I'm a new home owner and was wondering if there is a "right" way to use the double hung windows in the house. Should I open the top or bottom? Is there a seasonality to it? Does it even matter at all?
I've looked around and haven't seen this answered well or with most anything other than a "try and see."
Generally, is there anything special I should know to maintain the windows?
Can anyone shed some light?
If you open both the top and bottom about 3" the hot air goes out the top and cooler air comes in the bottom.
Generally one opens the bottom window, simply because it's easier. The features of the window tend to be designed with that in mind:
It's really up to you, however. There are good reasons to open the top instead - for instance, if you have small children and having them climb around the window is a concern. (No kidding - my friends 5 year old fell out a 3rd story window when the screen popped out)
If you have regular blinds/shades you may find it more useful to open the bottom, since that will allow unrestricted airflow. If you have Top Down/ Bottom Up blinds/shades, you might find it gives you a bit more privacy if you open the top of the windows and blinds.
Some windows will have locking mechanisms that allow you to lock either the top or bottom in place, while the other moves freely. In this case, it can offer better security if you can lock the bottom and open the top. A burglar would have to climb higher to gain access to the open window (though they could always just smash the windows, so it's not a huge security gain).
You may have animals (cats, etc.) that enjoy the open window, in which case they'd probably prefer you open the bottom.
From treehugger.com
"When air passes over your home, it works the same way as it does over an airplane wing: the Bernoulli effect causes the air on top and on the downwind side of the house to be at a lower pressure than on the upwind side. So if you have double hung windows, you can open the bottom section of the upwind side of the house (usually west) and the upper section of the downwind side (usually east), and the low pressure will suck the air through your house. Make the outlet openings (top section) larger than the inlet opening (bottom section), it increases the draft."
Opening the top sash allows for ventilation while maintaining privacy via top-down-bottom-up blinds, obscuring textured glass, or a similar solution for the still-closed bottom sash.
For bedrooms with only a single window, in the summer I like to put a window fan in the bottom (blowing in) and then open the top of the window to vent. Alternately, if there's an AC in the window but you don't want it on, you can open the top of the window to get fresh air without removing the AC unit. (My windows have screens that can slide up to the top of the window which is nice, although not all are like that.)
The top opening of the window was designed to let heat out of the structure it's installed in, while the bottom half was designed to let in cooler air because heat while cooler air tend to stay at the bottom during warmer periods of the year. If you any windows installed the upper portions of a structure, and want to cool it down a bit. Open the upper window while also opening the lower window in the structure to let cool in while hot air is vented out. I hope this answers shed a little light on the subject.
If you have awnings or eaves that overhang the windows, opening the top may reduce the chance of rain blowing in.
