Project Profiles: Education Facilities

Maury Hall, U.S. Naval Academy, Annapolis, Md.

TEAM

Roofing Contractor: Wagner Roofing, Hyattsville, Md.
General Contractor: C.E.R. Inc., Baltimore, (410) 247-9096

The project included 34 dormers that feature double-lock standing-seam copper and fascia metal.

The project included 34 dormers that feature double-lock standing-seam copper and fascia metal.

ROOF MATERIALS

Wagner Roofing was awarded the complete replacement of all roof systems. These included an upper double-lock standing-seam copper roof system, a bullnose copper cornice transition, slate mansard, 34 dormers with double-lock standing-seam copper and fascia metal, eight copper hip metal caps and a continuous built-in gutter with decorative copper fascia. Each of the dormers also had a copper window well.

The upper standing-seam roof was removed and replaced with 24-inch-wide, 20-ounce copper coil rollformed into 1-inch-high by 21-inch-wide continuous standing-seam panels that matched the original profile. The eave bullnose, which also served as the mansard flashing, was removed and returned to Wagner Roofing’s shop where it was replicated to match the exact size and profile.

The 34 dormer roofs were replaced with 20-inch-wide, 20-ounce copper coil formed into 1-inch-high by 17-inch- wide continuous standing-seam panels. The decorative ornate fascia of the dormers was carefully removed and Wagner’s skilled craftsmen used it as a template to develop the new two-piece copper cornice to which the roof panels locked. The cheeks and face of the dormers were also re-clad with custom-fabricated 20-ounce copper.

The oversized built-in-gutter at the base of the slate mansard was removed and replaced with a new 20-ounce copper liner custom-formed and soldered onsite. The replacement included a specialty “bull-nosed” drip edge at the base of the slate and an ornate, custom-formed fascia on the exterior of the built-in gutter. The decorative copper fascia included 85 “hubcaps”, 152 “half wheels” and 14 decorative pressed-copper miters. The original hubcap and half-wheel ornaments were broken down and patterns were replicated. Each ornamental piece was hand assembled from a pattern of 14 individual pieces of 20-ounce copper before being installed at their precise original location on the new fascia. The miters were made by six different molds, taken from the original worn pieces, to stamp the design into 20-ounce sheet copper.

In all, more than 43,000 pounds of 20-ounce copper was used on the project.

Copper Manufacturer: Revere Copper Products

ROOF REPORT

Maury Hall was built in 1907 and was designed by Ernest Flagg. Flagg designed many of the buildings at the U.S. Naval Academy, including the Chapel, Bancroft Hall, Mahan Hall, the superintendent’s residence and Sampson Hall. His career was largely influenced by his studies at École des Beaux-Arts, Paris. Examples of Flagg’s Beaux-Arts influence can be found in the decorative copper adorning the built-in gutter on building designs.

Maury Hall currently houses the departments of Weapons and Systems Engineering and Electrical Engineering. The building sits in a courtyard connected to Mahan Hall and across from its design twin, Sampson Hall.

PHOTO: Joe Guido

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Using Engineered Geofoam for Garden Roofs

For most of the past century, the rooftops of commercial and institutional buildings have largely been places to locate unsightly mechanical systems. Architectural treatments, such as parapets and screens, provide visual relief from such equipment. Now, roofing professionals and building owners increasingly look at the roof as “found space”—a place to be planted and used, instead of hidden.

Facebook’s Frank Gehry-designed MPK 20 building sports a 9-acre green roof using EPS geofoam from Insulfoam.

Facebook’s Frank Gehry-designed MPK 20 building sports a 9-acre green roof using EPS geofoam from Insulfoam.

Throughout the U.S., garden roofs (or living roofs) are growing in popularity with more than 5.5 million square feet installed in 2014, according to Green Roofs for Healthy Cities. Most of that total was for private rather than public projects, indicating this is not just a government trend. In addition to providing attractive and usable open space, garden roofs offer environmental benefits, such as helping to slow and filter urban run-off.

Some of America’s largest companies have installed green roofs. Ford’s Dearborn, Mich., truck plant final assembly building sports one of the world’s largest living roofs at 454,000 square feet. In 2015, Facebook opened its MPK 20 office building in Menlo Park, Calif., with a 9-acre living roof featuring a 1/2-mile walking trail and more than 400 trees.

If you haven’t worked on a garden roof yet, it is likely only a matter of time until you do.

Addressing the Challenges of Garden Roofs

Weighing a fraction of soil, EPS geofoam fill creates ultra-lightweight landscaped features on Facebook’s garden roof.

