Unless you live in an apartment or rented building and your landlord controls your building’s temperature (and if that is the case, we really feel for you), understanding how your thermostat works is actually a very, very useful thing. We don’t mean just being able to turn on and off heating and air units with a thermostat — we mean really understanding how to use the thermostat to heat/cool your home efficiently and at the lowest cost possible. There are tons of new “smart” thermostats on the market these days that creepily detect when you’re home and which can be…