Not sure, perhaps there is an underlying conviction that the situation will arise where a vegetated roof is not the most appropriate solution….

Perhaps I need to think of all the times that a vegetated roof might be most appropriate?

You see I wouldn’t advocate retro-greening the Sydney Opera House. (Nor would I wish to be without it as it is. Ditto many other roofs.)

So how would this principle work in an arid climate? Not sure! – but I guess there would/will be many roofs which are covered with bare soil for much of the year (or for all of a dry year) but which bloom like the desert when the rains come. Imagine the pleasure of driving through a desert time after a shower and seeing all the roofs covered in wild flowers: visual poetry – and a useful contribution to re-balancing the carbon cycle and reducing the need for wind turbines.

The International Green Roof Association calls them Intensive Green Roofs.[ http://www.igra-world.com/types_of_green_roofs/index.php ]

In the United States The Michigan State University is committed to green roof research.
[ http://www.hrt.msu.edu/greenroof/ ]

And it seems a ‘healthy’ amount of vanity has benefitted the realisation of a project? http://www.penick.net/digging/?cat=34 ]

Tom it would be a fanatastic project for landscape students to redesign the Willis Building green roof. Perhaps you could invite Norman Foster to the crits…the process might just spark his enthusiasm for landscape architecture (in other than rectangular pools, paving and plants)…then imagine!

In defence of architects (and the size of their heads) and their lack of landscape savy. There is alot to think about. And we do need a little help from our friends! Roofs were not historically about green space.

A little about firmness…(which is not really separable from commodity and delight)…

Roofs are not inherently the architect’s favourite part of the design – they are notoriously difficult to get right.

During the Renaissance the technique for designing domes was to try something and if it didn’t collapse then it was a success! [ http://www.skyarts.co.uk/art-design/article/renaissance-secrets-the-riddle-of-the-dome ] Brunelleschi’s 600-year-old dome on the Florence Cathedral still causes awe and wonder.

With the introduction of flat roofs in the Modern Movement architects tended not to answer their phones either when it rained or when it was very hot (the roofs which were made of bituminous material had a habit of slipping off!)

It is said that Villa Savoye’s roof commenced leaking almost immediately after the Savoye family moved in so Le Corbusier only narrowly avoided a lawsuit when the family fled France due to the German Army invading!

So getting to today’s green roof took some doing.

Utzon’s roof for the Opera House in Sydney was controversial too. Many believed it was impossible to construct. But I suppose they weren’t as familiar with the Aha moment and good engineers like Arups;

“The shells were originally designed as a series of parabolas, however engineers Ove Arup and partners had not been able to find an acceptable solution to constructing them. In mid 1961 Utzon handed the engineers his solution to the problem, the shells all being created as ribs from a sphere of the same radius. This not only satisfied the engineers, and cut down the project time drastically from what it could have been (it also allowed the roof tiles to be prefabricated in sheets on the ground, instead of being stuck on individually in mid-air), but also created the wonderful shapes so instantly recognisable today.”
[ http://www.sydneyarchitecture.com/ROC/QUA01.htm ]

There is very little garden at the Opera House but it is still a fantastic building in a fantastic setting! Perhaps landscape architects could have contributed to the urban design of the podium and promenade spaces?

What the world needs is more collaboration between brilliant architects and brilliant landscape architects. A major obstacle to this collaboration is that too many architects are educated to believe they need to collaborate with engineers without learning that the same level of fundamental collaboration is also necessary with landscape architects. I have the impression that when Fosters work with landscape architects they say: “here is a patch of space – please put in some paving some plants and perhaps a pool, if you can make it rectangular”. This is not the kind of brief they would want for the architecture.

Sustainability is a very ‘now’ topic. But sustainability =/ (does not equal) architecture/landscape or design. I still think this fundamental distinction is being missed.

Norman Foster [ http://www.architectsjournal.co.uk/architects/ ] takes the long and wide view of sustainability and begins his discussion with Buckminister Fuller.
[ http://www.youtube.com/watch?v=jNgkEGs1l4A&feature=player_embedded ] It is good to hear him talk as he has considerable technological and design credibility without being defined by ‘green-ness’. I think this is helpful and could help advance the design and collaborative understandings of sustainability significantly.

It is great also to see a healthy plethora of competitions about imagining the city! Although of course sustainability does not end with the city, but rather with human settlement.