Learning Leader #6: Green Roofs and Green Corridors for Urban Sustainability

Greening Our Cities from Rooftops to Pathways: Fun and Fresh Urban Sustainability Projects

Welcome to June as we celebrate Canadian Environment Week and World Environment Day! ?

I'm excited to launch this article series, #GoingGreen, where I will be discussing dimensions of environmental sustainability and sharing eco-friendly tips for going green.

We are diving into the eco-fun by learning about Green Roofs and Green Corridors!

Urban areas face challenges such as pollution, heat islands, stormwater runoff, and poor air quality. Green roofs and green corridors help manage these issues by improving air quality, reducing energy consumption, improving insulation, reducing rainwater runoff, and providing green spaces.

Green roofs and corridors are two sustainability strategies that help us go green. They serve distinct but complementary roles in urban ecosystem efforts by integrating natural elements into the built environment and contributing to urban sustainability.

Now, let's explore their benefits, challenges, design and maintenance tips, emerging trends and popular examples in real life and fiction to inspire us.

What Are Green Roofs?

Green roofs or living roofs are roofs covered with plants. They are vegetative layers grown on rooftops.

Green roofs turn the tops of buildings into gardens filled with flowers and plants.

Imagine a roof that is like a magical garden. Instead of tiles or shingles, it’s covered with grass, flowers, and maybe even tiny trees.

From prehistoric times, green roofs have been used in various forms for centuries, such as sod roofs in Scandinavian countries.

Green roofs are becoming increasingly popular in urban areas for their environmental, economic, social and aesthetic benefits.

Benefits of Green Roofs

• Economic Benefits: Green roofs help us reduce our energy consumption, provide insulation, and gain more energy savings. They minimize our carbon footprint and increase the property value of the buildings.

- Insulation: Green roofs are natural insulators that provide thermal insulation, reducing heating and cooling costs. They keep the buildings cool on hot days, like putting a hat on a building.

- Energy Savings: Improved insulation reduces heating and cooling costs.

- Increased Property Value: Green roofs can enhance the aesthetic appeal and market value of properties.

- Longevity of Roofing Materials: Green roofs protect the underlying roof membrane from UV radiation and temperature fluctuations, extending its lifespan.

• Environmental Benefits: Green roofs provide numerous environmental benefits, including reducing stormwater runoff, improving air quality, and creating homes for wildlife.

- Stormwater Management: They absorb and filter rainwater, reducing runoff and flooding risks. As the plants soak up rainwater, they help stop the streets from flooding.

- Air Quality Improvement: Vegetation on roofs can filter pollutants from the air, improving urban air quality.

- Biodiversity: Green roofs create habitats for birds, insects, and other wildlife. Birds, bees and butterflies made their homes in these rooftop gardens, thus contributing to biodiversity conservation.

- Urban Heat Island Mitigation Effect: Green roofs help reduce the urban heat island effect, where urban areas become significantly warmer than their rural surroundings due to human activities. By absorbing and reflecting less heat, green roofs contribute to cooling the city.

• Social and Aesthetic Benefits: Green roofs can enhance the visual appeal of buildings and provide recreational spaces for residents and workers.

- Recreational Spaces: Green roofs can provide areas for relaxation, gardening, recreation, food production, or even as backdrops for your next photoshoot.

- Mental Health Improvements: Access to green spaces has been shown to reduce stress and improve mental well-being.

- Group Engagement: Green roof projects can involve community participation, driving a sense of ownership and opportunities to bond and connect.

Challenges and Considerations for Green Roofs

• Technical Challenges

- Structural issues: Ensuring the load-bearing capacity of the buildings can support the additional weight of soil, vegetation, and water.

- Waterproofing and root barriers: Ensuring the roof remains leak-proof by protecting the building structure from water and root penetration.

• Economic Barriers

- Upfront Cost: High initial investment for design, construction and installation can be expensive, although long-term savings could offset this.

- Maintenance Cost: Upkeep costs for regular watering, weeding, and fertilizing and addressing issues like pests and invasive species.

