Green Roofs, Green Buildings, Green Cities
Dear Colleagues,
As the academic year comes to an end, 200 Massachusetts Avenue approaches completion and the north tower of 250 Massachusetts Avenue has topped out. (See Construction NotesTopping Off, dated January 18, 2017, https://medium.com/construction-notes/topping-off-1-18-2017-cf7341cd113 to recall the history of topping off ceremonies.) But before I get to the details, I want to thank the Equal Justice Foundation auction winners, Alyssa Leventhal, Eleanor Hughes, Carlton Tarpley, Seth Appiah-Opoku, and Josh Wentzel, for bidding on a tour of the site and Rebecca Nordby, BBC Vice President for Operations, for giving the tour. The Georgetown students provided money for a good cause, and they all enjoyed the behind-the-scenes look at the project.
Street lights now stand along the 2ndStreet side of 200 Massachusetts Avenue, curbs are being set, and the sidewalks around the building are nearing completion. Ground drains have been installed for the restaurant tenants, column covers are set in place, elevators are operating, and broken glass panes are being replaced.
Dirt has been pumped up to the roof and sedum is being planted, making visible the contours of the green roof. You may have seen the dirt-pump hose hanging from the roof a couple of weeks ago. Punch list items are being repaired, final inspections are taking place, attic stock is being stored, and the mechanical systems are being commissioned. The entrance doors and canopies await the Meyer restaurant group and the other tenants who will soon be occupying the building.
Work on the west side of the site advances. The North Block parking garage has reached grade, and lights, conduit, and fire suppression systems are being installed. Pepco vaults have been set, electrical switchgear rooms are being prepared, and plumbing risers and fire sprinkler systems are being installed. Interior walls are being built in the North Block garage with CMU blocks (concrete masonry units) and concrete is being poured for the floors and columns of the south tower of 250 Massachusetts Avenue. The bridge that will eventually connect the two buildings at the second floors is being fabricated.
Excavation continues for the Center Block and South Block parking garages. The Center Block should bottom out within the next two weeks. A third tower crane has been erected to lift materials and pour the concrete for the garages and the south tower of 250 Massachusetts Avenue. It will also be used for the foundations and columns of the Center and South Blocks. The old highway exit wall is slowly coming down to make way for the eventual E Street loading dock entrance.
As the earth warms and sustainability becomes a rallying cry to literally save the planet, cities and industries are striving to create buildings that reduce the heat island effect and minimize their carbon footprint. These initiatives, begun toward the end of the last century, led to a rating system that awarded points to developers who create buildings that meet specific environmental goals. In 1993, environmentalists Rick Fedrizzi, David Gottfried, and Mike Italiano created the U.S. Green Building Council (USGBC). Soon thereafter, they established the Leadership in Energy and Environmental Design (LEED) rating system. What started off as a small movement in 2000 has grown significantly. Architects now design buildings that incorporate natural resources, use materials recycled from other buildings, avoid practices and materials that may harm the environment, and limit waste in both the construction and operation of buildings. By 2005, more than 3,100 LEED-Certified projects existed in the United States. As of last year, 65,427 U.S. projects carried LEED registration and nearly 80,000 projects were participating in LEED activities across 162 countries.
The LEED rating system has four levels of achievement; Certified, Silver, Gold, and Platinum. Capitol Crossing has exceeded the Platinum level, thus making it one of the most environmentally friendly and sustainable buildings in the District of Columbia. To achieve a LEED Platinum designation, a project must accumulate at least 90 points from a 136 point system. Points are awarded in eight credit categories: Sustainable Sites; Water Efficiencies; Energy and Atmosphere; Materials and Resources; Indoor Air Quality; Innovation and Design; and Regional Priorities.
