Technical Innovation proposal :
Sustainable Green Roofs on the NAC Building at City College of New York
Writing for Engineering
Table content:
Introduction and Thesis Page 2
History Page 3
Technical Description Page 4
Other Engineering Innovation Page 5-10
The process of the Innovation Page 10
Expectation Page 11
Conclusion Page 12
Introduction:
CCNY is a well-known place for education and innovation, and it is important for the campus to take steps to reduce its carbon footprint. Green roofs are a simple and effective solution that fits with CCNY’s commitment to being good to the environment. As we look to the future, sustainability and climate consciousness is becoming an essential part of our daily lives. It is important that it is reflected in our education and learning process. It is more imperative that the college integrates pro-sustainability into their curriculum (architecture, engineering, education programs) and within their infrastructure.By turning the roof of the NAC building into a green space, CCNY can show how committed it is to sustainability while also getting a lot of benefits. Putting green roofs on CCNY buildings is a big step towards making cities more environmentally friendly.
A Proposal for Technological Innovation Regarding the Installation of a Green Roof on the NAC Building at City College of New York
History:
Green roof movements have been around since their inception in Europe back in the 19th century. Architects Friedensreich Hundertwasser from Germany and Ernst Cramer from Switzerland were among those who aimed to integrate nature into cities through this concept.
In North America during the 1960s & 1970s, Cornelia Hahn Oberlander’s notable contributions as a Canadian horticulturist cum landscape architect helped promote green roofs as vital elements in sustainable urban planning. Following their inception, green roofs have experienced ongoing evolution and continually increased global recognition. As a result, governments, municipalities, and architects have increasingly integrated green roofing systems into building codes and urban planning policies to encourage sustainable practices and tackle environmental concerns.
Specific:
For CCNYs campus these interventions can prove helpful in reducing urban heat islands’ impacts by moderating temperature fluctuations; improving air quality through cleaner air production; managing stormwater runoff through promoting rainwater retention capabilities within plant systems; providing wildlife habitats for diverse species; creating spaces for food production while enhancing learning opportunities relating to sustainability and ecology. Another advantage is the insulation function offered by the growing media layer, which reduces energy consumption by regulating indoor temperatures without depending heavily on air conditioning.
Technical Description:
A seamless integration between different layers is critical in providing efficient functionality to green roofs. Depending on a use case implementation of the various layers the depth of green roofs differ from 4-6”.
Main Layers (all depicted in Figure 1)
- Roof Deck
- Waterproofing membrane
- Root Barrier
- Drainage Layer
- Filter fabric layer
- Growing medium (substrate layer)
- Vegetation Layer
1. The Roof Deck, which provides fundamental support necessary for all the layers above it, be it constructed from materials like concrete, steel, or wood.
2. The Waterproofing Membrane layer sitting on top of the roof deck, offering maximum protection against water penetration to the structure below (see figure 2). In areas near vast bodies of water where rainfall levels are high throughout significant portions of each year, choosing thermal-sealed membranes capable of resisting heavy bouts of water flooding is crucial for optimal protection of structures beneath. The types of membranes that are commonly used are as follows: Built-up or modified bitumen, Rubberized asphalt (completely adhered to the deck), Thermoplastic membranes of polyvinyl chloride (PVC), Thermoplastic olefin (TPO) (sheets with seams), Ethylene propylene diene membrane (EPDM).
3. The Root Barrier layer continues above this and has several essential purposes, including acting as a buffer between green roof assembly and waterproofing membranes to protect against invasive plant roots that can cause damage over time (see figure 3). Various materials are used for constructing effective root barrier solutions, such as copper hydroxide-impregnated barriers, PVC, TPO, and Roof-sheeting but at its core, material specifications demand adherence to fundamentals like HDPE or impervious concrete design principles. FM Global sets standards for root barrier installation that all installers must follow. The criteria specify factors like seam overlap thicknesses and appropriate welding standards that must be met during installation.
4. The Drainage Layer-This component is responsible for eliminating excess water from the waterproof barrier while concurrently maintaining sufficient moisture levels required for plant vitality. A comprehensive drainage system comprising boards, pipes and drains facilitate effective water transfer. There are four main drainage material types used in green roof construction: cuspated sheets, entanglement sheets, granular material and structural drainage (see figure 4). Additionally, besides aiding in enhanced water management on roofs; this crucial element may also improve insulation’s compressive strength and thermal capacity while providing added protection for the root barrier or membrane.
5 Filter Fabric-The filter fabric layer in green roofs serves as an essential barrier that enables water to flow through while eliminating soil particles, debris and other unwanted materials. Its presence is crucial in endorsing the integrity and efficiency of drainage layers by thwarting the accumulation of fines that might obstruct its pathways.Generally, synthetic substances like polypropylene or polyester are employed to create filter fabrics for green roofs. These materials possess remarkable features including durability, decay resistance, and robustness against various conditions typical in green roof environments.
6 A specially designed Growing Medium is then added for optimal growth conditions that provide plants with the necessary nutrients and water required for growth
7 The Vegetation Layer shines brightly, providing greenery that thrives, adding beauty to any building. Green roofs offer ample scope for incorporating diverse vegetation types – be it grasses, sedums, or even small trees. Numerous factors, such as site-specific conditions and intended aesthetics guide the final selection.
