Top 10 Innovations in Window Technology
These days we take windows for granted, but the past 60 years of evolving window technology are punctuated by developments that, at the time they were introduced, completely disrupted the design, composition, thermal properties, and manufacturing process of windows for both new construction and remodeling. Here are ten innovations that revolutionized windows and, with them, the design of today’s structures and the lives of the people who live, work, and play in them.
1950s: Float Glass
Alastair Pilkington, technical director of British glass manufacturer Pilkington Brothers, claimed to get the idea for Float Glass while watching a dinner plate floating in the sink. His brain child was a method of floating molten glass over a bath of molten tin, an approach that by the late 1950s was producing flatter and more uniform glass than had ever been possible. This breakthrough was an important step down the path to today’s energy-efficient windows, as the higher-quality glass made possible the application of window films. Float glass is now used in all windows.
1950s: Insulating Glass
Although insulated glass was patented as far back as 1865 actual products only appeared in the 1950s under the name Thermopane. The first versions consisted of two panes welded together at the edges with a 1/4 inch dry air space between them – like the double glass liner of a Thermos bottle. By 2007 about 90 percent of all windows had insulating glazing.
1960s: Vinyl Windows
Although German window manufacturer Trocal introduced the first commercially viable vinyl windows in the 1950s, the technology first appeared in the U.S. in 1964, when Thermal Industries began offering vinyl unit to the replacement window market. Vinyl windows didn’t become a player in the new construction market until the late 1980s, but growth since then has been rapid. By 2009 they accounted for about 60 percent of all window sales.
Late 1960s: Clad Windows
The late 1960s saw an entirely new window category called clad windows. Andersen introduced its Perma-Shield vinyl clad window in 1966; Pella followed four years later with an aluminum clad product. Marvin was the first to offer a standard aluminum clad finish on its entire product line. Clad windows combine the look of a traditional wood on the inside with a weather-proof exterior that never needs painting. By 2003 about 93 percent of the 25 million wood window units sold in the U.S. market were being made with either aluminum or vinyl cladding.
1970s: Tilt-In Replacements
The first all-vinyl, double-hung tilt replacement window for the U.S. market was introduced by Pittsburgh, Penn.-based Polytex in the mid-’70s. Newer products such as Marvin’s Tilt Pac Double Hung Sash Replacement System, are cost effective options for upgrading an older double-hung.
1980s: Round Top Windows
Round Top windows had traditionally been hand-crafted by small millwork shops. Around 1980, market demand created the incentive for Marvin to develop manufacturing for round top windows. A Marvin engineer in R&D with experience in boat building applied his knowledge of curved, wooden frames to develop effective manufacturing processes for the Round Top window.
1980s: Low-E Glass and Gas-Filled IGUs
A low-E coating is a thin layer of transparent metal that slows heat transfer through the glass. In winter, it reflects some heat back into the room, while in the summer it reflects heat from the sun back out. The first commercially available low-E product was Southwall Technologies’ Heat Mirror film, released in 1981.
While low-E coatings lower radiant heat loss through the window, filling the air space in an insulated glass unit with a low-conductive gas reduces convective losses. The most common and cost-effective gas fill is argon, which is 34 percent less conductive than air. Some super-high-efficient windows use more expensive and less conductive krypton gas.
1990s: Impact Glass
Also called Hurricane windows, they’re subject to strict testing requirements, including the ability to withstand a hit from a 9-pound 2×4 shot out of a cannon at 34 mph, as well as 9,000 cycles of positive and negative pressurization. Building codes require these in hurricane-prone costal zones, as well as inland areas subject to tornados.
Mid-1990s: Ultrex Frames
The mid-1990s saw the introduction of window frames made from composite materials like Marvin’s Ultrex, a fiberglass material. It’s stronger than vinyl, wood or aluminum, expands and contracts less with changes in temperature, and has a vastly superior ability to block heat transfer.
2000s: Dynamic Glass
Two versions are currently available. Electrochromic windows control solar gain via a transparent conductor placed between the glass panes that gradually darken or lighten using an electric current. The glass blocks heat gain, but remains transparent. the window can be manually tinted or controlled by an automation system.