I purchased the 6,000 btu small window air conditioner for an 18 or 19 year old calico cat that I adopted after her owner pased away.  She does not care for my other cats, so she is living on the enclosed back porch.  The porch is air conditioned and heated, so it is her room, and she loves it.  The AC works hard during the hottest days, but it does a good job.