what size air cond. do i need for a room 16 by 13 by 9 feet?
Answers:
Usually this is calculated by looking at the square footage of the floor, which is 208. Your ceilings are fairly high, so I would go up a little. The suggesting range for 100-250 square feet is 5000-6000 BTUs. I would go for at least 6000 BTUs, maybe a little more depending on how hot the space gets. Something around 6500 BTUs would do a good job. Check out Consumer Reports for ratings.
Other answers:
6000 btu
6000 btu
I would think that a 1 ton window unit may suffice, from my experience. A larger unit may save energy and eclectricity.
It would operate less and prevent the compressor from start up so often, which uses a surge of electricity each time.
Don't take this as professional advice. Consult your dealer.
You didn't specify if room is on ground or upper level. Normally cooling requirements are based on ft2, not ft3. For 208ft2 you would need 4,000 btu's, but with additional height of ceiling, 5,000 would be plenty, as long as space is on ground floor.