Proposal:
We propose that the City College of New York installs green roofs on top of the NAC building. It is imperative for the campus to prioritize the reduction of its carbon footprint.
The NAC building, which is approximately 50 years old, shows signs of deteriorating infrastructure, giving rise to notable concerns such as increased energy consumption, ceiling leaks attributed to roof deterioration, and an outdated architectural design.
Although green rooftops have been prevalent for many years, they have not aligned with the sustainability ethos due to the use of unsustainable construction materials. Our intention is to adopt a more eco-friendly rooftop design and establish a truly viable system.
Fig 5. NAC building rooftop and possible areas of installation. (Alleyne, 2012)
Innovative Materials:
The growing medium, also known as the substrate is the most important part of green roofs as most of its benefits come from this layer. The soil used in green roofs differs from ground soil and holds significant importance due to its necessary characteristics, including appropriate porosity, pH level, nutrient content, and weight (Araújo de Almeida & Colombo, 2021).
Growing medium: “Inorganic substrates are used as the primary component in green roof growing media” (Graceson et al., 2014). Although the material generally used provide the desired results, they don’t necessarily contribute to the green initiative. For our green roof, we will be using a substrate made out of a mixture of urban waste compost and agro-industrial waste such as coconut fiber.
The compost will be made through a process called vermicomposting. We will be using worms to digest organic waste and turn it into a substance we call humus. The composition of the humus combined with agro-industrial waste would make the perfect medium for plants to grow due to its nutrients, water retention, pH levels and it’s load on the rooftop.
Fig 6. Graphic representation of substrate (Araújo de Almeida & Colombo, 2021)
Drainage and Insulation: As seen in Fig 1, green roofs are generally made of layers that have individual purposes. For our project, we plan to create a layer that has multiple intents. By using a tree-based material we eliminate the need for plastic. Our material will be made out of the cork tree which has amazing insulation properties comparable to styrofoam. It will also serve as a drainage medium thanks to its permeable properties. The cork-based material, due to its durability and rigidity will also play an amazing part as a root barrier. Cork is an amazing material for the success of the project due to its nature and properties which align with the project aspirations (Critical Concrete, 2021).
Waterproof barrier: A better and more eco-friendly alternative would be a rubber-based fabric made from the rubber tree. This fabric is waterproof, durable, and doesn’t contaminate the filtration system (Critical Concrete, 2021).
Process & Cost:
The construction of the green rooftop will take some time as there are many prerequisites to start the project. As seen in Fig 8, there are three crucial steps to carry out before starting the construction. Due to the age of the building, the structure needs to be inspected and studied for its capabilities and conditions. Results from this study will allow us to determine the amount of material and surface area that can be used based on the building’s structural integrity (Cryan, 2019). A design and rendering would give the school a concept and possible cost of the project. Once everything has been agreed upon, the next important step will be to prep the roof. This will involve fixing any roof irregularities, setting up an adequate drainage system, and clearing the surface where the green roof will be installed. The next steps involve mostly labor as we will be installing the green roof following the layer structure shown in Fig 1 while introducing our innovative steps.
The construction should take between 2-3 months and would be done in early Spring. The usable area of the roof is 68, 189 ft2 (Alleyne, 2012) with a cost of labor and material of $45 per square feet (Omoregie, 2023) putting the construction to $3,068,505 with of $75,000 annual maintenance cost (Shin & Kim, 2019). Our green roof will have a life expectancy of 50 years, therefore, expanding the NAC’s building roof lifespan by up to 30 years (EPA, 2022). City College has the resources necessary to reduce the cost of this project: Students part of the School of Architecture can be of great use when designing and planning the project. Partnerships with organizations such as The Gaia Institute, whose mission is to explore by performing research, developing, designing, and educating the correlation between human communities and natural system, is cost-effective materials. It will be beneficial for the school to open opportunities for students’ involvement as volunteers as this project can gather significant interest. Also having class projects involve the green rooftop could not only offer hands-on experience but also contribute to the long-term maintenance of the facility. Finally, the school can take advantage of the many federal and state grants and incentives associated with the sustainable effort.
Fig 8. Projected project timeline
Expectations, Life Expectancy and Maintenance:
If given the funding from The City College of New York to create a green roof on the North Academic Center (NAC) building, the expected amount of time needed to fully construct the green roof can vary. As part of the planning procedure, we’d need to not only have permission from CUNY but the materials needed to construct the green roof. The construction process can take as few as a couple days to as long as multiple weeks depending on how much of the roof we plan on using.
One of the positives about having a green roof is that it is very durable and built to last for decades if kept in good condition. According to a roofing megastore company website, it states “Green roofs have a life expectancy of around 40 to 50 years, giving them a lifespan that outperforms a number of alternative roofing options considerably”. Not only is the green roof is long-lasting but can also be the more beneficial option of roofing compared to others. Although the green roof by itself won’t be able to last for its expectation without the use of people assisting and tending to the green roof. Our initial choice of plants are some that are known for its longevity and toughness in order for the plants to be resilient towards harsh weather. Tying the green roofs to the education curriculum is also part of the goal once the green roof is complete. Students who are interested in botany can check out the green roof and even participate in taking care of the plants. There can also be community service work connected to the green roofs as well for anyone interested in it. Having these programs being involved with the green roofs would require its own schedule for students to enter the green roofs, preferably a schedule suitable for the average on-campus students. This will further help with the long-lasting effects of the green roof and gather students who are interested.
