I have been using a Nest Wifi enabled, internet connected, thermostat for about 3 months. Three of the coldest months ever in the NY area. I can say that I was a skeptic about their cost savings claims, but I wanted the ability to control the heating in my house from the internet. I took the plunge and installed them in my home. The first noticeable change came about a week from installation. I realized I was never cold in my home. With my original thermostats, I had a tendency to keep the temperature relatively stable at 65 degrees. I never set a schedule and infrequently lowered or raised the temperature due to my comfort. I guess you could chalk that up to laziness…. Sometimes that meant I was too hot or too cold and sometimes just right. With Nest, I followed their instructions, and basically I set the temperature to my comfort whenever I was in the house. In a few days, Nest had learned what temperatures I liked and at what time I liked them. Nest had also figured out when I was in the house and when I was not, allowing the temperature to drop the an “away” mode that saved on energy. One weekend morning after getting out of the shower I noticed that I was very comfortable even though I was still a little wet. Nest had figured out that on the weekends I get up a little later and it keep the temperature a little hotter a bit longer than normal, very nice Nest! As I became accustomed to Nest tailoring the temperature to my every whim, I began to think that I was probably using more energy than I ever had. Previously, I’d rarely touched the old thermostat and I was always cold in the winter, surely being comfortable all the time had to cost more… It turns out that I was wrong. One of the added features of the Nest thermostat is a monthly email describing how many hours you are heating your home per month. I had actually decreased my usage each month as the system had become more in sync with my habits. I also checked my energy bill from the same time last year (I know, not apples to apples due to weather) and it was roughly 15% less this year versus last. I for one am sold. I plan to continue to monitor for efficiency but from a comfort standpoint I’m very happy!