Re: But I don't want any of them
Nights vary in temperature everywhere, but like I said even my $50 Honeywell figures out when it needs to start heating to get the house to temperature so if I have it set to have the house at temperature X at 7:30 it will start heating earlier and have it at that temperature at 7:30. Nest provides no advantage there.
I could buy an external temperature sensor for it, but I've never seen the value of having a thermostat inside my house know what temperature it is outside. It can already tell when it is 0F outside versus 40F outside based on how quickly the house loses heat, there's little point to giving it exact information whether via an external sensor or having it able to access the weather over the internet. My house is at the programmed temperature in the morning regardless of how cold it was outside that night, so whatever it is doing doesn't need improvement as far as I'm concerned.
Besides the outside temperature is only part of the picture. I have an older house that despite my best efforts is more drafty / not as well insulated as a new one, so it loses heat more quickly when it is really windy out. I wonder if the Nest is smart enough to take that into account - and exactly how it knows how well insulated your house is? My thermostat is (as far as I know) basing it on how quickly heat is being lost, so if the heat loss of 20F and 20 mph winds is equal to 0F and 0mph winds, it will start heating the same number of minutes before the designated time.
Yes yes, knowing the outside temperature does have one use - it helps if the temp is changing dramatically over a short time, as when a cold front is coming through. If it was 40F and calm at night and my house was losing heat very slowly, and then a couple hours before I was due to wake up a strong cold front blew in with gusty winds, my thermostat may start adjusting the temperature up "too late", because it wouldn't know that it is now 20F with a 30 mph north wind. If I had an outdoor temperature sensor (and it used it, I think in mine it would be used for controlling auxiliary heat if you have a heat pump instead of a gas furnace like I have) it would know it has suddenly grown colder and start heating earlier. If I cared about that I'd get a thermostat that could handle it, but having it be a couple degrees colder than it "should" when I wake up is something I probably wouldn't even notice, and wouldn't care about for the two or three days a year this sort of thing might happen. I have more variability than that in my body's internal "thermostat" :)