1. Before looking into expensive mechanical options, think about how you can increase the comfort of the attic through better ventilation. Windows and skylights can be very effective in generating sufficient cross-ventilation to keep things as comfortable as necessary.
2. If you have central air conditioning, check with a heating and cooling contractor to see if your existing system can be extended to the attic. Often this is the least expensive and most efficient mechanical option.
3. A window- or wall-mounted air conditioner can be simple to install and very effective. It can also be an ugly addition to the exterior of your house, so you may want to choose the location carefully. Select a unit that is properly sized for your space.
4. Ductless, or split, air conditioners are becoming increasingly popular in the United States (they have long been in use in Japan). The compressor and condenser are installed outside, sending cold refrigerant through small lines that can be run up the walls to the attic. These units are easy to install and very quiet, but they are also a bit expensive. Consult a heating and cooling contractor for more information.