Weighing a fraction of soil, EPS geofoam fill creates ultra-lightweight landscaped features on Facebook’s garden roof.


Adding plants and park-like amenities to a roof increases the complexity of the roofing assembly. Garden roofs present two primary challenges for roofing professionals to solve: minimizing the dead load and preventing moisture intrusion.

The project team for the Facebook MPK 20 building’s green roof met this two-fold need—and more—with expanded polystyrene (EPS) geofoam.

Weighing considerably less than soil, EPS geofoam is an ultra-lightweight engineered fill that can be used to create contoured landscape features, such as hills and valleys. The material weighs from 0.7 to 2.85 pounds per cubic foot, depending on the product type specified, compared to 110 to 120 pounds per cubic foot for soil.

Despite its low weight, EPS geofoam is designed for strength and has better load bearing capacity than most foundation soils. Geofoam’s compressive resistance ranges from approximately 2.2 psi to 18.6 psi (317 to 2,678 pounds per square foot) at a 1 percent deformation, depending on the product.

The garden roof on Facebook’s MPK 20 building provides ample open space and a half-mile walking trail for employees.

The garden roof on Facebook’s MPK 20 building provides ample open space and a 1/2-mile walking trail for employees.

EPS geofoam is also effective at addressing the second challenge of garden roofs: managing moisture absorption. The moisture performance of the various components in a green roof assembly is critical; retained water imposes additional loads on the roof and increases the risk of water damage to the roof assembly. EPS geofoam meeting ASTM D6817 standards works well here as it only absorbs 2 to 4 percent moisture by volume, even over long-term exposure, and it dries quickly. The moisture performance of EPS has been demonstrated in extensive in-situ applications and real-world testing, including research conducted by the U.S. Army Corps of Engineers’ Cold Regions Research and Engineering Laboratory. After burying EPS in wetted soil for nearly three years, the lab found that the material absorbed only 1.7 percent moisture by volume.

In addition to enabling lightweight, durable landscape features and helping to defend against water, EPS geofoam provides thermal insulation in garden roofs. Roofing professionals have used EPS insulation in roof assemblies for decades because it offers the highest R-value per dollar among rigid foam insulations.

Expect More Demand

Although green roofs currently account for a small portion of the billions of square feet of roofs in the U.S., expect to see more demand for them given their aesthetic and environmental benefits. High-performance materials, like EPS geofoam, can help provide a long-lasting, durable green roof assembly.

PHOTOS: Insulfoam

A Dynamic Rooftop Renovation Lures a New Type of Workforce

Commercial office properties have always had to contend for tenants as a part of doing business and, increasingly, existing buildings are facing stiffer competition from new office properties offering integrated amenities packages that go way beyond the lobby coffee shop. As a new generation of employees enters the workforce, employers are challenged to secure leases that provide more than simple office space, instead offering an attractive combination of recreation, retail and relaxation options that feel more akin to a resort than a workplace. In the case of Prudential Plaza, a 41-story structure in Chicago built in 1955, the challenge for the building owners was to offer new value in a building originally designed to respond to a workforce that no longer exists.

The rooftop transformation is highlighted by a fully wired amphitheater, fire-pit lounge and a small lawn accompanied by a new 12,000-square-foot fitness center and a 7,000-square-foot clubhouse located inside.

The rooftop transformation is highlighted by a fully wired amphitheater, fire-pit lounge and a small lawn accompanied by a new 12,000-square-foot fitness center and a 7,000-square-foot clubhouse located inside.


Investing more than $85 million into building renovations, Prudential Plaza’s owners envisioned a top-to-bottom rehabilitation, crowned by a 13,000-square-foot amenities deck on the 11th floor. The rooftop transformation is highlighted by a fully wired amphitheater, fire-pit lounge and a small lawn accompanied by a new 12,000-square-foot fitness center and a 7,000-square-foot clubhouse located inside. These amenities are exclusively for building tenants and their employees. Kyle Kamin, a Los Angeles-based CBRE Inc. executive vice president and tenant broker who has clients in Prudential Plaza called the roof deck “a game-changer with an unbeatable view.”

Engineering

Certainly the idea of a gorgeous tenant recreation and lounge area would appeal to most; however, few outside of the design and construction industry would appreciate the immense challenge of adding this type of space on top of a 60-year-old roof. When Wolff Landscape Architecture, Chicago, was asked to partner with Chicago-based architecture firm Solomon Cordwell Buenz for landscape design, project manager Ishmael Joya quickly understood the complexities of the situation. Joya is a landscape architect with 15 years’ experience, specializing in green-roof construction.

