If you're looking for an alternative to central air or a window unit, you do have another option.
A ductless air conditioner can be ideal in a sunroom or other areas where you may not have ductwork. They are also ideal for rooms where your H-VAC system isn't enough.
Angie Hicks, creator of the Angie's List website, says, "A ductless air conditioner can cost about $1,500 to $2,000 per ton of cooling capacity. However, you need to remember while these systems are more expensive, ductwork can make you lose about 20% in efficiency."
H-VAC contractors say Homeowner maintenance is very easy. The important thing to do is keep the filters clean.
Angie Hicks advises that since ductless air conditioners are a little newer technology you want to make sure you have someone who is experienced in installing them.
Some ductless systems also provide heat. You may need to purchase a separate heat pump, but some models come with heat strips already installed.