Since Hurricane Katrina,1 the U.S. has been hit by several major hurricanes, including: 2005: Ophelia, Rita, Wilma 2007: Humberto 2008: Dolly, Gustav, Ike 2011: Irene 2012: Sandy Weather—and especially extreme weather— takes a toll on the building envelope, particularly roofing. Gale-force winds can dislodge roof shingles and lift rubberized sheet like paper. Falling tree limbs and sharp blowing debris are capable of cutting roofing as easily as a backhoe. Water can penetrate cracks, seams, and flashings and expand and freeze after winter storms. In addition, torrential rainfall or rapid snowmelt can quickly overwhelm building drains and gutters, as well as municipal stormwater management systems and local waterways. Responding to concerns of global climate change and the increasing incidence of extreme precipitation events,2 city governments3 and others continue to evaluate and encourage effective stormwater management to reduce urban runoff. Chicago, Philadelphia, New York, Seattle, and Portland all have stormwater management or incentive programs, as do many states and counties. These may include tax credits, water-rate discounts, and grants to building owners for sustainable designs, including roofing systems. BLUE ROOF BENEFITS AT A GLANCE Rooftop detention, also known as a blue roof or controlled-flow system, is an easily installed, cost-effective solution to temporarily store and gradually drain rainwater from the roof of a building. These systems: • Control the flow of water into local sewer systems • Help minimize runoff of contaminants into local waterways • Reduce the impact of peak stormwater on wastewater treatment plants. Blue roofs protect waterways from pollutants by reducing runoff during peak flow 1 2 • I n t e r f a c e Ma r c h 2 0 1 5 Figure 1 – Cutaway of typical assembly for plazas and inverted roof membrane assemblies (IRMA). Blue roofs can be designed in traditional insulated assemblies where retained water is visible, or in inverted or traditional insulated assemblies where retained water is concealed below pedestal-mounted pavers. Drainage mats or grids may also be required. periods and enabling more mixed stormwater and sewage to be treated at wastewater treatment plants. They also reduce the risk of sewer systems being overwhelmed, of street and driveway flooding, and of sewer backups in basements. Blue roofs work by retaining stormwater runoff and, through restricted-flow drains, allowing it to slowly enter the sewer system. These special roofs hold up to three inches of water and require high-quality, durable, waterproofing assemblies designed for rooftop detention use. They are typically designed to retain water for up to 24 hours. Delayed discharge gives local sewer systems a chance to recover and wastewater treatment systems a chance to process stormwater from other sources. Blue roofs are sometimes used in tandem with roof gardens and site landscaping to minimize watering requirements and maximize water retention at a site. Excessive rainfall may still overwhelm a local stormwater system, but collectively, the value of blue and green roofs can add up. While the impact of any single building may be small, every blue or green roof project and every building that uses these sustainability concepts serves as a beacon for others to follow. While there are other approaches, cold, liquid-applied reinforced membrane systems are in demand for sustainable waterproofing design, especially on many urban projects, because they offer a combination of advantages that help eliminate many of these concerns, including the most common causes of building leaks. (See Figure 1.) For these same reasons (summarized below) they are also valued for waterabsorbing green roofs and as stormwater detention systems (blue roofs), where they can act as a first line of defense against excessive precipitation. Of course, there are capacity and saturation limits. But if the pace of extreme weather is accelerating, blue and green roofs can also buffer less extreme precipitation events that also may be more frequent. (See Figure 2.) INSTALLATION • A monolithic waterproofing membrane system is seamless and bonds fully to substrates, including vertical surfaces. • Liquid-applied, resin-reinforced systems are self-flashing and self-terminating. This eliminates a common source of leaks, as well as the need for separate flashing materials and associated labor. PRECON is a composite sheet membrane comprised of a nonwoven fabric and elastomeric membrane bonded to an exclusive plasmatic matrix. This product provides a permanent seal between the membrane and poured concrete wall or floor. It helps prevent moisture migrat ion into the st ructure and improves resistance to termites, methane and radon gas. Make PRECON part of your next foundation waterproofing system. © W. R. MEADOWS, INC. 2015 For a solution based on your needs, visit wrmeadows.com or call 1-800-342-5976. WR_Meadows_ Precon_RCI_Interface_jan_Layout 1 1/ Ma r c h 2 0 1 5 I n t e r f a c e • 1 3 Figure 2 – The National Oceanic and Atmospheric Administration (NOAA) combines the averages of multiple above- and below-normal weather conditions across the continental U.S. This graph, limited to data on singular extreme one-day precipitation events, shows a distinct uptick in the data since 1970, as noted by the red line. Source: NOAA.4 Figure 3 – Illustration of sustainability features. 