GREEN ROOF DESIGN
GRACE SCHOENKNECHT
HORT 3044 | SPRING 2024
Overview of Design
Cincinnati has a distinct manufacturing corridor that forms a sort of ring through the city. Due to the nature of manufacturing processes, this type of land use generates a great deal of pollution and releases many contaminants into the air. Be it from the manufacturing process itself or from indirect sources (i.e. diesel truck engines used to carry goods), air pollution in this corridor poses a significant threat to human health and the environment. Eco Ring Cincinnati is a project that focuses on urban greening through Cincinnati’s manufacturing corridor. This green roof design is just one component of the greater system that is to emerge upon completion of the project. The green roof will be designed to retrofit the existing SORTA/Metro building in Lower Price Hill/ Queensgate, Cincinnati. The building is located east of the Mill Creek as well as a conglomeration of rail tracks that feed from the Queensgate Yard. The nature of this green roof design (and other remediation efforts) draws inspiration from the environmental master plan created for the Ford River Rouge Truck Plant in Dearborn, Michigan, which consisted of a large scale green roof located atop their trucking facility.
Location
Southwest Ohio Regional Transit Authority (SORTA) and Metro Queensgate Division Building located in Lower Price Hill / Queensgate, Cincinnati, OH.
Address: 1401 Bank St, Cincinnati, OH 45214
Users
This green roof is being designed with environmental resilience as its number one priority. The goals for the design are to manage stormwater runoff, reduce urban heat island effect, capture emissions produced from the surrounding transportation and manufacturing uses to improve air quality, and lower energy burden for the SORTA building. For these reasons, there are no anticipated users for the space. Indirect beneficiaries of the green roof may be users of the United States Postal Service building that is located southeast of the SORTA building and has a greater building height. This means that USPS employees and other users of this building may be able to look upon the green roof,
Type of Roof
Building Heights
Building Façade to Roof Ratio
The building facade to roof ratio refers to the proportion or ratio between the surface area of a building’s facade (exterior walls) and the surface area of its roof. The area of the exterior walls of the building is approximately 84,000 sqft, and the area of the roof is approximately 288,990 sqft. This implies that a larger portion of the building’s surface area is covered by the roof.
Architectural Character
The SORTA/Metro building features a utilitarian architectural character, prioritizing functionality and efficiency over ornate design elements. The building has a large, open floor plan with high ceilings to accommodate buses. The exterior façade consists of durable materials like concrete,
steel, and metal cladding, providing strength and protection from the elements. The building features large doors and loading docks, facilitating the movement of buses in and out of the building. There are limited windows throughout the majority of the building, except in the northern portion of the building which is used as an employee area.
CLIMATE & HABITAT
Seasonal Variations & Patterns
Cincinnati experiences distinct seasonal variations and diurnal patterns influenced by its location in the Midwestern United States.
During the summer months, Cincinnati typically sees warm temperatures with occasional heatwaves, with Lower Price Hill / Queensgate experiencing even higher
temperatures than surrounding suburban areas due to urban heat island effect. The summer also brings longer daylight hours and higher humidity levels. Diurnally, daytime temperatures can rise significantly, often reaching their peak in the afternoon before gradually cooling off in the evening. Summer evenings are generally mild, providing relief from the daytime heat. In contrast, winter brings colder temperatures, occasional snowfall, and shorter daylight hours. Diurnally, daytime temperatures are cooler, with the coldest temperatures typically occurring in the early morning hours before sunrise. Throughout the year, Cincinnati experiences variations in weather conditions, with occasional thunderstorms in the summer and cold fronts in the winter contributing to fluctuations in temperature and precipitation.