“Prudential Plaza is a classic figure in Chicago’s skyline and the first time we walked the project it was clear that the 4 1/2-inch-thick roof deck was going to present some design and construction challenges,” Joya remarks. Although the Wolff Landscape Architecture team has completed many green-roof projects, including renovations, Joya realized that adding what is essentially a mini-park to a very thin structural surface was going to require out-of-the-box thinking. “In any roof-deck renovation, it’s critical to reduce the weight of the building materials because the building is only designed to support a maximum amount of weight and that can’t be compromised,” he says.

Joya worked closely with the design team’s structural engineer, Wiss, Janney, Elstner Associates Inc., Chicago, to make sure the appropriate products were specified to support the expected weight of each area of the renovation

Demolition and Interim Roof

Like many large-scale occupied renovation projects, Prudential Plaza’s overall renovation was executed in multiple phases, allowing construction activities to take place while tenants maintained their typical routines. Romeoville, Ill.-based Preservation Services Inc., a commercial roofing company, was responsible for rehabilitating the original 11th-floor roofing structure. The original roof was a modified bitumen membrane that had been applied directly to a layer of lightweight concrete and covered by 2- by 2-foot pavers. Preservation Services carefully removed the pavers, old membrane and thin layer of concrete.

Investing more than $85 million into building renovations, Prudential Plaza’s owners envisioned a top-to-bottom rehabilitation, crowned by a 13,000-square-foot amenities deck on the 11th floor.

Investing more than $85 million into building renovations, Prudential Plaza’s owners envisioned a top-to-bottom rehabilitation, crowned by a 13,000-square-foot amenities deck on the 11th floor.

Because the building is located adjacent to a series of vaulted streets, the construction team was unable to use a high-reach crane because the weight of the crane would have required special provisions and necessitated street closures. Consequently, crews carried all removed debris down through the freight elevators during the night while the building was largely empty. At the end of each night, a single-ply EPDM membrane was rolled out, seamed and secured to protect the under structure from possible water penetration the next day.

Once demolition was complete, the EPDM was opened in select areas so repairs to the concrete slab could be made by other trades. When repairs were complete, a single layer of torch-applied modified bitumen membrane was applied to the deck along with additional structural steel required to support the added weight of trees, planters, patios and people. Finally, a white, granular-surfaced modified bitumen roof over tapered isocyanurate foam insulation was installed making the undersurface ready for the plaza deck renovation work.

Weight Considerations

Joya recommended a lightweight expanded polystyrene (EPS) material with high compressive strength that is used to reduce axial loading on structures. He has found the product very easy to work with, which saves time and money, ultimately allowing designers to put more of the client’s investment into tangible value users will see and feel rather than subsurface building materials.

On the Prudential Plaza roof-deck renovation, two types of EPS were used. EPS 15 was used in areas that would largely be filled with plants and wouldn’t bear much foot traffic. EPS 46, chosen for its high compressive strength, was used as a structural fill across the design’s many grade changes and in areas that would bear more weight of roof-deck occupants. For Joya, another advantage of using the EPS is being able to see the shape of the assembled product and make any required changes before the concrete is poured and work becomes significantly more complicated.

PHOTOS: Wolff Landscape Architecture

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Projects: Office and Warehouse

BMC ISSAQUAH, ISSAQUAH, WASH.

Because of the steep slope of this roof, the Columbia Roofing & Sheet Metal crew installed 60-mil Sureweld HS (High Slope) TPO.

Because of the steep slope of this roof, the Columbia Roofing & Sheet Metal crew installed 60-mil Sureweld HS (High Slope) TPO.

Team

Roofing Contractor: Columbia Roofing & Sheet Metal, Kent, Wash.
Project Foreman: Rudy Sanchez

Roof Materials

Because of the steep slope of this roof, the Columbia Roofing & Sheet Metal crew installed 60-mil Sureweld HS (High Slope) TPO. HS TPO contains more fire-retardant chemicals in the membrane to help decrease the spread of fire. In addition, 1/4-inch Securock Glass-Mat Roof Board was installed, which gave the building a Class A fire rating while helping protect against moisture and mold.

TPO Manufacturer: Carlisle Syntec Systems
Roof Board Manufacturer: USG

Roof Report

BMC Issaquah manufactures doors and high-end cabinetry. The industrial building features a 525-square barrel roof that was very wet and experienced dry rot. The crew replaced nearly 150 sheets of plywood throughout the project.

