Complex Made Simple

Forests in the Sky: Milan high-rises go truly green

The International Highrise Award enjoys great prestige because, unlike other similar competitions, it is granted neither for a building’s height nor form. Instead, the prize — bestowed by the German Architecture Museum, the city of Frankfurt and DekaBank — honours criteria such as sustainability and innovation. And this year’s winner, Milan’s Bosco Verticale (Vertical Woods), has that in spades.

The 2014 jury, led by architect Christoph Ingenhoven, cited Italian architect Stefano Boeri’s work for its environmental ambitions in difficult circumstances. Piazza Gae Aulenti, in an area of new construction around Porta Garibaldi, is Milan’s ugliest square. The huge urban space on the northern edge of the historic city centre is virtually empty of people at night. With its skyscrapers and buildings of international companies that are present in every large city in the world, it looks like something between Berlin’s Potsdamer Platz and the Dubai Mall.

Only a closer look reveals something unusual behind Italy’s tallest building, the Torre Unicredit by César Pelli: two black towers of differing heights with 100 white balconies that look like pulled-out drawers.

The towers, which were completed a little over a month ago, are somewhat reminiscent of the women’s opened drawers in Salvador Dalí’s The Burning Giraffe. But just how right it is that the buildings have been baptised the Bosco Verticale is only perceptible from up close.

Unlike the imagery in the project’s prospectus, the vegetation on the balconies is still far from jungle-like. But vegetation there is, and it is so impressive that hordes of tourists come here to take pictures of the towers.

“The Bosco Verticale is a worldwide unique architectural experiment, a model for future inner cities,” says its architect, 57-year-old Stefano Boeri. He hails from an influential local family, was an urban planner for many years, and ran for mayor of Milan two years ago.

The Bosco Verticale could be described as an attempt to bring the forestland Milan so urgently needs back to the built-up city. The 20,000 shrubs and 800 trees on the balconies, covering a total surface of 8,900 square metres, incidentally serve aesthetic purposes, but they are primarily meant to ensure a better micro-climate in the apartments, filtering dust particles from the air and producing oxygen.

But the residents, whose apartments cost between EUR one and 10 million each, won’t be out there with clippers, shovels and watering cans. The plants are watered automatically with the help of an electronically controlled system that pumps non-potable water from the ground water via hoses into the balcony planters.

A permanently installed crane on the roof makes controlling the growth of the trees possible. Three gardeners have been hired to maintain the vertical woods that cover the equivalent of one hectare (2.5 acres). They are charged with pruning, fertilising, and generally caring for the plants year-round.

For reasons of aesthetics and safety, residents are not allowed to make individual additions to the plantings, so rose breeders will have to find somewhere else to pursue their hobby. “But most of the residents will be thankful that plant maintenance is taken off their hands,” Gatti says.

Of course, that luxury has it price. Residents have to pay some EUR seven per square metre of living space annually for the care of their woods.

Standing in the huge, minimally furnished entrance area of the larger tower, Boeri, the architect, thinks it’s a pity that so few can afford to live in Bosco Verticale.

But the buildings are also a prototype, he says, and to develop prototypes more money is always required in the beginning. The costs would pay for themselves if the model is replicated. Thanks to the international prize, the chances of that happening are quite good.

© The New York Times 2014