DESIGN: Australia’s greenest skyscraper has a highly energy-efficient glass skin

The curving glass walls of the soaring interior atrium of 1Bligh, Australia's most energy-efficient building designed by the architecture firms of Ingenhoven + Architectus. photo: h.g. esch, hennef

The sweeping 28-story glass atrium and floor-to-ceiling windows of the recently opened  1 Bligh Street, a circular high-rise office building situated in the heart of Sydney, Australia’s financial district, embody the striking aesthetic potential of glass architecture. Yet 1 Bligh is as much about function as form. The building is outfitted with a double-skin glass and acrylic façade, which makes maximum use of natural light and even allows the building to regulate its own temperature.
Double-skin glass façades are nothing new; they appear on the “Gherkin” building in London and on real estate firm GSW’s headquarters in Berlin, to name a few. However, 1 Bligh is the first of its kind in the southern hemisphere. On its most basic level, a double-skin is pretty much what it sounds like: two layers of glass surrounding one building—a ‘building within a building.’ At 1 Bligh, an inner skin composed of a series of double-glazed windows is enclosed in an outer skin of single-sheet laminated glass, according to Australia’s Facility Management magazine.

The double skin of 1 Bligh is evident from this view of the exterior of this office building in the heart of Sydney's business quarter. architecture: ingenhoven + architectus. photos: h.g. esch, hennef

The inner skin provides thermal insulation, and the outer skin has ventilation slots that help push out hot air. The two skins are 600 millimeters (almost 2 feet) apart, leaving room in between for computer-controlled Venetian blinds that protect the inner wall from the sun, while still reflecting natural light into the building.

This complex system of insulation and ventilation has dramatically lowered 1 Bligh’s energy consumption; according to the building’s website, the use of a double-skin glass facade “facilitates a 42-percent CO2 reduction when compared with similar sized conventional office towers.” This, among other green features, helped 1 Bligh earn Australia’s highest Green Star energy rating in 2011.

An aerial view of 1 Bligh puts its cutting-edge design in context. architecture: ingenhoven + architectus. photos: h.g. esch, hennef

Of course, you don’t need to understand the hidden workings of 1 Bligh’s double-skin windows to appreciate the elegance of its design. Natural light floods into the soaring open atrium, and fresh air flows through the building with the aid of a natural ventilation system. Architects Christoph Ingenhoven and Ray Brown of Architectus, who collaborated on the design, positioned the building so that every visitor, no matter where she stands, has an unobstructed view of Sydney Harbour. Futuristic glass elevators encircle the open lobby, creating a mood of easy accessibility. If you ride an elevator to the top, you’ll emerge onto a glass-walled roof terrace, complete with an energy-saving rooftop garden.

The glass skins of 1 Bligh come to life when lit from within at night. architecture: ingenhoven + architectus. photos: h.g. esch, hennef

1 Bligh is not Ingenhoven’s first venture into environmentally friendly glass buildings. He also designed Japan’s first highrise to feature double-skin glass façades, and he has employed the technique in several other large-scale projects. Currently, Ingenhoven is working on his first initiative in the United States: the new Google headquarters in Mountain View, California. Construction for that project is rumored to begin later this year.

Click here for an interactive panoramic view of 1 Bligh’s glass atrium.

—Lindsay Lowe