Lincoln Center Grows a Green Roof

There wasn't a reflecting pool, and the decrepit warehouse in the background didn't look much like the Met Opera House, but other than that, the miniature lawn installed in a Jersey City parking lot gave a visitor a good sense of what Lincoln Center's future campus lawn –– a grass roof to be installed on top of an as-yet-unnamed restaurant –– will look like. The turf was bright green; the ground, firm and dry, invited sitting or reclining. Except for the chill October wind, it was the perfect spot for a picnic.

Don't rush to pack your sandwiches, though. The green roof — part of Lincoln Center's $650 million West 65th St. redevelopment plan –– won't be installed until the spring or summer of 2009. In the meantime, the architects, Diller Scofidio + Renfro and FX Fowle Architects, in collaboration with a turf expert, Frank Rossi, and a horticulturalist, William Harder, have been testing a mock-up of the lawn, 1/16 the size of the real one, in a little-used parking lot in New Jersey. Yesterday afternoon, the various parties assembled to check on the state of the lawn.

Over the last year, the architects and their experts have tracked the condition and appearance of three types of grass planted on the mock-up. Mr. Rossi, a professor of turfgrass science at Cornell University, said they're close to declaring a winner. A special variety of the turf-type "tall fescue" kept its color best through the winter.

The architects also wanted to try out the effectiveness of the irrigation and drainage system they had planned. Although there are many green roofs in Manhattan –– Bryant Park, above the New York Public Library stacks, is one –– Lincoln Center's lawn offers particular challenges. It may be the only curved green roof in the city. Visitors will ascend the 10,500-square-foot lawn from plaza level; at its highest points, it will be 20 feet off the plaza.

Green-roof technology has advanced dramatically in recent years. Lincoln Center's lawn will be planted on top of what's now a standard 14 inch package of waterproofing, insulation, a plastic layer to stop the roots, a moisture retention mat, a drain mat, and soil.

So far, on the mini-lawn, the system has worked well. "The whole packaged system has drained much better than we thought," one of the Diller Scofidio + Renfro architects, Pablo Garcia, said. "We've come out after storms, and the ground was dry."

Green roofs have become popular in cities because they absorb storm water and reduce temperatures that can be up to 10 degrees warmer in urban areas than surrounding rural ones.

"Everybody acknowledges that it's pretty unreasonable to tear cities down and make a forest again," Edmund Snodgrass, a horticulturalist and author of "Green Roof Plants," explained." The question is how can we get more vegetation in cities, because that's what will cool things down. Sidewalks and roads aren't really options, but roofs are."

Then there's the visual appeal. "A lot of good environmental practices aren't sexy to look at," Mr. Snodgrass (whose name means "short grass" in Scottish) said. "But a green roof is one of those new environmental features that's very visible and very easy for people to integrate into their consciousness."

In addition to environmental concerns, the architects wanted to "get two spaces for the price of one" –– by having both the restaurant and a lawn on the same footprint –– Kevin Rice from Diller Scofidio + Renfro said.

Mr. Rossi said that the timing of Lincoln Center's season –– essentially, fall to spring –– meant he had to choose a type of grass that would look good even in the cold months. For a while, he considered embracing the problem and choosing a grass that would forthrightly go brown in winter."That would have been an extreme look," he said. "It wasn't the look they were going for."