London’s First Green Built Skyscraper

Buildings built with a green ethos in mind — that is, achieving significant gains in energy efficiency — often have a knack for standing out from other buildings around them. Perhaps none so much as the recently finished 30 St. Mary Axe, London’s first environmental skyscraper.

Located in the heart of the City of London, 30 St. Mary Axe is a radical building: socially, environmentally, technologically, spatially, and architecturally. The building, designed by the London-based architecture firm Foster and Partners, is the new London Headquarters for the Swiss Reinsurance Company, one of the world’s largest reinsurance companies. This is more than just a fancy building for the client Swiss Re, it’s the embodiment of a growing company sentiment that renewable energy and green building need to be increasingly incorporated into modern life. Swiss Re has been openly and vociferously concerned about the effects that global warming could have on the earth in the form of catastrophic natural disasters. As an insurance company for insurance companies worldwide, they have a stake in the issue. The building’s distinctive form is an instantly recognizable addition to the skyline and has already become a landmark in Europe’s leading financial center. The tower embodies a highly progressive environmental strategy, with its aerodynamic shape maximizing the amount of natural lighting and ventilation to significantly reduce the building’s energy consumption. Equally important is its improved working environment with better views for everyone. St. Mary Axe is an environmentally progressive building incorporating many green building features. A comprehensive range of sustainable measures mean that the building will use up to 50 percent less energy than a traditional prestige office building. Fresh air is drawn up through the spiraling light-wells to naturally ventilate the office interiors and minimize reliance on artificial cooling and heating. The light-wells and the shape of the building maximize natural daylight, moderate the use of artificial lighting and allow views out from deep within the building. The balconies on the edge of each light-well provide strong visual connections between floors and create a natural focus for communal office facilities. The interior atria are expressed on the exterior by the distinctive spiral bands of gray glazing. A number of complex fluid dynamic studies of the local environmental conditions suggested a strategy for integrating the building with its site and allowing it to use natural forces of ventilation. The 180 meter, forty-story tower breaks with the conventions of traditional box-like office buildings. Its circular plan is tapered at the base and the crown to improve connections to the surrounding streets and allow the maximum amount of sunlight to the plaza level. The circular plan enables much of the site area to be used as a landscaped public plaza, with mature trees and low stonewalls that subtly mark the site boundary and provide seating. Half of the tower’s ground level will be shops and a separate new building houses a restaurant serving an outdoor café spilling out onto the plaza. The exterior form of 30 St. Mary Axe explores a series of progressive curves with the aid of parametric computer-modeling techniques. The shape and geometry have affinities with forms that recur in nature. The pinecone for example, has a natural spiral and, like this building, opens and closes in response to changes in the weather. The building’s smooth shape also directs air movement around the building and minimizes the amount of wind at plaza level to improve pedestrian comfort. The external diagonal steel structure is by virtue of its triangulated geometry, inherently strong and light, permitting a flexible column-free interior space. The exterior cladding consists of approximately 5,500 flat triangular and diamond shaped glass panels, which vary at each level. The glazing to the office areas consists of a double-glazed outer layer and a single-glazed inner screen that sandwich a central ventilated cavity, which contains solar-control blinds. The cavities act as buffer zones to reduce the need for additional heating and cooling, and are ventilated by exhaust air that is drawn from the offices. The glazing to the light-wells that spiral up the tower consists of open-able double-glazed panels with a combined gray-tinted glass and high-performance coating that effectively reduces solar gain. For photographs and Quicktime video clips of the building, see the following link.
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