Conclusion:
Implementing these types of greenery into our lifestyle can benefit different aspects of our life. Having a green roof in an environment such as a college campus gives students and faculty the opportunity to be more in touch with nature with the green roof’s long-lasting properties.
References
Alleyne, A. (2012). (rep.). Rooftop PV System for the NAC Building of CCNY. Appropedia. Retrieved from https://www.appropedia.org/Rooftop_PV_System_for_the_NAC_Building_of_CCNY#The_North_Academic_Center.
“An Introduction to Green Roofs: Roofing Advice.” Roofing Materials & Suppliers Megastore, 26 July
2022, An Introduction to Green Roofs | Roofing Advice (roofingmegastore.co.uk)
Araújo de Almeida, M., & Colombo, R. (2021). Construction of green roofs via using the substrates made from humus and green coconut fiber or sugarcane bagasse. Sustainable Chemistry and Pharmacy, 22, 100477. https://doi.org/10.1016/j.scp.2021.100477
Critical Concrete. (2021). Green Roof For Urban Sustainability. Retrieved from https://www.youtube.com/watch?v=u2WOSjn1pr8.
Cryan, L. S. (2019, August 6). Everything You Need to Know Before Installing a Green Roof. https://www.brownstoner.com/interiors-renovation/green-roof-what-you-need-to-know-installation-cost-benefits-plants-sedum/
EPA. (2022, July 13). Using Green Roofs to Reduce Heat Islands. https://www.epa.gov/heatislands/using-green-roofs-reduce-heat-islands
Graceson, A., Hare, M., Hall, N., & Monaghan, J. (2014). Use of inorganic substrates and composted green waste in growing media for green roofs. Biosystems Engineering, 124, 1–7. https://doi.org/10.1016/j.biosystemseng.2014.05.007
“Green Roofs.” GSA, 4 June 2021,
Omoregie, J. (2023, February 15). How much does a green roof cost in 2023?. Lawnstarter. https://www.lawnstarter.com/blog/cost/green-roof-price/
Shin, E., & Kim, H. (2019). Benefit–cost analysis of green roof initiative projects: The case of Jung-gu, Seoul. Sustainability, 11(12), 3319. https://doi.org/10.3390/su11123319
U.S. Environmental Protection Agency | US EPA. (n.d.-a). https://www.epa.gov/sites/default/files/documents/GreenRoofsSemiAridAridWest.pdf
Reflection:
Nathan Jainarain
Technical Innovation Reflection
Writing for Engineering
5/23/23
This assignment developed required many skills that would propel my career and future professional life. Our specific innovation was the establishment of green roofs on the North Academic Building of CCNY. My specific responsibilities in this group assignment were the technical description of green roofs and benefits they provide. During my research I learned about the components of urban green roofs, the types, and their use cases. The technical description required me to have knowledge of material, function, and location of the specific details of green roofs. This project also caused me to have a better knowledge of sustainability by learning about the benefits of green roofs and the problems they solve. I achieved various learning outcomes in this assignment including the ability to locate research sources and assess their credibility. I was required to do this to provide an accurate comprehension of the benefits of green roofs and the specific necessary components. Furthermore, I was able to compose a text that presented my stance whilst using supporting sources and critical analysis. In the assignment I also included a section which details the history of green roofs and another that describes the specific benefits to CCNY. In these sections I presented my stance and supported it with historical evidence from scholarly articles to make a clear cohesive message about the uses of green roofs.
In order to complete this assignment, we had to brainstorm various methods to be efficient. Given our time in class we were able to create an outline of what we wanted to get across. We still faced difficulty in the beginning understanding what each of us had to do and what innovative features we wanted to include. We met with google meets to further understand what our personal responsibilities for the presentation and paper were going to be. For us all to be on the same page we created a google docs that gave specific points and subtopics split between us that we wanted to address. The beginning of the assignment was pretty tough as a group since with such a open ended assignment it was harder or all of us to stay on the same page. This assignment more than any other requires social communicative skills for us all to create a cohesive message. Time management was also tough at the start and so to solve this we started incorporating deadlines for the group. If we needed more time we could still inform the group on the chat, but this kept us all accountable to each other and was a major factor in us finishing the assignment. Many of the methods we incorporated we used before in the assignment prior in this assignment it was to another scale due to it being more information and work that had to get done. In the team socially I was very active, which I feel helped contribute to the group’s productivity. I called for us to meet up to discuss how we plan to split up work, what ideas we wanted to focus on and how we plan to work on the assignment in general. I contributed ideas and presented the benefits of greenhouses their specific effects to ccny and what we could innovate. Overall this assignment provided the opportunity to utilize various skills that will be valuable in my future career.
