Design 40A Section 2
December 9, 2014
The California Academy of Sciences Living Roof Raw Materials
In 2008, The California Academy of Sciences building in San Francisco was reopened to the public after undergoing a major reconstruction and design process to become and operate as a self-sustaining and “green” structure. One particular aspect that this museum features is a 2.5-acre “green” and “living” roof that was designed to be self-sufficient and to naturally generate energy to power the building’s day-to-day functions. Our group chose to focus on the Academy’s “living” roof, and to trace the materials, energy, and waste and emissions used throughout the roof’s life cycle, from its beginning and construction, to its daily energy use and recycling and processing of waste. The museum promotes their building and roof as being a leader in sustainable design and practices, which has contributed to their two platinum LEED certifications (Leadership in Energy and Environmental Design), one from 2009 and the other from 2011, awarded by the U.S. Green Building Council.1
Although the Academy presents their living roof as a self-sustaining “green” roof, our group wondered if the roof was actually as “green” as it claims to be. From our research we found that while the outside the roof is the image of “green” and sustainable design since almost all the raw materials come from recycled materials, and they use other “green” technologies like solar panels, many of the roof’s materials that were used consumed large amounts of energy in the ways that they were produced, and even in the ways that they were recycled and repurposed for the use and construction of the living roof. The roof’s materials may have consumed more energy in their acquisition than the Academy’s design originally intended for, but in 2008 when the building was reopened, the living roof was at the forefront of green roof design, and in the process of its creation, new innovations like Rana Creek’s sustainable BioTrays were developed, which have since then promoted green roof design and have made it more accessible to the general public, and more efficient to construct.2
Raw Materials Acquisition and Manufacturing, Processing, and Formulation
The most extensive part of the living roof’s design is all of the raw materials the Academy used in the construction of their project. Many of the raw materials used are recycled materials, or a percentage of a material contains recycled resources. Yet something that we do not always remember is that in order for any one material to be recycled, it still takes energy to do so. When a material is recycled, it must be converted into a reusable product, which requires energy that came from electricity that has been generated by either coal-fired or fossil-fueled power plants. For example, 100% of the steel used in the construction of the living roof was recycled, but that still meant that the steel had to be processed and repurposed before it could be used by the Academy.3 A limitation and failure of our research was finding how the recycled materials used were recycled and how much energy that must have taken. Yet through what we have learned in class about energy and coal-powered and fossil-fueled powered electricity plants, we are still able to speculate that large amounts of energy were used in the recycling process of the roof’s raw materials.
Instead of using 100% Portland cement for the roof’s concrete, the Academy used a mixture of cement that had 15% fly ash and 35% slag.4 Fly ash is a byproduct of coal powered electricity plants, and slag is a byproduct from smelting ore in a purification process.5 By using these materials in cement instead if using 100% Portland cement, CO2 emissions can be lowered by 40%.5 Portland cement is toxic to our environment because the global production of Portland cement can be attributed for at least 5% of the world’s CO2 emissions, (for every pound of cement produced, 1 pound of CO2 goes into the atmosphere), and annually the U.S. makes 75 million tons of this cement, which releases 80 million tons of CO25,6.
