Medical Research Facility Showcases Eco-Social Construction

Kemper System Belfer Medical Research Building

The rooftop on the Belfer Medical Research Building not only houses HVAC equipment but serves as a rainwater detention system. The reinforced membrane waterproofing system by Kemper System was applied to the roof deck before the pavers were put in place on a pedestal system.

The Belfer Medical Research Building on the campus of New York’s Weill Cornell Medical College was designed to be a 19-story model of eco-social construction. Designed by Todd Schliemann of Ennead Architects, the building showcases a number of sustainability features, including a storm water detention system on the roof.

Built for a cost of more than $630 million, the tower includes 13 stories of research laboratories. The tower has three roof levels at the 17th, 18th and 19th floors. The rainwater detention system, known as a “blue roof,” not only helps regulate storm water discharge, but it feeds a water fountain and irrigates planters on the second-floor terrace.

In general, rainwater detention systems can either collect water in holding tanks and then meter it to the public sewer system, or retain it on a waterproofed roof expanse. The blue roof on the Belfer Research Building uses the latter strategy. It complies with New York City requirements and can hold up to 3 inches of water.

Roof Materials

Proper waterproofing on the project is essential. The solvent-free and odor-free KEMPEROL 2K-PUR cold, liquid-applied membrane system was used for waterproofing the blue roof. It was also used on the terrace and fountains on the lower level. The reinforced membrane system is designed for long service life and backed by an extended-wear warranty.

Eagle One Roofing Contractors Inc. of Astoria, N.Y., a certified applicator of the Kemper System, applied the waterproofing system. The two-part resin system is designed to fully adhere to the substrate, and is fully reinforced with fleece. The resulting membrane is completely seamless and unaffected by ponding water and ice. According to the manufacturer, it resists exposure to UV light, chemicals, oils and solvents. It is impervious to bio-deterioration and is both root- and rot-resistant, so it is also ideal for green roofs and landscaped areas.

Roof Report

The supporting structure below the roof was designed to carry the water load, with an allowance for heavy snow or ice buildup. The roof deck is concrete slab and includes a layer of rigid insulation below the waterproofing membrane for added energy efficiency. The gravity-fed drainage system was carefully sized to control the speed of drainage without the use of pumps, sometimes required for rainwater detention systems that use holding tanks. On the roof sections, the waterproofing sections were topped with concrete pavers on a pedestal system.

Construction at the Weill Cornell Medical College, both interior renovations and new construction, is designed to meet a minimum LEED Silver status. This project was designed to achieve Gold certification, the nationally accepted benchmark for the design, construction and operation of high-performance green buildings.

This illustration shows the assembly used for the blue roof on this project. The cold, liquid-applied reinforced membrane system was topped by concrete pavers. Image: Kemper System America Inc.

This illustration shows the assembly used for the blue roof on this project. The cold, liquid-applied reinforced membrane system was topped by concrete pavers. Image: Kemper System America Inc.

On the south side of the building, Ennead created a double-skinned, fritted glass curtain wall with openings and sun-shading devices that absorb the sun’s heat before it gets trapped inside, which would require the HVAC system to pump out more cold air. Continuous ribbon windows flood the building with natural light, and energy-efficient HVAC, lighting controls and water-conservation systems save on power and resources. The building’s green infrastructure is expected to shrink Weill Cornell’s energy bill for it by about 30 percent and reduce carbon dioxide emissions by about 26 percent compared to a building complying with the minimum requirements set by typical industry guidelines and standards.

The building includes a high-tech, multi-zoned HVAC control system to manage the indoor environment within different spaces. Biomedical laboratories, for example, generally require special air filtration systems supported by high-volume air circulation. Each of the laboratory levels includes four fume vents to the outside, except for the chemistry laboratory on the top floor, which uses 40 vents. In addition to thermostats and humidity sensors, indoor spaces utilize occupancy sensors to assist in regulating the ambient indoor environment and lighting to improve energy efficiency.

