A:Answer Jules,
Having a window is not required. HOWEVER, ventilation is required. The unit must have ventilation to operate properly.
Good News: You can narrow your search to "Ventless" or "Ductless" Air conditioners. They are not as prevalent, but do exist.
Remember, Research is much cheaper than buying something only to find out it will not work
Brand Loyalty is a good thing, but research multiple units by multiple manufacturers and search for reviews until you narrow it down to the top three. Comparison shop between the three factoring in cost, longevity, warranty, functionality, and most importantly... will it suit your SPECIFIC needs?
Happy shopping,
Jeff