1 4 • I n t e r f a c e Ma r c h 2 0 1 5 WEAR LIFE • Fully reinforced membrane systems are available that resist chemicals, corrosives, UV light, rot, and roots— and that are unaffected by standing water, snow, and ice. • Because of the full substrate bonding, it is easy to pinpoint leaks due to damage from storms, etc. Damaged areas require only localized repair. • Extended warranties are available for terms of 20 years or longer. • An additional layer of a reinforced membrane system can be applied at any time over properly supported substructures, including existing reinforced membranes (overlay), to extend or completely renew service life for another term. RENEWABLE MATERIALS • Solvent-free and odor-free membrane systems are available with resins based on renewable resources. When the membrane must finally be removed, materials are inert. • Solvent-free and odor-free systems are especially important for schools, medical facilities, and occupied buildings, as well as new construction. Since the liquid resin is applied cold, it is also safer for applicators. These collective attributes also make these reinforced systems ideal for white roofs with high reflectivity that can reduce building cooling requirements. Blue, green, or white roofing may also qualify for LEED credits such as: LEED Stormwater Design SS Credit 6.1 (1 point) SS Credit 6.2 (1 point) LEED Heat Island Effect SS Credit 7.2 (1 point) BEACON OF SUSTAINABLE DESIGN Today, sustainable design goes well beyond the traditional goal of energy efficiency and implies a “triple bottom line” that considers people, the planet, and profitability. It generally means taking a longerterm view, which may imply a higher initial capital outlay in favor of solutions that last longer and are more cost-effective in the long run. Perspectives may differ, but it appears the global environment is already in transition. So the question for decision- makers becomes, “How quickly do we choose to adapt?” The Belfer Medical Research Building at Weill Cornell Medical College in New York, NY, offers a variety of sustainability features, including a “blue roof” stormwater detention system. (See Figure 3.) THE BELFER MEDICAL RESEARCH BUILDING BLUE ROOF The Belfer Medical Research Building, designed by Todd Schliemann of Ennead Architects (New York, NY), includes three roof levels at the 17th, 18th, and 19th floors. The rainwater detention system not only helps regulate stormwater discharge, but it also feeds a water fountain and irrigates planters on the second-floor terrace. The system uses a solvent-free and odor-free cold liquid-applied membrane system for waterproofing the blue roof as well as the terrace and fountain on the lower level. The reinforced membrane system is Ma r c h 2 0 1 5 I n t e r f a c e • 1 5 American Hydrotech, Inc. 303 East Ohio | Chicago, IL 60611 | 800.877.6125 | www.hydrotechusa.com © 2015 Garden Roof is a registered trademark of American Hydrotech, Inc. American Hydrotech introduces the Garden Roof® Planning Guide iPad® app – a first-of-its-kind digital brochure that helps design professionals take a vegetated roof from initial concept to completion. Packed with photography, technical information and videos, design professionals can explore assembly options and components, growing media and vegetation, and learn about topics such as design considerations, economic and sustainable benefits, installation and maintenance, and much more. 19 years of vegetated roof experience… brought to life in one app. Download your copy today at hydrotechusa.com/GRPG designed for a long service life and is backed by an extended warranty. Eagle One Roofing Contractors, Inc. (Astoria, NY) applied the waterproofing membrane and is a manufacturercertified applicator. The two-part resin system fully adheres to the substrate and is fully reinforced with 165g fleece. The resulting membrane is completely seamless and unaffected by ponding water and ice. 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. 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 complies with New York City requirements and can hold up to three inches of water (Figure 4). Carrying the Load Water is densest at 39ºF (4ºC). One cubic foot of water weighs 62.427 pounds, or 5.2 pounds per square foot per inch of depth. The supporting structure below was designed to carry the water load, with an allowance for heavy snow or ice buildup. The roof deck is a concrete slab and includes a layer of rigid insulation above 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 that are sometimes required for rainwater detention systems that use holding tanks. ENERGY-EFFICIENT CURTAIN-WALL DESIGN On the south side of the building, Ennead created a double-skinned, frittedglass 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. (See Figures 5 and 6.) 1 6 • I n t e r f a c e Ma r c h 2 0 1 5 Belfer Medical Research Building, built and equipped at a cost in excess of $630 million, opened in January 2014. The 19-story state-ofthe- art landmark structure is 260 ft. long x 100 ft. wide at the base, and the tower includes 13 stories of research laboratories equipped with advanced research instruments. Interior spaces are designed to foster collaboration of cross-disciplinary research teams. What was your role on this project? The strategic plan for Weill Cornell Medical College outlined the basic purpose of the new research building. My role was to be in charge of the architectural programming effort and to manage all the design phases up until the project was awarded for construction. What is involved with architectural programming, and what was the process? Architectural programming develops a plan for the interior, which begins by listing all the spaces in the building and their relationships to one another. It also lists all the facilities that should be in the building (such as laboratories, meeting rooms, offices, social spaces). This is usually accomplished by interviewing the people in the user groups— in the consulting, research, and educational programs—that are going to be in the building. The Belfer