Which is cheaper?? - Air conditioning question - please click - thanks.?

Question

Which is cheaper:

(1) Running central AC throughout my house (1200sf) at 78 degrees all night, so it comes on/off maybe every 20 minutes, OR,

(2) Shutting off AC and running a window unit just in my bedroom, set at 70 degrees, which probably will just run nonstop all night.

Thanks.

Answer 1

the more consistent you are with your central unit, the cheaper your bill will be.

Answer 2

It depends on your comfort level.  If you're planning on running the window unit at 70 all night, are you leaving the heat pump for the rest of the house completely turned off? That will cause your heat pump to run itself to death to get the temp back down (that is, if it's hot outside) when you want to be out in the rest of the house.

Personally, I set my house as high as I can stand it in the daytime (84), and at night I set it to 77 (my bedroom gets colder than where the thermostat is, and I cant sleep if I'm hot.)  I cant have it set the same all the time, because my internal thermostat is screwed up, lol--I can be freezing at 84 one minute and burning up at 77 the next. :)

It is definitely more energy-efficient to keep it as constant as possible.

Answer 3

I'm a window AC person. Why cool a whole house when you only use one room at a time??

Answer 4

I agree with alvarz.  We have window unit in the living room, and at night we turn it off and open up the windows.  It also depends on where you live if that works or not.  Even in the summer we get a nice breeze @ night.