Urban Cooling Through Green Infrastructure: Alleviating Urban Heat Island Effect in NYC

By: Kamilla Egamova, Joel Alex, Jihad Touijeur, Raymond Tu

Writing For Engineering

Professor Julia Brown

May 6th, 2025

Summary: 

This proposal outlines a multifaceted engineering approach to mitigate the Urban Heat Island (UHI) effect in densely populated cities like New York City. The UHI phenomenon results in significantly higher temperatures in urban areas compared to rural surroundings, leading to severe environmental and health consequences. Our group proposes three cost-effective and sustainable strategies: green roof installations, tree canopy expansion, and the application of reflective pavement coatings. Each intervention aims to reduce surface and ambient air temperatures, cut energy usage, and lessen heat-related health risks, particularly for vulnerable populations.

Our research draws from EPA case studies, Census Bureau data, and peer-reviewed climate reports. We estimate a preliminary project budget of approximately $750,000 for pilot implementations across several city blocks, with costs broken down by materials, labor, and maintenance.

This project is led by a team of undergraduate engineering students at CCNY, each bringing relevant coursework and experience in environmental systems, sustainable design, and urban planning. Several team members have participated in faculty-led research on climate adaptation strategies and have completed internships focused on municipal infrastructure. We are seeking funding to pilot these solutions and demonstrate their effectiveness in addressing rising urban temperatures.

Introduction:

Today, a majority of the world’s population lives in urban areas. In the United States, up to 80 percent of the population resides in cities [1], where managing temperature has become increasingly critical. The combination of heat-retaining materials in urban infrastructure, limited vegetation, dense development, and waste heat generation contributes to the urban heat island (UHI) effect—where urban areas consistently experience elevated air temperatures compared to nearby rural regions. This “measurable increase in ambient urban air temperature… [results] in significant temperature differences between urban and rural areas” [2], amplifying the impacts of global climate change and extreme heat events.

Although the idea of cities being slightly warmer may seem minor, the effects of UHI are far-reaching. Prolonged heat exposure increases the risk of heat-related illnesses and deaths, especially among vulnerable populations [3]. Conditions such as heat stroke, dehydration, cardiovascular complications, and respiratory problems are more likely in overheated urban environments. UHI also drives up energy demand for cooling, which can strain electrical grids, increase greenhouse gas emissions (particularly if nonrenewable energy is used), and accelerate water evaporation—contributing to shortages and further environmental stress.

This proposal focuses on New York City as a starting point for targeted UHI mitigation. NYC’s dense urban layout, aging infrastructure, and large population make it particularly vulnerable to the effects of extreme heat. We aim to implement green roofs and localized, pilot-scale interventions across several neighborhoods to assess feasibility and impact.

Project Description

Our proposal targets the issues presented by urban heat island effect by implementing green roofs atop buildings in the New York cityscape. 

Green roofs are roofs with soil and plants above waterproof barriers and drainage layers atop a conventional roof. This layer of vegetation helps lower ambient temperatures through a combination of shading from the sun, evapotranspiration–the transfer of water by evaporation and exhalation of water from plants and soil into the air, and from insulating effects. They are a cost-effective way to reduce ambient air and surface temperatures, regulate stormwater runoff, and improve air quality [5], and can reduce rooftop ambient air temperatures by up to 20°F [4]. Lowering the ambient air temperatures can help lower the demand for air conditioning in urban environments, which contributes to lower energy consumption and reduced energy-related emissions. Cooler neighborhoods reduce the risk of heat-related illnesses, and lower energy needs can reduce energy-related emissions. Thus leading to improved health and safety of cities, particularly for groups at risk, such as the elderly and low-income populations. Green roofs also have the capacity to absorb rainwater in the soils or act as a storage system that can reduce the runoff water and relieve pressure on storm drain systems. Stored water from green roofs can be used as a non potable source of water for irrigation or flushing toilets. Additionally, they also  improve air quality by preventing emissions and sequestering pollutants from the air [5]. It is also worth mentioning that green roofs are a way to bring greenery to an otherwise gray cityscape and provide a mental health boost by bringing people closer to a natural space.

Green roofs are an accessible solution to the UHI effect and can be fitted onto a wide range of buildings and fill different roles. Cheaper green roofs can be very accessible and can be constructed simply to be lightweight and support smaller plants to serve their cooling roles. More expensive, heavier green roofs can be made to support large plants and trees, be publicly accessible, and be aesthetically pleasing installations. These larger scale green roofs are less accessible due to their cost and require more structural support, but can be considered in new construction projects while cheaper, smaller green roofs can be considered as a retrofit on existing buildings [4]. Though green roofs generally have a higher initial cost than traditional roofs, their temperature regulating effects and improvements to building efficiency allow them to offset their costs by protecting roofing membranes from extreme temperature shocks, saving on building energy costs, and managing stormwater runoff and their associated fees. Additionally, green roofs are designed to last at least twice the lifespan of a traditional roof, further providing long-term savings. 

