Where do you find the greenest community in the western world? A rural village where everyone grows their own vegetables in a communal allotment and walks their kids to the local school, one of those new zero carbon suburban Passivhaus developments like BedZed in the UK where the buildings require next to no heating, or perhaps one of those virtually car free Dutch towns where everyone whizzes round on bicycles?
That's right; crowded, grid locked, high rise New York is "unintentially the greenest city in the world".
Speaking at Library House's inaugural Cleantech conference earlier this week, Choa who works for international environmental urban design practice EDAW, argued that far from being the polluting monstrosities they are often perceived to be very densely populated cities are in fact "the greenest places on the planet".
According to Choa, the secret to the green lifestyle inadvertently lived by many New Yorkers lies in the city's unusually high population density and the co-location of residential and commercial properties which allow many people to walk to work.
This high population density can only be supported by high-rise living, but Choa insists that apartment blocks are, again inadvertently, amongst the greenest buildings around. "In an apartment you have at most two external walls and, unless you are on the top or bottom floors, apartments above and below you," he said. "There is a lot being done to make houses like those at the BedZed development greener, but densely populated apartments are still much greener than the greenest green home."
Co-locating commercial and residential properties also cuts emissions associated with travel as people can "live 80 percent of their lives within five minutes of home", said Choa. In contrast, cities such as London, which are "in love with low rise", are doomed to see any improvement in the energy efficiency of homes and offices undermined by the fact people still have to commute long distances to work.
Choa also argued that public services and mass transit systems become far greener and more efficient when population density is high. He claimed that the unreliability of the London Underground network is a direct result of the city's low population density which means that the Tube can not generate enough revenue per kilometre of track to justify the investment necessary to deliver reliable services. In contrast, the tightly packed five districts of New York, he argued, generate enough revenue per kilometre of rail to underpin sufficient investment.
This high-density school of urban planning is becoming increasingly influential amongst architects interested in environmental sustainability and Choa's speech was followed by a presentation from Khaled Awad, director of property for Abu Dhabi's Masdar project for a new alternative energy city and R&D hub.
He detailed how the plans for the new city had been developed to follow the same principles of high density living found in Manhattan, adding that the walled city - which will be powered using renewable energy from a concentrated solar power plant and wind farm - had been developed using integrated design approaches that should allow people to live within 200m of all essential services.
Whether Europe with its traditional love or low rise buildings can ever embrace high density urban living is debatable and when questioned about the widespread cultural opposition to crowded cities and the perception that they have a lower quality of life, Choa admitted that as a life long fan of city living he was "biased" in his claims that well designed high density cities could improve quality of life.
However, while it is unlikely Europe will embrace high density living any time soon, it does remain inherently carbon inefficient to have a scenario such as that currently found in the City of London where hundreds of thousands of people commute up to a hundred miles or more to work each day before heading home in the evening to leave just a few thousand full time residents.
And while it may be difficult to get Brits and other Europeans to turn their backs on rural and suburban living city planners and businesses choosing new office locations need to be more aware that one of the biggest steps they can take to both reduce carbon emissions and improve their staff's work life balance is to better integrate transport networks and commercial and residential properties.
Living in an apartment just round the corner from work may not be everyone's idea of the perfect home, but may be it is time we took a few more lifestyle tips from the Big Green Apple.
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