Growing Seasons & Planting Time
For green roofs in Cincinnati, the optimal planting time typically falls within the spring and early summer months, after the threat of frost has passed and temperatures begin to rise. This allows for sufficient time for plant establishment and root development before the onset of summer heat. Planting during this period also coincides with the active growing season for many plant species, ensuring they can take advantage of favorable conditions and establish robust root systems. Additionally, planting during the spring and early summer allows plants to acclimate to their new environment and establish themselves before facing the challenges of extreme heat and drought common during
Cincinnati’s summer months. With that said, the type of roof system incorporated into this design is a pre-vegetated modular system, so plants may be grown outside of the region during differet times before being installed on the roof.
Wind Patterns
Cincinnati’s prevailing wind direction is predominantly from the southwest during the warmer months (spring and summer) and from the northwest during the cooler months (fall and winter). This pattern is influenced by the general flow of weather systems across the region.
During the spring and summer, prevailing southwest winds may bring warm and humid air into downtown Cincinnati. In the fall and winter, prevailing northwest winds may bring cooler and drier air into downtown Cincinnati. The SORTA building is roughly north/south facing (skewed lightly NE/SW). This means that the building would experience oblique wind patterns, with prevailing southwest winds during warmer months potentially exerting greater pressure on its southern facade and prevailing northwest winds during cooler months exerting a stronger force on its northern facade.
Sun Exposure
The SORTA building is located just east of the Queensgate Rail Yard. This means that there are no significant buildings or other structures that would impact sun exposure from the west. East of the SORTA building is a series of manufacturing buildings located
along Mclean St. These buildings are generally about the same height as the SORTA building and therefore will not cast significant shadow onto the roof of the SORTA building.
The SORTA building is positioned roughly north-south, meaning the eastern side of the building will experience sun throughout the day, shifting to the western side of the building as evening approaches.
Rain Patterns
While some parts of the country have been experiencing increasing drought, Cincinnati is actually experiencing an increase in rainfall events. Due to the fact that Cincinnati utilizes outdated combined sewage overflow systems (CSOs), increased rainfall can cause serious negative impacts to the city’s stormwater infrastructure, leading to sewage back-ups and flooding (Green Cincinnati Plan, 2023). The implementation of a green roof to help capture some rainfall and slow the runoff process can help mitigate the negative
impacts of heavy rainfall occurrences. According to the Green Cincinnati Plan (2023), Cincinnati has been experiencing a 5-10% increase in rainfall since 1950. Currently, the average annual rainfall for the city is about 42 inches.
Rain patterns and amounts generally vary by season. In the springtime, Cincinnati will start to experience an increase of rainfall as warmer temperatures cause more frequent weather activity. During the spring the amount of rainfall can vary, but the area will generally experience occasional thunderstorms and some heavy downpours. During summer months is when Cincinnati will typically experience the greatest amount of rainfall. These storms are often associated with warm, moist air masses and can produce localized flooding, particularly in low-lying areas, areas with poor drainage, and areas with high amounts of impervious surfaces, such as Queensgate. Afternoon thunderstorms and other heavy rainfall events are more frequent during this season. Rainfall begins to decrease as fall approaches when compared to the summer months, but rainfall remains relatively consistent. Due to passing cold fronts and occasional remnants of tropical systems, some heavy rain showers may occur. Winter is generally the driest of the seasons for Cincinnati, though some rain events may still occur. Precipitation is likely to occur as snow or a wintry mix as the temperatures approach and dip below freezing.
Other factors that affect rainfall in Cincinnati include its proximity to the Ohio River, and
FIGURE 6: SITE SUN DIAGRAM
may even be influenced by the Great Lakes. The moist air masses that are generated by these bodies of water will contribute to Cincinnati’s precipitation events. Additionally, frontal systems, both warm and cold fronts, play a significant role in bringing rain to the region throughout the year.
EPA Ecoregion
Cincinnati is situated within the Eastern Corn Belt Plains ecoregion, which is characterized by fertile agricultural land, rolling hills, and a mix of deciduous forests and farmland. This ecoregion experiences a temperate climate with distinct seasons, including hot summers and cold winters.
