The second reason for our interest in green roofs is that when used in the aggregate they are capable of changing the urban environment by modifying climate, facilitating water drainage, and improving the water quality of rivers.

The third reason is one of aesthetics. In dense cities, green roofs are seen from above and become what I have called a fifth façade, a vista of green expanses rather than of black tar. In concert with this they give pleasure, creating enjoyable places in which to be.

There is a fourth reason: the incredible asset to a city of being able to create private or public green space in existing buildings without having to acquire new land.

The development of ideas about green roofs emerged from a theoretical proposal for Long Island City, Queens, New York, to examine the idea of having individual, privately owned green roofs aggregate to encompass an entire urban area. Such a study is not just a matter of examining things at a large scale; rather, it requires looking at the small and the large at the same time. We chose Long Island City be-cause the prevalence of “pancake” buildings (low buildings with a very large footprint) meant that green roofs would make more of a difference there.

Silvercup Studios, Long Island City Diana Balmori

Green roofs interest us—not in and of themselves—but as an urban tool. Of greatest interest is the idea that green roofs represent one form of the integra-tion of landscape and architecture for larger urban purposes. They represent an integration of living materials with inert materials; through the living materials, biological functions are integrated into the workings of a city. I see this as the future direction of urban work.

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Our study resulted in a series of graphs which showed how the greening of Long Island City roofs and their parking lots could produce a green surface the size of Olmsted’s Prospect Park in Brooklyn—the size of park we no longer consider possible to create—without having to purchase any land.

We also produced graphs to show succinctly the function and advantages of green roofs.

The Long Island City story was made into a PowerPoint presentation and a booklet. The presentation of these ideas in public forums resulted in two Long Island City commissions, Silvercup Studios and Gratz Industries.

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Grants were written to fund the creation of two demonstration green roofs in Long Island City. Although not all of the funding was fully in place, both the Silvercup Studios and Gratz Industries projects had suf-ficient financial commitments to move forward.

Because we had to justify every expense, we set out to build the most economical, sustainable green roof possible to serve as a prototype. This meant we would be designing a minimal vegetated layer, or extensive green roof, that would require very little maintenance and little or no irrigation after the first growing season. Because of weight load considerations, only a shallow depth (between three and three and a half inches) of planting medium could be used, which also meant that we couldn’t mound the soils to use topography as a design element. Sedums are among the few plants that thrive in such shallow depths of mineral material and that can survive under the harsh solar and wind conditions found on an urban roof.

Funding for a monitoring study of the Silvercup Studios green roof was written into our original grant pro-posal so that we could have actual data, analyzed by environmental scientists, to present to city officials, business owners, developers, and the general public. The resulting temperature data on Silvercup is very precise, the data on water management less so; but the performance of all the parameters meas-ured was higher than expected.

Green roofs allow individuals to take action. The fact that Stuart and Alan Suna of Silvercup Studios and Donald Gratz and Roberta Brandeis Gratz of the Gratz Company wanted to install a green roof and make it visible to the thousands of motorists crossing the Queensboro Bridge daily was the driving force for this change. They believed in the benefits of the project and they wanted to make that change vis-ible to others. It is this high visibility in a city, from tall buildings as well as from bridges, which makes the green roof into a fifth façade and a candidate for design. The green roof declares that each of us can bring about change. It embodies the ecologists’ credo: “think globally, act locally.”

Encouraging a massive adoption of this land-scape requires setting a variety of economic forces in motion: tax abatements for creating green roofs, tax assessments for sending ex-cessive water to the public drainage system (already a practice in Germany), and new ways of comparing the true costs to a city of constructing new drainage structures to the costs of a passive system of green roofs, which also reduces the heat island effect. (One challenge to implementing such chang-es is that the accounting for infrastructure occurs in a longer time frame than politicians’ short terms in office.) An added incentive for a citywide implementation of this landscape is the opportunity it provides to develop a lo-cal industry for green roofs.

The Silvercup roof, with its twenty sedum types, varied leaf colors (bright chartreuse to blue-gray green) and textures (small pebble-like leaves to tall stalks and wide leaves) and diverse bloom times and colors (yellow, pink, and white blooms, from spring through fall), used a modular green roof system of recycled plastic. Bands of orange fabric were placed to increase the roof’s visibility from the Queensboro Bridge, crucial to the public education role of this project, given its location and intention.

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