Parking lots have typically not been associated with green and energy-efficient design and building practices. But according to some experts, that’s beginning to change.
“Extensive changes are being made to reduce the carbon footprint of surface parking lots,” said Matt Jobin, AIA, project manager, Rich and Associates, Southfield, Mich., the oldest firm in North America dedicated solely to parking design and planning.
Such changes are long overdue. Surface lots can be particularly damaging to the environment since paved surfaces contribute to urban heat island effect (UHI), which can lead to increases in summertime carbon footprint of surface parking lots, peak energy demand, air conditioning costs, air pollution and greenhouse gas emissions. But with some planning, according to Jobin, this effect can be minimized.
“To help combat UHI effect, designers and planners are utilizing cool paving materials in their surface lots,” he explained. “These materials are lighter in color and permeable, allowing for air movement and evaporation.”
Alternative paving methods are also replacing traditional asphalt or concrete. These pavers remove the pollutants and sediments that accumulate in stormwater runoff, as well as control the amount of runoff released into local water supplies.
One example given by Jobin features porous pavement and a stone reservoir underneath the surface lot.
“Stormwater passes through the porous pavement into the reservoir,” he explained, “which helps filter the water of automobile oil, grease and sediment that frequently accumulates in parking lots.”
If soil conditions are right, no sewer pipes are necessary, as the filtered stormwater is absorbed back into the natural aquifers in the earth.
“In the locations where pipes are necessary, the porous pavement and stone reservoir ensure stormwater is released at a much slower rate than in a typical drainage infrastructure system, guaranteeing a municipality’s sewer system is not overwhelmed,” Jobin said.
Other examples of effective alternatives to traditional asphalt or concrete include interlocking concrete blocks, gravel, paving stones, wood mulch and brick.
Trees and other canopies that offer shade can further lessen UHI. The placement of nearby buildings can provide a similar effect at critical sun times.
A rain garden is another landscape solution that can be used to reduce a surface lot’s negative effects on the environment. Positioned inside an “island” at the end of a parking row, rain gardens feature specially engineered planting soils and selected plants.
“The soil and vegetation helps lower nitrogen and phosphorus levels in stormwater before it’s collected in a stone reservoir below the surface,” Jobin said. “The stormwater is then absorbed into the ground or discharged into a municipal sewer system.”
A bio-ware is another popular landscape element. Featuring dense vegetation, bio-swales are open channels or depressions that modestly slope to a destination. Stormwater captured in the bio-swale moves down grade, is slowly treated (the vegetation helps remove pollutants), and then released to into the ground or storm sewer.
“However, unlike rain gardens, bio-swales require a large amount of surface space to properly work,” Jobin advised.