A. "The repairs are simple," says Jeff Ediger, owner of Oak Brothers Trim (773-279-9064). His pros will remove heavily painted windows and bring them to the shop, where they’ll strip, plane, tighten, and refinish the sashes. If a sash is too badly rotted to resuscitate, they’ll make a new one.

When they reinstall the windows they’ll replace the old ropes with either new rope or brass or bronze chains. The weight and pulley system that controls the opening and closing of the window is housed behind the jamb. Oak Brothers will make sure the jamb is stripped of paint so the sash can glide up and down easily and not release lead paint particles into the air. Many other local firms do window repair, including Empire Millworks (773-569-0273) and Just Sashes (773-205-1429).

The cost of window restoration varies widely, depending on the size of the window and the amount of work needed. You can expect to pay as little as $200 to have a single window unstuck and its cords replaced, as much as $2,200 for a complicated restoration job.

Are old windows (in good condition) as energy-efficient as new ones?  Yes, say the pro-restoration people. Wood is an insulator, as is air. Pair your old, restored wood windows with storm windows and you are nicely insulated against air and noise. "The more air [between the panes], the higher the efficiency rating," says John Videckis, owner of Just Sashes. There are two to three inches of air trapped between a window and its storm compared with about a quarter inch trapped in a thermal-pane replacement window.

You can use aluminum triple-track storm/screen combos, or have wood storms and screens made. Modern wood versions are a far cry from the old, heavy ones our parents and grandparents had to install and de-install, seasonally, from the outside. Both Videckis and John Conway, owner of Empire Millworks, make wooden storms and screens with glass and screen inserts that you can clip in and out of their frames from inside your house. The units range from about $275 to $400, not installed or painted.

Who will speak for replacement windows? Plenty of people, including architect Richard Becker, principal of Becker Architects (595 Elm Pl., Highland Park, 847-433-6600). Becker, whose firm does preservation work on some 20 houses a year, says, "You have a better idea of what you’re going to get with a new product with a warranty. When you buy a whole new frame, you get a better end result."

James Fraerman, principal of Fraerman Associates Architecture (508 Central Ave., Highland Park, 847-266-0648), a firm that has won awards for historic preservation, says you have to weigh the restoration of windows against the historic value of the house. "If there’s no historic value to the house, I would lean toward custom replacement windows," he says.