Rating Replacement windows

The benefits that replacement-window manufacturers tout aren’t always, well, as clear as glass.

Consequently, although you’ll find an increase in the number of windows that are made of aluminum, vinyl and wood, as well as vinyl windows that have increased numbers of air chambers in their frames, the energy-saving benefits of either of these changes can be difficult to determine. However, manufacturers claim that the overall performance of their windows has improved slightly as a result of the new designs, regardless of how, and experts back the premise of those claims.

Meanwhile, in the past 3 years, manufacturers have marketed window-opening control devices (WOCDs), which are a safety feature that can prevent windows from being opened beyond 4 inches to prevent accidental falls by children. Unfortunately, hidden expenses exist among brands of windows, as well as some design flaws that make it impractical to open most casement windows fully.

HYBRID WINDOWS. Manufacturers Hurd, Jeld-Wen and Weather Shield developed models that merge aluminum, extruded vinyl and wood into a single window. All of these materials long have been used in windows, but this marks the first time that they’ve been used together.

You won’t find a “hybrid” label on these products. Manufacturers use vague labels such as “tri-core” or “fusion technology” to describe these designs. We coined the term “hybrid” to describe what they are—a product that looks like a standard aluminum-clad wood window (aluminum exterior, all-wood frame, wood interior) but has the thermal advantages of vinyl, which does a better job of insulating than wood does.

The vinyl components of hybrid windows are designed to improve the window’s U-factor, which measures how well that a window prevents heat from escaping a home in the winter and intruding in the summer; and air-infiltration rating, which measures how much outside air that a window allows to enter your home. Manufacturers also tout vinyl’s capability to withstand damage from moisture and other elements better than wood does.

Five experts who independently test and rate windows tell Consumers Digest that measuring exactly how much the vinyl components that are in hybrid windows contribute to the window’s U-factor and air-infiltration ratings is impossible, because similarly constructed windows that lack the vinyl components don’t exist to allow for comparisons. Nonetheless, experts confirm that extruded vinyl conducts less heat and allows less air leakage than wood does. For this reason, manufacturers of hybrid designs say their vinyl components produce a 0.02 improvement in U-factor over equivalent all-wood versions. Data from computer models suggest that this translates into perhaps a 3 percent reduction in heating bills.

Vacuum-Sealed Windows Promise Better Insulation

Hurd introduced its hybrid technology, which consists of a vinyl frame that’s sandwiched between an aluminum-clad exterior and a wood interior, in its double-hung windows in October 2011. The company in 2009 introduced that construction technique in its awning windows, which are hinged at the top and open from the bottom; and its casement windows, which are hinged on the side and open outward.

In January 2013, Jeld-Wen entered the hybrid discussion by introducing the W-2500, which is an aluminum-clad wood window that includes a vinyl sill. In March 2013, Weather Shield launched its Signature Series, which has a design that’s similar to that of Hurd’s hybrid awning, casement and double-hung windows in that it has a vinyl subframe—the interior portion of the overall frame.

At press time, Hurd’s H3 was the only hybrid window that was available in a replacement configuration. Jeld-Wen and Weather Shield were mum on using hybrid technology in replacement windows. Based on claims of performance improvements and our discussions with other manufacturers, we expect to see additional hybrid windows enter the market, although we don’t know when that might occur.