Go green and save money with a programmable thermostat

Heating and cooling accounts for more than 40 percent of the average home's energy consumption. According to the EPA, installing a programmable thermostat in your home and using it properly can save you $180 in energy costs every year. That means a programmable thermostat can pay for itself over time, but the key is using the thermostat properly. If it’s difficult to program or too inflexible for your daily routine, you might never recoup your investment. Here's a hands-on look at three of the latest and greatest, including the much-talked-about Nest.

The idea behind a programmable thermostat is to conserve energy by heating or cooling your home only when you’re there to enjoy it. To accomplish that goal, the thermostat should at least be capable of triggering four events each day: It should trigger your HVAC (heating, ventilation, and air conditioning) system to warm or cool your home to a target temperature when you wake up, adjust the target temp so the system is largely idle while you’re away at work, return your home’s interior to a comfortable temp when you come home again, and render the system largely idle while you’re asleep.

Good, better, best

A basic programmable thermostat will do this for a price tag less than $20, but most devices in this price range will be extremely limited. Many don't have the smarts to distinguish between weekdays (when most people are away from home because they're at work) and weekends (when most people are at home for longer hours); they treat all seven days the same.

The Hunter 44110 shown here (street price around $20), is what's known as a "5-2" thermostat. It's better than most thermostats in this price range in that it allows you to create one four-event schedule for Monday through Friday, and a second four-event schedule for Saturday and Sunday. But like most devices in its price range, the Hunter is incompatible with HVAC systems that utilize heat pumps or that are capable of performing multi-stage heating and cooling.

Doubling your programmable thermostat budget to $40 or $50 buys you more flexibility—and potentially more energy savings. Most devices in this class are either 5-2 devices (like the Hunter) or 5-1-1 devices. The latter are more flexible because you can program one schedule for Monday through Friday, a second for Saturday, and a third for Sunday. Many programmable devices in this price range are not sophisticated enough to work with complex HVAC systems.

Move up to the $100 range, and you’ll find programmable thermostats that allow you to establish a unique schedule for each day of the week. Devices in this price range will also boast extra features, such as a touchscreen display (much easier to use than mechanical buttons), a vacation hold setting (suspends programming when you expect to be away from home longer than usual), and periodic reminders to change your HVAC system’s air filter.

But these thermostats are just as dumb as the less-expensive alternatives in one respect: You need to make physical contact to program them or to change any of their settings. If your schedule varies a lot, you might find yourself wasting energy heating or cooling an empty house because you had to work late, you got stuck in commute traffic, or you went out for dinner and a movie. Or you might come home or wake up to an uncomfortable house because you left work early, or you’re home on a weekday holiday and forgot to change the thermostat’s program before retiring for the night.

Three top-shelf programmable thermostats 

The programmable thermostats reviewed here—Honeywell’s Wi-Fi Touchscreen, Nest Labs’ Nest Learning Thermostat, and Venstar’s ColorTouch T5800—are at the top tier of stand-alone devices: They deliver all of the features described above, but they can also be connected to your wireless router. Once on your network, you can program and control them using your personal computer, tablet, or smartphone from anywhere you have Internet access.

So if you leave work early, you can dial into the thermostat from your personal computer and adjust the thermostat so your home will be at a pleasant temperature when you get there. If you wake up to a cold house on a weekday holiday because you forgot to adjust the thermostat the night before, reach for your smartphone or tablet without leaving the comfort of your warm bed.

In addition to displaying a message when you need to change your air filter, some of these high-end thermostats can send the same information via email. Now you can buy the filter on your way home instead of making a special trip to the hardware store. And that’s not all they can do. Need a reminder to schedule annual service for your system? Want to be informed if someone at home overrides your programming? Would you like a warning if your home’s temperature reaches extremes that might be dangerous to your pets or that will freeze your pipes? These high-end thermostats can do all that and more.

The ultimate programmable thermostat

These days, no discussion of programmable thermostats would be complete without coverage of the Nest “learning” thermostat. We reviewed that device, and it largely lives up to the hype—it’s by far the best stand-alone thermostat we tested.

But the absolute best way to manage your HVAC system is to tie it into an overall home-control system that includes motion sensors, smoke and carbon-monoxide detectors, door and window sensors, and a central control panel. Examples include systems from Vivint, FrontPoint Security, Schlage's Nexia Home Intelligence, and Lowes Home Improvement's Iris. Here's why I think that:

Much of the hype surrounding the Nest is related to its ability to program itself, using its integrated motion sensor to detect when a house is occupied and when it’s empty. It will learn your routine over time and manage your HVAC system accordingly.

A home-control system equipped with motion sensors ostensibly designed to detect an intruder can use those sensors to program a connected thermostat just as effectively. In fact, such a system will be capable of doing it faster and more accurately because it can use motion sensors installed at multiple locations inside the home, where the Nest must rely on someone walking past it.

The Vivint system I have installed in my home (one of three home-control systems named to PCWorld's 100 Best Products of 2012) is a case in point. In addition to its thermostat adapting to my comings and goings based on sensor activity, it will also automatically shut down my HVAC system for one hour if a smoke or carbon monoxide detector triggers an alarm. This will prevent smoke or fumes from circulating through the house. I can set an “away” temperature that automatically adjusts the thermostat when I arm the alarm system and leave for the day—which is better than any schedule I might program, because it’s a response to an actual event as opposed to a prediction of one.

And when I am operating on a routine schedule, I can conserve energy by having the system automatically adjust the thermostat’s target temperature when it’s exceedingly hot or cold outside: Rather than have the air conditioner struggle to cool the house to 76 degrees when the outdoor temps hit 105 degrees, for instance, I programmed the system to automatically adjust the thermostat’s target temp to 78 degrees under those conditions. I'm still comfortable compared to being outdoors, but my HVAC system is consuming a whole lot less energy to do it.

The obvious downside to an all-encompassing home-control system such as this is the cost:  In addition to buying a programmable thermostat, you’ll need to buy all the other equipment that goes with it (door and window sensors, motion sensors, a master control panel, and more); plus, you’ll need to pay a monthly service charge of anywhere from $8 to $80 per month. You’ll get a lot more functionality than climate control, but it will take longer to recoup your investment. (Having said that, an Iris Comfort & Control kit is a great starter solution; and with a price tag of $179, it's $70 cheaper than the Nest. Click here to read my review of the Iris product line.)

None of the programmable thermostats reviewed here come with any monthly service fees, and each one will pay for itself fairly rapidly. The only downside is that if you decide to build out a complete home-control system later, you'll likely need to replace whichever stand-alone thermostat you buy today because none of these are designed to be incorporated into a larger system.

With that in mind, read our in-depth reviews to find out which model is right for you.