we sleep with the windows open probably 300 days a year. of the remaining 65 days, and probably 30 of those we simply close the windows, and even then we usually turn the electric heater on for 1 hour, turn it off, and go to bed. Also we live in a one bedroom apartment on the top (3rd floor) of a building that is surrounded on 3 sides. you couldn't stick a credit card between our building and the neighbors. no heat leaking out there. lastly our front windows face south, and a result we get a huge heating effect.
i should add i just moved here from Boston 2 years ago, so i'm used to apartments that are less than 60 degrees in the winter with the heat cranking! Plus i'm a big fan a winter camping (last time i camped on the east coast it hit minus 15F), so give me a down comforter, and i'm toasty. northern european genes i guess
as for the admin costs of the electric bill...i don't know...maybe as apartment dwellers we're not charged the same basic rate as house owners.
but i'll tell you, compared to living in Boston... rents about the same (although less square footage), i don't need a car (subtract $600), and virtually no utilities. not to mention vastly better quality of life.