Baggage handlers and air traffic controllers know Madrid Barajas International Airport by the semantically loaded abbreviation MAD, but there's actually something soothing about the airport's new Terminal 4. Heaven knows there's little sanity to be had in air travel these days. Planes are so cramped they make steerage accommodations on a 19th century ocean liner look luxurious. Security has supplanted service as the byword of airport customer relations. And at most international terminals, the term “port of entry” doesn't suggest the act of arrival so much as a cavity search.

In this brutal context, Terminal 4 comes as a revelation of humane placemaking, realized through high-tech design. The hub for Iberia Airlines and its Oneworld Alliance partners, such as American Airlines, British Airlines, and Quantas, Terminal 4 was designed by the London-based Richard Rogers Partnership (now Rogers Stirk Harbour + Partners) with local architect Estudio Lamela and U.K. lighting consultants Speirs and Major Associates.

Terminal 4 opened in 2006; it was designed to double the airport's capacity, to an anticipated 50 million passengers per annum by 2050. Most airport authorities deal with growth through accretion, the result, as at many hospitals, being complexes of mind-boggling density and disorder. Rogers, however, is famous as a high-tech pioneer, and at Terminal 4 he enforced strict adherence to the modernist trope of form follows function. The complex is laid out as a sequence of parallel linear volumes, subdivided into a main building and a satellite that are separated by several hundred feet of tarmac and linked by an underground train. The volumes clearly correspond to the different moments in the passenger arrival and departure processes, and light and color act as organizing devices throughout.

There are six parallel volumes in total—three short and one long in the main building, and one short and one long in the satellite. Despite their differences in length, the volumes have the same basic structure: Rows of canted Y-form columns support a continuous roof canopy. The structural modularity isn't monotonous. The canopy, a dominant visual element through much of the interior, billows and ripples in gentle response to the subdivisions of structure, space, and program below; its form connotes flight without succumbing to clichés about airplane wings and tail fins.

In every bay, the canopy's bamboo-clad ceiling parts to make way for oculi that admit daylight through translucent ETFE plastic louvers. Beneath certain oculi, Speirs and Major suspended three metal halide projectors focused on two-directional mirror reflectors, supplementing the sun on overcast days. The canopy resolves itself on the exterior as a scalloped overhang, which provides shade during the intense Madrid summers with assistance from canted steel louvers along the glass façades.

Along the three-quarter-mile length of the two longer volumes, the Y-form columns that support the roof canopy are painted in a graduated spectrum of colors, shifting from blue at one end, through green, yellow, and orange, to red at the other end. The columns' chromatic scale plays like the song “Chopsticks” across the façades and along the interiors, reinforcing the significance of light to the project while imparting a subtle sense of place and rhythmic movement that would be absent from a monotone colonnade.

Rogers houses the main airport operations beneath the canopies in open, multi-story structures of exposed concrete. Wells between each structure transfer daylight to the lower levels and demarcate different zones in the arrival and departure sequence. Glass-walled elevators and catwalks with glass pavers make connections between the various zones and levels, without inhibiting the distribution of daylight.

The underside of each slab is lined with custom luminaires with a saucer-like form that the designers charmingly call “The Wok” and that neatly echoes the geometry of the oculi. The luminaires, aligned on a grid, take the place of a conventional suspended ceiling, and the gaps between the circular fixtures afford glimpses of the concrete slab and metal ductwork and conduit above—a classic Rogers high-tech peekaboo effect.

If Rogers has a shtick, it is the sometimes playful, sometimes fetishistic exposure of technology as a kit of parts. Certain design features at Terminal 4, the saucer lights and glass-walled elevators, for instance, have made appearances in earlier projects, such as his 1986 Lloyd's of London tower. But where Lloyd's is a celebration of technology for its own sake, with the same kind of shiny attractiveness that adolescent boys find in anime and Xbox, Terminal 4 is a far more gentle place, thanks in large part to the quality and temperament of its natural and electric lighting.

Roger's ambitions for architecture seem to have evolved over time. Not that he has lost the modernist faith in technology. Instead, he is putting technology to work for people. Le Corbusier's old adage, “la maison est une machine à habiter”—the house is a machine for living—still applies. What's changed at Terminal 4 is not the definition of building as machine, but the relationship between machine and life.