Adaptive Reuse – Rooftop Gardens



Chicago City Hall-  Rooftop Garden

When Mayor Richard Daley proposed a garden on the roof of city hall, the idea was ridiculed. But 12 years later, the garden continues to improve the energy efficiency of the building by retaining rainfall in the soil and cooling the building from the top down. The garden roof was built to last twice as long as a traditional roof and has provided the city with praise-worthy scenery where there was only tar before. City Hall set an example, and now more than 200 other buildings in Chicago are topped with gardens.

In principle, adding greenery on a rooftop has merit. So my initial reaction to seeing a green roof in the plans for a new student services building was positive, until it came out that there would be no access to this meadow and it wouldn’t be seen from neighboring buildings - but it did earn the LEED credit Sustainable Sites 7.2: Heat Island Effect. It is interesting to read the intent of that credit: To reduce heat islands to minimize impacts on microclimates and human and wildlife habitats. It strikes me as being just one more admonition of what we should not do. This is sustainability as dictated by the righteous.

This new building will house dining establishments. The campus actually owns a small farm, which provides organic produce for the food services department. A truly integrated, sustainable campus might have caught this opportunity to build a garden on the rooftop, to harvest and supply the dining hall. Of course, that would also presume that there was some cooking going on in the dining facility. I’m wondering if Bruegger’s could use some lettuce or tomatoes?

The adaptive re-use of existing rooftops is becoming a common theme in urban redevelopment. The caveats are the structural capability of the roof to hold the additional weight and people, and safety railings. In most cases, it is still advisable to design gardens which are lightweight and moveable, for ease of long-term roof-top maintenance. We’ll leave the goats on the rooftop pasture for the Swiss Alps. On the other hand, I’m daydreaming about a small urban set-up with a hyroponic garden on the roof, with the liquid fertilizer provided by a small vermiculture (that’s a worm farm..) operation which is fed from food scraps from the ground floor restaurant, and a few chickens…

Green roofs make sense both from the standpoint of reducing urban heat island effect, but also to provide more spaces to connect people to nature. Whether in new building design, or existing structural renovations, the potential for adaptive re-use as greenspace is worth considering. This might mean setting up rooftop rain collection, installing dumbwaiters to bring the compost up to the roof, providing water spigots, structural bases for future greenhouses or pavilions. Establishing the infrastructure for future scenarios is least expensive to install at the time of initial construction.

I can only hope that one day in the future, some student will propose that our rooftop lawn takes on a more culinary flair.

P.S. For the GREATEST report on Roof-top Gardens, fresh off the press from the Australian Government, and the predecessor PhD dissertation from Dr. Brett Roe which researched constructed wetlands, hydroponics and industrial wastewater. This is the first study to research the integration of these technologies, and is very pertinent to urban planning.