Many window replacement companies promise homeowners substantial energy savings, some even a lifetime warranty. Of course, whether or not that window performs in the way it was designed to depends on competent installation. But what does that consist of, and who's qualified to do it?

Today an increasing number of replacement window companies use certified installers — both employees and subcontractors — who are tested on procedures outlined in manuals issued by Installation-Masters, of York, Pa., or the American Window and Door Institute (AWDI), of Juno, Fla. Since 1989, AWDI has certified more than 7,000 installers, and Installation Masters nearly that many since 2000.

Certification aims to reduce service callbacks, maximize product efficiencies, and show installers how to work faster and smarter.

AWDI provides installation manuals, and mandates classroom instruction and an open-book test with 120 questions. Installers are required to have a minimum of one year's field experience before applying for certification training. A key aim of any certified installer program, notes John Jervis, executive director of AWDI, is consistency.

Jervis notes that an Oct. 2007 Consumer Reports article, which suggested that homeowners looking to replace windows should hire a certified installer, lent weight to the value of certification.

PEACE OF MIND For companies that use certified installers, it can be a defining difference. “There's a huge fear out there,” says Sven Kramer, general manager of Stanek Windows, in Cleveland. That fear is of shoddy workmanship.

To reassure homeowners, Stanek Windows offers a warranty covering both product and installation. “The important thing for homeowners to know is that these installers are trained with us and certified through us,” Kramer says. “So if someone takes a shortcut, I have to accept responsibility down the road.”

Increasingly, certification is seen as necessary to the perception of professionalism that companies seek. Window Depot USA, in Little Rock, Ark., specifies that its more than 50 dealer licensees use AWDI-certified installers. “When your sales rep is talking to [homeowners] across the kitchen table and explains that your installers are AWDI-certified and that the installation is as important as the quality of the window, it matters,” president Jim Venable says.

PROBLEM PREVENTION Since 2006 Newpro, headquartered in Woburn, Mass., has required that its 25 installers pass the InstallationMasters course. Tom Foxon, the company's director of installation, and a certified instructor, teaches the two-day class. Installers must have one year of field experience before applying for certification.

The course includes an audio, video, and PowerPoint presentation and is followed by a 70-question closed-book test. Foxon says that the value of certification is twofold: “It gives us a set of standards to follow, and it allows our installers to identify potential problems and correct them before putting the window in.”