Chicago is home to this year's Greenbuild. If you believe the marketing hype, it's the biggest green building educational event in the world with more than 2,500 exhibitors and 100 lecture sessions on everything from urban planning to climate and carbon-neutral design.
Yes, we are allowed to write and say the dreaded words - climate change - in the land that, for so long, was in political denial of the phenomenon.
I am usually sceptical about these type of events - is it not all just slick marketing, cheesy salespeople and death by Powerpoint? This time however, I am truly overwhelmed at one of 25,000 delegates.
That is twice as many people as those who saw my beloved Queens Park Rangers play football last Saturday! Architects and designers, developers and facility managers, to product inventors and entrepreneurs, have all paid to be part of this new movement of green building awareness that is spreading through America. That it is happening in the land of over consumption, is quite astonishing!
But does interest equate to action I hear you ask? Well Chicago boasts about having some of the greenest architecture in the US with almost 200 LEED (Leadership in Energy and Environmental Design) certified and registered buildings. LEED is the equivalent to the UK green building rating tool – BREEAM (Building Research Establishment Environmental Assessment Method).
This is more than any other city in the states. It also has more square feet of planted or planned green roofs than all the US cities put together – a useful piece of trivia for the forthcoming Christmas party networking circuit.
So what has been the tipping point? Why is the green building movement of such relevance that President Bill Clinton provided the keynote address…aside from his conference fee?
It is, perhaps, because buildings over their lifespan are responsible for 40% of the world's energy use, 40% of the world's solid waste generation, 40% of the world's greenhouse emissions, 33% of resources and 12% of water use.
More people now live in cities than in the countryside so ensuring that the design and operation of buildings provide the best possible environmental performance is essential.
In the US, it appears that the drive for green buildings has come from progressive mayors, like Mayor Daley in Chicago who has positioned green buildings as a central feature for the city's environmental action agenda.
In his own words he believes that a healthy environment is not only consistent with a strong economy and improved quality of life, but essential for both. This drive has influenced the market, one delegate told me the public sector requirement for LEED has impacted on the commercial market, too, with clients realising that they need to demonstrate their sustainability credentials.
But LEED, like BREEAM, has its distracters and isn't perfect. But, people are aware of it and it will evolve further. And it is such widespread recognition that will lead to positive change in the future.
l Dr. Paul Toyne, Bovis Lend Lease head of sustainability and regular blogger on www.nce.co.uk