USDA Plant Hardiness Zone
Cincinnati falls within USDA Plant Hardiness Zone 6b, which means the average annual minimum winter temperature ranges from -10°F to -5°F (-23.3°C to -20.6°C). Gardeners and landscapers in Cincinnati should select plants that are hardy to Zone 6b to ensure they can withstand the winter cold.
AHS Heat Zone
Cincinnati is typically classified as AHS Heat Zone 7, indicating that the region experiences approximately 60 to 90 days per year with temperatures above 86°F (30°C). This heat tolerance rating is important for selecting plants that can withstand hot summers and occasional heatwaves.
BIOLOGICAL DIVERSITY
Some native species of flora are as follows: Trees
• Eastern Redbud (Cercis canadensis)
• Ohio Buckeye (Aesculus glabra)
• Red Oak (Quercus rubra)
• White Oak (Quercus alba)
• Sugar Maple (Acer saccharum)
Shrubs and Bushes
• Spicebush (Lindera benzoin)
• Serviceberry (Amelanchier spp.)
• Blackhaw Viburnum (Viburnum prunifolium)
• Witch Hazel (Hamamelis virginiana)
• Ninebark (Physocarpus opulifolius)
Wildflowers and Perennials:
• Wild Bergamot (Monarda fistulosa)
• Purple Coneflower (Echinacea purpurea)
• Black-eyed Susan (Rudbeckia hirta)
• Virginia Bluebells (Mertensia virginica)
• Wild Columbine (Aquilegia canadensis)
Grasses and Grass-Like Plants:
• Little Bluestem (Schizachyrium scoparium)
• Switchgrass (Panicum virgatum)
• Eastern Gamagrass (Tripsacum dactyloides)
Cincinnati, Ohio, lies within the Eastern deciduous forest region, characterized by a diverse range of plant species adapted to the region’s climate, soil types, and topography.
• Sedges (Carex spp.)
Birds
Despite being in an urban area, downtown Cincinnati supports a diversity of bird species. This includes both resident species and migratory birds that pass through during spring and fall migrations. Common urban birds include sparrows, robins, cardinals, pigeons, and waterfowl.
Insects and Pollinators
Urban green spaces provide habitat for insects and pollinator that play essential roles in pollination, ecosystem functioning, and maintaining biodiversity in urban environments. These species include bees, butterflies and beetles.
Small Mammals and Amphibians
While larger mammals are less common in urban areas, downtown Cincinnati still supports populations of small mammals and amphibians, such as squirrels, rabbits, mice, frogs, and salamanders.
SOURCING & INSTALLATION
Staging and Storage
During the construction phase, staging and storage will take place utilizing the parking lot located south of the building. Overflow parking created due to the reduction of spaces can utilize the building’s employee lot on the north side of the site. This is where deliveries will be taken, and where construction equipment (such as cranes and lifts) will be stored. Throughout the construction process, materials that have not yet been moved to the roof will be stored
here as well. The use of a pre-vegetated modular tray system will significantly reduce the burden of staging and storage during the construction process, and also means that soil will not need to be blown onto the roof.
Water Sources & Irrigation
One of the catalysts for this project is the fact that Cincinnati has been experiencing increased rainfall over recent years. The increased rainfall is negatively impacting the cities combined sewage overflow (CSO) systems that are still in place, causing flooding in areas, especially properties in the Mill Creek Valley, such as the SORTA/Metro building. Additionally, the modular system used in this design will not have a particularly deep growing media depth. With these things in mind, the green roof has not been designed with an irrigation system, and will rely on rainfall to irrigate plants.
Materials & Plant Sourcing
One of the precedents I studied for this project is the Ford Rouge River Truck Plant in Dearborn, MI. The project consulted the company XeroFlor for their modular, prevegetated system. XeroFlor has a system, the XF-TR system, that would be used for this project. The company offers a sedum mat option which they are able to ship. This option would work well due to the fact that aesthetics is not the primary objective for this project, and therefore a curated plant selection and design is not necessary.