• Regulatory and Policy Issues

- Building codes: Navigating local regulations and requirements.

- Incentives: Accessing subsidies and grants to support green roof projects.

How To Design and Maintain Green Roofs

1. Pick a Roof to Start Small: You can begin with a small section of the roof to see how it works. Choose a safe spot that's strong and safe to walk on.
2. Design with Professional Help: Hire experienced workers to assess the roof and install necessary waterproofing, drainage layers and root barriers to protect the building. Make sure the roof can hold plants and use a lightweight soil mix designed for green roofs. Conduct regular inspections to ensure integrity.
3. Use Simple Plant Choices: Select drought-resistant and low-maintenance plant species like sedums, wildflowers and grasses. Choose native species to support local biodiversity. Consider seasonal changes and opt for plants suited to your local climate and roof conditions to ensure year-round greenery.
4. Make Maintenance Easy: Create a plan for regular maintenance tasks like watering, weeding and fertilization as needed. Monitor the health of the plants and address any pest or disease issues promptly. Use sensors and remote monitoring technology to optimize irrigation and maintenance.
5. Monitor Progress With Feedback: Track energy savings and stormwater retention to quantify environmental benefits. Collect feedback from occupants and visitors to assess the roof’s social and aesthetic impact.

Some Popular Green Roofs

1. City Hall Green Roof, Chicago, USA: A pioneer in the green roof movement, this 20,000-square-foot garden is over 2 decades old and serves as a model for urban green roof projects. Its native plants not only beautify but also reduce energy costs, improving local air quality.
2. Nanyang Technological University, Singapore: An important example of the value of deliberate planning in our educational institutions, there are extensive green roofs on multiple buildings across the campus for stormwater management and reducing heat island effect.
3. Vancouver Convention Centre, Canada: One of North America's largest green roofs, covering 6 acres with over 400,000 native plants. Its design promotes biodiversity and energy efficiency while keeping the city cool.
4. ACROS Fukuoka Prefectural International Hall, Japan: A lush terraced green roof that blends nature into the urban landscape, resembling a hill covered in plants. With over 35,000 plants, it offers recreational space and aesthetic value while improving air quality and urban cooling.
5. Zephyr Palace, Costa Rica: A luxury hotel with extensive green roofs that enhance sustainability and guest experience, driving eco-tourism and economic growth. The design drives energy savings, and provides aesthetic appeal, and ecological value.

What Are Green Corridors?

Green corridors are vegetation stretches connecting parks, nature reserves, and other green spaces. They facilitate wildlife movement and enhance biodiversity.

Green corridors are usually natural or semi-natural linear spaces that connect different habitats in urban areas.

Historically, green corridors have evolved from natural landscapes to intentional urban planning tools aimed at reducing the negative impacts of urbanization.

Urban areas often face issues of habitat fragmentation and loss of biodiversity. Green corridors help address these issues by creating continuous habitats, improving ecological connectivity and providing green spaces for recreation.

Benefits of Green Corridors

• Ecological Benefits

- Habitat Connectivity: Green corridors reconnect fragmented habitats, allowing for the free movement of wildlife which is critical for species resilience and promoting genetic diversity.

- Boosting Biodiversity: Green corridors provide habitat and migration routes for wildlife. The paths of trees and plants connect parks and forests, so animals like squirrels, birds, and butterflies can travel safely without getting lost.

- Ecosystem Services: Green corridors provide essential services like pollination, , air and water purification, and carbon sequestration.

- Climate Regulation: Trees and plants in green corridors help cool urban areas, reduce the heat island effect, absorb pollutants, and improve air quality. They help clean the air so everyone can breathe better. They also provide shade on hot days, making the city cooler.

• Economic Benefits

- Property Value Increase: Proximity to green corridors often raises property values and attracts investment.

- Tourism Potential: Green corridors can become attractions, drawing tourists and boosting local economies.

- Public Health Cost Savings: Improved air quality and recreational spaces can reduce public health costs by encouraging active lifestyles and reducing pollution-related diseases.

