Text description provided by the architects. General description
The Hostler Center design responded to its unique social and environmental context. Situated on Beirut’s seafront and main public thoroughfare, the new 204,000 square foot facility includes competitive and recreational athletic facilities for swimming, basketball, handball, volleyball, squash, exercise and weight training. The program also includes an auditorium with associated meeting rooms, cafeteria with study space, and underground parking for 200 cars. Responding to the scale of buildings and outdoor spaces of the existing campus, the University’s original plan for a single large scale building and similarly scaled open plaza was challenged. Instead, multiple building volumes were proposed that interconnected a continuous field of habitable space with gardens on multiple levels. These building volumes are further organized around a series of radial “streets” oriented toward the sea and woven together by a series of courtyards, circulation paths, and spectator areas; negotiating the elevation change from the upper campus to the sea front. To preserve the significant existing landscape, buildings were sited to maintain existing trees on the site. The design for the new Hostler Center synthesizes architecture and landscape to create a set of richly varied and environmentally diverse spaces for people to gather in throughout the day and evening.
Key environmental aspects
In traditional Mediterranean cities, the use of urban and architectural space is closely calibrated with the natural environment. Daily migration allows social activities to "condense" at various locations as spaces are exploited for their microclimates – sun or shade, thermal mass with radiant surfaces, and natural ventilation. Many of the sustainable design strategies used in the project couple these traditional techniques with contemporary technologies. While intended to increase social interaction, all of the strategies focus on reducing the requirements for energy and water consumption. The program is organized as a cluster of interior and exterior spaces instead of into a single building, thereby allowing the building form itself to redistribute air, activity and shade. The east-west orientation of the building forms help to shade exterior courtyards while reducing the amount of southern exposure. The orientation also directs nighttime breezes and daytime sea breezes. Green spaces on the rooftops allow for a more pleasing physical and visual integration with the upper campus as well as providing usable rooftop areas for activities and reducing the amount of exposure to the sun. Usable program area on the site is increased with shading and ventilation at outdoor spaces.
The movement of air and people in the project are analogous. Like the circulation paths, wind naturally flows between the upper campus and the Corniche below. The steep hillside topography of the AUB campus, being north facing and densely planted, offers an unusual microclimate, where air cooled by these shaded portions of the campus drops towards the sea during the day, creating a constant cooling and flushing of the air. At night, the site’s prevailing winds are redirected toward the land by its proximity to the Mediterranean Sea. The building volumes and circulation are woven together by a series of intimate social spaces emphasizing lush and aromatic foliage, cool shade, and the sound of moving water. The Hostler Center uses rooftop gardens (green roofs) for primary social gathering at night. The theater, café, and gymnasium/squash court connect directly to primary rooftop gardens and an amphitheater for evening concerts. In addition to conserving as many existing native trees as possible, new native plantings were added throughout the complex. Some non-native plant species were removed and replaced with sea and drought tolerant species.
Process and Results
Given the desire to build efficient spaces that minimized energy usage, the process focused on the most efficient organization of program or finding opportunities for mixed-use spaces. Expansion spaces and breakout spaces were defined in courtyard areas and rooftops as well as spaces serving as circulation. These spaces provide the flexibility to accommodate a wide range of events and visitors, and take advantage of indigenous patterns of use. Traditional Mediterranean cities use of urban and architectural space is precisely calibrated to the natural environment, and there is a daily migration within zones and levels as spaces are exploited for their microclimates—created by sun or shade, radiant surfaces and thermal mass, and ventilation. This example of sectional migration which responds to changing temperatures contradicts modern ideas of universally cooled interior spaces and suggests regionally specific strategies for circulation and overflow spaces. Spatial diversity is the key to this environmental strategy, and people occupy and adapt to spaces in an ongoing cycle of interaction with daily and seasonal change. Programmatic spaces are designed for specific athletic programs and for a range of flexible uses. All are designed for longevity and durability.
The University advocated environmental issues as fundamental to the design of the Hostler Center. They also suggested that the project act as a demonstration project for environmental building strategies in the region. Sustainable attributes of the project were identified early in the process as a necessity given the destruction of infrastructure during the civil war and the lack of new reliable municipal infrastructure. For example, the electrical grid in Lebanon is not capable of meeting peak demands in the hot summer months, and rolling blackouts occur daily as a result. It was important to plan for different scenarios of future energy, water and sewer capacity and for the Hostler Center to support the University’s ability to be self-sufficient.
The design focus shifted from providing cooling for the building in schematic design and expanded to providing cooling for the lower campus as opportunities were identified. Originally the project included solar desalination and seawater cooling. This system was redesigned, desalination was value-engineered out and seawater cooling from below the site was used with a low energy absorption chiller. The new absorption chiller is fueled by a heat source (either steam from waste heat or steam produced by boilers), requiring only a small amount of electricity to run pumps. For AUB, this means a dependable chiller solution that relies on an alternate fuel source other than electricity during peak demand times for electrical usage. Instead of adding huge chiller equipment to the electrical grid, it is possible to either recover some of the heat from on-campus power generation, or produce steam with boilers. This alternative provides chilled water and cooling for the lower campus.