Green roofs are wonderful things; like a thick blanket, they keep roofs cool in summer and warm in winter. They have been around for centuries in Scandinavia and Iceland, where they moderate the cold winters and sometimes very hot summers. They reduce the “heat island” effect, where the air above and around the old black roofs gets hotter, making them hot properties in cities. Some, like Toronto have made them mandatory; other cities like Chicago give financial assistanceto promote them. The provide habitat for birds and insects, even goats.

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Until recently, green roofs used to just lie there and do their thing; most roofs aren’t designed to be accessible to the public. This famous roof on top of Mountain Equipment Co-op in Toronto can be only be reached by ladder and attic hatch.

Then developers and architects realized that they could be amenities, enjoyed by building residents, and started extending the elevators and stairs so that roofs had proper, legal access. The developer of 250 Hudson Streetin New York just spent three million bucks on his green roof, but says in theNew York Times:

“The green roof is a magnificent amenity for 250 Hudson Street,” says Jonathan D. Resnick, president of Jack Resnick & Sons Inc. “Our tenants are enjoying the beautiful roof garden, and benefit from its sustainable qualities.

ESRI Canada just opened a very interesting green roof designed by Scott Torrance; they are tenants and when their lease is up have to take the green roof with them. But they say it was worth the trouble; it creates “a visually-stimulating and enhanced workplace environment that is expected to help improve productivity.”

Architects then went one step further, and started designing their buildings with green roofs in mind, turning them into an architectural feature, sometimes the main feature of the building, as in the California Academy of Sciences.

Julien De Smedt architects brought green roofs down to the ground to provide beach access to residents of Rimini, Italy, another example of how green roofs are changing architecture.

“The powerful and recognisable pattern evokes sand ripples and sea waves and has the incredible ability to allow both longitudinal and transversal connections : to facilitate the meanderings of passers-by strolling along the boardwalk while at the same time integrating the street connections coming from the city.”

Green roofs are also changing the way architects present architecture. Usually renderings are shot from ground level; roofs are ugly. Now Zaha Hadid highlights the aerial perspective, the view that none of us will ever get to see of Seoul’s Dongdaemun Design Park.

Now we are beginning to see green roofs being used as greenwashing, as a method to put buildings where they shouldn’t be, or sell them to communities that don’t want them. Kenzo Tange did the master plan of Nanyang Technological University in Singapore; they call it a “garden campus” because of the park he designed in the middle of it, to be the “green lung” of the campus. So what do they call the new School of Art, Design and Media in the middle of it?

“a non-building building, as CPG director Hoong Bee Lok puts it, that would allow it to build on the central green space without taking away from it.” So if you want to put a building in a park, wrap it in grass. I wonder what Tange would have said.

Or in Brooklyn, put a water plant in a park and put a green roof on it. As the Architects Newspaper described it:

“When this heavily secured compound is completed in 2012, it’s due to be topped by far more than just new turf. Grimshaw and landscape architect Ken Smith have designed one of the largest and most intensive green roofs to date, which is also a fully functioning driving range. And an irrigation system for the golf course. And an integrated security program for the facility below. Think Pebble Beach meets the Biosphere meets Rikers.”

Building? What building?

At some point a few of these are going to get built, and people are going to realise that green roofs are being used as the new equivalent of mirrored glass; Architects used to show renderings of towers reflecting birds and clouds to somehow make it disappear and be more palatable to residents and planning officials. In the end, people got a big box covered in mirrors. We should be careful that we don’t get sold a whole lot of big boxes with green boxtops, always shown from above. When you are at street level it will be a very different picture.