Another raw material the Academy used for the living roof is blue jean insulation.4 A mixture of 90% recycled denim jeans and 10% cotton batting can be combined to create a safer building insulation.7 Blue jean insulation is better for our environment because it is made from a renewable material (cotton), is not made with toxic formaldehyde, and it does not disperse airborne pollutants like standard fiberglass insulation does.7
The living roof is composed of ten different layers of materials.8 The first layer (the bottom) is the recycled steel, the second layer is the mixture of fly ash, slag, and regular (Portland) cement, and the third layer is the recycled blue jean denim insulation.3,4,7 The fourth layer is a thermal plastic waterproofing, which being made of plastic and therefore from petroleum products, is not the greatest roofing material for our environment.9 The next layer is a level of plastic polystyrene (Styrofoam) insulation, which is also made from petroleum, and consequently is the second most harmful material to be produced when it comes to levels of CO2 released into our atmosphere.10 Polystyrene also takes tens to hundreds of years to biodegrade, and it has carcinogenic properties, meaning it can be cancerous and harmful to both humans and animals.10 Following the polystyrene is a protective layer of vinyl (PVC), which is yet again another known carcinogen because the main component of vinyl is VCM gas (Vinyl Chloride Monomer), which is highly toxic to both our environment and to humans.11,12 Vinyl is also extremely flammable, which is not the greatest material for a building, considering that the building could catch on fire during some point of its use.10 The next level is a plastic drainage layer, that prevents the rotting of plants’ roots and the erosion of soil, yet this layer can still have negative environmental effects since it is a petroleum product.9 Just below the soil is a sheet of a polypropylene filter.8 Polypropylene is a plastic, but the practices followed in its production are more environmentally-friendly and follow strict codes to keep CO2 emissions lower than other plastics, both in the way that it is made and recycled.13 Polypropylene is also different from other plastics because it has been designed to be used for many years without needing to be replaced like other plastics.14 It is durable, water-resistant, heat-resistant, and it does not need large amounts of energy to be recycled.14 Yet, since polypropylene is a plastic, it still takes many years for it to decompose and biodegrade.9 The second to last layer is the six inches of soil, which comes in part from the BioTrays that house the plants on the roof, and from serpentine soil.15 The main component of serpentine soil is an aggregate called serpentinite that is a blue-green rock that naturally forms on the San Andreas Fault, which causes the soil to need less water and fertilizers to stay healthy.15 Also, scoria (like pumice), organic compost, sand, and fir bark are used to make up the soil.16 All of these components can be found locally and are renewable materials.16 The tenth layer is the external “living” surface of the roof that consists of the plants and the BioTrays that Rana Creek designed to house the roof’s vegetation.8 The BioTrays are 17” square containers that are made from coconut coir (a leftover coconut fiber waste material that is harvested and processed in the Philippines), and natural latex that comes from tree sap, instead of being made from plastics.17,18 Over 50,000 BioTrays were used, which are also permeable and biodegradable and will overtime decompose and become part of the soil used on the roof.17 With the use of these BioTrays, Rana Creek was able to grow, transport, and install the plants in the same containers which required only a third of materials needed because the Academy was able to just use one material to perform all three tasks.18 The last layer of the roof is the 1.7 million plants, which are all native species to California.19 There are in total nine plants species installed on the roof, including beach strawberries, self heal, sea pink, stonecrop, tidy tips, miniature lupine, California poppies, California plantain, and goldfield plants.19 All of these plants were grown in Rana Creek’s nursery based in Carmel, CA (near Monterey) then delivered and planted on the roof in the BioTrays.20
The Academy also installed solar panels that surround the perimeter of the living roof, containing over 60,000 photovoltaic cells that generate 213,000 kilowatts of energy for the museum’s use, which is only roughly 5% of the energy needed for their daily operations.21 Considering how energy intensive it is to produce the silicon disks that make up photovoltaic cells, and all of the toxic chemicals that are used in the cells’ production, only getting 5% “clean” energy back from the roof’s solar panels is not the most efficient use of energy.22
One last component of the building that we were unable to find much information about was the skylights (the windows) on the plant-covered hills of the roof. The skylights are constructed from glass, but they also are designed to automatically open when portions of the building get too warm, which we can hypothesize, must use electricity to do so.3
Distribution and Transportation
