Optimizing wind and water: cooling tricks in Beirut
The Charles Hostler Student Center at the American University of Beirut.
Fabric Architecture | September 2012
By Frank Edgerton Martin
In arid climate cities, the way people use architecture and urban space changes with the time of day. Fabrics for shading, screening and evaporative cooling can be part of sustainable strategies to make these microclimates more comfortable. Throughout the Middle East, such commonsense tools have long been part of garden and architectural vernaculars.
Designed by VJAA, the Charles Hostler Student Center at the American University of Beirut is a masterful blend of historic Mediterranean urbanism and modern technologies. In its winning AIA design award submission, VJAA, Minneapolis, Minn., wrote that in Beirut, social activities “migrate” vertically and “condense” at various locations throughout the day. During the hot sunny hours, shop owners and families tend to use lower shaded spaces. At night they migrate to the rooftops.
Inspired by the city and the classic Beirut house that steps down hillside sites to catch sea breezes, VJAA designed the Hostler Student Center as a 3-D system of courtyards, passageways and roof gardens. Shading, breezes and the radiant cooling effects of water are all optimized in this 19,000m2 project.
An earlier campus master plan by Sasaki Associates Inc. had called for a large student building facility fronting a similarly large open space. But the VJAA team sensed that more fine-grained urbanism and local materials might offer lessons for energy conservation and comfort, both indoors and out.
At both the American University of Beirut (AUB) and Tulane University’s new Lavin-Bernick Center for University Life VJAA used metal mesh scrims to create cascading water walls offering both evaporative and radiant cooling benefits. Yet while Tulane’s water walls are set inside a large public gathering space, Beirut’s falling water is outside. Both projects merit comparison for the similarity of their student center building programs and their contrasting climactic conditions.
Whereas summers in New Orleans, La., are hot and humid, Beirut’s semi-arid summers are typically hot and dry. There are cooler temperatures with some rain in December and January, but, for the most part, outdoor campus spaces are quite habitable for most of the year if their form and orientation can make the most of breezes and allow for user “migration” with the sun.
Founded in 1866 to offer an American style liberal arts education, AUB is located on a dense 30-hectare (73 acres) urban campus sited above the ocean that cascades down to the Corniche, Beirut’s grand oceanfront boulevard. In response to this unique microclimate and Beirut’s urban traditions, VJAA broke up the center’s program of athletic facilities, café and auditorium, creating a cluster of five buildings along courts and passages that could optimize changing breezes and shade.
Working with climate engineer Matthias Schuler of Transsolar, VJAA organized the buildings around a series of radial “streets” oriented toward the Corniche to catch the seabreezes. The campus’s steep topography promised many creative opportunities for responsive design. During the day, air cooled by the shaded portion of the tree-covered campus drops down toward the sea along the radial streets creating a flushing effect with cool air. At night, winds from the Mediterranean flow upward though the campus. Cisterns are located to capture winter rainwater for later summer use; gray water from building systems is recycled for irrigation.
Making use of the campus location, VJAA draws seawater from the nearby ocean (piped from 30m below the surface) into a central plant that provides chilled water for radiant cooling at the pool, gymnasium, squash courts and café. After desalinization, seawater offers radiant and evaporative cooling for the two cascading water walls similar to those used inside Tulane’s student center.
VJAA designed two large 6m wide by 7.7m high waterwalls to employ metal mesh panels for cooling the outdoor terrace level. Like fountains in Persian gardens and courtyards, Beirut’s two outdoor waterwalls (made of stainless steel mesh scrims) guide smooth broad “sheets” of falling water. Their cool mist radiates outward into seating areas and, when the dew point is high, the walls’ lower temperature can reduce surrounding humidity by condensing water out of the air like an ice-filled glass on a summer day.
In its proposal for the AUB’s new student center, VJAA argued that the best architecture grows out of understanding local climate and its effects on human activity. “The project is as much about human behavior, collegiate life and even politics, as it is about questions of architectural form.”
VJAA’s student center projects in New Orleans and Beirut teach us that fabric solutions in shading and water walls are only one part of a larger integrated strategy of understanding site, seasons and daily weather. VJAA’s deep understanding of arid climates and architecture is almost certainly the reason it was awarded this student center project in an international competition. When time-tested local solutions are combined with new products and technologies for ventilation, cooling, heating and water capture, great gathering places can be built that draw people at different times of day simply because they are so inviting.