Sir John Sorrell, BBC Green Room 20 May 08;
There are precious few examples of cities that are attempting to reduce energy and resource consumption and improve the quality of life for their citizens, says Sir John Sorrell. But nothing is going to happen, he argues, until politicians accept that they have a mandate to make the tough choices needed.
Some people think that cutting carbon means denying ourselves the things that make life enjoyable - no shopping, no fun - but I see it differently.
Tackling climate change isn't about self-denial, it's about reinvention; reinventing towns and cities, redesigning the way they work, and changing the way we all manage our lives.
As the government's design champion, the Commission for Architecture and the Built Environment (CABE) reviews proposals for 350 of the most significant new buildings and spaces every year.
Out of all those homes, schools and health centres, we have only seen a handful with any serious ambition for sustainability.
Things may be changing, but far too slowly, which is why we are organising a climate change festival, which is being held in Birmingham from 31 May.
It gives us nine days to show we can do something positive and surprising together about climate change, centred on the way we build and use our cities.
Living the dream
We are not just asking people to see their city through new eyes; we are asking them to dare to dream about the kind of place that could be created over the next 10 years through cutting carbon.
Which begs the question: how can you tell if you live in a sustainable city?
It currently costs a place like Birmingham, England's second largest city, up to £1bn a year to import its energy, yet only a tiny proportion of it is green.
The trick is to harness and capture the energy that is already there from the Sun, ground and air, and create decentralised energy distribution systems.
This is a lost art; the Royal Festival Hall was extracting energy from the River Thames to heat its building 50 years ago.
Buildings must change. For me, the glass tower of the Seagram Building in New York defines the time when energy was plentiful.
You effectively designed rows of desks in a sauna, and then simply added air conditioning.
Most of the buildings around us today will still be standing for decades to come, so it's their energy performance that must change.
Keeping an even temperature inside any building means serious insulation. Homes in an average large city produce more than two million tonnes of carbon dioxide (CO2) each year. This is because the vast majority of older houses leak heat.
So if I were to suggest three tests for a sustainable city, this would be my first: are there grants or local tax incentives available to help people green their homes?
Car-free life
The second thing is about how we live our lives, not just how we live in our homes.
Our carbon footprints reflect how we get to work, how we shop, where our friends are.
It is interesting that the biggest carbon savings at BedZed, the UK's veteran eco-housing development, have been made as a result of establishing a car sharing scheme.
Cutting private car use generally means civic leaders being prepared to risk a few brave decisions.
For example, when a new suburb was built in the German city of Freiburg, they ran a tram service from the moment the first resident moved in.
This meant empty trams at first, but now nearly half of its residents are car free. Not so foolish after all.
So my second test for a sustainable city is whether you have a genuine transport choice.
Is it just as cheap and convenient to go by bus, tram and local train as it is by car?
Until it is, heavy traffic will continue to put most people off walking and cycling, which are the personal transport options that score best for fitness and protecting the planet.
Greening the city
My third test is about greenery. Are a lot more big trees being planted; are acres of new allotments coming on stream; are parks being properly maintained?
Greenery is critical to counterbalance the "urban heat island" effect from hotter, drier summers, when night-time temperatures remain high because of heat retained by brick and tarmac.
Plants only cool the air if they stay green, which means capturing heavy winter downpours instead of letting them just flood the drains.
Storage can be cunningly disguised as beautiful water features.
And greening a place properly includes the roofs. In the northern English city of Sheffield, even bus shelters now sport green roofs to filter pollution.
There will be something else common to all truly sustainable towns and cities: they will be more prosperous than unsustainable ones.
This is because carbon emissions are only one sign of the inefficient way in which natural resources are being used.
As all these resources dwindle, economic pressure is growing to use them more wisely.
Future-proofing a city means creating the markets for green businesses and green technologies, and designing the space and facilities to support them.
In a well-designed, sustainable city, most residents believe their future and their progress are linked to its future.
If you are on a low income, you may have little choice about where you live.
So with fuel prices soaring, you want to live somewhere served by affordable public transport. You want your local authority to help with home insulation, and invest in local green energy which will protect you from perennial price hikes.
Whether you are looking at London leading on congestion charging, or San Francisco leading on solar power (with a system the size of a football field on top of its convention centre), it is clear that strong civic leadership matters most of all.
We need that kind of vision, backed by serious investment, when it comes to planning and managing the towns and cities of tomorrow.
Why isn't it happening everywhere? Because politicians don't seem to know that they have a public mandate to make tough decisions.
We want the climate change festival to show them that they do have that mandate, and give them the confidence to do the right thing.
Sir John Sorrell is chairman of the Commission for Architecture and the Built Environment, the government's design champion
The Green Room is a series of opinion pieces on environmental topics running weekly on the BBC News website
