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Among these functions are some that a building envelope is normally expected to deliver: protection from the elements, light transmission, power distribution, and exterior appearance. But unlike conventional walls, SmartWrap envelopes can also display information, and miniature systems embedded in the relatively thin walls can produce light and absorb solar energy for electricity production.

Inside the Plastic

The film substrate is polyethylene teraphathalate (PET), which is commonly used in beverage containers. PET is transparent, strong, inexpensive, quick drying, recyclable, and water and mildew resistant. Inkjet printing and roll-coating onto PET can be done under normal room conditions, eliminating the cost and complication of manufacturing in clean-rooms or at high temperatures.

Despite its thinness, the film provides thermal properties normally associated with more massive building components. Embedded in SmartWrap are microcapsules of phase change materials (PCMs). The microcapsules embody latent heat, which is absorbed and released as they change phase — going from solid to liquid or liquid to solid. Just as massive adobe moderates extremes in temperature, PCMs can regulate latent heat in structures that are completely enclosed.

To provide lighting and information display, SmartWrap uses organic light-emitting diode (OLED) technology, which is thin, flexible, and self-emissive. This technology is based on organic molecules that emit light when an electric current is applied. The small molecules can be deposited onto plastic substrates.

To power the embedded OLED system, SmartWrap also incorporates organic photovoltaics (OPVs). When illuminated with broadband light, the polymer absorbs energy and transfers electrons to the coating. When attached to electrodes and in contact with a light supply, this system provides a steady stream of electrons providing electricity.

Producing the Smart Skin

The printable SmartWrap skin is made up of the PET substrate, an applied or embedded layer, and various printed layers. The printed layers give the material its distinctive appearance and functionality. OLEDs are attached to the surface of one layer. An organic thin-film transistor works in conjunction with the OLED performing as its circuitry. PCMs are added to the surface of the polyester during the printing process.

The deposition printing method is like inkjet printing. Materials of various colors or properties are suspended in a solution that is then sprayed or deposited upon the substrate and "dries" much like an ink on paper.

Roll-coating is one of the methods used to create the final SmartWrap sheets. This is a process of laminating materials from two different rolls. Large amounts of materials can be laminated together in a short amount of time.

Today's Prototype

Due to current limitations of cost and available printing technologies, two levels of prototype SmartWrap are displayed on the pavilion. Most of the film is a nonfunctioning simulation. The OLEDs, OPVs, and PCMs, are simply represented graphically in colors obtained by more conventional large-format inkjet printing.

The working prototype of SmartWrap that went on display in the pavilion is a wall of film made up of the PET, PCMs, glass LEDs, thin-film photovoltaics, and simulated batteries, wired by silk-screened silver conducting ink. This is combined with a second layer of PET with aerogel pockets separated by an entrapped air barrier.

The effective thermal resistance (insulating value) of the working prototype is about the same as a conventional concrete block and brick bearing wall with a 2-inch (50-millimeter) airspace and 2 inches (50-millimeters) of expanded polystyrene insulation. However, the SmartWrap weighs approximately 1/100 as much as the masonry wall.

In reference to the Cooper-Hewitt exhibit, exhibitions curator Matilda McQuaid wrote: "Ideally the only limitation to the type of technology that can be incorporated in the SmartWrap is that it must be capable of being miniaturized and suspended in printing ink. Does this mean that we will soon see the day when the basic technology used to activate a building becomes virtually invisible?"

If Kieran and Timberlake have their way, building materials like SmartWrap will eventually put architects in closer contact with construction processes and give customizable, intelligent construction practices an unprecedented economy of scale.

The SmartWrap pavilion remained on exhibit at New York's Cooper-Hewitt National Design Museum from August 5 through October 10, 2003. It has since been displayed at other venues.

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Construction: Skanska USA and Corinthian Construction Co., New York.

Inside the SmartWrap-covered pavilion, designed by KieranTimberlake Associates, at an exhibition at the Cooper-Hewitt National Design Museum. Photo: Barry Halkin An aluminum frame structure supports the "intelligent" plastic sheeting. Photo: Elliott Kaufman Floor plan, temporary SmartWrap pavilion. Image: KieranTimberlake Associates Elevations, temporary SmartWrap pavilion. Image: KieranTimberlake Associates An aluminum frame structure supports the "intelligent" plastic sheeting. Photo: Barry Halkin In real applications, the plastic walls will be printed with photovoltaic cells, electrical circuitry, and various information services. Photo: Elliott Kaufman Printed opacity and transparency lets the SmartWrap also behave like traditional walls and windows. Photo: Elliott Kaufman   Click on thumbnail images to view full-size pictures.