Photo: Kemper System America Inc.

TEAM

ARCHITECTS
Todd Schliemann, Ennead Architects, LLC, New York
William Cunningham, Weill Cornell Medical College, New York

ROOFING CONTRACTOR
Eagle One Roofing Contractors, Inc., Astoria, N.Y.

ROOF AND WATERPROOFING SYSTEM MANUFACTURER:
Kemper System America Inc., West Seneca, N.Y.

From Green to Blue: Making Roof Systems Sustainable in Urban Environments

Municipal storm-water managers historically have focused on controlling runoff from ground-level impervious surfaces, such as roadways, sidewalks and parking areas. However, the next frontier in storm-water management is rooftops. In urban storm-water management, roofs are part of the problem and potential solution. An exciting new technology to control rooftop runoff is known as blue roofs. Over the next several years, New York City alone will spend several billion dollars on green infrastructure solutions to address its storm-water-control problem, and blue roofs will be a key part of these efforts.

Blue-roof trays are held in place with stone ballast and hold up to 2 inches of water. The tray systems resulted in a 45 percent reduction in roof runoff during rainfall events in a New York pilot project.

Blue-roof trays are held in place with stone ballast and hold up to 2 inches of water. The tray systems resulted in a 45 percent reduction in roof runoff during rainfall events in a New York pilot project.

Blue Roofs

The roofing industry has become very familiar with the use of vegetated, or green, roofs. The vegetative layer grown on a rooftop provides shade and removes heat from the air through evapotranspiration, ultimately reducing temperatures of the roof surface and the surrounding air. By reducing the heat-island effect, these buildings require less energy to cool in the summer and use fewer natural resources (oil or other fuel) in the process.

However, an even newer and less-well-known sustainable technology applicable to roofs is the blue roof. A blue roof temporarily stores rainwater in any of a number of types of detention systems on the roof. They are most applicable and provide the most benefit in highly urbanized cities that are serviced by combined sewers. Combined sewers handle sewage and rainwater runoff from roofs, streets and other impervious surfaces. On dry days, these combined sewers can easily handle the amount of sewage flowing through them to the local treatment plant. However, on days with heavy rain, these combined systems can easily overflow with rainwater and raw, untreated sewage. This combined sewer overflow, or CSO, can flow into local sensitive receptors, like streams, ponds and oceans, contaminating the natural resources and killing fish and other wildlife dependent on them.

The beauty of blue roofs is they can store much of this rainwater during and immediately after a rainstorm, temporarily preventing it from reaching the sewer system. In this way, CSOs are minimized and local natural resources are protected. When the storm is over and the sewer system has the capacity to handle it, the blue-roof retention materials are designed to slowly release the stored rainwater back into the storm-drain system.

This blue roof in New York uses a check dam to retain storm water.

This blue roof in New York uses a check dam to retain storm water.

NYC Pilot Program

Our firm, Geosyntec Consultants, along with environmental engineers Hazen and Sawyer and HydroQual and water-management firm Biohabitats, designed and implemented a groundbreaking blue-roof system in New York. The New York City Department of Environmental Protection (NYCDEP) retained the team to implement a sustainable green infrastructure retrofit pilot program to demonstrate how rooftops can reduce the frequency and volume of CSOs in the city. The objective was to design and install storm-water controls to quantify the benefits of sustainable approaches as a viable solution to reduce storm-water flows to the city’s CSO system. Rainfall of less than 1/2 inch can overload the system and result in untreated discharges. The use of sustainable green infrastructure, like blue roofs, to reduce storm-water inputs to the combined system is one of many approaches New York City is considering to help solve this problem.

