Five years ago I bought the Lennox Elite XC-17 (
http://www.lennox.com/products/air-conditioners/XC17/) from Apri's. It cost $5001 for a 2,300 sqft house with large west facing windows. It's definitely overkill for the house but large, quiet, and very energy efficient. I'm in my den right now and it's below my window but all you really hear is a low-grade hum. I'd say in a typical Calgary summer I really don't notice any difference in my power bill but it might go up $25-30 per month - definitely not enough to consider turning it off. I'd highly recommend this to anyone and Arpi's was excellent.