A good idea for rooftops everywhere: Put them to public use.
Seventeen million people live in Shenzhen, China—it is the electronics workshop for the world. A giant rail terminal and depot for repairing trains were built near the bridge to Hong Kong, with a roof 1200 meters long and 50 to 60 m wide, about 15 m high. The building acted as a giant wall, cutting the residential areas off from the waterfront.
Beijing landscape architects Crossboundaries describes the project:
“The main goal of the project was to make use of the existing, yet previously underutilized rooftop area, and to better integrate the building into the fabric of its surroundings, while simultaneously rethinking the civic function of urban design in the 21st century. One of the challenges was to accommodate the needs of different user groups: first, to improve the quality of physical education in the surrounding schools, second, to provide places for the general public to enjoy leisurely sports, and third, to establish facilities for professional sports events and competitions with an audience.”
The roof was long enough that it could be divided into five sections serving a school, a professional sports training area, another school, and an area for the general public.
The architects note: “In a functional sense, the strip satisfies the needs of multiple user groups for sport and leisure facilitation, becoming a linear recreation hub serving the neighborhood.”
There are a series of trails running the length of the park, with great views of the city and of the harbor, high enough so that one can look over the vast border control plaza leading to the bridge to Hong Kong.
The designers applied “environmental and sustainable principles” like lots of wood, green areas, “and permeable architectural structures, not only for buildings, but also for bridges and rails.” They note: “The greenery planted along the pathways provides shade, while also contributing to efficient drainage and microclimate conditions.”
“Our linear park is like a missing puzzle that plugs into the neighboring communities,” concludes Binke Lenhardt, the other co-founder of Crossboundaries. “It creates the necessary physical and visual link between the urban tissue and the seaside and, along the way, aims to satisfy the schools’ and the public’s ever growing need for recreational spaces and room to breathe in a dense, urban environment.”
The most interesting thing about this scheme is the way it puts an existing roof to use: There are millions and millions of square meters of roof that could be put to use as rooftop farms, solar energy facilities, or as we see here, public uses. The problem is that most roofs are not designed to take much more load than a bit of mechanical equipment, people walking around, or in northern climates, a bit of snow.
When you add stuff on top of roofs, the building often needs additional bracing for wind and seismic loads. It might even need to have the foundations beefed up. On one project I worked on as a developer, we had to beef up the columns with weird plates and braces so they wouldn’t punch right through the footings. In another, we had to build a monster steel truss structure up through the middle of the building to brace the whole thing.
So there are not likely going to be a lot of projects like the Shenzhen Skypark—not too many buildings have concrete roofs that you can just go and add stuff to. But it does show how useful rooftops can be. And if they can’t hold a sports field, then fill’em up with solar panels.
SOURCE: Tree Hugger, 3 December 2021.
Author: Lloyd Alter is Design Editor for Treehugger and teaches Sustainable Design at Ryerson University in Toronto, Canada.