All together, though, green roofs “often (but not always) [take] significantly more than 5 years” to pay back their initial cost–which means their payback period is longer than what is commonly acceptable to developers. [5] Additionally, the costs of green roofs can increase greatly with roofs that are larger, require more heavy maintenance and material costs, aesthetic needs, and public access [6]. Yet, it is still important to recognize that not implementing a green roof can still be costlier not just in maintenance and utility bills but from the discomfort and health risk associated with extreme heat and worse air quality. 

Budget:

In order to implement this green infrastructure initiative in a NYC neighborhood, we estimate the cost to be $750,000. This is a cost accounting for factors such as labor costs and material sourcing. We are mainly focusing on the implementation of green roofs, as that is the bulk of our budget. This is a pilot that will be used to measure initial results, environmental impact, and as a possible model for future projects.

Item	Estimated Cost
Green roofs (3 buildings)	$500,000
Education and community engagement	$100,000
Permitting and monitoring	$150,000
Total	$750,000

The total proposed budget for this pilot program is $750,000. We are planning to install green roofs on 3 large public buildings. As this is a pilot program, we plan to focus on a limited geographic area such as the South Bronx, East Harlem, or Brownsville where there aren’t many existing green roofs. The $500,000 green roof budget will include structural assessments, waterproofing measures, drainage systems, irrigation, and post-installation maintenance. It will also cover the cost of sensors that can be used to monitor variables such as moisture and temperature to better ensure that the roofs will perform as intended. We will allot $100,000 for education and community engagement. This will help to fund public workshops, educational materials for schools, and collaboration with non-profit organizations. We have included this in our budget because we believe that this will help to raise public awareness for sustainable infrastructure. We have also reserved $150,000 for permitting and monitoring measures. This will help to cover city permit fees, inspections, and environmental monitoring. A portion of this funding will also support environmental monitoring such as the installation of temperature and stormwater retention sensors. These components will ensure that the project will meet regulatory requirements.

Conclusion:

Urban heat islands are a major concern in New York City. These conditions trap heat and raise local temperatures. Low-income communities are disproportionately affected as they have limited access to cooling infrastructure. As climate change progresses, UHI will only continue to cause more negative environmental and public health consequences.

Our proposal is intended as a response to the problems that UHI poses. By implementing solutions such as green roofs on buildings, we can lower rooftop and surrounding temperatures and also contribute to improved air quality and energy efficiency. Beyond technical benefits, green roofs represent an opportunity to better engage with communities about climate adaptation. By placing a portion of our budget towards education, we ensure that local residents and students are better informed to sustain these changes. 

With a total investment of $750,000, our pilot program serves as both a practical mitigation strategy and a possible model for future projects. The program directly tackles the concerns that UHI pose while fostering a sense of community involvement. With the projects’ implementation, we are ensuring that NYC is able to not only withstand rising temperatures, but also to build a greener and cooler urban future

References 

[1] US Census Bureau. (2022, December 29). Nation’s Urban and Rural Populations Shift Following 2020 Census. Census.gov; United States Census Bureau. https://www.census.gov/newsroom/press-releases/2022/urban-rural-populations.html 

[2] Climate Central. (2023, July 26). Urban Heat Hot Spots. Www.climatecentral.org. https://www.climatecentral.org/climate-matters/urban-heat-islands-2023 

[3] Druckenmiller, H. (2023, March 14). Urban Heat Islands 101. Resources for the Future; Resources for the Future. https://www.rff.org/publications/explainers/urban-heat-islands-101/ 

[4] United States Environmental Protection Agency. (2014, February 28). Heat Island Effect. US EPA; US EPA. https://www.epa.gov/heatislands 

[5] Cost-benefit considerations for green roofs – Minnesota Stormwater Manual. (2010). State.mn.us. https://stormwater.pca.state.mn.us/index.php/Cost-benefit_considerations_for_green_roofs

[6] U.S. Environmental Protection Agency. (2018). Estimating the environmental effects of green roofs: A case study in Kansas City, Missouri. EPA 430-S-18-001. https://www.epa.gov/sites/default/files/2018-09/documents/greenroofs_casestudy_kansascity.pdf