Council on Tall Buildings and Urban Habitat
 

 30 St Mary Axe Technical Tour
Conference Technical Tour
June 13, 2013
Robert Lau
30 St. Mary Axe is one of the most recognizable buildings on the London skyline Photo by: Toby Philips
LONDON - Since its completion in 2004, 30 St. Mary Axe has become a firm favorite, referred to by Londoners as “The Gherkin.” Incorporating multiple green features, including operable windows and multi-story atriums, it set a new standard for high-rise design in London and beyond.

The significance of the Gherkin is that it was the first in a high-rise district within London. Many others have now followed in its path. At 40 stories, it is not a significantly tall building globally, but is very much so in London. The old Baltic Exchange covered the entire site (street to street) before it was demolished in an IRA bombing in 1992. An initial desire was to open the grade to a pedestrian plaza instead of building over the entire site. As a result, the ground floor has an inviting pedestrian experience.

The twisting, cylindrical form is a result of the desire to provide natural ventilation, which produces a positive stack effect from any wind angle. The insertion of slots into the floor plates comes from a desire to introduce natural lighting into the deeper office areas. The final result is a series of five-degree twisting atria of six floors each. The entire building is sprinklered, and each atrium contains smoke curtains at the top floors to control any smoke produced.

Delegates gathered in the lobby © Dario Trabucco
The structure of the tower is in the diagrid perimeter. This has been designed for gravity loads, but the innovative structure, acting almost like a shell, is also stable in wind. The perimeter was custom-fabricated but the interior skeleton of the structure is comprised of standard steel components. This created a 30% custom-to-70% standard steel fabrication ratio, for economy.
One of the six floor atria of 30 St. Mary Axe
The double skin provides natural ventilation for many times of the year, adding to energy savings. Shades between each layer of the façade control the sun's glare. The atria act as buffers to limit extremes in temperature and to provide sufficient ventilation flow.

The Class A offices continue to provide exceptional space. The raised floor and suspended ceiling offices are physically separated, but viewable from the atria. Even though newer office projects have developed around the Gherkin, it continues to be a premium address.
Delegates gather for a group photo during the tour
The most spectacular spaces in the building are the 39th floor restaurant and 40th floor bar. The restaurant has 180-degree views of London. The bar has a breathtaking 360-degree complete view of all of London and beyond. No columns or mechanical equipment obstruct the view. The glazing has been carefully engineered to provide views out without letting admitting harmful UV rays. This feature makes the building particularly well-suited to its environs, despite its initial controversy over shape. One delegate stated, “London without clouds is Paris!” Day or night, this is the best spot in London to view the city.
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