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.
Analysts tell Consumers Digest that, in theory, replacement or new-construction hybrid windows might be less expensive to produce than their conventional aluminum-clad counterparts are, but, based on our research of replacement windows, the price that you pay for either is similar.
NUMBERS GAME. Another means by which manufacturers are claiming improved performance ratings for their windows is through the increase of the number of air chambers that are in the frames of their vinyl windows. Five manufacturers say they increased the number of air chambers that are in their vinyl windows during the past 2 years.
The typical increase is to 12 air chambers from six; Pella puts 18 air chambers in its 350 Series. However, Pella estimates that the 18 air chambers that are in its vinyl window improves its U-factor rating over models that have eight air chambers by 0.02, which is the same amount that manufacturers of hybrid windows say their vinyl adds to wood. Because additional air chambers aren’t the only design variable in any new window model, it’s impossible to say whether having more air chambers translates into higher prices.
The frames of vinyl windows aren’t solid pieces but are constructed of a series of chambers. Adding air chambers breaks up the convection, or the circulation of air that can transfer heat from one surface to another, that occurs in open air space, so more chambers can reduce heat flow, says Ray Lamb of National Certified Testing Laboratories, which independently tests windows. However, the extra plastic that’s used to create additional chambers also conducts heat, he says.
Certified product testers and simulators say it’s impossible to determine at which point chambers become too numerous to improve a window’s U-factor rating effectively. The maximum number of chambers varies greatly from window to window, they say, based on how those chambers integrate with other design factors, such as how the chambers are positioned relative to exterior and interior surfaces and whether the chamber walls run parallel or perpendicular to other components that might transfer heat. Two experts suggest that too few windows exist that lean on this concept to determine conclusively whether the design actually works. If it does, other manufacturers likely will follow suit.
Lamb points out that the walls that are in air chambers add support to an otherwise open space within a window’s frame—similarly to how supports are added to a bridge—which translates into a stronger window frame. All of the vinyl windows that have triple-pane glass include chambered designs, and we found several windows that are capable of accommodating triple-pane glass that have fewer than 18 air chambers and cost, on average, $68 less than the Pella 350 Series window ($372).
An upgrade to triple-pane glass will net you a 0.11 improvement in U-factor, which computer models suggest will reduce your annual heating costs by 8 percent, or $75, depending on where you live and your home’s configuration, heating system and insulation. An upgrade to triple-pane glass in the Pella 350 Series window costs 30 percent more, or $111 per window. So, if you replaced, say, 10 windows, it would take 10 years for you to recoup your costs.
Consequently, we believe that you shouldn’t become mesmerized by the number of air chambers that a vinyl window has or by hybrid designs that add vinyl to wood windows. Instead, you should focus on a window’s performance ratings, which can be found on the National Fenestration Rating Council label that’s affixed to the window or to its packaging or that’s published in the product’s literature.
ON FILM. Glass that has thin layers of film suspended within the air space that’s between the panes of double-pane windows isn’t new, but the number of windows that use this technology increased in the past 3 years. Three manufacturers—Hurd, Kensington and Marvin—now use suspended film in their windows, with a fourth, Ply Gem, possibly on the way in 2014. Serious Windows (now Kensington) was the only manufacturer that we found that sold this type of window nationally in 2010.
Suspended-film technology provides the same benefits as triple-pane glass does but without the weight and structural requirements. The film improves a window’s U-factor and in some cases its solar heat-gain coefficient, which measures how much of the sun’s heat that a window rejects.
Because suspended-film glass weighs one-third less than triple-pane glass does per square foot—or about 17 pounds less per 3-by-5-foot window—that equals less labor and fewer achy muscles if you install the windows yourself.
Pricewise, we found that windows that use suspended-film glass are slightly more expensive compared with those that have triple-pane glass. For example, Hurd’s 3-by-5-foot clad-wood casement window that has suspended film costs $925. The triple-pane version costs $900. Both provide insulation of R-4 (equal to a U-factor rating of 0.25).
Southwall Insulating Glass, which produces suspended-film glass for window manufacturers, confirms that changes in how its product is made will make it easier and less expensive for window manufacturers to incorporate suspended-film glass into standard designs. Manufacturers wouldn’t say whether the savings would be passed along to consumers.
SAFETY HITCH. No matter what type of window or glass package that you seek, you’re likely to notice that every manufacturer now includes WOCDs. The inclusion of WOCDs is prompted by a minimum-sill-height requirement (the distance between your floor and the bottom of your window) that’s on the rise in local building codes. WOCDs are an accepted alternative to the sill-height requirement if the WOCDs prevent a window from being opened more than 4 inches unless you override the devices manually. (The measurement is based on the size of an infant’s head.)
The idea is to prevent children from accidentally falling from windows, and it’s no small concern: According to 19 years of research that was conducted through 2008 at Center for Injury Research and Policy of Research Institute at Nationwide Children’s Hospital, 14 children and adolescents on average were treated each day for injuries that stemmed from accidental falls from windows. American Academy of Pediatrics says 31 percent of children’s fall injuries during that period were from first-story windows.
(You’ll have to consult your local building inspector’s office to determine whether such child-safety requirements exist. You also will have to verify that WOCDs are permitted under your local fire-safety code.)
Only three manufacturers sold WOCDs 3 years ago, but in 2013, all 12 of the manufacturers with which we spoke say they make WOCDs available as an option.
Not all manufacturers include the installation of WOCDs in the price of their windows. Seven manufacturers charge, on average, $13.40 more per double-hung window for the factory-installed hardware. Five other manufacturers will ding you an average of $19 per window for the hardware, but they don’t install it. (Three years ago, only one manufacturer had factory installation; two provided the hardware only.) That installation will set you back another $8–$30 per window unless you do it yourself, according to contractors with whom we spoke.
Four manufacturers also provide factory-installed WOCDs for their awning and casement windows, typically for about $32 per window. Two other manufacturers charge just for hardware. Silver Line charges $6.60 per window, while Alside charges a whopping $75 per window. Having a contractor install these devices costs about the same as the installation price for WOCDs on double-hung windows.
WOCDs for double-hung windows are simple enough to override—you press in on two small retainer clips to open the window fully—but the same isn’t true to override the WOCDs that are on most awning and casement windows. Most WOCDs for awning and casement windows require you to remove the window’s screen before you can open the window more than 4 inches.
However, two manufacturers, Andersen and Marvin, make casement windows that don’t require you to remove the screens to open the windows fully. Marvin’s WOCDs are mounted to the window’s frame—outside of the screen—and Andersen’s are incorporated into the crank handle. These WOCDs will set you back $100 and $80, respectively, per window. Marvin’s WOCDs come factory-installed; Andersen’s don’t. Contractors say their design makes them slightly more expensive to install—$20–$40 per window.
WOCDs can be a huge expense, but if you have small children present, the devices might be priceless.
Drew Vass is a regular contributor to Consumers Digest. He has written on a wide variety of home-improvement topics that range from garage doors to home heating systems.