Eager to decrease those increasingly high cooling and heating bills? Your window of opportunity for energy savings is closer than you think. In fact, it's framed right there on the wall next to you in the form of your windows, where as much as one-third of your home's heat loss occurs, on average, per the Energy Information Administration, Washington D.C.

Replacing those older, energy-wasting double-hungs, casements, bows, bays, transoms, sliders and other windows with new ones can improve the look, feel and thermal efficiency of your home - if you choose the right products, that is. The problem is that not all new windows are built alike and it's easy to get confused by marketing claims, industry lingo and sales pitches. But experts say one of the best investments you can make is to choose passive windows that can significantly lower your energy bills, increase climate comfort and boost your home's resale value.

A passive window is a type of high-performance, well-insulated, airtight window that's designed to improve the overall energy performance of your residence.

"A window system with passive performance allows the heat of the sun to come into the home and warm it in the winter, limiting the use of your furnace, while keeping heat outside during the summer, limiting use of your air conditioning," says Dan Parrish, senior product engineer at Pella Corporation in Pella, Iowa.

"Passive" means it's been created to use the natural movement of air and heat, with minimal mechanical help from a furnace or air conditioner, to sustain a comfy climate; the word "passive" also refers to a "passive house," which conforms to a voluntary but strict building standard - invented in Germany - used to construct ultra energy efficient and eco-friendly buildings. You don't have to have a home built to passive house standards to enjoy the perks of passive windows, although they perform even better when installed in a passive house.

Meredith Marsh, communications manager for the Passive House Institute US (PHIUS) in Chicago, says typical features found in passive windows can include two to four panes of glass (colder climates require more panes), argon or krypton gas between the panes, low E coatings on the glass layers, warm edge spacers, and insulated vinyl, fiberglass, wood, or composite wood frames - all of which combine to provide a superior product compared to a standard window.

"The benefits of passive windows include improved all-season thermal comfort for occupants, no surface condensation, reduction of outside noise to provide a quiet interior environment, and improved energy savings that can result in reduced furnace and air conditioning size," says Marsh.

Expect to pay more for passive windows: based on recent PHIUS data, they range from $55 to $120 per square foot installed compared to around $40 to $55 per square foot for conventional dual pane vinyl replacement windows, although prices can vary widely depending on the size, features/materials, market, manufacturer, installer and other factors.

"We are currently installing passive windows in one of our projects, and their cost is only 5 percent more than if we were to install typical windows we usually use for other projects," says Jorge Mastropietro, AIA, principal and founder of New York City-based Jorge Mastropietro Architects Atelier.

The return on investment can be immediate and impressive, allowing you to possibly recoup your costs faster than expected.

"On one of our latest retrofit projects where we installed new passive triple glass pane windows, new wall insulation and roof insulation, the client spent $70,000 but reduced his monthly utility bills by around $1,000 - equating to an investment payback period of around six years," Mastropietro says.

Your mileage may vary, however.

"Return on investment and performance of passive windows will depend on many factors like your climate, building characteristics, the orientation of the window, how well it is installed, the temperature you maintain in your home and if you use window coverings like blinds, shades and curtains," says Tad Everhart, a certified passive house consultant and building certifier in Portland, Oregon.

As with any home improvement project, it pays to do your homework before choosing a passive window brand and installer. You can research passive window products and find a PHIUS-certified professional at phius.org. Be sure to compare features and warranty claims carefully.

 

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