Criteria for a window unit
Before selecting a window or portable unit, Consumer Reports recommends three considerations: "size it correctly, note the noise, and factor in the window location."
Portable unit prices
Prices at Home Depot in 2010 start at $99 for a small room unit with 5,000 BTU and increase in price with size and power. A unit with 18,000 BTU cools 1,000 square feet for $349.
Central air system costs
Central air systems cost between $6,000 and $10,000 to install in homes already fitted with a forced air heating system with ductwork in place, according to CNN Money. Adding ductwork will increase estimated costs by $2,500 to $4,000.
Rate the noise
Some room units are noisy when running and may disturb light sleepers, warns Consumer Reports.
Check the size
Be sure to install an appropriately sized unit for the space, as the U.S. Department of Energy warns that "many people buy an air conditioner that is too large."