An LED display has a life of its own.

» At first glance, Barcelona's new Hotel Habitat, which is currently under construction and expected to be completed by 2007, resembles the slew of design hotels that have sprouted in recent years in many major urban centers around the world. Its principal architects are a young, adventurous Barcelona-based collective called Cloud-9, which has invited other architects with similar attitudes toward integrating architecture with art, performance, and technology to trick out the 135-room hotel.

Enric Ruiz Geli, one of Cloud-9's principal architects, distinguishes Hotel Habitat from the rank and file of boutique hotels, referring to it as 'cultural.' Although the project uses design to attract guests, it takes the idea one step further by inviting artists to regularly create works within its public spaces, transforming a component of the building into an art gallery. When it opens, the hotel will become an ever-shifting panoply where visitors can come not only to bask in the high-end design, but also to get a taste of what is happening in contemporary art.

Its nod to the art world is only one facet of this innovative project. More remarkable is the stainless-steel strand mesh that drapes over the 11-story building, an orthogonal tower of stacked rectangles that cantilevers off its glass base and steps back to form a series of terraces toward the top. This mesh, supported by a system of poles, houses 5,000 LED-loaded polycarbonate discs. By day, the building looks like an unhappy robot ensnared in a net of its own creation, but at night, when the discs light up, the hotel becomes something else altogether.

When speaking about this project, Ruiz Geli prefers the metaphor of a tree, in which the discs are like leaves. He expounds upon this comparison: 'As Gaudi learned from the forms of nature, and as modernism learned from the image of nature, we learn from the behavior of nature. Nature is performative, and we like our architecture to perform.' Of course, the irony is that in order to create an architecture that resembles nature, Cloud-9 has looked to and used technology. Not an outlying phenomenon, but a trend: the more technology evolves, the closer we come to matching the efficiency with which many of the natural world's systems perform.

In fact, Hotel Habitat's 'leaves' are performative, and in more ways than one. The discs, which cover the sun-exposed face of the building, act like their natural counterparts by producing enough shade to reduce energy consumption (in this case, associated with air-conditioning) by 15 percent. This canopy also creates a microclimate between itself and the building-a mild zone, somewhere in temperature between the sun-baked streets and the cooled interior. One has to imagine it will make the terraces and planted areas all the more enjoyable in summer.

Even more phenomenal is that each disc is completely autonomous. At night, when the LEDs 'come alive,' there is no universal switch that feeds them an electrical current, or system of wires in the steel mesh running to each unit. Rather, every disc is equipped with its own photovoltaic cell, battery, RGB LED, and central computer. The computers track the date and turn the lights on automatically at the pre-programmed time of nightfall. Furthermore, they measure the amount of electricity stored by the disc's battery during the day and, based on that information, activate a corresponding color of light. For example, at 10 percent energy, the LED will glow a less-energy-consumptive red; at 100 percent, it shines white; and in between is the delicate gradient of the spectrum. The result is a varied pattern of colored light, generating a nighttime aura around the somewhat humdrum structure.

This innovative system is fully self-functioning, without need for a human operator. Cloud-9 worked with Italian lighting consultants iGuzzini Illuminazione to complete the devices; however, the idea patent is owned by the architects. When the illuminated leaves reach the end of their life cycle, in about 10 years, it will not be a result of the LEDs, but the batteries. At that time, the entire leaf with all its components will be replaced, and with the constant progression of technology, there will surely be a next generation with a longer life span.

The leaves were also designed to be considerate of their surroundings. Situated at the edge of town, on the Gran Via, the major thoroughfare that connects central Barcelona with the airport, Hotel Habitat is located in a highly populated area. The light produced by the LEDs is relatively self-contained. Each polycarbonate disc is opaque green on the building side and transparent on the opposite side, so that no light shines into the rooms or illuminates anything around the hotel. As Ruiz Geli says, 'The leaves don't light the street or the rooms, but themselves-like a firefly.'

Visitors to the recent 'On Site: New Architecture in Spain' exhibition at the Museum of Modern Art in New York may have seen an impressive model of the hotel, complete with 5,000 tiny LEDs illuminating in time to a clock that speeds its way through a year. In the model, the light pattern is based on one datum per month-an average of the amount of daylight the architects expect the building to be exposed to. In the actual building, however, this patterning should change every day as the electronic 'leaves' receive varying amounts of sunlight, depending on the weather, position and intensity of the sun, and any accidental phenomenon.

Ruiz Geli refers to this flow of light as a 'map of energy,' but its resonance goes deeper. The skin of leaves that wraps the building becomes a mechanical mirror of nature, and its lesson is one of randomness: day to day, the pattern of light evolves in a continuous performance of individually acting particles. Though guests may have to step back from the building to recognize its ever-changing façade, Cloud-9's enshrouding mesh of artificial leaves trumps any artistic statement that may be on display within the hotel: here you have a painting that changes every night, a representation of the prevailing light conditions at this location on earth, and an architecture that combines function, information, and expression in one tidy bundle. It is the best result one can expect from an adventurous experimentation with technology. aaron seward

project Hotel Habitat, Barcelona
client Habitat Grupo Inmobiliario, Barcelona
architect/interior designer Enric Ruiz Geli, Cloud-9, Barcelona
lighting designer James Clar and Max Zinecker, Cloud-9
lighting consultant iGuzzini Illuminazione, Recanati, Italy
collaborating architects Acconci Studio, Brooklyn, New York; Ruy Ohtake, Sao Paulo, Brazil
images/renderings IK Studio, Girona, Spain