The Value of Top-Notch Windows

Industry improvements are helping to make homes more energy efficient.

These custom windows were made by H. Hirschmann LTD in West Rutland, Vermont. Architect Tom Murdough of Murdough Design in Boston designed the home, and Wood & Clay Inc. of Gilford built it. 

Investing in high-quality, energy-efficient windows can save a bundle on heating and cooling costs in the long haul.  

 Experts note that window quality and construction has improved significantly in the last twenty years, with higher quality and more stringent energy-efficiency ratings.

“Windows are one of those things it pays to do well from the beginning,” says Paul LeVeille, a high-performance-building specialist with The Jordan Institute, a Concord-based nonprofit with a mission to solve climate change in New Hampshire by making buildings more energy efficient.

“Windows used to be a single sheet of glass. Over the last couple of decades, we’ve seen the standard become double-glazed with inert argon gas or higher-quality krypton gas in between the sheets,” LeVeille says. The gas layer doesn’t conduct heat from one layer of glass as easily as air does.

Plus, there is more to a window than meets the naked eye.

“Most people assume all windows are the same. They go to the lumber yard and say, ‘I need five windows,’ without asking questions,” LeVeille says, adding that there is much more customers can—and should—do to make informed choices.

“Consumers have a lot of choices,” he says. “The windows may cost more but will pay for themselves over time.”

Heat loss and ratings

Windows are essentially thermal holes that lose and gain heat in four ways: conduction, convection, radiation and air leakage. Heat transfer is expressed with U-factors. A low U-factor indicates higher insulating value. Conversely, R-values are a measure of a material’s ability to resist heat transfer. High-efficiency-coated windows also have a low-emissivity, or Low-E, rating.

An easier way to shop for high efficiency windows is to look for the NFRC sticker. LeVeille says the National Fenestration Rating Council (NFRC) tests the U, R and Low-E ratings of windows, doors and skylights. “Basically they compare apples to apples,” LeVeille says.

A NFRC certification label includes energy performance ratings on the U-factor, the solar-heat-gain coefficient, air leakage and visible transmittance (how much daylight or visible light comes through). The label includes information on construction materials used and glazing. Recently updated energy codes lower the U-factor from 0.35 to 0.32, improving the window’s ability to keep heat inside a building, according to the NFRC website.

A changing marketplace
Meredith-based architect Christopher Williams—whose firm, Christopher P. Williams Architects, PLLC, won the 2011 LEED Residential Green Building of the Year Award from the New Hampshire Green Building Council—lauded the rating code changes for 2013.

“With the code changes, window manufacturers are driven to produce higher and higher performance windows,” Williams says. “It’s a bit like getting better mileage from your car.” There have been significant improvements in sealing, glazing and weather stripping, he says. Triple-glazed windows are now easily available.

Williams concurred that high-efficiency windows are worth the investment. “Windows are not the place to save money,” he says, noting that manufacturers are becoming more agile in the marketplace by offering custom shapes and sizes, and flexibility with color and trim options. He says manufacturers frequently change their installation procedures, but on the job site, installers may not be aware of the upgrades. “One thing I’d advise anybody,” Williams says, “is to make sure the contractor reads the current information regarding installation.”

Solutions for older homes

Owners of older or historic homes and buildings have options when it comes to improving energy efficiency while maintaining the integrity of the structure. The message that the New Hampshire Preservation Alliance conveys is, essentially, “Don’t toss those old windows!”

Specialists at Window Master, Inc. in Dublin are dedicated to saving old, wood windows as well as upgrading their energy efficiency and ease of operation. Since the company launched in 1994, Window Master has performed hundreds of upgrades to historic homes, colleges and universities, and commercial structures throughout New England.

The company’s chief estimator, Tim Patch, says Window Master uses a bi-glass system that allows for the cost-effective installation of insulated glass in old windows.

Installers replace old, single-pane glass with a double pane and then re-glaze and weather-strip the window, keeping the original wooden frame and sash. Old weight pockets—the ropes with weights at each vertical side of the window—are replaced with an insulated, hidden spring balance.

Patch says most older windows were made from hard woods, not from the soft, fast-growth pine used today. “That wood in the older homes and structures was the best you could get,” he says. “We can’t grow it any more.”

Window Master, known for its restorations, does not use vinyl or fiberglass windows.

From buying the best new windows to restoring existing windows, the quality and energy-efficiency of windows and materials, such as weather stripping and glazes, are improving exponentially.