VIEW LINES
Visibility of Roof
The roof will be visible only to two groups. The first is SORTA/Metro employees who have access to the roof with a small patio area on the south side of the roof. The other group is USPS employees and customers. The USPS building, located southeast of the SORTA/ Metro building, is the only building that has a greater height than the SORTA/Metro building, and therefore will have visibility of the roof. Both of these groups will primarily have visibility of the southern portion of the roof.
POLICY & CODES
The SORTA/Metro building is zoned as Manufacturing General (MG) and therefore any planned projects would have to adhere to the requirements set forth in the zoning code for this use. Furthermore, the Ohio Building Code (OBC) sets forth requirements that vegetative roofs must comply with. Chapter 15, Roof Assemblies and Rooftop Structures, lays out requirements for rooftop design and construction. The OBC also states that vegetative roofs must comply with Sections 1607.12.3, Occupiable Roofs, and 1607.12.3.1, Vegetative and Landscaped Roofs. Finally, the OBC states that vegetative roofs must comply with the requirements set forth in the Fire Code.
PRECEDENTS
Ford River Rouge Truck Plant, Dearborn, MI, USA
The Ford River Rouge Truck Plant green roof is an expansive and pioneering project, covering approximately 10.4 acres atop a manufacturing facility in Dearborn, Michigan. This extensive green roof is one of the largest in the world and features a combination of sedums and prairie grasses. Its innovative design helps mitigate stormwater runoff, reduce urban heat island effects, and improve air quality. The project utilized a prevegetated, modular tray system. The green roof showcases how large-scale industrial facilities can integrate green infrastructure to enhance ecological resilience and minimize environmental impact.
FIGURE 9 (TOP): PROJECT OVERVIEW
FIGURE 10 (RIGHT): VIEW OF VEGETATION FROM ROOF
FIGURE 11 (LEFT): GREEN ROOF INSTALLATION
Vancouver Convention Centre West, Vancouver, BC, Canada
The Vancouver Convention Centre West green roof spans over six acres, making it one of the largest in North America. It features a blend of native plant species, including grasses, sedums, and wildflowers, creating a biodiverse ecosystem. This extensive green roof serves as a habitat for local wildlife, absorbs rainwater to reduce runoff, and insulates the building, reducing energy consumption. Its innovative design incorporates sustainable materials and helps mitigate urban heat island effects, contributing to a healthier urban environment. The Vancouver Convention Centre West green roof showcases the city’s commitment to sustainability and serves as a model for green building practices worldwide.
Jacob K. Javits Convention Center, New York, NY, USA
The Jacob K. Javits Convention Center green roof covers 6.75 acres atop the sprawling complex in New York City, making it one of the largest green roofs in the United States. This extensive vegetative roof comprises sedums, grasses, and native plants, creating a lush urban oasis. It reduces stormwater runoff, mitigates heat island effects, and improves air quality in the city. The green roof also provides habitat for birds and insects, enhancing biodiversity in the urban environment. With its sustainable design and environmental benefits, the Jacob K. Javits Convention Center green roof exemplifies New York City’s commitment to green infrastructure and eco-friendly urban development.
FIGURE 12: AERIAL VIEW OF VANCOUVER CONVENTION CENTRE GREEN ROOF
FIGURE 13: AERIAL VIEW OF JACOB K. JAVITS CONVENTION CENTER GREEN ROOF
DESIGN
Typology
The primary objective for this green roof design is to provide environmental benefit as part of a neighborhood/city-wide system of green stormwater infrastructure (GSI). GSI has a variety of benefits, with a major one being managing stormwater runoff. The City of Cincinnati is experiencing increased rainfall, and our outdated sewer infrastructure us struggling to manage it all. Other benefits of this green roof design include mitigating urban heat island effect by creating a cooling roof, and improving air quality through the use of premeditation plants. After environmental considerations, secondary benefits of this roof design include reducing energy costs (as green roofs assist with building temperature regulation) and providing an improved employee area for SORTA/Metro employees.
