Okay…Here’s the Dealio…
I live in Florida…
It’s apparently really Hot here…and getting Hotter every day…
My wife and I are in a constant battle…
We keep the house nice and cool…and our electric bill frequently reflects this fact…which brings me to my question…
Is it more economical…(my wife’s idea) to open up all the doors up stairs…and run the AC…
or…
To close up all the doors up stairs…and run the AC…
I have no real factual basis for why I believe that having the doors closed upstairs…is a better idea…I think I just believe that if you individually cool each room…it would be better than trying to cool off the entire upstairs as one big open room…
Any thoughts…Comments…Pointing and Laughing?
Thanks…
RickyC:smack:
Where are the returns? Hallways or in each room? You probably have one or two large returns for each floor. So, opening or closing doors would affect airflow from vent to return.
You can chill a room pretty effectively by shutting the door, but I don’t think you’ll get more economy that way. The system is designed for an airflow of some sort, after all.
Sorry to point out that FLORIDA + AIR CONDITIONING * AUGUST = AC RUNING ALL THE TIME.
Where is the thermostat? It’s that area that you have to pay attention to. If it’s in the upstairs hallway, and there are no registers in the hall, and you keep the rooms closed, the only cool air getting to the thermostat is having to work it’s way up from downstairs. And Heat Rises, Cold falls.
What my mom, the cheap chick that she is, would do is close off the registers in rooms that aren’t used often and then close the doors. No use cooling what isn’t absolutely necessary.
Efficient cooling of a house relies not only on pumping cold air into each room, but also removing hot air - that’s what the return vents are for.
If you’ve got return vents in each room, it will probably be slightly more efficient to keep the doors closed as the return line will be sucking air out of its designated room only and not other places like the hallway, etc.
If you’ve only got a return in one area, you’ll need to leave the doors open in order to allow the return to remove the hot air from all rooms.
My house serves as a good example:
On the second floor, we’ve got one big return vent in the hallway, but only one of the 3 bedrooms has its own return. That one bedroom is cooled more efficiently (read quickly) if the door is left closed. However, the doors to the rooms with no returns must be left open if sufficient cooling is to be acheived. If the doors are left closed, there is no means by which to remove the hot air from those rooms.
So, to answer your question…depends where the returns are.
I think the central air makes the question more complex. With a window air conditioner, it’s fairly simple. The smaller the area you are cooling, the smaller the air conditioner you need to do the job and the less power you require. So if you shut off unused areas of the house and live in a smaller climate-controlled area, you’ll use less power. (Although there will be some heat seepage as internal walls are not typically insulated.)
But…central air is usually sized for cooling a specific square footage, and it’s actually supposed to be running at a fairly constant duty cycle. If the house gets cooled too fast, you lose the dehumidifying effect of the air-conditioning process. So if you lower the area you are cooling, say by shutting the vents in the rooms you aren’t using (and assuming that your thermostat is not in one of those rooms ), you will save some energy but the system won’t be operating at peak efficiency and the air will be too humid, so it won’t seem as cool.
However a lot probably depends on the geometry of the house. For example, you have one room that gets a lot of solar heat, I suppose you could save some energy by shutting that door so that the warm air from that room doesn’t reach the thermostat and cause the rest of the house to be actually colder than what you expect.
), you will save some energy but the system won’t be operating at peak efficiency and the air will be too humid, so it won’t seem as cool.