The main challenge during installation was safety because of the extreme slope. The barrel roof is nearly 60-feet tall from the bottom to the top of the barrel, making installation on the edges difficult because crewmembers had to hot-air weld rolled product on a nearly vertical surface. The HS TPO added another level of difficulty while welding along the edges.

The project was completed on May 1, 2015.

PHOTO: Columbia Roofing & Sheet Metal

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Today’s Roofs Provide Additional Square Footage for Developers and Owners

How much traffic can a roof system bear? The fact is, live loads on roofs are getting much bigger as building developers and owners seek to allow more indoor-outdoor uses and rooftop amenities, such as seating areas, gardens and even fire pits and pools, which draw people to the roof. Plus, the dead load may be increasing thanks to those living material installations, such as planters and vegetative roof gardens. These assemblies usually require or hold water—adding to the dead load—as well as frequent maintenance and inspections, which mean a few more people (and more live load).

Muzeiko, a 35,000-square-foot LEED Gold children’s science discovery center in Sofia, Bulgaria, includes a rooftop science play area with a lush green roof, climbing wall, rain garden, outdoor activity space and an amphitheater. PHOTO: ROLAND HALBE, COURTESY LEE H. SKOLNICK ARCHITECTURE + DESIGN PARTNERSHIP

Muzeiko, a 35,000-square-foot LEED Gold children’s science discovery center in Sofia, Bulgaria, includes a rooftop science play area with a lush green roof, climbing wall, rain garden, outdoor activity space and an amphitheater. PHOTO: ROLAND HALBE, COURTESY LEE H. SKOLNICK ARCHITECTURE + DESIGN PARTNERSHIP


“We’ve known the benefits of a green roof from a water-management point of view for some time,” says Joshua Zinder, AIA, principal of JZA+D, Princeton, N.J., noting that more than 70 percent of the water that hits the roof is absorbed. “Increasingly, we see the roof as an opportunity for generating revenue or enhancing the value of the building. One of the ways we’re now helping developers reposition older office and industrial properties is by determining if we can create roof farms or indoor-outdoor spaces not only on the ground floor, but also on the roof planes.”

The case of the rooftop garden with public access is a growing trend, too, and “one must ensure that the roof structure has the necessary structural capacity to support rooftop activity,” notes Kelly Luckett, author of Green Roof Construction and Maintenance. Local codes vary for live loads and dead loads, he explains, and the project team calculates the green roof assembly as part of the total dead load. “Water in excess of that which saturates the growth media, snow and people visiting the green roof are all considered part of the live load of the structure,” Luckett adds.

Just as important, the roofing system has to resist the wear and tear of the live loading. The three main concerns for exposed structural elements, such as roofs, balconies and terraces, are protection from weathering, water ingress and environmental damage. Pedestrian walkways must also ensure long-term durability.

A look at the latest trends in “activating rooftops” reveals even more reasons for roofing contractors, architects and facility owners to look more carefully at specification documents and installation methods for these live-load roof zones.

A new Department of Sanitation complex in New York City, designed by Dattner Architects with WXY Architecture + Urban Design, both of New York, features a dynamic façade of moving metal fins and a 1.5-acre planted roof, which contribute to the LEED Gold operations. PHOTO: WADE ZIMMERMAN, COURTESY WXY ARCHITECTURE + URBAN DESIGN

A new Department of Sanitation complex in New York City, designed by Dattner Architects with WXY Architecture + Urban Design, both of New York, features a dynamic façade of moving metal fins and a 1.5-acre planted roof, which contribute to the LEED Gold operations. PHOTO: WADE ZIMMERMAN, COURTESY WXY ARCHITECTURE + URBAN DESIGN

Skylife and Community

For residential projects with rooftop terraces, careful specifying and installation of green roof assemblies is critical. “We like using liquid membrane roof and extensive green-roof systems, such as sedum carpet,” says Andrew Franz, AIA, LEED AP, principal of Andrew Franz Architect PLLC, New York, adding that the systems work well because the drainage mat is modular, lightweight, and easy to install and adjust—something that is important on uniquely shaped urban rooftop terraces.

Recent projects by Franz include a 2,800-square-foot garden terrace for a family of four in Manhattan. A bluestone floor extends from the dining area to the terrace’s softscape herb garden, further blurring the boundary between in-doors and out. “The green roofing system also includes a protection mat, which protects the roof membrane, a filter sheet of very lightweight soil to protect the drainage mat and the sedum carpet,” Franz says.

