31st October 2011- John “Bill” Taylor, ASLA, of Carol R. Johnson Associates, and Mark Walsh-Cooke and Tom Kennedy of Arup, gave a talk on “The Next Generation of Net-Zero Park Design” at the 2011 ASLA annual meeting.
Problem: the earth’s resources are finite. The amount of usable freshwater, air, and, of course, oil, make up a very small amount of the planet. And, with the population growing, scarcity is bound to increase. Complicating matters, climate change is real. We will continue to see more flood events as the amount of rain is concentrated in fewer, stronger storms. More and more, our lives will be interrupted by unpredictable weather patterns. Tom Kennedy with Arup asked, “Where do we draw the line?”
“Net-zero” parks may be part of a global effort to deal with these changes. Bill Taylor, a landscape architect with Carol R. Johnson Associates, said that “the next generation of parks will be part of a massive urban and regional retrofitting.” Net-zero is a term used to quantify sustainability by paying close attention to a project’s impacts and resource consumption – usually in terms of water, carbon, and energy. When it comes to designing net-zero parks, however, there are more questions than answers. How is net-zero defined? According to Kennedy, net-zero is a lot like the term “sustainability” in that there are almost as many definitions for it as there are references to it. For landscape purposes, should net-zero refer to operational or lifetime costs? Does it involve offsetting carbon or energy expenditures? Does it consider the carbon impact of deliveries made to the site, or of importing water? ”Net-zero is not really well defined yet,” said Kennedy. He proposes that while the definition is flexible, one should decide on their own definition of net-zero early on in a project’s lifespan.
Taylor indicated there has been growing momentum around net-zero concepts in parks. Some precedents for net-zero park parameters may be found in New York City Mayor Bloomberg’s PlaNYC and his Parks department’s “A Plan for Sustainable Practices within New York Parks.” In addition, the National Park Service has recently declared their intention to focus on energy efficiency in future projects, avoiding the use of any fossil fuels where possible. Taylor also pointed to environmental concerns abroad. A recent article published by Harvard Business School asserts that over $500 billion dollars are projected to be spent on building “environmentally-sound” cities from scratch over the next decade.
Several examples from practice were used to describe components of net-zero park design. Shams, in Dubai, which is to be located on a man-made island, is an example of “net-zero passive cooling of the public realm.” The design promises to use passive cooling to lower ambient temperatures by 4 to 7 degrees C. This is accomplished by creating 75 percent tree canopy, lowering the park level by 8 meters below surrounding streets, using cold deep sea water to flush canals that run along pedestrian corridors, and by surrounding the park with air-conditioned retail shops that exhaust cool air into low-lying areas. The temperature difference between the air and the cold water canals will also enable heat exchangers to be used to cool surrounding buildings. Taylor acknowledged that irrigating trees in the public realm with water from desalination comes at a high energy cost.
Another Central Park, this one in New Songdo City, South Korea, demonstrated rainwater harvesting strategies that would result in no civic water being needed for irrigation. A Jack Nicklaus Golf Park was used to demonstrate a low-tech solution to maintaining water level in the site’s ponds. The ponds were retrofitted with large diameter sub-surface pipes that connect them to each other so that water is distributed evenly without the use of pumps.
Mark Walsh-Cook with Arup then outlined a landscape modeling strategy dubbed Integrated Resource Management (IRM), which optimizes strategies for development. This came out of the need for a more rigorous planning tool to maximize resource efficiency. As Walsh-Cook says, “We need to achieve more with less.” IRM compares different design scenarios, which includes land use percentages, and measures the results through the lens of key performance indicators such as carbon, energy, and water use.
Ultimately, said Kennedy, we need to reduce our per-capita demand for finite resources. Unfortunately, there’s very little in the way of governance in this matter, forcing us to change our behavior. As far as landscape architects, “We are the governance. We need to self-police, and push each other.” Perhaps this means pushing forward with defining and implementing net-zero design. As Taylor said, “our future will be determined by our involvement in setting parameters.”