During the roof’s construction, a minimum of 20% of all raw materials used came from sources that were within a 500 mile range, which lowered the costs and emissions associated with moving the heavy materials.23 All of the plants that were delivered and installed in the BioTrays were grown at the Rana Creek nursery in Carmel, CA, which significantly lowered the fuel needed and the CO2 emitted to transport the plants.19 In our research it was difficult to discover the exact locations where each material came from, but we did find that the coconut coir used in making the BioTrays came from the Philippines, which must have taken time and energy to arrive in California.18
Use/reuse and Maintenance
The Academy’s living roof was designed to be self-sustaining, but we found that only a portion of their design goal is show to be true. Plants cover 87% of the living roof, which naturally cools down the roof and the city space around it.19 The six inches of soil work as an insulation layer that keeps the inside of the building 10 degrees cooler in the summertime, which allows the Academy to use less A/C.24 The plants do not need to be fertilized or sprayed with pesticides because the nine plant species attract various kinds of birds, bugs, and bees that naturally pollinate the vegetation and keep them healthy and fend of plant predators.19,16 However, the roof was originally designed to not need artificial irrigation to sustain the plant life, but in order to establish the plants, and to maintain the “green” looking roof all year-round, in order to attract visitors in the dryer months, the Academy ends up using 1.5 million gallons of water annually to irrigate the roof.25
Recycling and Waste Management
One of the greatest “green” features of the living roof is its ability to absorb and reuse rainwater for irrigation and for the building’s daily operations. This ability prevents 3.6 million gallons of storm water runoff from getting wasted, and through a closed loop recycling system the water can be saved and reused.26 The plants can hold up to four inches of water, which then seeps through the soil into a chamber that filters the water and feeds it back into either the plants or the plumbing.26 Since most of the waste associated with the roof came from the gathering of the raw materials, we found that after construction, the living roof does not create much waste. Even when plants must be replaced on the roof and weeds must be removed, that only generates green waste that becomes compostable and reintegrated into the soil.24 However, there were wasted materials from the previous building when the new building began construction. At least 90% of the old materials were recycled for other construction projects around the SF Bay Area, but these materials still had to be recycled and use energy to repurpose the materials, while the other 10% of materials were wasted and put in the landfill.23 Also, overtime the roofing layers will need to be replaced, and since most of the layers are made of plastics, those materials will not biodegrade for centuries and will take large amounts of energy to be recycled.8
The California Academy of Sciences Living Roof may have used some materials that require lots of energy to produce and emit high amounts of CO2, like polystyrene and solar panels, but at the same time the roof utilized byproducts like fly ash and slag in the cement they used, and also other waste products like coconut coir for the BioTrays, that helped balance out the amounts of energy and raw materials used to build and maintain the roof. The Academy’s roof is certainly living, and although it may appear to be a “green” roof from the outside, some hazardous practices that are not so “green” were used, like extra irrigation. At the time of the living roof’s design and construction, it was considered one of the world’s greenest and environmentally conscientious buildings. After researching the Academy’s roof, and especially after looking into the acquisition and manufacturing of the raw materials used, we now know that this assumption is not the entire truth. However, the roof’s design may be improved upon in the future, and since 2008 when it was reopened, the Academy’s living roof has inspired many to further develop green roof design all over the world.
1. "The California Academy of Sciences Receives Second LEED Platinum Rating From U.S. Green Building Council." The California Academy of Sciences. Calacademy.org, 27 Sept. 2011. Web. 5 Dec. 2014. <http://www.calacademy.org/press/releases/the-california-academy-of-sciences-receives-second-leed-platinum-rating-from-us-green>.
2. Brenzel, Jonathan. "Bio Tray Module for Green Roofs." Apartment Therapy. N.p., n.d. Web.
28 Oct. 2014. <http://www.apartmenttherapy.com/bio-tray-module-for-green-roof- 65730>.
3. "California Academy of Sciences / Renzo Piano." ArchDaily. N.p., 28 Sept. 2008. Web. 04 Dec. 2014. <http://www.archdaily.com/6810/california-academy-of-sciences-renzo-piano/>.
4. "Project: California Academy of Sciences." Solaripedia. N.p., 2009. Web. 04 Dec. 2014. <http://www.solaripedia.com/13/102/6030/california_academy_of_sciences_illustration.html>.
5. "Stronger, Cleaner, Greener Concrete." US Concrete. N.p., 2014. Web. 02 Dec. 2014. <http://us-concrete.com/ef_technology.asp>.
6. Gadja, John W., and Martha G. VanGeem. A Comparison of Six Environmental Impacts of Portland Cement Concrete and Asphalt Cement Concrete Pavements. Tech. no. PCA R&D Serial No. 2068. Skokie, IL: Portland Cement Association, 2001. Web. 3 Dec. 2014.<http://www.nrmca.org/taskforce/item_4_technicalsupport/a%20comparison%20of%20six%20environmental%20impacts%20of%20portland%20cement%20concrete%20and%20asphalt%20cement%20concrete%20pavements%20-%20sn2068.pdf>.
