Central, programmable stats:
2nd floor: 85 away, 74 home
1st floor: 74 daytime (for the dogs), 85 nighttime (the're upstairs with us)
Basement: 74 always, barely runs, for dehumidification
This is mostly for cost rather than carbon footprint. While I still do it, I've been thoroughly convinced that any individual conservation, recycling, etc efforts are bullshit things to make use feel better about ourselves rather than make any difference toward the environment. Until there are business regulations, nothing makes a difference since you account for the tiniest fraction of consumption.
We need to stop inconveniencing ourselves for the sake of appearances, because it just avoids ever having the conversations on things that could actually make a difference.
Individual conservation is indeed only a tiny fraction of consumption, but it is the only tiny fraction that you have full control over. Yet I think there are benefits to individual conservation besides the feel-good and that microscopic fraction.
There is a social aspect. Humans are social creatures. An outlier -- which I am pretty sure I qualify as -- can make it easier for others to nudge their own thermostat a degree or two. It can also show some amount of general societal willingness to accept business regulations that would affect end consumers. Individual conservation can also help keep the idea of conservation in mind, as that chosen inconvenience affects daily life.
That said, if the individual conservation is preventing those critically important business regulations from being talked about, proposed, or enacted, then I'd definitely prefer the conservation effort be put toward establishing those regulations.
 While I don't know the precise form those regulations might take, I can guess that building construction and maintenance, HVAC systems, and vehicles will be significant targets.
I've been thoroughly convinced that any individual conservation, recycling, etc efforts are bullshit
The more I think about this, the more I disagree with it. One of your examples, recycling, is a significant part of that disagreement. Recycling is one of the great conservation success stories. It went from largely nonexistent to immensely supported (and subscribed to) at multiple levels of society. While there are some communities that still have no recycling options -- not even a recycling center where you can take your recyclables -- most if not all big cities, and an awful lot of smaller cities and towns, offer comprehensive curbside recycling.
Individual recycling is, as you point out, a tiny fraction. However, those tiny fractions add up. The EPA reports the US having a 34.3% recycling rate
; that's a whole lot of tiny fractions stuck together into something much bigger.
The tiny fractions can, and in most cases must, add up for other conservation. Even the largest coal-fired power plants, with capacity in excess of 2 gigawatts, are less than 0.1% of the 24,000 terawatt-hours
(warning: extremely large PDF; you want page 24) of energy production worldwide. While their tiny fraction is substantially larger than our tiny fraction, it's still tiny, and has to be added to a whole bunch of others to add up. Further, reductions in individual power consumption will help determine when and whether new plants get built, or if existing plants get run on fewer generators.
The single biggest energy consumer under the individual control of most people in their house is heat
. Turning the heat down in the winter, as well as closing up leaks and insulating, produce big wins. Air conditioning, while nowhere near as large, will also benefit from that insulation, and altering your AC setting is a nontrivial single-point savings.
The other big energy consumer under individual control is a vehicle. The average US household uses just under 11,000 kWh per year
. A gallon of gasoline is 33.7 kWh
. Driving a 30 mpg car 10,000 miles a year consumes just over 11,000 kWh per year. If you're really looking to reduce energy consumption, drive as little as you can.
With enough people making changes, such as we've achieved with recycling, we need not wait for the commercial regulations to see significant results.
 A 2 gigawatt plant, if run at that capacity for a year, would produce 17.5 terawatt-hours of electricity.Edited at 2016-08-11 01:45 pm (UTC)
I have central air, set to 75, occasionally lower because the room with the thermostat doesn't get the afternoon sun. I haven't tested whether the thermostat is correct in its measurements, but heretofore I always used 77/78 in the summer and was comfortable, but in this current place that feels really hot. I personally love having windows open but in the southern states have gotten in trouble with the humidity and mildew issues if I don't at least nominally run the ac sometimes.
I had one tenant who would set the temp in the summer to 68. and in the winter to 75. Logically that makes no sense! I tried to point out how wasteful this was, not to mention hard on the systems. Don't know if it did any good--they were used to never having to pay for utilities.
I'd not actually run across someone with the habit of setting the AC colder than the heat, though I had expected they existed. I am baffled why someone would do that.
I do not have central AC, which mean that the (single) window AC is set to either 69 or 70, which keeps the rest of the house around 76 or 77.
Blinds generally stay drawn during the day, to reduce incoming heat -- and windows/fans get opened if it's cool enough (and dry enough).
Central air: 75F when I'm home, system off when I'm not (where "not" means traveling, since when I'm not traveling, I'm home 24x7). I've had my AC on for the sum total of a week and half this year. In the winter, oil heat set at 60F when home and 45F when not (to keep the pipes from freezing). If I'm gone for more than a couple weeks, I'll drain the pipes and shut off the water, too. Unsurprisingly, I show up as extremely efficient to my electric company.
We have room-ish AC: ductless minisplits. One big one for the dining room/living room on the 1st floor, room-specific ones for our workrooms, bedroom, and guestroom. If we turn them all on, the effect resembles central AC, carrying over to most of the house (save the sunporch).
All units are off by default. When turned on, they tend to get set in the 75-78 range. (Once I set mine to 80 during a heat wave.) Occasionally I'll set the downstairs one as low as 72 if I'm having a lot of people in the dining room playing games; AFAICT, "72 at unit" == "75-76 at people".
One of the many lovely things about minisplits is that they don't use up windows, so even in rooms with only one window when the weather cools off we can just open the window instead.