Other recent projects with active green roofs demonstrate the benefits of strong PVC membranes, such as at the modern 93 Bright Street townhouse in Jersey City, N.J., designed and developed by Jorge Mastropietro, AIA, whose firm JMA is based in New York City’s Soho neighborhood. Another example, called Trouthouse, designed and built by the Brooklyn-based thread collective, is a showcase of “passive design” principles that reduce energy use, recapture water and even allow for a roof-mounted shade structure that doubles as photovoltaic panels.

The new LEED Gold-certified facility for Gateway Community College in New Haven, Conn., was designed with a vegetative roof to create a new community area on the top floor. According to construction manager Providence, R.I.-based Dimeo Construction, which worked with Providence-based Gilbane Building Co. and the New York office of architect Perkins+Will on the project, the “multi-level student gathering area steps up from the ground floor to a rooftop garden. The green roof also supports photovoltaic panels on a special framing system.”

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Porous Pave Wins Gold-level Innovation Award

Porous Pave was judged a Gold-level winner for product design in the 2015 IIDEXCanada Innovation Awards competition.

Porous Pave was judged a Gold-level winner for product design in the 2015 IIDEXCanada Innovation Awards competition.

Porous Pave was judged a Gold-level winner for product design in the 2015 IIDEXCanada Innovation Awards competition. An eco-friendly green building product, Porous Pave is a highly porous, flexible and durable pour-in-place, permeable pavement material. Porous Pave XL consists of 50 percent recycled rubber chips and 50 percent stone aggregate with a proprietary liquid binder. IIDEXCanada, Canada’s National Design + Architecture Exposition & Conference, co-presented by the Interior Designers of Canada (IDC) and the Royal Architectural Institute of Canada (RAIC), was held in Toronto.

“We engineered Porous Pave with greater permeability per square foot than other permeable and pervious paving materials,” says Dave Ouwinga, president, Porous Pave Inc., the product manufacturer. “It can therefore achieve stormwater retention goals with smaller installations, saving money on materials and labor.”

“The recycled rubber in Porous Pave, processed from reclaimed scrap tires, imparts flexibility, so in contrast to concrete and asphalt, Porous Pave withstands freeze-thaw cycles without heaving or cracking,” says Jim Roth, president, Porous Pave Ontario, a Canadian distributor of the product. “The rubber content also makes it slip-resistant.”

Porous Pave Ontario entered the product in the IIDEXCanada Innovation Awards competition. Organized by IDC in 1984, the annual awards celebrate innovation in product design and exhibit creativity.

A panel of IDC members, who are all registered interior designers, judge product entries based on design objectives, design and technical innovation, market application, and sustainability. Entries are scored on a 0-100 scale, with Gold-level awards requiring a score of at least 90. Only five of the 30 product winners, including Porous Pave, attained the Gold standard. Among this year’s winners, Porous Pave was the only outdoor product for landscaping, hardscaping and on-site stormwater management applications.

The IIDEXCanada award is Porous Pave’s second honor this year. BUILDINGS magazine selected Porous Pave as a 2015 Money-Saving Product. Porous Pave was one of the superior building products showcased for commercial building developers, owners and facility managers in the magazine’s June 2015 issue.

A Permeable Pavement Patio Outside a Performance Space Features a Distinctive Musical Note Pattern

Since performing its first concert in 1939, the West Michigan Symphony, a professional orchestra in Muskegon, Mich., has been a vital part of the region’s cultural landscape. In spring 2013, the symphony decided it was time to expand its administrative and ticketing services. It moved into offices in the newly renovated Russell Block Building. Located in downtown Muskegon, a block away from the Frauenthal Theater where the orchestra performs its concerts, the historic Russell Block Building was constructed in 1890.

The porous-paving material had to express the musical note motif the landscape architect envisioned for the patio. It is the quintessential design element for the entire rooftop project.

The porous-paving material had to express the musical note motif the landscape architect envisioned for the patio. It is the quintessential design element for the entire rooftop project.

“With the move, the symphony also realized a long-held dream: establishing a flexible space where we could expand educational offerings and stage smaller fine-arts performances,” explains Carla Hill, the symphony’s president and CEO.

Named The Block, the 1,800-square-foot space offers seating on two levels for up to 150. In addition to providing an intimate venue for a variety of arts performances, The Block is available for meetings and special events. The west-facing windows of The Block look out toward Muskegon Lake. However, there was a problem: Outside the windows, an unimproved and unappealing tar roof marred the view.

“In conversations with the symphony and Port City Construction & Development Services, which planned and managed the building renovation, we started envisioning the transformation of the unadorned roof into a rooftop patio and garden,” says Harry Wierenga, landscape architect, Fleis & VandenBrink Inc., Grand Rapids, Mich.