Geosyntec’s role on the team was to design several storm-water pilot studies, including blue roofs. Our blue-roof designs included installing risers on rooftop outlets that would result in ponding of water around the outlets, small dams on the roof surface using check dams of angle-iron to create ponding and the most successful technique—blue-roof trays. We developed specially designed trays, held in-place with stone ballast, to hold up to 2 inches of water. The tray systems resulted in a 45 percent reduction in roof runoff during rainfall events. If blue-roof trays were installed on all roofs in an entire drainage area to a CSO, the results would be significant in solving the CSO problem. In addition, trays are more practical because they can be spaced around existing equipment on roofs and moved during repairs and maintenance of other rooftop systems.

Geosyntec Consultants designed a blue roof that included installing risers on rooftop outlets that would result in ponding of water around the outlets.

Geosyntec Consultants designed a blue roof
that included installing risers on rooftop outlets that would result in ponding of water around the outlets.

Roof-system Protection

Protecting the integrity of a roof membrane is an important consideration for roofing and building contractors that are considering installing a blue roof. Blue-roof-tray systems offer the best protection because they rest on top of existing membranes and ballast systems and do not result in any membrane perforations that require additional waterproofing. Other blue-roof systems, like check dams or new drain inserts, may require additional waterproofing. The bottom line is if the roof membrane is old, compromised or currently leaking, any type of blue roof would be problematic until a new membrane is installed.

In addition, during the pilot projects, we took great care to inspect and test the roofs for load-bearing support—a step that should be conducted for all blue and green roof systems.

As we look to the future, roofs in urban areas will most definitely become a major part of the storm-water solution, and blue-roof technologies will evolve to become a common practice.

Learn More

NYCDEP has posted information about blue roofs and other urban green infrastructure for CSO control on its website.
The U.S. Green Building Council offers an online course about blue roofs for storm-water management.

PHOTOS: Geosyntec Consultants

Downtown Storm-water Management

Founded in 2002, Xero Flor America (XFA) is the official U.S. distributor of the Xero Flor Green Roof System. XFA has made its home in Durham, N.C., since 2006 when the company relocated its national headquarters from Lansing, Mich. In July 2012, it moved locally into renovated offices in The Republik Building, located at 211 Rigsbee Avenue in downtown Durham’s historic district.

Originally constructed in the 1940s for the Durham Insurance Service Co., The Republik Building is perhaps known to local history buffs as the home of WSSB radio. Robert Shaw West, chairman and CEO of The Republik, a local firm offering brand strategy and communication services, purchased the property from the city of Durham. He renovated the outmoded offices into a more contemporary, open and collaborative work environment in 2006. XFA decided to become more connected to the business community downtown and searched for offices in the historic district—ideally in a building where the company would have the opportunity to showcase its green roof system. West had space available on the second floor for XFA to lease.

Completed in February 2013, the 2,343-square-foot Xero Flor green roof atop The Republik Building is the first green roof installed on a building in Durham’s downtown historic district.

Completed in February 2013, the 2,343-square-foot Xero Flor green roof atop The Republik Building is the first green roof installed on a building in Durham’s downtown historic district.

“It was serendipity,” West says. “Xero Flor was looking for offices downtown, and we had space. Plus, we had to reroof our building last year. Since we needed a new roof, it was an ideal time to also consider adding a green roof, which supports our commitment to sustainability.”

Completed in February 2013, the 2,343-square-foot Xero Flor green roof atop The Republik Building is the first green roof installed on a building in Durham’s downtown historic district.

Going Green on the Roof

In addition to the standard building-permit process, putting a green roof on a historic building required additional review and approval.

According to Anne Kramer, urban designer with the Durham City-County Planning Department, except for certain minor items, such as repainting a previously painted surface, most changes to building exteriors within an official historic district require a Certificate of Appropriateness (COA). The Durham Historic Preservation Commission oversees the process locally.

The commission’s goal is to ensure preservation of the architectural character of the historic district’s buildings and, therefore, had to ensure adding a green roof to the building would not alter or disrupt the appearance of downtown Durham. Demonstrating a green roof would not be visible from the street level was especially important. With the COA from the preservation commission, XFA and The Republik had the green light for the green roof. But first Baker Roofing, Raleigh, N.C., installed the new structural roof.

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