VANCOUVER I Vancouver’s $535-million convention centre expansion is to have one of the biggest “green roofs” in North America.

Measuring almost 2.4 hectares (six acres), the state-of-the-art roof will cap the new convention facility to be built on a 4.2-hectare (11.3 acre) site west of Canada Place at the foot of Burrard Street.

Composed of a mixture of grasses and drought tolerant plants, the “living roof” has been specifically designed to provide a sustainable habitat for birds and insects.

It will also capture, purify and recycle rainwater, act as a buffer to reduced the noise of float planes, lower the cost of heating and cooling the building, and provide a more attractive view for residents of the expensive waterfront highrise condos in the new Harbour Green neighbourhood.

The design team for the project — a collaboration of U.S. and Canadian architects — outlined the proposal for the roof system in Vancouver this week, pointing out that green-roof technology is fast becoming internationally recognized as one of the most environmentally friendly and progressive innovations in contemporary building design.

With its origins in the simple cob-houses of antiquity, the green roof is being embraced world-wide as a way to cool down the “heat islands” that cities have become by turning barren rooftops into oxygen-generating, pollution-absorbing green spaces.

Jim Brown, principal at LMN Architects in Seattle, says the main idea with Vancouver‘s convention centre extension project is to make sure the building, which will cover the equivalent of four city blocks, has a natural link to the green spaces that stretch from Stanley Park to Canada Place.

To achieve the desired look and neighbourhood ambience, Brown says, the architectural team developed a concept of “folded landforms” that gave the building its ultimate shape, with rooflines angled to create a sleek, low profile as well as pleasing view corridors.

“Viewed from the water, we wanted the building to glow at night like a lantern. We want it to look like a beacon, a beautiful object, on the waterfront,” Brown says.

The green roof was chosen because not only would it add a natural continuity to the rhythm of the existing green space, it would provide an opportunity to create a viable and sustainable habitat for birds and insects.

Technological expertise on how to plant the roof and create appropriate soil conditions and drainage is being provided by Californian Paul Kephart, one of North America‘s top green-roof experts who has worked on numerous projects over the last 15 years.

Kephart will also be working on the design of systems to capture, purify and recycle rainwater. He is also conducting tests to determine the best plants for the site. At the moment, he thinks sedums, grasses and herbs will work well, especially when they are grown in the same medium in which they will be ultimately planted on the roof.

While the main roof will not be accessible to the public, there are lower areas — technically still part of the roof system — that the public will be able to visit. They could also be used for educational purposes.

Jacques Beaudreault, of Musson Cattell Mackey Partnership, architects in Vancouver, says he was a “bit nervous” when he first heard of the proposal for a green roof but he came round to seeing the advantages after hearing from Kephart.

“I think it will be fantastic. It will provide a natural termination of the green spaces from Stanley Park to Canada Place.”

Beaudreault also points out that one of the benefits of a green roof is that the vegetation protects the roof membrane from destructive ultra-violet rays. “A green roof can actually extend the life of a roof.”

Green-roof technology has been used extensively throughout Germany and Holland for several years. It is estimated there are now more than 10 million square metres of green roofs in Germany, including a meadow-like roof on top of a commercial building in Kassel. In Holland, the roof of the international airport in Amsterdam has been covered with sedums

In North America, there are several significant projects, including the four-hectare roof at Ford Motor Company’s factory in Detroit, the $1-million roof garden above Chicago‘s city hall, and the roof of the Gap’s $60-million corporate headquarters in San Bruno, California.

Scientists at Weston Design Consultants in Chicago reckon that with enough green roofs they could lower the temperature of an entire city. According to Weston’s study, a drop in roof temperature of a few degrees means a 10-per-cent reduction in air-conditioning needs for the building below.

In Vancouver, the Law Courts building on Robson Street has a green-roof, as does the library, which has a meadow of ornamental grasses on its roof. The vast field of grasses has been planted in a curving pattern to symbolize the Fraser River.

A cloister-like courtyard garden at Cathedral Place on West Georgia and lawns on the top of the Portland Hotel residence on Hastings Street are two other intelligent uses of roof spaces to create esthetically pleasing garden environments.

Construction on the convention centre expansion is due to start in October. Work is scheduled to be completed by 2008.

The expansion will more than triple the convention space that currently exists at the Vancouver Convention & Exhibition Centre.

The project is expected to generate more than $1.5 billion in economic benefits for industry as well as 6,700 person-years of employment during construction and an additional 7,500 full-time jobs throughout the province once it is completed.

OPEN HOUSES

A number of open houses have been arranged to allow public discussion of the convention centre expansion project. The times and dates are as follows:

– June 16, noon to 6:30 p.m, Waterfront Station.

– June 19, 10 a.m. to 4 p.m, UBC Robson Square.

– June 22, noon to 5 p.m., Coal Harbour Community Centre.

– June 24, open house from 5 to 7 p.m., public meeting from 7 to 9 p.m. at the Vancouver Public Library.

City staff and project team staff will be at all events along with a model of the project and other information panels.

© The Vancouver Sun 2004