• Social and Health Benefits

- Mental and Physical Health: Access to green spaces is linked to lower stress levels, improved mental health, and increased physical activity.

- Social Benefits: Green corridors offer recreational spaces, enhancing urban livability and mental health.

- Cultural Enrichment: Often designed with cultural and historical elements, green corridors can enrich the cultural fabric of a city and provide spaces for community events and activities, nurturing social interaction and community pride.

- Recreational Spaces: These corridors offer residents green trails for walking, biking, and other recreational activities. There are safe, green paths where children can ride their bikes and play, just like a long, winding playground.

Challenges and Considerations for Green Corridors

• Technical and Ecological Challenges

- Urban Constraints: Limited space and existing infrastructure can pose significant challenges.

- Habitat Fragmentation: Ensuring corridors are effective in connecting fragmented habitats and supporting diverse species.

• Economic and Financial Barriers

- Funding: Securing initial and ongoing funding for development and maintenance.

- Financial Sustainability: Demonstrating the long-term economic benefits to justify investment as setting up comes with a high upfront cost from the public coffers.

- Land Acquisition: Securing continuous land for corridors can be difficult in densely populated areas.

• Regulatory and Policy Issues

- Zoning Laws: Navigating complex zoning regulations to implement green corridors.

- Policy Support: Advocating for policies that support green infrastructure and urban biodiversity.

How To Design and Maintain Green Corridors

1. Assessment and Planning: Assess current green spaces for new connections. Conduct feasibility studies to find potential routes. Engage stakeholders, including communities and government agencies. Create a master plan outlining the vision, goals, and actions for the corridor.
2. Design: Plan a corridor that incorporates native vegetation to support local wildlife. Ensure connectivity by linking existing parks, natural areas, and urban green spaces. Include amenities such as trails, benches, and educational signage.
3. Implementation: Secure funding through grants, partnerships, and fundraising. Use a phased approach to manage costs and minimize disruption. Start with high-impact areas to show success and gain support. Involve all stakeholders in planning and development.
4. Maintenance: Ensure ongoing maintenance to keep the corridor healthy and functional. Establish a management plan detailing routine maintenance, invasive species control, and habitat monitoring. Train staff and volunteers for regular upkeep. Engage the community to nurture ownership and care.
5. Monitoring and Evaluation: Use ecological indicators to monitor and assess the corridor’s impact on biodiversity and ecosystem health. Collect data on usage patterns to understand community engagement. Adapt management practices based on monitoring results to ensure long-term success.

Popular Green Corridors

• Cheonggyecheon Stream, Seoul: A formerly polluted urban waterway that was transformed into a vibrant green corridor that is enhancing ecology, improving water quality, and recreation. Now a scenic green area for people to enjoy.
• The High Line, New York City: A linear park built on an old train track above the streets. This elevated green corridor, once a disused railway, now provides green space in a dense area, leading to significant improvements in urban biodiversity, community engagement, and property values.
• Park Connector Network, Singapore: A city-wide network of green corridors that links all the parks and nature reserves, promoting biodiversity and active transportation while also improving urban mobility.
• Emerald Necklace Conservancy, Boston: A historical chain of parks and green spaces connected by parkways that continues to provide ecological and recreational benefits, linking diverse urban areas. It's network enhances urban green connectivity.
• Green Link Belt, Copenhagen: Green corridors have been woven into urban planning to enhance resilience and sustainability, promoting urban biodiversity, supporting climate adaptation, and improving quality of life.

Emerging Trends for Green Roofs and Green Corridors

1. Green Infrastructure Policies: There is increasing support and incentives by governments to drive the incorporation of green infrastructure in urban planning as we move to a net zero future.
2. Global Adoption and Adaptation: The success stories from diverse regions and climates will serve as case studies that can be used in the design and development of green roofs and corridors tailored to local cultural and ecological contexts.
3. Smart Technologies: There are ongoing innovations in material and construction techniques for lightweight and durable materials. Plus researchers are looking to integrate smart building technologies and green roofs in providing equitable opportunities for buildings and homeowners.
4. Smarter Cloud-based Systems: The use of sensors and automated systems for real-time monitoring of corridor health and usage will increase with advancements in generative artificial intelligence.

