DIY Do it Yourself or Not®

A window air conditioning unit, designed for easy installation in a window opening, does a fine job of cooling a room. However, the unit in effect closes the window, preventing you from using the window in mild conditions. An alternative that keeps the room cool, and frees up the window for operation, is to build an air conditioner into a wall so it’s permanently installed and out of the way. This works particularly well for cooling a small addition or part of the house that isn’t cooled naturally or by other units. When a unit is mounted high on the wall, it does a good job of cooling the space efficiently and effectively. A key requirement is to place it near a 115-volt electrical outlet, or have one added near the location on the wall.

A carpenter will build in a 10,000 BTU energy-efficient air conditioner into a wall for $750, which includes the labor, framing material and the unit. If you have carpentry experience, you can do the job for $550, the cost of the unit and framing material, and save 27 percent. You’ll have to cut away enough of the interior wallboard to frame in an opening, and then position the unit in the opening and secure it. Then you cut the siding and trim out the opening on the exterior. You may have to repair and paint the walls and trim if you damage them during installation.

Tip: Before cutting into a wall, check that there are no pipes or wires concealed behind it.