Capitol Crossing has been designed to achieve Platinum designation by scoring highly on the various criteria in each category. An integral part of Capitol Crossing’s certification is its green roof. There are two types of green roofs — intensive green roofs and extensive green roofs. Sarah Dowdy, writing for Howstuffworks, defines green roofs this way. “Intensive green roofs are essentially elevated parks. They can sustain shrubs, trees, walkways and benches with their complex structural support, irrigation [systems], drainage [capabilities], and root protection layers. The foot or more of growing medium needed for an intensive green roof creates a load of 80–150 pounds (36–68 kilograms) per square foot. Extensive green roofs are relatively light at 15–50 pounds (7–23 kilograms) per square foot. They support hearty native ground cover that requires little maintenance. Extensive green roofs usually exist solely for their environmental benefits and don’t function as accessible rooftop gardens.” Capitol Crossing, while maintaining an extensive green roof, will still enable tenants to access the planted portions of the roof via a roof-top terrace.
In 1960, Germany became the first country to develop and market green roof technology. Green roofs soon became popular in Switzerland, the Netherlands, Norway, Italy, Austria, Hungary, Sweden, the United Kingdom, and Greece, and are now proliferating in the United States. The green roof atop Chicago’s City Hall is one of the most famous, combining elements of both intensive and extensive green roof segments, as well as a semi-intensive system on one roof. The city is expanding its green roof program by giving building owners incentives to retrofit their roofs so the number of green roofs is increasing every year. Many old buildings in other cities have been retrofitted with green roofs. The oldest green roof in the United States, the one atop Rockefeller Center in New York City, was built in 1936 for purely aesthetic and pleasure purposes. It was refurbished in 1986. The oldest green roof in the world is the Torre Guinigi in Lucca, Italy. The tower house was built in 1384 during the turbulent wars between the Italian city-states. No one knows for certain when the seven oak trees were planted on the Tower roof; but by 1600, the tower with its trees appeared in a contemporary drawing of the city. The trees that stand today are holm oaks, large evergreen oak trees that are native to the Mediterranean region. The name harkens back to an ancient name for holly. Although the Torre Guinigi oaks have been replenished over the centuries, several of the existing seven holm oaks are hundreds of years old.
Capitol Crossing maintains an extensive green roof covering over 50% of the exposed roof area that will require little maintenance but will provide an aesthetically pleasing setting for the roof-top terrace. The plants sit in a thin layer of dirt that rests on a waterproof membrane. That narrow hose dangling from the roof, that I referred to earlier, pumped the dirt up to the roof from a supply sitting on the deck. While the beauty of the green roof may enchant and soothe the building’s patrons, its environmental effects will benefit all of us. The natural insulation of a green roof reduces energy costs, absorbs storm water, sequesters carbon, improves the air quality of a city, and reduces the heat island effect by increasing evapotranspiration — the process of transferring moisture from the earth to the atmosphere by the evaporation of water and the transpiration from plants. Some plants can also attract birds and butterflies, aiding the environment and bringing moments of respite from the building patrons’ busy day. Even though the installation of a green roof costs more than a conventional roof, developers and owners of the building may get a financial benefit as well. Researchers at Penn State University’s Green Roof Research Center determined that a green roof can last three times as long as a regular roof by reducing the effect of ultraviolet radiation and physical damage. They also have a stable surface temperature that is lower than that of a conventional roof, again creating a long-term cost saving.
Green roofs are only one feature of a green building. The World Green Building Council defines a green building as one that in its design, construction, or operation reduces or eliminates negative environmental effects, and thus creates positive effects on our climate and natural environment. Green buildings preserve precious natural resources and improve our quality of life. The LEED system implements this definition. As I mentioned earlier, Capitol Crossing has exceeded the points necessary to achieve LEED’s highest designation, Platinum. The design and construction teams met the platinum criteria in part by developing a site with linkages to and accommodations for alternative modes of transportation. Architects used triple pane high-efficiency windows separated by argon gas to control heat and enhance views. They designed skylights equipped with sensors to darken when the sun gets too hot. They used ceiling and wall systems, adhesives, and coatings that emit low to no levels of volatile organic compounds, all critical for LEED Certification. Many of the materials used in the building come from within five hundred miles of the site — a LEED requirement, thereby lessening the pollution that would arise from long-distance sourcing. And it is not just the finished product of the materials that is evaluated. Concrete, for example, is provided by Miller and Long, a regional company. But BBC engineers also evaluated the components of the materials, like the sand and gravel, to ensure that the concrete met LEED standards.
