I have a window about 4 feet by 4 feet about four feet up from the ground i need to cover up. But the cottage is tiny and i don't want to put in a bamboo that will grow to 40 ft.
If your temps rarely get below 12F for long periods of time, then Bambusa multiplex 'Golden Goddess' might do well.
And, it's a clumping bamboo, so you won't have to worry about it running and sending out growth where you don't want it.
A Fargesia would work too.
O. acuminata ssp. aztecorum
This can grow to 20 feet but that wold be under ideal conditions so it will probably not get that tall and temp is good to 22F. Next to a house or in protected area maybe less. It is a beautiful bamboo that would nice to look at as a view. You can find more info by googling mexican weeping bamboo or going to http://www.americanbamboo.org/SpeciesSourceListPages/SpeciesTableO.html
I have some Drepanostachyum sengteeanum which is really beautiful and seems to grow to about 10 feet high in my climate.
Here is a link that might be useful: Bamboo