Built in 2003, the David L. Lawrence Convention Center was the world's first green convention center and was awarded the Gold LEED??????+ certification for a new building. Thanks in part to a newly installed 20,000 square foot green roof, the convention center is now Platinum LEED??????+ certified for an existing building.

Surrounded by windows, the South Terrace space serves as a flexible event area while showcasing the benefits of green roofs. A plaza allows space to set up for large banquets yet is still intimate enough to entertain small groups. The dynamic yet simplistic design sets the urban mood and helps highlight the existing sculptural cable bundles that hold the iconic sweeping roof in place.

The 20,000-square-foot South Terrace Green Roof: solidifies the Convention Center as a national leader in green technologies; creates a half an acre of green space in an urban setting; helps attract events looking for green facilities; and teaches the environmental benefits of green roofs and native meadow plants to hundreds of thousands of people who visit every year.

Sustainability
Environmental goals included reducing stormwater runoff, energy costs, and the urban heat island effect. Interpretive signage was used to illustrate the benefits of green roofs and identify some of the native plants that contribute to biodiversity and habitat.

 
Through natural root intake processes and evapotranspiration, the plants remove pollutants from the air; an estimated amount equal to the annual air pollution generated by 255 cars.

To minimize irrigation water, a soil monitoring and relay control system was installed to track green roof soil moisture and temperature. It is estimated that the roof retains up to 80 percent of stormwater.

The white pavers used on the terrace plaza have the high solar reflectance index of 85 in order to reduce temperatures. In addition, studies have shown that green roofs remain up to 50 degrees cooler on hot summer days.

And during construction, 73% of the former roof materials were recycled or donated while 60% of purchased materials met sustainable requirements.

Landscape Architect's Scope
Transforming an existing unused leaky roof into a 20,000 square foot green oasis, project goals for the South Terrace included creating an attractive space that anybody could rent, serving as an educational tool promoting the environmental benefits of green roofs and increasing the economic stability of the convention center.

Pashek + MTR contributed the master plan, schematic design, design development and planting plan.

The intent was to create a dynamic yet simplistic design to set the urban mood and help highlight the existing sculptural cable bundles that hold the iconic sweeping roof in place. Specified to have recycled glass blasted pavers, the meandering blue pathway that divides a native meadow from a low growing sedum planting was meant to symbolize the nearby Allegheny River and stormwater runoff. The path also allows visitors to wander away from the event plaza and explore the plantings and cable bundles in more detail.

The landscape architect, engineers, and other green roof specialists collaborated with the client to achieve the installed design; weighing options of materials against aesthetics, durability, and cost. In addition to the client, the landscape architect was required to work with a developer, facilities manager, and roofing contractor to create a design that met all the stakeholders' needs.

Environmental Impacts
Besides reductions in stormwater runoff and roof surface temperature, contributing to a moderation of the urban heat island effect, the impacts include decreased energy use by cutting roof to temperature fluctuations, which eases heat loss in the winter and heat gain in the summer. In addition, construction of the green roof meant that less of the removed materials were sent to a landfill.

The design also led to increases in: biophillic advantage, species biodiversity, roof membrane longevity and the marketing value of the Convention Center while it enhances the visitor experience by reconnecting humans to the natural environment.

The unique, yet simple design concept has captured the attention of numerous agencies, which have used built photos of the project on their websites and printed materials to demonstrate effective green strategies in the Pittsburgh region. These include: Pittsburgh Sewer and Water Authority on their Pittsburgh Green Infrastructure website (The PWSA is currently under consent order with the Pennsylvania Department of Environmental Protection to reduce combined sewer overflows in Pittsburgh's rivers); Three Rivers Wet Weather, a non-profit environmental organization also focused on addressing our region's wet weather overflow issues to improve local waters; and this year's "Greenroofs and Walls of the World" calendar.

In addition, the project was given the Honor Award for Outstanding Professional Design, from the Pennsylvania/Delaware Chapter of the American Society of Landscape Architects.

As seen in LASN magazine, January 2020.