10 Oct 09 | The Toronto Star
by Brian Breuhaus
Chicago skyscraper creates roof-top garden as part of retrofit project to slash energy use 80%
John Huston admits that the tallest green roof in the world, an oasis 90 stories above the streets of downtown Chicago, won't provide much in the way of energy savings or environmental benefits.
It's just too small.
Huston says the 3-by-4.5-metre plot near the top of the 110-storey Willis Tower, known until this year as the Sears Tower, has a larger meaning.
"If you can do it on the 90th floor, you can do it anywhere," says Huston, one of the tower's owners."We want the building to be a leader."
It's a project that may interest builders in Toronto, too, which in May became the first North American city to require green roofs on all new large buildings.
On the Willis Tower, low-maintenance plants such as sedum were planted 18 months ago. The garden will be expanded next year to cover half the roof, or about 2,300 square metres altogether, Huston says.
Ladybugs have even moved in, says Sara Beardsley, of Adrian Smith + Gordon Gill Architecture, which is designing the project.
The green roof is part of a massive $200- to $300-million retrofit of the tallest building in North America. Huston says the project will carve 80 per cent off the amount of energy used by tower.
The retrofit, which is expected to begin next year, came about due to three factors: a city mayor used to getting his way despite massive budget deficits, the owners of the building wanting to keep tenants amid a recession and, well, windows.
The tower needed its aging single-pane windows replaced. "You get a lot more energy savings and increase your comfort factor by getting double-pane (windows)," says Huston, founder and executive vice-president of American Landmark Properties, Inc., which bought the building in 2004. However, architects continually told him that the building, completed in 1973, could only support single-pane.
"I said, `I don't like that answer.' " Huston kept pushing. Finally, the architects found a way to augment the brackets. With that, insulated windows - possibly a triple-glazed model, it has not been finalized - could be fitted into the steel structure.
Once the window project came together, the rest of the pieces fell into place. "Once you do the windows and the curtain wall system (the protective exterior wall), you've sealed the envelope, or skin of the building," Huston says."Then we can look to the inside. Once it's properly insulated, we can reduce our (energy) loads quite substantially."
He says it made sense to do a total retrofit because it would inconvenience the tenants less and would be simpler to get grants and other financing help. Other retrofit projects include wind turbines, new fixtures in the bathrooms, solar panels and even a modern hotel next door.
Huston says the energy savings will go to the tenants, who pay the building's operating costs.
The tower is about 80 per cent full right now, and a pending deal with United could push it over 90 per cent.
"You either lead or you're left behind," Huston says. "This building has always been a leader in the market, it has always been a leader in Chicago and it's been a leader around the world. In order to keep that, this project is essential."
Although the City of Chicago has massive budget deficits that have forced the government - and city libraries - to shut down on certain weekdays, it continues to fund environmental projects with longer-term savings in mind.
Green roofs are a "poster project," for the city, says Suzanne Malec-McKenna, commissioner of the city's environment department.
She says Richard M. Daley, who has been mayor for two decades, came back from a trip to Europe in the late 1990s determined to push green roofs in his hometown.
First, Daley ordered one for the top of City Hall. Today, Chicago boasts more than 650,000 square metres of green roofs on hundreds of buildings - more than any other city in North America.
The City offers grants of up to $5,000 for green roofs and other grants for cool roofs, which reflect heat. Chicago now requires that any new building built with city funding cover at least half of its roof with greenery, Malec-McKenna says.