Wierenga designed a 900-square-foot green roof (including 380 square feet of vegetation and a 520-square-foot patio area) as an accessible and appealing outdoor space. His design invites patrons of The Block to the outdoors onto a landscaped rooftop patio.

First Things First

“The existing roof was a tar roof over a concrete deck. Some holes had been boarded over and patched with tar,” notes Gary Post, manager, Port City Construction & Development Services LLC, Muskegon. “If the rooftop patio and garden had not been incorporated into the project, we would not have replaced it. We had to reroof to support the new rooftop outdoor space.”

The Port City Construction & Development Services roofing crew removed the existing roof down to the concrete deck, which they repaired. Two new roof drains were added to improve drainage. A single-ply membrane was selected for the new roof. The crew fully adhered the new membrane to the deck. The crewmembers then installed a geotextile fabric to protect the membrane and rolled out a geotextile drain sheet atop the protection fabric. The drain sheet facilitates drainage to the existing and two added roof drains.

A new 40-inch-high wall around the perimeter shelters the space and enhances rooftop safety. The porous paving’s gray and black custom-color mix harmonizes with the color of the wall.

A new 40-inch-high wall around the perimeter shelters the space and enhances rooftop safety. The porous paving’s gray and black custom-color mix harmonizes with the color of the wall.

A new 40-inch-high wall around the perimeter was constructed to shelter the space and enhance rooftop safety. Preparations also included widening the opening out to the rooftop from the interior of The Block. Glass double doors would be installed to establish a generous and transparent transition from indoors to outdoors.

Permeable Pavement

The project team applied a multi-faceted set of factors in evaluating options and selecting a pavement material for the patio:

  • To eliminate standing water and allow excess stormwater to flow to the drains, the paving material had to be permeable.
  • The plan called for installing the patio and green-roof elements on top of the geotextile drain sheet. The paving material would have to work with the modular green roof selected for the project.
  • The paving material had to be lightweight. By regulation, the maximum static plus live load for the roof is 100 pounds per square foot.
  • For easy access and safety, the pavement had to be low profile to minimize the threshold at the entry into The Block.
  • To create visual interest within the rectangular shape of the roof, the design emphasizes irregular shapes with angles to break up the space. The paving material would have to be flexible to adapt to the design.
  • The musical-note motif Wierenga envisioned for the patio is the quintessential design element for the entire rooftop project. The paving material had to offer the versatility to express the design.
  • Finally, a green-building product was preferred.

The project team considered composite decking and pavers. However, these linear materials were not flexible enough to adapt to the shape of the patio or sufficiently versatile to convey the musical note design.

PHOTOS: Porous Pave Inc.

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A New Report Finds Sustainable Roofs Deliver Millions in Benefits to ‘Roof Aware’ Cities

“Roof Awareness” has come a long way during the years. It used to be that people only thought about their roofs when something went wrong. Building owners then started realizing that making smart choices about the roof could save money on energy costs. Roofs are now seen as essential platforms for cities to meet energy-efficiency and renewable-energy goals, to improve the health and quality of residents’ lives, and to achieve social equity. A new effort to better quantify those benefits and costs shows cities with good roof awareness are reaping millions in economic benefits.

TABLE 1: Summary of cost-benefit analysis results (NOTE: There is no internal rate of return, simply payback, or benefit-to-cost ratio for rooftop PV because we all rooftop PV systems are financed with a PPA [so there is no upfront cost to DGS]).

TABLE 1: Summary of cost-benefit analysis results (NOTE: There is no internal rate of return, simply payback, or benefit-to-cost ratio for rooftop PV because we all rooftop PV systems are financed with a PPA [so there is no upfront cost to DGS]).

With that change in role comes new challenges for evaluating what type of roof makes sense for building owners and cities alike. There are well-developed building models and field studies that give us great insight into how sustainable roofing—that is, reflective, vegetated or solar roofs—saves energy and energy costs. But there is not a single tool that could evaluate all the benefits that accrue from good roofing choices beyond energy savings, such as better health, enhanced air quality, greater stormwater management and improved social conditions. Until now, that is.

A recently released report—the “Affordable Housing Smart Roof Report”—from Washington, D.C.-based Capital E, a firm dedicated to accelerating the transition to a low-carbon economy, now allows city officials and owners of affordable housing developments to see and calculate the full lifetime costs and benefits of roof decisions. “This is the first model that helps the user puta dollar value on the various benefits of sustainable roofing options. We see this as a great tool for contractors looking to quantify the full benefits of sustainable roofing for their potential clients. It will also help city officials to enact policies that recognize the value of smarter roofing that may not be directly visible on the building owner’s books,” says Keith Glassbrook, a Capital E senior analyst and one of the lead developers of the new model.