Research Building was interesting to program because at the onset, we didn’t know what specific research would go into the building as it was being designed. So the research facilities were designed in a fairly generic way. We tried to design spaces that could be used by almost anyone. That was done by assembling a panel of our faculty who consulted with us to help us develop the space program for the building. How is this programming project different than others at Weill Cornell Medical College? The programming for this building is a real departure for us at Weill Cornell. Up to now, laboratories and academic space have always been assigned to the various academic departments—such as medicine, surgery, or biochemistry—and each department has its own labs. The Belfer Research Building is different because we want to encourage collaborative research across various departments, concentrating on various diseases. For instance, we will have laboratories researching brain and mind diseases, and we may have researchers there working side-byside with those from the departments of neurology, neurosurgery, or psychiatry. We are assigning laboratory spaces with these groupings in mind, and we have a connecting stair between every pair of floors to encourage communication. So we are breaking down traditional academic silos and developing a cross-disciplinary approach to problem- solving and research innovation. Other areas of research focus include cardiovascular and pediatric diseases. What about LEED and the broader context of sustainability? All of our construction at the Weill Cornell Medical College—both interior renovations and new construction—is designed to meet a minimum LEED Silver status. We are a party to the university presidents’ agreement among multiple universities pledging to make their buildings sustainable. Then there is New York City Mayor Bloomberg’s Plan 2030 to increase sustainability of city buildings by that year. Between these various mandates, we design everything to earn LEED Silver status. Belfer, though, is the first building for which we’ve applied for Gold certification—the nationally accepted benchmark for the design, construction, and operation of high-performance green buildings. Weill Cornell Medical College. An Interview With Campus Architect Bill Cunningham Continuous ribbon windows flood the building with natural light and energyefficient HVAC, while lighting control and water-conservation systems save on power and resources (Figure 6). The building’s green infrastructure is expected to shrink Weill Cornell’s energy bill 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. HVAC The building includes a high-tech, multizoned 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, with 40. In addition to thermostats and humidity Roof Testing CSA A123.21-14 – Exp has been conducting tests since 2007. – FM-4470 is no longer used as the basis for specifications for non-insured buildings. – CSA A123.21-14 has been based on NBC requirements since 2005. – CSA A123.21-14 is likely to be included in the 2015 NBC. – Get a customized waterproofing system that meets your actual needs, at a lower cost. – Benefits such as increased service life of roof covering materials. Michel Desgranges, T.P. Director of Roofing & Waterproofing t : 1.819.850.6247 | m : 1.819.314.6995 michel.desgranges@exp.com 2400, rue Canadien Drummondville, Qc J2C 7W3 CANADA First laboratory ISO 1705 in North America! Ma r c h 2 0 1 5 I n t e r f a c e • 1 7 Figure 4 – Roof with active venting system. Hidden below the pavers on the “blue roof” of the Belfer Medical Research Building, a cold liquid-applied reinforced membrane system encapsulates and wraps all penetrations and curbs. The assembly includes a drainage layer below the insulation. Figure 5 – Double-skinned curtain wall with openings. sensors, indoor spaces utilize occupancy sensors to assist in regulating the ambient indoor environment and lighting to improve energy efficiency. REFERENCES 1. “Since Hurricane Katrina.” NOAA. List of All U.S. Hurricanes. http://www. aoml.noaa.gov/hrd/hurdat/All_U.S._Hurricanes.html. Accessed January 15, 2015. 2. From “Climate Change Indicators in the United States: Heavy Precipitation.” U.S. EPA. Updated August 2013. www.epa.gov/climatechange/ indicators. Accessed June 2014. 3. Water Environment Research Foundation (WERF) www. werf.org. Accessed June 2014. 4. National Oceanic and Atmospheric Administration (NOAA). “U.S. Climate Extremes Index: Extremes in 1-Day Precipitation (Contiguous U.S.) Step 4. http://www.ncdc.noaa.gov/ extremes/cei/graph/4/01- 12. Accessed January 16, 2015. 1 8 • I n t e r f a c e Ma r c h 2 0 1 5 At your own pace, on your own time, at your fingertips … Roof Drainage Design Roof System Thermal and Moisture Design Roofing Basics Roofing Technology and Science I Roofing Technology and Science II Rooftop Quality Assurance Wind Design for Low-Slope Roofs – Part I: Understanding ASCE 7-05 Wind Load Calculations for Members Wind Design for Low-Slope Roofs – Part I: Understanding ASCE 7-10 Wind Load Calculations Wind Design for Low-Slope Roofs – Part II: FM Global Guidelines and Best Practice Considerations Online Educational Programs www.rci-e-learning.org Brian Kelly, CSI, CDT, is National Project Design & Specification Manager for Kemper System America (West Seneca, NY). Kelly delivers AIAcredited presentations on blue roofs, green roofs, and other sustainability topics at American Institute of Architects (AIA) forums and other venues around the country. Kemper System is a global leader in roofing and waterproofing technology and holds the original patents on cold liquidapplied reinforced membrane systems. Brian Kelly, CSI, CDT Figure 6 – Cutaway of the curtain wall design.
