AIArchitect This Week | Performative Landscapes: The Sustainable Sites Initiative Rating System Creates a Tool for Ecological Restoration

Summary:As true, net-zero energy buildings come closer and closer to fruition and announcements of new carbon-free cities of tomorrow seem to be made every other month, there comes a reality check from the American Society of Landscape Architects (ASLA): sustainable buildings themselves can’t save the world.

The Queens Botanical Garden was used as a sustainability case study in designing the Sustainable Sites Initiative. Its sustainable landscape features include a green roof, rain water cistern, and a filtering system that cleans rainwater with gravel. Image courtesy of the Sustainable Sites Initiative.

Even for building’s pursuing the highest levels of sustainable performance (like the International Living Building Institute’s Living Building Challenge), simply powering up a table saw to cut sustainably harvested wood will inject excess fossil fuel emissions into the atmosphere. Buildings might generate extra renewable energy that can be sold back into the power grid, but they can’t clean the soil, air or water, or actively rebalance carbon emissions levels. Buildings can be minimally harmful, but alone they can’t be wholly regenerative. For that, sustainable designers have to dig deeper, to the landscapes buildings occupy.

“We started with the idea that landscapes can give back,” says Susan Rieff, executive director of the Lady Bird Johnson Wildflower Center.

As the rating system moves through committees, public comments, and further drafts and revisions, Rieff and her collaborators hope the process ends with a system that will be a “critical positive”, as ASLA CEO Nancy Somerville, Hon. AIA, says; restoring the ecological balance of the natural world.

Ecosystem services
This Sustainable Sites Initiative collaboration stretches back three years. The group released the latest draft of the rating system in early November with a call for pilot projects that will be open till February 2010. They hope to have a final version of the system in place by 2012. ASLA is looking for 75 to 100 pilot projects of all stages of development and geographic locations. Any type of designed landscape (that is larger than 2,000 square feet) is eligible for the program: transit corridors, parks, residential yards, parking lots, and corporate or university campuses.

A steering committee composed of ASLA members, Wildflower Center and Botanic Gardens staff, as well as parks and recreation officials, conservationists, and academics is designing the system. While this group manages the overall development of the rating system, technical committees sort through specific topics like soil, water, and vegetation. Landscape contractors also have been included in the process.

The system has nine credit categories arranged chronologically across the building process. They are:

Each credit (15 prerequisites and 51 that are optional) has a number of points attached to it. Some credits are assigned a single amount of points, other have a range of points that can be earned. The system’s 250 total points are divided into four certification levels. One star is the lowest level of certification, four stars is the highest. Rating system designers are hoping that the Green Building Certification Institute will act as a third party certifier for the system, much as they do with the USGBC’s LEED rating system. In fact, the Sustainable Sites Initiative has taken many cues from how the USGBC has organized their green building system. A USGBC staff member sits on the Sustainable Sites steering committee, and landscape organizers say that they hope LEED and the Sustainable Sites Initiative can one day be integrated to complement each other. Sustainable Sites is also somewhat similar to the LEED for Neighborhood Development rating system in that it takes site issues into account, but it doesn’t operate on an urban scale like LEED ND.

The categories that hold the largest point amounts in the system all deal with primary landscape features and impacts. The soil and vegetation category (the single largest section) contains more than one-fifth of the system’s entire points. Second in point allocation, the water category contains 44 points. Next down the line, the materials category consists of 36 points. Integrated design practice models are encouraged by the landscape sustainability system. It’s Operations and Maintenance category contains 23 points, including credits that encourage development of greyfield and brownfield sites, as well as landscapes near public transit systems. One credit rewards using renewable energy systems, and because the development of landscapes doesn’t often require built interventions that consume significant amounts of power, energy performance is inherently de-emphasized compared to building rating systems.

The Sustainable Sites Initiative encourages (but does not require) performance monitoring once projects are complete. This is a part of sustainable design where landscape architects (and architects) often fall behind. “A lot of people are using these strategies, but not a lot of projects are able to figure out how to monitor them over time and really prove they’re doing what they’re supposed to do,” says Deb Guenther, a landscape architect with Mithun in Seattle who sits on the Sustainable Sites steering committee.

This monitoring category was boosted in importance when the rating system committees applied their credit weighing system and assigned point totals to the previous 2008 draft. The weighting system assigned points in accordance with the central presumption of the Sustainable Sites Initiative: that landscapes can provide active, regenerative natural services for the earth. The system is based on 12 such “ecosystem services” that include erosion control, cleaning the air through photosynthesis, filtering water, providing animal habitats, and climate regulation. Credits that affect the greatest number of ecosystem services, or mitigate the greatest number of harms caused by landscapes, were given greater point totals.

Beyond requiring landscape designers to monitor the performance of their projects, Sustainable Sites might also require them to send this data to a central database where it can be researched. (Somerville says this option is “on the table,” but not yet codified in the current draft.) The latest iteration of LEED (Version 3), requires the collection of performance data for two years after a project is completed. Also like LEED, Sustainable Sites is designed to take into account geographic and climatic differences in landscapes. For example, some water credits reference climate regions in defining how much water should be allowed to collect on site.

Little bad vs. positive good
Contrary to common perceptions, it’s not automatically environmentally beneficial to plant new landscapes. “Just because a landscape is green doesn’t mean it’s a healthy, sustainable landscape,” Rieff says. True green landscape design is more subtle and complex. Newly developed landscapes could require inappropriate amounts of water, power, or day-to-day maintenance, not to mention toxic pesticides and fertilizer.

Together, landscape architects and architects are getting used to thinking about building and development performatively; in terms of what ecological services designed interventions can provide. But the two groups are coming to distinctly different conclusions on the performance potential of their respective professions.

Buildings, says landscape architect and steering committee member Jose Alminana of Philadelphia-based Andropogon Associates, “can be very good at doing little bad. Landscapes, on the other hand, are alive. They have the capacity to evolve over time and be regenerative. Therefore, their contributions are going to be potentially positive as opposed to neutral. You can have a zero-energy building, but you wouldn’t be able to have a building that actually sequesters carbon like a landscape could.”

Indeed, the potential to repair the damage caused by carbon emissions is arguably greater with the Sustainable Sites Initiative than with even the most stringent sustainable building ratings system. And it doesn’t hurt that the landscape architects’ system can be pervasively applied to nearly any kind of construction project anywhere. “Every project has a site,” says Alminana, “but not necessarily every project has a building.”