the auxiliary heat under these circumstances. Or, you might be able to sidestep it by having the system slowly step up the heat, perhaps one or two degrees per hour, so that the thermostat never sees that large differential.

Or, like we do, just forget about it altogether and keep it at 68. If we go away for the weekend or longer, we turn it down to 50.

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ErikNo Gravatar April 20, 2012 at 1:39 pm

If you assume all things being equal to the previous year(heat usage, hot water usage, cooking on gas stove, gas drier usage, average sunlight and wind exposure), and consider a 2% average temperature difference is negligible, then your overall savings were 31% over the previous year. However, the price difference for the gas was an average of 21% less meaning that your savings for the thermostat would only have been the remaining 10%. $41 is 10% of your previous winter’s heating costs so you paid for your new thermostat in just those 3 months. If you extrapolate that efficiency savings for the 3 hottest months that you will be using your AC and over the life of the unit I would say you made a very good purchase. Thanks for the article and the great data!
I would like to install a programmable thermostat in my home but I am concerned about the cheapness of the units and the bad reviews that they all seem to get and the fact that many of them cannot have their sensitivities adjusted so that they actuate for temperature differences of 1 degree or less which causes a furnace or AC compressor to kick on and off every few minutes all day. I’m afraid that the end result of this would be a shortening of the overall life of the unit and a risk of premature failure of the units or components that would require expensive replacement. Have you encountered anything like this with your unit?

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