Q. Are there any good alternatives to window-unit air conditioners? Central air doesn’t seem to be an option in our vintage building.

A. One choice to consider is the Mitsubishi Mr. Slim (mrslim.com), a ductless air-conditioning system that is quieter and more efficient than a traditional window unit. Because it’s wall-mounted, you don’t have to sacrifice a window to be cool. And though it’s more expensive than a window unit-about $3,000 to $3,500 for a 9,000-BTU appliance-it is much cheaper than central air.

Steve Ignoffo, manager of Unique Indoor Comfort (551 S. Route 83, Elmhurst, 630-833-4400; uniqueindoorcomfort.com), describes how it works: “There are three pieces to the air conditioner: an air handler (or blower), a condenser, and a remote control. The air handler, which makes no noise, is mounted on a wall inside your house, and the condenser, which makes all the noise, is mounted on the outside. They are connected by refrigerant lines running through a three-inch hole in your wall behind the blower. You operate the unit by remote control because the air handler is mounted high on the wall.”

Chase Coffey, who owns a co-op in a 1920s building in Hyde Park, chose the Mr. Slim because his apartment has casement windows that can’t accommodate conventional window units. “We wanted the best unit we could find for the money,” he says. “We got one condenser and two blowers for two rooms. You can set each blower separately with the remote control. The system works great; it cools down our whole apartment quickly and quietly and is energy-efficient. We’re very happy with it.” Coffey’s unit was installed by B&B Heating and Cooling (16308 107th Ave., Orland Park, 708-403-2276).

Another possibility is SpacePak (spacepak.com), a high-velocity central air-conditioning system with a central blower unit that might fit in a closet. It could also be installed in an attic, crawlspace, or basement. The cool air is distributed through flexible tubing threaded through walls, ceilings, and floors, then sent into your rooms through inconspicuous round outlets, two inches in diameter, in the ceiling (or in the walls or floors, if you prefer, like a central vacuuming system). As SpacePak requires no bulky ductwork, no major remodeling should be necessary, though you will need to hire an air-conditioning contractor to install the system. Prices vary with the size and configuration of your home; you might expect to pay $6,000 for a 1,000-square-foot space. The system is available at American Vintage Home Heating (1225 Green Bay Rd., Wilmette, 847-251-5255).