The building’s storm water system recycles the rain that would otherwise wash into the sewer system and uses it to cool the building. The recovered water is stored in six large, cast-in-place, concrete holding tanks. As it is needed, the water goes through a storm water treatment system, and then into large fiberglass holding basins where it can be used to supplement the water used for the cooling towers. Six hydrodynamic separators remove unwanted particles from the storm water supply. Ground water is also collected through the underdrain system beneath the garage. It is routed to a ground water treatment room in the garage. After it is treated, it goes into one of two cast-in-place concrete holding tanks. This water is used to supplement the storm water recovery basins should they ever empty out. Three grease separators also capture grease and oil from restaurant disposals and electric vaults to prevent them from entering the water and waste streams.
Volatile organic compounds found in the soil were abated and the waste from the project was managed and disposed of according to sound environmental principles. PGP and BBC are separating and recycling 90% of the waste generated on this project. That is 15% higher than LEED requires for Platinum certification. I could go on but you would be reading all day. Suffice it to say that the Capitol Crossing project will provide significant buildings in the drive for an environmentally safe District of Columbia.
A building does not need to be LEED certified to be green but many developers opt to participate in the LEED system to enhance the value of the property and to attract tenants looking for lower built-in utility costs. According to a 2016 study by Dodge Data & Analytics, green building practices double across the globe every three years. Builder Magazinereports that “out of 5.77 billion completed square feet across 165 countries, over 1.3 billion completed square feet of LEED-certified space exists in the United States across 38,353 projects, commercial and residential alike. That’s enough space to cover almost all of Staten Island, or about 23,000 football fields.” Boston, New York, Chicago, San Francisco, and San Jose are in the forefront of the green building movement. Moreover, the above article reports that Washington, D.C. is the LEED capital of the nation when one considers “LEED-certified square footage across all construction types.” The District has also been named the first LEED Platinum city in the world based on metrics such as water, waste, and transportation, while factoring in education, prosperity, equity, health, and safety.
The increased awareness of environmental depredation has resulted not only in more LEED certifications and an increase in green buildings, but also in a movement to create green cities. According to E/The Environmental Magazine, the Green Cities Movement is “a loose association of cities focused on sustainability. This emerging movement encompasses thousands of urban areas around the world all striving to lessen their environmental impacts by reducing waste, expanding recycling, lowering emissions, increasing housing density while expanding open space, and encouraging the development of sustainable local businesses. One of the earliest Green Cities is Curitiba, Brazil. In the 1960s, a planner and later mayor named Jaime Lerner changed the conception of that city in rebellion against the Brasilia model favored by the national government. In Lerner’s words, “It was a change in the conception of the city. Working, moving, living leisure … we planned for everything together. Most cities in South America separate urban functions — by income, by age. Curitiba was the first city that, in its first decisions, brought everything together.” Today, Curitiba has become the gold standard in sustainable urban planning: variously called the “green capital,” the “greenest city on Earth,” and the “most innovative city in the world.”
Today, more than half of the world’s population lives in cities. More than two-thirds of the total investment in infrastructure in the next fifteen years will be made in cities. But because of increased population and the development of unsustainable buildings, cities generate heat and green-house gases that create heat islands. For example, cities are one to three degrees hotter than their surrounding area in the day-time and twelve degrees hotter at night. Science NewsMagazinerecently cataloged the deaths in various cities around the world since 1986. Europe’s 2003 heat wave killed 70,000 people, 20,000 of them in France alone. Russia lost 10,000 people in 2010, and India lost 2,500 people in 2015. Since 1986, more people have died in the U.S. from heat than from any other weather related disaster. If cities and the human race are to survive the Anthropocene devastation of the planet, we need to accelerate the transition to healthier and sustainable environments.