TABLE 2: Present value summary of costs and benefits for the three technologies on all low-slope DGS roofs (NOTE: All PV is financed with a PPA so there is no upfront cost to DGS; results may not sum due to rounding).

TABLE 2: Present value summary of costs and benefits for the three technologies on all low-slope DGS roofs (NOTE: All PV is financed with a PPA so there is no upfront cost to DGS; results may not sum due to rounding).

Building the Tool

Rather than reinventing the wheel, Capital E identified existing tools, models and methods from the huge base of existing science for each item in its cost-benefit analysis. The model integrates these individual, detailed components into a form that is accessible and easy to use for non-scientists and that provides straightforward results in dollars per square foot.

The model is an extension of an analysis undertaken for the Washington, D.C., Department of General Services (DGS) as part of its Smart Roofs Initiative. The initiative is designed to help Washington achieve its aspirations to become the greenest, healthiest, most equitable city in the U.S. by using the roofs of city-owned buildings more thoughtfully. DGS owns and controls more than 400 buildings in Washington, including office buildings, schools and hospitals. The city is using this portfolio (28 million square feet of buildings with approximately $62 million in annual energy expenditures) to drive deep improvements in energy efficiency and achieve other objectives.

Like a growing number of cities, Washington, D.C., is committed to using its roofs to deploy photovoltaic panels to generate electricity, cool roofs to reflect sunlight and reduce unwanted heat gain in summer, and green roofs to cut stormwater runoff that results in water pollution and requires construction of expensive water-treatment plants and other grey infrastructure. Tommy Wells, a former councilmember and current director of the District Department of the Environment, summarized the reasons in the Smart Roof cost-benefit report’s press release: “Past research shows that ‘smart’ roof strategies that reduce extreme temperatures in buildings can literally save lives. This new report provides additional justification for cool, green, and solar roofing solutions by showing that they also make compelling financial sense as we work to make D.C. a healthier and more sustainable city.”

Washington has been among the most advanced cities in the nation in deploying sustainable roof technologies. But because there was no established methodology for quantifying the full cost and benefits—including health benefits—for any of these technologies, Washington to date had not been able to quantify the full costs and benefits of these roof choices or compare the merits of each to make informed decisions about which technologies to deploy and at what scale. The analysis undertaken by Capital E to remedy this issue concluded that DGS’ Smart Roofs program can deliver between $47 and $335 million in benefits to the city over 40 years, depending on the roof technology chosen.

More Analysis

A parallel analysis was funded by the New York-based JPB Foundation, which seeks to enhance the quality of life in the U.S. by creating opportunities for those in poverty, promoting pioneering medical research, and enriching and sustaining the environment. JPB Foundation launched its analysis based on the success of this initial analysis by DGS. This time, the model was adapted to evaluate actual affordable-housing buildings in Baltimore; Los Angeles; Philadelphia; and Washington, D.C. The sample buildings, which were part of the National Housing Trust, Washington, or Columbia, Md.-based Enterprise Community Partners Inc.’s portfolios, included steep- and low-slope roofs, high- and low-rise structures, as well as some attached row houses. The project team for this study included the National Housing Trust; Washington-based American Institute of Architects; Washington-based Global Cool Cities Alliance; Enterprise Community Partners; and U.S. Green Building Council, Washington. In each city and building type evaluated, the model found sustainable roofs would generate more benefits than they cost (first cost and maintenance) and would, in some cases, have an immediate payback.

The results were variable by building and city but they confirmed that sustainable roofing was the superior economic choice compared to traditional dark roofs in the cities studied.

The JPB Foundation analysis shows there is no one-size-fits-all solution to maximize value with sustainable roofing. For example, green roofs made the most sense in Washington, D.C., because of the city’s stormwater rules. On the building in Baltimore, cool roofs were the best choice. The results were variable by building and city but they confirmed that sustainable roofing was the superior economic choice compared to traditional dark roofs in the cities studied.

A second phase is currently underway by JPB Foundation to extend the model to large areas of cities to capture the impact of sustainable roofs at a community scale, as well as other technologies, such as reflective pavements, and to better quantify some of the social benefits of cooler, more enjoyable surroundings.

Green Roof Provides Learning Opportunities at the University of Iowa’s Pappajohn Biomedical Discovery Building

Established just 59 days after Iowa became a state in 1847, the University of Iowa, Iowa City, boasts a number of firsts. In 1855, it became the first U.S. public university to admit men and women; at that time, its enrollment consisted of 124 students—41 of which were women. In 1873, it was the first school to grant a law degree to a woman. In 1895, it became the first university to place an African American on a varsity sports team.

