A Review of the Nest Thermostat
Reducing household energy consumption is often associated with a reduction in occupant comfort. Fortunately, there are solutions that break from this stereotype and the Nest Thermostat is one of them.
At the time of receiving my Nest, I had never installed a thermostat myself. I expected to spend over an hour removing the old mercury thermostat, mounting the Nest and making sense of the tangle of colorful wires coming out of the wall. To my surprise, I had the old thermostat off the wall in ten minutes. I had the Nest mounted and wired up correctly in another 13 minutes, with the help of the Nest installation video and included screwdriver. I was continually impressed by the simplicity and elegance of the design, all the way down to the built-in bubble level to assist with perfect alignment.
The thermostat snaps easily onto the base and charges its internal Lithium-ion battery from the 24V control wires. I followed the on-screen instructions by spinning the metal ring on the front and pressing it to make selections. I connected it to my Wi-Fi network and entered my zip code and email address. This allows the Nest to connect to the Internet so it can automatically download software updates, find weather information for my area, email me monthly usage reports and allow me to control the thermostat from anywhere with my smartphone or tablet.
After finishing the short setup, the Nest repeatedly tried and failed to update itself. I left it alone until morning, by which time it had completed its task. Since then, I have not noticed a single glitch or anomaly. Something unusual that I did notice was the way it constantly improved itself by adding new features and learning behaviors from my wife and me. About a month after installation it downloaded an update that included something called Airwave.
How Airwave works. Airwave turns the compressor off a few minutes before reaching your target temperature. It then runs the fan alone until it reaches the temperature you want. What makes Airwave a Nest exclusive is its ability to learn exactly how much cooling can be done with the compressor off. Only Nest automatically shuts off your compressor at the right time to maximize your savings.
Nest Labs released its second generation thermostat at the beginning of October, 2012. Unlike many electronics corporations which abandon their older hardware, Nest released an update for the first generation thermostat, giving it many of the features of the new one. One such feature that I began using immediately is called Heat Pump Balance.
How does Heat Pump Balance work? Heat Pump Balance monitors how well your heat pump is working, the current weather, and the weather forecast. It uses this info to minimize how often expensive auxiliary heat is used and predict how to best use it in the future. Heat Pump Balance gives you three options to choose from:
Max Savings - This is the best setting for saving energy. In Max Savings mode, Nest gives the heat pump more time to get to your target temperature before turning on AUX and sets a lower AUX lockout temp.
Balanced - This is the Goldilocks of the settings: it will give the heat pump more time to work, but will still turn AUX on quickly if it looks like you won’t get you to your target temperature on time. Balanced has an AUX lockout temp somewhere between Max Comfort and Max Savings.
Max Comfort - When you choose Max Comfort, Nest will make sure you’ll get to the temperature you want, even if it means using auxiliary heat. Max Comfort is the default setting for Heat Pump Balance and generally gives you a higher AUX lockout temp.
Off - You can also turn Heat Pump Balance off entirely and adjust your AUX lockout temperature yourself.
I opted to use the Max Savings setting. I immediately noticed that the heat pump runs for much long periods of time and uses AUX heat sparingly. Another interesting feature is that it keeps the heat pump running even when it does use AUX heat, knowing that the small amount of heat it can bring in from outside will still be more efficient heat.
Since the Nest has learned my work and sleep schedule, the only times I have to adjust the temperature are when I am doing something out of the ordinary. I usually just observe it doing what I used to do. When I walk by, it lights up to show me it is set to the temperature I want for that time of day. When I leave home knowing that the house will be empty for several hours I usually set it to Away mode. Often, I select Away at the thermostat just before walking out the door. Sometimes I am in a hurry and think of it after I have left the house, so I pull out my smartphone and set it to Away using the free Nest app. Occasionally I forget altogether but Nest has me covered here. Auto-Away is a feature that uses the built-in motion and light sensors to set itself to Away if it notices the house is empty during a part of the day when we are typically home. In the year I have had the Nest, it has only gone to Auto-Away a few times when someone was home. The Auto-Away feature can be turned off if the thermostat is located in a remote area of the house.
It may be my analytical nature but I love to get the Nest Energy Report for my home. Once a month, I get the report in my email that shows me a summary of the last month's heating and cooling and compares it to the previous month. It also gives some possible reasons for why my usage has increased or decreased. For example, the excerpt shown below is from my November Nest Energy Report and shows that I used much more energy that month than I did in October. It also shows that November was much colder and that I would have used even more energy without an efficient setback schedule.
Another part of the Nest Energy Report that gained my attention is the tip. This particular tip shown below recommends one of the less glamorous energy upgrades: air sealing and insulating. It advises using the Nest to track energy savings related to improving the air barrier and thermal envelope of a home.
Among other features, I believe the Heat Pump Balance and Nest smartphone app have saved me the most. I highly recommend this thermostat to others, especially to those who leave an empty home for a large portion of the day. It will not solve all your HVAC problems and there are certain systems with which it is not compatible but it is one of the most elegant and powerful thermostats I have found in the $200-$250 range. Nest claims it is compatible with 95 percent of residential HVAC systems in North America.