Norman Foster, a famous architect in the world.
T he one of landmarks in London is located at 30 St Mary Axe, nicknamed the Gherkin by local because of its special shape. From the photo left , this building looks like a cigar or an egg. As the Design Book said, its steel structure is made of diamond shape and covered uniformly around the outside with glass panels. In the same time, it is rounded off at the corners. It has a lens- like dome at the top that serves as a type of observation deck. The Gherkin is also the first tall building in London. It is designed by "A green building incorporates design, construction and operational practices that significantly reduce or eliminate its negative impact on the environment and its occupants. Building green is an opportunity to use resources efficiently while creating healthier environments for people to live and work in. Green building can also significantly reduce construction and performance costs."- Green building council Australia
How does the Gherkin work
As a green building, how does the Gherkin work? Mr Foster wanted to achieve energy saving though a unique steel structure. The Foster + Partners Specialist Modelling Group (SMG) looked at aerodynamic forms that would induce natural ventilation across the office floors. This design will decrease the usage of air-conditioning in this building. As Matthew Kitson, who heads Hilson Moran’s environmental modelling division said, mores air flows round the side of cylinder than around a rectangle. Because of it, it picks up speed and creates higher negative air pressures at the sides and back. Furthermore, the pressure differential between the front and back of the Gherkin leads to air through the building more effectively.
The Gherkin is nearly a prefect building. Its special shape also solves the problem- whirlwinds at the base. From parametric modelling which base on the mathematics of turbulence, simulate a building's aerodynamic properties, it is easy to find that a cylindrical shape responds better to air currents than a square one and reduces whirlwinds. The fact that the tower bulges out in the middle, reaching its maximal diameter at the 16th floor, also helps to minimise winds at its slimmer base.(Freiberger M, 2007) In aesthetics, it is round rather than square, it bulges in the middle and tapers to a thin end towards the top, and it's based on a spiralling design.
A model of air currents flowing around the Gherkin. Image © Foster + Partners. |
Although the Gherkin can supply an outstanding energy saving plan for all tenants, most of tenants do not choose it. “We try to sell the whole energy package to every new tenant through their M&E consultant,” says Steve Brown, the building services manager. Unfortunately his exhortations have so far fallen on deaf ears, as all tenants except for Swiss Re have opted for full, all-year-round air-conditioning. How to operate a sustainability building maybe will become a more important question for the investors.
Meanwhile, due to the inefficiency insulation of glass wall, the glass wall whether it will be a good choice for future design also needs to be seen.
Resources:
Swiss Re—The Gherkin—30 St. Mary Axe, accessed 7 April 2015, <http://www.webpages.uidaho.edu/arch504ukgreenarch/casestudies/swissre1.pdf>.
Freiberger,M 2007, Perfect buildings: the maths of modern architecture, +plus magazine, accessed 7 April 2015, <https://plus.maths.org/content/perfect-buildings-maths-modern-architecture> .
Gherkin, interior,accessed 7 April 2015,<http://www.building.co.uk/gherkin-interior/3034986.article>.
30 St Mary Axe: A gherkin to suit all tastes, accessed 7 April 2015,<http://www.building.co.uk/30-st-mary-axe-a-gherkin-to-suit-all-tastes/3111783.article>.