As such, the university’s new Pappajohn Biomedical Discovery Building was designed and built with sustainability in mind. PHOTO: Roof Top Sedums LLC

The university’s new Pappajohn Biomedical Discovery Building was designed and built with sustainability in mind. PHOTO: Roof Top Sedums LLC


In more recent years, the university has strived to lead via its environmental efforts. As a Green Power Partner of the Washington, D.C.-based U.S. Environmental Protection Agency, the university pledges to reduce the environmental impact of electricity generation through the use of renewables. In 2010, it established its first sustainability plan—2020 Vision UIowa Sustainability Targets, which contains the following goals:

  • Become a Net-negative Energy Consumer
  • Green Our Energy Portfolio
  • Decrease Our Production of Waste
  • Reduce the Carbon Impact of Transportation
  • Increase Student Opportunities to Learn and Practice Principles of Sustainability
  • Support and Grow Interdisciplinary Research in Sustainability-focused and Related Areas
  • Develop Partnerships and Advance Collaborative Initiatives, both Academic and Operational

Among the University of Iowa’s strategies to achieve its sustainability goals is ensuring all new construction and major renovations on campus achieve a minimum LEED Silver certification from the U.S. Green Building Council, Washington.

The 200,000-square-foot, 6-story building, which officially opened in October 2014, boasts many environmentally friendly attributes.

The 200,000-square-foot, 6-story building, which officially opened in October 2014, boasts many environmentally friendly attributes. PHOTO: Scott Nagel


As such, the university’s new Pappajohn Biomedical Discovery Building was designed and built with sustainability in mind. The 200,000-square-foot, 6-story building, which officially opened in October 2014, boasts many environmentally friendly attributes, including glow-emitting sealants, paints, carpet and other materials; water-efficient landscaping; and recycled content and regional materials. It also achieves an-other university first: three green roofs, one of which provides students the opportunity to grow medicinal plants.

Opting for Trays

Des Moines, Iowa-based landscape architecture firm Confluence has been completing projects at the University of Iowa for many years through its Iowa offices—Des Moines and Cedar Rapids. Confluence was hired by the project’s architect of record, Rohrbach Associates PC Architects, Iowa City, to complete landscaping around and on top of the Pappajohn Biomedical Discovery Building in the form of three green roofs that total approximately 6,440 square feet. Despite the building’s consider-able roof area, the design team opted to install the green roofs on lower roof areas upon which building occupants would be looking. The rest of the roof cover is a reflective membrane system.

Confluence provided the layout for a modular green roof on the three distinctive roof areas. Patrick Alvord, PLA, RA, LEED AP, a principal in Confluence’s Cedar Rapids office, notes the chosen tray system was off-the-rack, which is what made it appealing to him and his colleagues. “We spent a lot of time talking to the manufacturer and they were just great to work with,” Alvord says. “We had a number of case studies of work they had done in the Chicagoland area that had proven very successful, so we had a very high level of comfort right out of the gate.”

Alvord opted to use the 6-inch-deep tray model because it would provide some flexibility in the plant materials that could be specified. “We were able to specify different plant materials in the plan of the roof to coordinate with shade, densities and location,” he says. “In areas where the roof would be highly visible from floors above, we did some patterning with the plants. In areas where we had the opportunity to go deep, we planted deeper-rooting plants that will grow taller and provide a denser plant palette.”

The plants are a mix of native and adaptive Iowa plants, as well as recommendations from the green-roof supplier. “It’s a mix of perennials, grasses and forbs, ranging from sedums to liatris to a number of different things,” Alvord notes.

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Fewer Limitations for Green Roofs

The limits of green-roof feasibility are being redefined by ZinCo’s Summer Plains system combined with Aquatec.

The limits of green-roof feasibility are being redefined by ZinCo’s Summer Plains system combined with Aquatec.


The limits of green-roof feasibility are being redefined by ZinCo’s Summer Plains system combined with Aquatec. An extensive or intensive green roof can be created on a flat, sloped or even an inverted roof, depending on the selected substrate depth and the suitability of the plants for the given location. The first layer is a protective layer on the root-resistant waterproofing membrane. This is followed by the Aquatec AT 45 water distribution, storage and drainage elements in conjunction with the DV 40 wicking mat. Water is drawn upward through the wicking mat and made available to the substrate directly in the root area. The system is intended for all green roofs that require an additional irrigation system and will provide particular cost savings in arid regions where irrigation is required.