'They are an investment. I don't want to design things that will look old in a few years. There are sofas I designed 20 years ago but they are timeless. I try to create contemporary classic design.'

Citterio has the understated style befitting of a native of Milan (he was born in nearby Meda, a city famous for furniture-making, which perhaps predestined his career choice in the most propitious way). It's easy to guess that the flashy, over-the-top decadence that sometimes accompanies luxury is not to his taste.

Now in his early 60s and his fourth decade of designing, Citterio is still full of enthusiasm and energy for his industry. His business, in partnership with Patricia Viel, with whom he has worked since 1999 (hence the banner Antonio Citterio Patricia Viel and Partners), stretches across Europe, America and Asia. He has flown in for 24 hours for the Business of Design conference in Hong Kong and does the same for meetings in Singapore, where he has a new project on the go.

The luxury residential tower on Singapore's Orchard Road has Citterio's 'contemporary classic' philosophy written all over it. 'It's an incredible opportunity; everyone has heard of Orchard Road,' says Citterio. 'Everyone. In Milan it's Via Montenapoleone, in Los Angeles it's Rodeo Drive, in New York it's Fifth Avenue, and in Singapore it's Orchard Road.'

His design drawings show duplex apartments with luscious gardens at entry level and suspended swimming pools on the upper floor. 'You arrive in your garden - even if it's on the 18th floor,' says Citterio. 'It's like a little townhouse - you open the gate and go through the garden to reach the front door. It's not a condominium; it's like a villa in the sky.'

It's certainly a seductive mix. The slinky swimming pools and verdant terraces make the properties look more like five-star resort hotels than city apartments. Clearly Citterio had this in mind - possibly his own Bulgari hotel design in Bali - when he took on the project: 'Yes, a resort. It's like you are in a fantastic hotel and you are staying in the presidential suite.'

Citterio believes that the higher standards in luxury hotel design have had an influence on how the people who stay in them want their homes to look now. 'Hotels have created a new demand for the market. People are more sophisticated now. They understand more about design. They want massive bedrooms with lots of closet space, the bathroom is not just for function but a space for private time, and the kitchen is no longer just for cooking and eating but a place to meet. And, of course, the amount of money they are spending on the property is more [these days] so they want more from it.'

Unusually, the building is freehold - the previous building being bought (and razed to the ground) by YTL Land and Development, which approached Citterio after seeing his Bulgari hotel design in Milan. Orchard Boulevard is also a rare project in that Citterio is working on it holistically. He is responsible for the architecture and the interior design, and has carte blanche on every detail from electrical switches to door handles: 'We are working on the master plan to the finish.' Far from being overwhelmed, it's an arrangement that he is comfortable with.

'The more work you do, the more creativity you have,' says Citterio. 'If you have worked for many years, you see how things are put together. It makes sense to combine products. I understand how people live and how they use things - the wardrobes, the faucets, the total experience. It's easier when you can use skills in both architecture and interiors.'

In fact, with his experience and at his age, you get the feeling he doesn't want to work any other way now. 'If I don't do the interiors and someone else does, I'm not really happy. And if I do the interiors and someone else has done the architecture, I'm not happy either,' he says.

Citterio has that rare knack of being able to design in multiple mediums: whether it's a building or an interior, an office or a home, a lamp or a running machine, the design process comes naturally to him. His work, such as the folding trolley Barista for Kartell, can be seen on display at the Museum of Modern Art in New York and Centre Pompidou in Paris, and his numerous awards include the highest industrial design prize in Italy and the Royal Designers for Industry in Britain. Understandably then he is not troubled by much when it comes to design.

'If you don't have diversity then you don't understand the project fully. I always think of how someone is going to use the space because I also design products [that will go in them]. Some architects just do buildings so they don't know the right dimensions for fitting in furniture or how the light will work.'

Light is crucial to Citterio's design ethos - it can make or break a space. 'Lighting is a really important part of the project because it affects the emotions. When you go in somewhere you feel good, you feel you're in the right place or sometimes it doesn't feel right.'

Work begins on Orchard Boulevard next year and the project is due for completion in 2015. It is Citterio's first residential project in Asia but not, it seems, for lack of interest.

'For many years I've tried to work in Asia, but it's been difficult to find a good partner,' he says. 'We work on really high quality projects and we never found someone with the same vision as us. YTL has the same standards as us.'

Citterio also has a bounty of other projects in Asia lined up, but he says he has been asked by the clients not to talk about them.

There's another Bulgari hotel in Beijing (following the opening of the London Bulgari hotel just in time for the Olympics next year), and another luxury hotel is planned for Nanjing as well as a possible further resort in China for a client Citterio says he can't name.

And on his view of Hong Kong, Citterio says: 'It's one of the most energetic cities in the world. When I'm here I feel the energy, the creativity and the youth. It's like New York in the 1970s - I was there then and Hong Kong feels like that now.'