Programming
Due to the fact that this green roof has not been designed with public use as an objective, programming for the roof is limited. As far as accessibility goes, the roof will only be accessible to SORTA/Metro employees, and can be accessed from within the building through a series of doors/hatches (see Roof Access Points diagram, page 4). The roof will incorporate a series of maintenance paths, as seen in the design plan on page 15. The paths connect access points as well as providing access for maintenance purposes across the roof. There is also a eighteen inch clearing
from the parapet to the vegetative area to support the structural integrity of the roof that also creates a maintenance path around the perimeter of the roof. The employee area will offer a small seating area, giving employees the opportunity to take their breaks in this area while eating a meal, playing cards, etc. The roof will only be accessed by employees and maintenance people during the day, so lighting is not a consideration. Due to the fact that the roof’s structural load is not incredibly high, there will be no shelter or shading area constructed on the roof in the employee area, or elsewhere. There will be a storage container located within the employee area for storage of maintenance equipment. Stormwater collected from the green roof can be contained and used for other purposes, such as cleaning and maintenance of the Metro bus fleet (see Roof Drainage and Slopes diagram, page 4). The rooftop systems have been considered as part of this design, with an eighteen inch vegetative free zone around the major structures. Minor systems will be integrated into the vegetative areas.
Planting Plan
The SORTA/Metro building is located in a manufacturing area of Cincinnati, next to an active rail yard. Additionally, the use of this building is to house Metro’s bus fleet. For these reasons, improving air quality is part of the primary objective for the project. Preference will be given to plants that can preform phytoremediation. The pollutants that have been considered are diesel exhaust, particulate matter, lead, cadmium, and
arsenic, as these pollutants are likely present in the area. Additionally, plants were selected based off there ability to thrive within an extensive green roof system with growing media depth of 2”-6”. Grasses including Fescues, Blue Grama Grass, and Sideoats Grama will be incorporated into an extensive planting of sedums. Sedums that have been considered include Sedum album, spurium, kamtschaticum, rupestre, reflexum, and sexangulare.
FESCUES BLUE GRAMA SIDEOATS GRAMA
SEDUM ALBUM
SEDUM RUPESTRE
SEDUM SPURIUM
SEDUM REFLEXUM
Installation and Maintenance Plan
The SORTA/Metro building is positioned to easily accommodate the installation of a green roof. Construction vehicles can easily move around the site due to the fact that the building is not directly surrounded by other buildings, and is already intended to facilitate the movement of large vehicles (buses). The complex has multiple parking lots, one of which will be able to serve as a staging and storage area during installation. The green roof will be low maintenance. The shallow depth of the growing media will deter weed growth. Rainwater will be used as irrigation. Yearly fertilizing should occur during the spring time.
Project Cost
Project costs will be kept to a minimum due to the following factors:
SEDUM KAMTSCHATICUM
SEDUM SEXANGULARE FIGURES
• Extensive roofs are generally cheaper due to their simpler design and lower maintenance requirements
• Accessibility of the roof and the use of a modular, pre-vegetated system will minimize labor and installation costs
• Aesthetics and user experience are not the primary objectives of this design, so costs can be saved in the selection of materials and finishes
The large scale of the roof will increase project costs.