7. "Denim to Insulation." Smarter Business : Smart Design. National Resources Defense Council, 19 Mar. 2011. Web. 27 Oct. 2014. <http://www.nrdc.org/business/design/denim.asp>.
8. Cheng, Kay, and Anne Brask. San Francisco Green Roof Typologies. Digital image. San Francisco Planning. San Francisco Planning Department, n.d. Web. 4 Dec. 2014. <http://www.sf-planning.org/ftp/files/Citywide/greenroof/greenroof_FINAL-GreenRoofPoster-aaa.pdf>.
9. Freudenrich, Ph.D. Craig. "How Plastics Work." HowStuffWorks. HowStuffWorks.com, n.d. Web. 05 Dec. 2014. <http://science.howstuffworks.com/plastic.htm>.
10. "Polystyrene Fast Facts." The Way To Go by Harvard (2008): n. pag. Isites.harvard.edu, 2008. Web. 5 Dec. 2014. <http://isites.harvard.edu/fs/docs/icb.topic967858.files/PolystyreneFactSheets.pdf>.
11. Siegele, Lindsey. "Is PVC Safe? The Vinyl Debate." Mother Earth News. N.p., 2010. Web. 05 Dec. 2014. <http://www.motherearthnews.com/green-homes/the-vinyl-debate.aspx#axzz3L5S7VCkj>.
12. "Vinyl Chloride Monomer (VCM) Production." PVC. Pvc.org, n.d. Web. 04 Dec. 2014. <http://www.pvc.org/en/p/vinyl-chloride-monomer-vcm>.
13. Johnson, Todd. "What Is Polypropylene Used For?" About. About.com, n.d. Web. 05 Dec. 2014. <http://composite.about.com/od/Plastics/a/What-Is-Polypropylene.htm>.
14. "Polypropylene - An Environmentally Responsible Product." Environment. Ambro.co.uk, n.d. Web. 05 Dec. 2014. <http://www.ambro.co.uk/page/environment/index.html?activetablist=environment>.
15. Marinelli, Janet. "Green Roofs Take Root." National Wildlife Federation. N.p., 2007. Web. 04 Dec. 2014. <http://www.nwf.org/news-and-magazines/national-wildlife/gardening/archives/2007/green-roofs-take-root.aspx>.
16. Kephart, Paul. “California Academy of Sciences - Green Roof Research Project.” Message to the author. 6 Dec. 2014. E-mail.
17. "BioTray System by Tremco Roofing and Building Maintenance." BioTray System by Tremco Roofing and Building Maintenance. Buildings.com, 2011. Web. 02 Dec. 2014. <http://www.buildings.com/article-details/articleid/12212/title/biotray-system-by-tremco-roofing-and-building-maintenance.aspx>.
18. Gonzalez, Shelby. “Ground control in northern California.” Fabric Architecture (2008). Web. 28 Oct. 2014. <http://fabricarchitecturemag.com/articles/0908_f3_ground.html>
19. "California Academy of Sciences (CAS), The Osher Living Roof." Greenroofs.com Projects. Greenroofs.com, 2007. Web. 04 Dec. 2014. <http://www.greenroofs.com/projects/pview.php?id=509>.
20. "Projects / Realizing Shared Goals." Rana Creek Designs. Ranacreekdesign.com, n.d. Web. 1 Dec. 2014. <http://www.ranacreekdesign.com/projects/>.
21. Cantor, Steven L. Green Roofs in Sustainable Landscape Design. New York: W.W. Norton, 2008. Print.
22. "Environmental Impacts of Solar Power." Union of Concerned Scientists. Ucsusa.org, 2013. Web. 5 Dec. 2014. <http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/environmental-impacts-solar-power.html#.VIPy1Cg_5UF>.
23. "Choosing Sustainable Materials." California Academy of Sciences. Calacademy.org, 2008. Web. 1 Dec. 2014. <http://www.calacademy.org/choosing-sustainable-materials>.