I recently learnt about Microsoft AI for Earth which is using data to build a global environmental network and help save the planet. I am excited to see how it could help in the adoption and management of green living spaces.

Some Fun Fictional Green Roofs and Corridors

1. Consider the Lorax’s lush rooftop with bright, colourful Truffula trees that help the environment in The Lorax by Dr Seuss
2. Picture a rooftop covered in bioluminescent plants like Pandora’s forests in Avatar
3. Think of the lush roof terraces from the Highgardens of House Tyrell in Game of Thrones.
4. The magical plants that change colours and glow at night in the Herbology greenhouse atop Hogwarts in Harry Potter.
5. Imagine the sight of a magical rooftop garden in the heart of the city, where anything is possible like the the Rooftops of London in Mary Poppins.

Green roofs and corridors offer a wonderful way to contribute to sustainability and help people enjoy a unique green space. They are vital components of sustainable urban design, each offering unique benefits for biodiversity, climate resilience, and well-being.

Consider starting and supporting such green living spaces.

Thank you for reading!

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If you enjoyed this article, don’t forget to like, share, and comment with your experiences and tips for going green!

Footnote: This article was inspired by a conversation with Emma Tamlin who works with the Environment & Climate Team for the City of Toronto. We met at the Liberty Village Eco Fair while I was volunteering for Free Geek Toronto. Her insights sparked my curiosity to learn more.

Toronto was the first city in North America to have a mandatory green roof by-law, which requires new developments with a certain gross floor area to include green roofs. This by-law applies to residential, commercial, institutional, and industrial buildings.

The Green Roofs program in Toronto is designed to encourage and support the installation of green roofs on buildings throughout the city.

The city has an eco-roof incentive program that provides financial incentives of up to $100,000 for installing green and cool roofs on existing buildings and new buildings not subject to the green roof by-law. These incentives help offset the costs of installation and promote wider adoption.

For more details, you can visit the City of Toronto's official page on Green Roofs for comprehensive information on the by-laws, incentive programs, and benefits of green roofs.

Additionally, a discussion about this article, focusing on the state of the over 30 green corridors in Medellín, Colombia after 8 years, prompted me to contemplate the possibilities of designing and developing Green Roofs and Green Corridors in coastal and populated cities like Lagos, Nigeria.

The upfront cost of setting up and the maintenance culture it requires make it seem like an unrealistic expectation for developing countries, but I remain cautiously optimistic for the future.

References and Additional Resources

Books

- The Green Roof Manual by Edmund Snodgrass and Linda McIntyre

Videos ?

- How Green Roofs Can Help Cities | NPR

- TED Talk: The Case for Nurturing a City's Other Green Infrastructure – Trees by Matt Grubisich

Podcasts

- Food Garden Life: Green Roofs for Healthy Cities

- Sustainable Futures: Designing Green Communities and Buildings: Green Roofs for Healthy Cities

- The Ecological Podcast: Green Roofs for a Greater Geneva

Websites and Articles

- Green Roofs for Healthy Cities

- The Benefits of Green Roofs on National Geographic

- Benedict, M. A., and McMahon, E. T. (2006). Green Infrastructure: Linking Landscapes and Communities. Island Press.

- Gill, S. E., Handley, J. F., Ennos, A. R., and Pauleit, S. (2007). Adapting cities for climate change: The role of the green infrastructure. Built Environment, 33(1), 115-133.

- Bowler, D. E., Buyung-Ali, L., Knight, T. M., and Pullin, A. S. (2010). Urban greening to cool towns and cities: A systematic review of the empirical evidence. Landscape and Urban Planning, 97(3), 147-155.

- Berardi, U., Ghaffarian Hoseini, A., and Ghaffarian Hoseini, A. (2014). State-of-the-art analysis of the environmental benefits of green roofs. Applied Energy, 115, 411-428.