Green Roof Design
IMAGE REFERENCES
FIGURES 1 - 5: Google Earth Imagery
FIGURE 6: Google Earth Imagery, https://www. suncalc.org/#/39.1172,-84.538,16/ [Various Dates]
FIGURE 7: https://static1.squarespace.com/ static/57f6ab9f3e00be42ddd79a9c/t/5e5d52bf3172f13e8 208bf67/1583174335883/XF%2BTR_Typical+Layers.pdf
FIGURE 8: https://xeroflornorthamerica.com/xf-tr
FIGURE 9: https://mcdonoughpartners.com/projects/ ford-rouge-center-landscape-master-plan/
FIGURE 10 - 11: www.greenroofs.com/projects/fordmotor-companys-river-rouge-truck-plant/
FIGURE 12: https://www.csla-aapc.ca/awards-atlas/ vancouver-convention-centre-expansion-project
FIGURE 13: https://gothamist.com/news/how-an-8-acre-greenroof-atop-the-javits-center-is-boosting-nyc-biodiversity
FIGURE 14: https://shop.stoverseed.com/products/ celestial-strong-creeping-red-fescue
FIGURE 15: https://seedsource.com/blue-grama/
FIGURE 16: https://www.wbseedco.com/ native-grasses/sideoats-grama/
FIGURE 17: https://theoriginalgarden.com/p/plants/flowers/ perennial-biennial-plants/sedum-album-white-stonecrop
FIGURE 18: https://www.llifle.com/Encyclopedia/SUCCULENTS/ Family/Crassulaceae/34356/Sedum_spurium
FIGURE 19: https://www.rareroots.com/products/ sedum-kamtschaticum-variegatum
FIGURE 20: https://www.whiteflowerfarm. com/38220-product.html
FIGURE 21: https://en.wikipedia.org/wiki/Petrosedum_rupestre
FIGURE 22: https://mountaincrestgardens. com/sedum-sexangulare/
FIGURE 23 - 24: Google Earth Imagery
SOURCES
1. “Design Details.” XeroFlor North America, xeroflornorthamerica.com/xf-green-roof-systems-1. Accessed Feb. 2024.
2. “Ecoregions of Indiana and Ohio.” Environmental Protection Agency, gaftp.epa.gov/EPADataCommons/ ORD/Ecoregions/oh/ohin_eco_lg.pdf. Accessed Mar. 2024.
3. Famulari, Stevie. “Phytoremediation Database.” Stevie Famulari, GDS, www.steviefamulari.net/phytoremediation/. Accessed Mar. 2024.
4. “Ford Motor Company’s River Rouge Truck Plant.” Greenroofs.Com, 12 Nov. 2020, www.greenroofs.com/ projects/ford-motor-companys-river-rouge-truck-plant/.
5. “Ford Rouge Center Landscape Master Plan.” William McDonough + Partners, 21 June 2021, mcdonoughpartners.com/projects/ford-rouge-centerlandscape-master-plan/.
6. “Green Roof Design Principles: Professional Services.” XERO FLOR, www.xeroflor.pl/en/green-roofs/principles-ofdesigning-green-roofs. Accessed 1 Apr. 2024.
7. “Jacob K. Javits Convention Center.” Greenroofs.Com, 19 Apr. 2022, www.greenroofs.com/projects/jacob-k-javitsconvention-center/.
8. Lombard, Retha. “Animals in Ohio.” A-Z Animals, 18 Aug. 2023, a-z-animals.com/animals/location/north-america/ united-states/ohio/.
9. “Native Plant Catalog.” Cincinnati Nature Center, www. cincynature.org/media/plant-sale/2023-PlantSaleFullCatalog.pdf. Accessed Mar. 2024.
10. “Ohio Building Code.” Ohio Department of Commerce, 2017.
11. “SunCalc Sun Position- Sun Phases Calculator.” SunCalc, www.suncalc.org/#/39.1172,-84.538,16/2024.12.01/12:00/1/3. Accessed Mar. 2024.
12. “USDA Plant Hardiness Zone Map.” The National Gardening Association, garden.org/nga/ zipzone/?zip=45237. Accessed Mar. 2024.
13. “Vancouver Convention Centre West / Expansion Project.” Greenroofs.Com, 18 Aug. 2022, www.greenroofs.com/ projects/vancouver-convention-centre-west-expansionproject/.