Taking, for example, the hundreds of New York City bus shelters which were erected in 2006, how do you approach designing for the public realm?

There’s absolutely no reason why everything you look at in the street shouldn’t be worth looking at. There’s no need to throw anything away. When you’re doing 1,000 bus shelters, whether each one costs $2,000 or $2,020 doesn’t matter. The common factor should be that they’re designed with quality and can be repaired and looked after. It’s a classic problem—–you can see things damaged after a week.

And that’s probably more damaging to the public realm than if it were never there?

Yeah, exactly. Because people are long-suffering, they just move down the street.

How do you make train stations and airports specific to their cities?

We recently got the commission to design the airport in St. Petersburg, Russia, and we were nearing the end [of the design process], and the client said, “Everything works, but this airport could be anywhere in the world.” So we thought about it and said, “What’s unique here is the climate. You’ve got a hell of a lot of snow and you don’t like it because chunks fall off and get dirty.” So we designed an inverted roof that captures the snow—–which, incidentally, is good insulation—–and then drains it like a funnel. We spent quite a bit of time on the roof because of that, and we noticed that the city is characterized by a roofscape with tiny glints of gold—–the reason being that in winter it has practically no sunshine. So we decided to insert a couple of very small louvers in the roof that were gold and would catch the sun. We didn’t put onion domes over it; we just added subtle touches, and I think they were appreciated in the end.

The key thing in Melbourne’s Southern Cross Station was that in summer it gets very hot and sticky and unpleasant, particularly in the railway station. So we did a roof that looks like sand dunes. Wind goes over the roof and there’s suction to suck out hot air and diesel fumes. Also, we will collect rainwater off the roof and use all the pedestrian walkways that run under the tracks as reservoirs for watering the landscape. Workers are installing that system now, two years after the station opened, and the city’s paying for that because it wants the water.

When designing such expansive environments, is it possible to address the individual?

Ideally, you would want to destress the situation, by making restaurants and lounges pleasant—–but really you want to be efficient. That’s one of the factors about this low-budget flying that’s happening at the moment: You’re not being as stressed on those trips as you would be in the crowded major hub airports, and a lot of people get a buzz out of that.

We just redid Zurich’s airport, where the client asked us to double the size but not to use any more energy. It was a terrific challenge—–a lot of it was timing electronic devices by controls and using daylight whenever possible. We also increased efficiency by bringing the train station right underneath the airport. You can check your bags as soon as you get off the train. It’s really, really efficient.

And the preparedness to spend money on finishes that last a long time means the city can keep the place clean and pay attention to detailing. We studied the machines it uses for cleaning and decided to make the radius of the curve [of the wall] to equal the radius of the cleaning machines. Everyone says the Swiss are obsessed with cleanliness anyway, but it does make life much more pleasant if you’re not sitting on a seat with torn fabric and coffee stains.

In a city where there’s not a strong culture of mass transit, what should a train hub or an airport do to encourage it?

One of the good things about doing decent public design in a prominent place is people look at it and say: Why can’t we have that everywhere? It’s happening in London—–on the new Jubilee tube line—–a different architect designed each station, and they’re interesting places in their own right. Even if it’s simply lighting and finishes, why can’t it be pushed through the rest of the system? Most people in the transport world know the value of quality, but they also have their backs against the wall in terms of expenditure, so there’s always a compromise.

Your generation of British architects is setting the standard of transport facilities around the world. How does sustainability factor in to your approach?

It’s quite complex—–we did the Rolls-Royce factory, sunken into the ground in an area of outstanding natural beauty. It has a grass roof. But a lot of people ask: What’s so green about a Rolls-Royce? I put it to them: They just had their centenary and 98 percent of their cars are still on the road. They don’t get scrapped, they get repaired—and the older ones are probably the most beautifully looked after. The company knows who owns them, where they’ve been, and, on the whole, they take them back at the factory. And that is extra-green. You’ve got to do a bit of lateral thinking on these green issues. It’s quite important to be pragmatic. The one thing we have to watch very carefully is polarization. There are a great number of green things people can nibble at the edge of and a lot that are quite doable.

But people need a lot of education to do that, right?

Well, yeah. But one example: There is little in the way of recycling on the streets of some cities. If you think of the amount being generated every day, maybe legal control of recycling would make a huge difference. This leads you straight back to our discussion of street furniture because if a street is packed out with bins it’s not a very pleasant place to be, but…

Part of the challenge is designing a beautiful garbage can?

Yeah, and making people feel it’s sensible to stick a can in one bin and a newspaper in another. It’s design psychology: You can make bins big enough and the right shape so they’re easy to use with the lids open. In teeming cities with little public wealth, it might be appropriate to concentrate on providing large recycling containers so that people cannot remove them.

Is it fair to say that if a city’s service is easy to use, people will have an easier time loving it and investing back in it?

Yes. An example is Barcelona: They upgraded themselves for the Olympics—–earning a terrific reputation for design and civic space—–and they’ve also really kept it up.