24. Green, Jared. "Three Years Later: California Academy of Sciences' Living Roof Also Educates the Design Community." The Dirt. Dirt.asla.org, 13 Oct. 2011. Web. 05 Dec. 2014. <http://dirt.asla.org/2011/10/13/three-years-later-san-francisco%E2%80%99s-california-academy-of-sciences-living-roof-also-educates-the-design-community/>.
25. Shao, Maria. "A Green Roof Over Your Head." The Registry San Francisco (2013): 21-30. Green Roofs. Theregistrysf.com, 2014. Web. 4 Dec. 2014. <http://www.nibbi.com/wp-content/uploads/2014/01/2013_10_17_The-Registry_A-Green-Roof-Over-Your-Head_entire-magazine.pdf>.
26. James L. Sustainable Solutions for Water Resources: Policies, Planning, Design, and
Implementation. Hoboken, NJ: John Wiley, 2010. Print.
Life Cycle Research Paper
6 December 2014
California Academy of Sciences Green Living Roof: Embodied Energy
Since its opening date in September 2008, the California Academy of Sciences–– located in the Golden Gate Park of San Francisco, California–– has sparked worldwide interest in sustainable design and is “considered to be one of the most environmentally friendly museums in the world.” 2 Awarded two LEED platinum awards (New Building Construction in 2008 and Building: Maintenance and Continued Operations in 2011), the Academy continues to strive for sustainable practices and operates under its mission: “to explore, explain, and sustain life”3. The most innovative feature of the Academy is its green living roof, which has inspired a nation-wide interest and demand for green rooftops.
Raw Materials Acquisition
The Academy’s architect and the entire construction team strove to make a building that was as sustainable as possible. Many of the building’s materials were sourced from the California Bay Area, if not at least within 500 miles of the construction site. The roof included the following materials (ordered from bottom-most layer to the top-most layer):
100 % recycled steel
Concrete, consisting of 15% fly ash (coal power plant byproduct), 35% slag (smelting ore byproduct), and Portland (standard) cement
Recycled blue jean insulation
Plastic polystyrene (Styrofoam) insulation
Protective layer of vinyl (PVC)
Plastic drainage layer
Plastic propylene filter layer
Serpentine soil (6 inches), consisting of serpentinite (natural rock that forms on the San Andreas Fault), scoria (a pumice-like stone), organic compost, sand, and fir bark
BioTrays, made from coconut coir and natural tree sap, containing the plant-life
Steel is one of the most recycled materials in the world, and creates a very high return yield. Since creating new steel requires steel scraps as virgin material, recycling the metal is highly encouraged. Steel’s high return yield and wide variety of uses, including automobiles to new construction, creates an energy-efficient recycling process.
Unfortunately, the same cannot be said for concrete. Recycling concrete prevents useful materials adding to landfills, but the process of creating concrete, whether using virgin material or recycled concrete, requires lots of energy and emits greenhouse gases.
Several of the roof layer materials includes plastic or vinyl sheets, which are not readily biodegradable and thus become a problem for waste management. Additionally, the process of creating plastic is chemically intense and emits toxic gases that create an unsafe and unhealthy environment for workers and for the ecosystem.
Blue jean insulation is a more eco-friendly alternative to the traditional fiberglass insulation, which uses formaldehyde and carries airborne particulate pollutants. While this is a popular alternative, the recycling of denim pants into cotton insulation does not yield a high percentage of useable material; one pair of jeans creates enough insulation to cover “an area the size of a switch faceplate.” Given the fairly small yield, creating denim insulation does not seem to be an energy or material efficient process.
The soil used on the roof is locally sourced, but required heavy machinery to gather and transport all the soil necessary to cover the 2.5 acre rooftop.
The BioTrays that contained the roof’s plant material was designed by Rana Creek Design, the project’s landscape consultant from Monterey, California. Made of natural tree sap and coconut coir, a waste product sourced from the Philippines, the BioTrays required energy to transport the materials and collect the coconut coir.
Manufacturing, Processing, and Formulation
As with any large-scale commercial project, large and heavy machinery are required for construction. The construction process requires lots of electricity and fossil fuels to power the machinery, in addition to the manpower and time needed to construct such a large expanse and uniquely-sloped roof design.
