The following is a report on a project I worked on in a team for an environmental innovation competition.

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Problem:

The Urban Heat Island (UHI) Effect results from heat-absorbing materials used in cities, increasing local temperature. Prevalent across metropolitan India, UHIs increase heat by up to 8 -10 degrees Celsius and cause a drastic drop in air quality. This rise in temperature results in higher electricity usage from air conditioning, further increasing the carbon footprint. TerraRoof plans to target Mumbai, a city with average summer temperatures reaching up to 38°C (100°F).

Solution Brief:

Terraroof is an urban planting solution designed like an extensive green roof, aiming to mitigate the urban heat island effect by providing shade and insulation. According to the US Environmental Protection Agency, this can reduce building cooling costs by up to 30% and insulate up to 90% of heat, reducing temperatures by 10-20 °C. It consists of 8 layers from top to bottom: a roof deck, insulation, waterproofing layer, protection layer, drainage layer, filter layer, growing medium, and vegetation. A 1 square-meter, tray-like design makes maintenance easy, maximizing cost and construction efficiency. It will also improve air quality and provide aesthetic value.

Design Components:

The growth medium layer combines soil, straw, and cocopeat, allowing water retention and sufficient porosity for air circulation. The drainage and filter layer are an integrated system using drip irrigation, with the filter layer made of recycled polyester, promoting water drainage while preventing soil erosion. The protective layer is a bio-based thermoplastic polyolefin that prevents root penetration, and the waterproofing layer has a root barrier accompanied by metal edging.

Vegetation Layer:

The vegetation layer will be on a pre-installed sedum mat with aloe vera, bamboo palm, and lemongrass—species suitable for Mumbai's maritime climate and high rainfall. They require minimal maintenance, have increased mobility, and provide flexibility within the design. Lightweight and engineered substrates will support plant growth while reducing overall weight, offering optimal conditions for plant establishment and root growth. Mesh gutter guards can be installed with wood or other edgings that permit drainage to hold soil in place. Surface water is the primary source of hydration. Further, environmentally friendly herbicides like clove oil and vinegar would be used for weed control.

Impact:

Mumbai’s climate is maritime, and rainfall is above 200 cm. Considering this, plants suitable for these conditions have been chosen. The average cost of bamboo palms and lemongrass is Rs. 300 (3.61 USD) per kilogram, and including installation costs, the total accounts for up to Rs. 950 (11.4 USD) per square meter. TerraRoof is 80% cheaper than existing solutions in Mumbai.

Implementation Strategy:

Partnerships with educational institutions and corporate businesses will be formed to develop curriculum materials, conduct workshops, and offer field trips, providing students with hands-on experiences. Partnerships with local community groups will facilitate the solution reaching users directly. Social media platforms will be leveraged for widespread awareness through visually appealing content and interactive campaigns. Collaboration with local newspapers for editorial features and press releases will also be pursued.

Conclusion:

TerraRoof provides numerous benefits, such as reducing carbon dioxide, temperature, cost of electricity, and noise. For example, bamboo palm, the main plant targeting the city of Mumbai, is ideal for reducing carbon dioxide since it matures in 2-5 years and has good height and mass of plants and leaves for more photosynthesis since a plant's biomass is directly proportional to its CO2. Under conditions like more shade coverage, greater transpiration rate and less humidity, there is a reduction in the temperature of the area, providing a cooling effect and also saving the cost of electricity spent on using air conditioners.

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I am grateful to have worked on this solution with a team consisting of Srikoustubh Karanam, Akshara Singh, Kashni Tiwary, and Saanvi Rao Nagavaram. Let’s all work towards ideas that can usher in a more sustainable future for all!