Tomorrows windows

Store Equipment & Design, Jan, 2000 by Brenda Delhanty, DON McCANN

The window is evolving from a passive film to a highly technological barrier that participates in HVAC while enhancing interior look and productivity

Tomorrow's windows will not sit back while we look through them, they will compel us to look at them.

From Thin films that offered little light and much exposure to the elements, windows have evolved into highly technological parts of a building skin. Bringing in light, reducing glare and protecting building occupants from excessive hear or cold, windows contribute to both the building's appearance and its occupants' ease and comfort.

Where windows used to be a luxury, to be used sparingly amongst the more practical barriers of wood, concrete, stone and metal, technology now allows them to be used instead of these old-fashioned materials.

Low-E glass, used in conjunction with insulating units, will allow visible light transmittance of up to 70 percent, while reducing solar heat gain by almost half and also reducing the harmful UV rays that enter through uncoated glass.

For stores, opening up the facade brings other advantages. Since opening a prototype store in 1993, Wal-Mart has found that store departments that are daylit experience higher sales than those lit with artificial light.

Buildings that incorporate some kind of natural lighting, either through windows or skylights, benefit occupants in higher productivity, fewer sick days and a more relaxed environment.

HVAC WINDOWS

In the foreseeable future, windows will be more than a passive player in a building's makeup. They will participate as part of the heating, air conditioning and ventilation system. Gathering the sun's energy, windows of tomorrow, equipped with photovoltaic cells, will generate energy for a building.

Other technology involving variable solar control glass will allow building occupants to "dial" up the amount of sun or shade coming through a window. These electrochromic windows could take the place of shades or curtains, change colors or be directed to display a design or sign when turned on. Holograms will be used to help gather the sun's energy and can also be used to project images.

THE VIEW INSIDE

Advances seen on interior glass will soon be making their way onto the building exterior. For example, open a glass door in a store's refrigerator and it stays clear, thanks to conductive coating within the glass. That same technology will be making its way into the commercial building environment, in uses such as control towers or skylights--places where windows need to be clear of snow, frost or condensation.

Anti-reflective glass, commonly used to clearly display museum pieces, is moving into the retail display case arena, and into the architectural world in storefronts and even stadiums.

No discussion of the future of glass would be complete without discussing the role it plays in security. From bullet-proof to hurricane-resistant, laminated glass protects in two ways: by offering a view of what's around us and by acting as a barrier.

In its Window Industry Technology Roadmap, the U.S. Department of Energy Efficiency and Renewable Energy envisioned a future for windows that "offer added value by providing energy, entertainment and information with enhanced comfort, lighting, security and aesthetics, in harmony with the natural environment."

In the future, windows won't be just portals onto the world but will be active participants in it.

Brenda Deihanty is marketing communications manager at Viracon, Owatonna, Minn., a fabricator of architectural glass products.

Don McCann is the company's architectural design group manager and an AlA-accredited seminar presenter.

Evolving skylights

Skylights bring natural lighting into buildings, but they are more than just giant windows in a roof.

Skylights are laminated and can be used as an insulating unit. Laminating the glass reduces UV exposure and strengthens the unit. Insulating glass, especially in combination with low-E, reflective or high-performance coatings, will dramatically reduce the amount of the sun's heat reaching the occupants.

Silkscreened patterns on skylights offer additional benefits. The screened patterns, whether standard or custom, allow for filtering or directing daylight and reducting glare. Custom patterns, along with standard and custom colors, allow the architect to make a unique statement.

Skylights are also likely to be the first target market for electrochromics, technology that will allow for variations in the amount of sunshine entering the building. Skylights will be used soon in passive daylight management, using fiber optics or lens technology to direct light to darker areas in the building and save on energy costs.

Also look for skylights to be part of a photovoltaic system, where special units gather energy from the sun's rays and convert it to electricity for the building.