Despite the political pushback from those who deny human-engineered climate change, some cities and states are making an investment to alter urban life and perhaps life itself for the better. The New Climate Economy organization reports that investing in sustainable infrastructure such as public transport, building efficiency, and waste management can create energy savings to the tune of $16.5 trillion by 2050. The New York Timesrecently reported that California will become the first state to require the installation of solar panel installations in all new homes by 2020. The installations are expected to add $8,000 to $12,000 to the cost of construction but the return will mean lower long-term energy costs and the reduction of fossil fuels in the production of energy. New York City has planted one million new trees since 2007. Other cities such as Portland and Eugene, Oregon, San Francisco and Oakland, Boston, Chicago, and others are making similar investments. During 2017, Washington, D.C., activated North America’s first “intelligent” wastewater pumping system, equipped city trash cans with solar-compacting sensors, adopted five dockless bike-share pilot programs, and installed free Wi-Fi across 17% of the city. And, as I mentioned before, the District was named the world’s first LEED Platinum city. In 2017, WalletHub named the District of Columbia the sixth greenest city in America, preceded only by four California cities and Honolulu. In addition, Washington also won the 2017 Smart Cities Dive Award as City of the Year Award as the industry’s top disruptor and innovator. These awards demonstrate that the District of Columbia is now considered a world leader among Green Cities for its efforts to ensure that we live and work in a healthy and vibrant place.
Spring is a time of rebirth. Leaves unfold on our trees, flowers bloom in our gardens, and lush green grass, dormant over the long winter, reappears. The earth begins anew. The students of Georgetown’s class of 2018, as they leave their years of legal training behind and embark on new adventures in a rapidly changing world, begin anew as well. How are they to view this planet and this tension between deep pessimism and renewed optimism as they begin these new adventures? For those of you who will return to us for classes next year, this somewhat sobering yet inherently optimistic view of the future should remind you to celebrate a good grade but also to understand that a less than great grade will not define you. You will always offer more to the world than the recounting of a single examination. We need your innate talents, your energy, and your optimism to bring science back to its rightful pedestal in our policy decisions. Your lives will be rich in value if you maintain that optimism as you go forward with an understanding that the life of the planet is really in your hands.
The words of David Gottfried, one of the founders of USGBC, are especially appropriate at a commencement. He asks us, “What are we doing here? What are you doing for the planet? How do we create a life of legacy and purpose that is renewable and regenerative; that gives you the wealth and the income that you need and, even more importantly, is the planting of seeds that create a future that we’re proud of for our children and theirs?” Think deeply about those questions and answer them for yourself and the generations that will come after you. Your time is now; but you hold the future of the planet in your hands.
We at Georgetown are justifiably proud of you and your accomplishments and we expect you to answer David’s question as a true son and daughter of Georgetown forever.
Wally Mlyniec
PS: If you want to continue receiving Construction Notesafter you graduate, send me your email address or follow them on https://medium.com/construction-notes.
SOURCES
Special thanks go to BBC employees Brad Williams, Assistant Project Manager; Andrew Williamson, Project Manager; and Brian Williamson, Project Engineer who provided background for this Construction Note.
Thanks as always to my editors, Abby Yochelson from the Library of Congress and Betsy Kuhn from Georgetown Law.
David Adler, Cities, Story of Cities #37: How Radical Ideas Turned Curitiba Into Brazil’s ‘Green Capital’, The Guardian, May 6, 2016, https://www.theguardian.com/cities/2016/may/06/story-of-cities-37-mayor-jaime-lerner-curitiba-brazil-green-capital-global-icon
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