Law's firm, the Oval Partnership, is responsible for three installations at the biennale, including Garden of Towers. It also designed the Hong Kong exhibition, whose green metal frames and exposed wires evoke the cluttered vitality of Hong Kong's streets. "For us, architecture is a cultural activity," says Law, leaning back into a chair in the airy garden cafe of the Metropole Hotel, a few minutes' walk from the Hong Kong pavilion. He looked only a bit weary after two long days of opening events.

Slightly worse for wear was Law's British colleague, Jonathan Pile, who had been up until 3am celebrating the opening with architects from Oval's offices in Hong Kong, Beijing and London. "It's the first time we've all come together," Pile says. "The biennale is a real exchange of ideas."

It has been 20 years since Law and Pile founded Oval with fellow architect Patrick Bruce, but it still has the energy of a much younger firm. Its projects across Asia have earned it a name for thoughtful designs sensitive to their environment, both natural and urban. All three of Oval's offices contributed to the biennale, which runs until November 25.

One project features a pair of benches, at the Hong Kong exhibition in Venice and at MegaBox in Kowloon Bay, that transmit sound and information from one city to the other.

Law says hotels have a "disproportionately large impact on the way Asian people strive to live", and while that mostly means a slavish attention to the latest trends in room design, he thinks it could extend to something more significant, such as convincing people to recycle water. "Hotels can be powerful networking tools," he says.

Elements from conceptual projects often find their way into Oval's real-world work, such as the timber-clad Innhouse Hotel in Kunming , Yunnan province, which heats water with solar energy, recycles rainwater and grey water, and maximises natural light and ventilation through tall windows and cantilevered balconies. The sustainability of the hotel, and its warm yet minimalist design, earned it several awards this year, including a Royal Institute of British Architects International Award.

Oval is also leading the way on research into laminated bamboo, an extraordinarily strong natural construction material. Bamboo, a type of grass, grows faster and absorbs more carbon dioxide than trees. Last year, the firm completed the world's first multi-storey laminated bamboo house in Kunming.

Hong Kong is a less fertile ground for experimentation, but Oval has nonetheless made a mark with eye-catching new projects such as 5 Star Street, a sleek, understated luxury apartment tower, and a series of redesigned public spaces around the same chic corner of Wan Chai.

The inspiration came from years of work in Wan Chai, where Oval has its Hong Kong office and where Law has been involved in projects like the transformation of the Blue House into a social housing and cultural complex. "We're the opposite of a so-called global practice," Pile says.

Despite working internationally, Oval keeps its studios hands-on, open to exchanges of ideas and rooted in a local context. "We are really looking through the local conditions," he says. That's a sentiment shared by another biennale exhibitor, Cave Architecture Design Studio, founded last year by former Oval architect Christopher Leung with two architecture-school classmates and two young members of the Ling family, which owns the Kwai Hung Group, a property developer and construction conglomerate.

On a bright, hot afternoon, buffeted by a steady breeze off the Venice Lagoon, Leung sits on a restaurant terrace with three of his partners: architects Stanley Ho and Karman Leung, and Clarence Ling, who runs the business side of the firm. As their lunches arrive they discuss their experience running a new firm in a city known as a tough place for ambitious architects.

Ho, Christopher and Karman met while studying at the Bartlett School of Architecture in London. It was a shock to return to Hong Kong, where architecture is subservient to commercial interests and restrictive building codes. "It's hard knowing that something you can do in Europe, is just not going to be possible in Hong Kong," Ho says.

Still, striking out on their own was worth the risk. Before he helped found Cave, he was working for a local firm. "I was doing a lot of paperwork," he says. "If you work for a big firm you're always working for someone else, but anyone who has studied architecture has something to say."

In just over a year, Cave has already started work on half a dozen projects, including office interiors, serviced apartments, hotels, a botox clinic and building facades. Their latest project is perhaps the most ambitious: a serviced apartment block on Queen's Road West that draws its character from the surrounding neighbourhood of Sheung Wan.

The same approach can be seen in Cave's biennale installation, an unruly vertical community of self-built homes on the site of the Kai Tak airport. Taking its cues from the Kowloon Walled City, which was demolished in 1993, it is a statement against the cookie-cutter designs favoured by the government and big property developers.

"We're seeing how all this diversity can come together to create an unplanned city," Karman says. "Everybody takes responsibility for the city."