In addition, the landscape architects from Rana Creek spent three years designing and developing live mockups of the roof. The steep slopes and unusual shape of the roof required these mockups to ensure that the plants would successfully take root and absorb enough rainwater. These mockups needed to use all the materials from the final installation, in addition to any alternative materials that were tested. Rana Creek Designs was also responsible for designing and creating the BioTrays, which used mycorrhizal fungi to inoculate to the coconut coirs. This process required time and special attention to make sure that the fungi bonded correctly with the coconut fibers to create a strong and long-lasting container for the plants to take root in. Rana Creek also tested and selected the final nine plant species used on the roof, in addition to growing them in the BioTrays before their installation on the roof.
Distribution and Transportation
The green living roof serves several purposes for the Academy of Sciences: it promotes and sustains local wildlife, it insulates the building and helps reduce the need for air conditioning, and it stands as an educational model for the public. The Academy puts a strong focus on raising awareness for the roof and creating educational and promotional marketing media for the living roof. Their marketing collateral includes paper flyers, signage on the roof deck, and a page on their website dedicated to the roof. These items, especially at a large quantity, require lots of resources–– such as paper, toxic inks, and electricity–– to meet the Academy’s needs.
Additionally, the roof deck is mainly accessed by a staircase, but building codes require at least one elevator access for handicapped visitors to meet ADA requirements. This requires a substantial amount of energy, especially considering the millions of visitors the Academy receives each year who might use the elevator.
Use, Reuse, and Maintenance
The living roof was designed with the idea that it could be a self-sustained system. While the plants on the roof are native to the area and promote a local ecosystem, the roof still requires maintenance procedures to retain the look and functionality that the Academy strives for. These procedures include weed maintenance, irrigation, composting, and filtering and recharging the absorbed rainwater for reuse in the Academy’s plumbing system, aquarium, and roof irrigation.
During the dry months of the year, the Academy irrigates the roof using groundwater from the Golden Gate Park and from the filtered rainwater absorbed by the roof. Ari Harding, the Academy’s building systems director, insists that such irrigation is important, and that keeping the roof green year-round helps continue and promote the educating qualities of the roof and the value of its sustainable qualities.
One of the roof’s most important roles is to regulate the indoor temperatures of the museum. This is made possible with the skylights that are embedded into the living roof. These skylights contain sensors that gauge the interior climate, and open and close automatically when certain temperature limits are reached. This is an extremely useful function of the roof, and allows the Academy to operate without an air conditioning system, which significantly lowers the energy usage of the building as a whole. However, t is unclear how much energy the automated skylights require to constantly gauge the temperature and be motorized.
The rainwater absorbed by the living roof enters a recharge station and then runs its course through the Academy’s aquifer chamber before being distributed to the aquarium, the building’s plumbing system, and the roof for irrigation during dry months. This process seems to require a substantial amount of energy, but the Academy strives to maintain all the rainwater absorbed by the roof in an efficient closed-loop system.
The roof also contains 60,000 photovoltaic cells on the roof that “generate 213,000 kilowatt-hours of energy per year”, which equates to about 5% of the Academy’s total energy needs for operation. Considering that creating photovoltaic cells is energy-intensive, creates toxic waste, and emits greenhouse gases, the use of photovoltaic cells on the roof as a regenerative energy source does not seem to be the most efficient use of energy and materials for the building or the living roof.
The majority of the energy required for the roof’s waste management is focused on the weed management and rainwater absorption. Since the Academy uses the decomposed plant material from the roof to create its own compost, this waste becomes part of a closed-loop system. The rainwater that is absorbed by the roof is also part of a closed-loop system; 100% of the water absorbed by the roof is filtered through the Academy’s aquifer chamber and is reused to irrigate the roof during dry months, maintain the aquarium, and cycle through the plumbing system.
In general, the California Academy of Sciences’ living roof is a sustainable design, but there are several areas in which it can be improved upon for future models of living roofs. The creation of the BioTrays was innovative and used purely organic materials, which can be commended excluding the fact that the coconut fibers had to be sourced from the Philippines. If future living roof designs can be created using locally-sourced, biodegradable, and energy efficient materials, the
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