Green Roof Cost Benefit Analyses From Around the World
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Introduction
Many studies from around the world examine the economic value of green roofs, yielding diverse results. These results depend largely on the following factors:
The scope of the study
Public and/or private benefits; one building or many buildings;
Which costs are included
Capital and/or maintenance costs;
What private benefits are included or excluded;
What public benefits are included or excluded and how are they monetized;
The time frame of the study - first cost or lifecycle; and
The discount rate used (a higher rate results in a lower value of future cost savings such as roof longevity).
We have assembled a summary of publicly available green roof cost-benefit studies that are available on the internet. These studies illustrate the wide range of approaches used to estimate the value of the green roofs. Ultimately, the economic value of a project is the result of its unique circumstances such as the specific performance goals, the policy environment, existing or new buildings, and the maturity of the market with overall costs dropping as market activity grows. It also depends, in some cases, on a measure of trust that a green roof, particularly an accessible one, will add value to a building and its ability to generate rents. In the absence of these private benefits, studies typically find that public incentives are often required to tip the scales in favor of implementing a green roof.
Summary of Cost-Benefit Studies
North America
An Economic Analysis of Green Roofs: Evaluating the Costs and Savings to Building Owners in Toronto and Surrounding Regions
Authors: Toronto and Region Conservation Authority (TRCA) under the Sustainable Technologies Evaluation Program (STEP)
Year: 2007
Institution / Funder: Prepared by Toronto and Region Conservation Authority (TRCA) under STEP; funded by the Government of Canada’s Great Lakes Sustainability Fund, Toronto and Region Remedial Action Plan, City of Mississauga, City of Toronto, Orlando Corporation, and Fisheries and Oceans Canada
City / Country: Greater Toronto Area (GTA), Ontario, Canada
System Type: Green roof
Subtype: Extensive
Scale: Building
Key Findings: This study compares the long-term costs of an extensive green roof to a conventional roof for a typical one-storey office building in the Greater Toronto Area. It looks only at costs and savings that affect the building owner, such as installation, maintenance, energy savings, and how long the roof membrane lasts. The results show that green roofs cost more overall than conventional roofs under normal private-sector conditions. While green roofs can save money through slightly lower energy bills and a longer membrane lifespan, these savings are not large enough to offset the higher upfront installation cost. The analysis also shows that factors like the discount rate and initial capital cost have a much bigger impact on the results than energy savings do. The study concludes that green roofs are more financially attractive when incentives are provided or when evaluated from a public-sector perspective, but they are generally more expensive for private building owners.
Final Report: Toronto Green Development Standard Cost-Benefit Study
Authors: Ted Kesik, Anne Miller
Year: 2008
Institution / Funder: Ontario Centers of Excellence, Federation of Canadian Municipalities
City / Country: Toronto, Ontario
System Type: Green roof
Subtype: Not specified
Scale: Regional
Key Findings
The future of green development in the Greater Toronto and Hamilton Area (GTHA) is threatened by a shortage of qualified architecture, engineering, and construction (AEC) professionals. Without architects, engineers, landscape architects, project managers, and other specialists, implementing the Toronto Green Development Standard will be difficult. Skilled construction workers are declining, with nearly 50,000 Ontario workers expected to retire soon and no distinct replacement strategy. Energy conservation provides the largest benefits of the standard, followed by improvements to urban and energy infrastructure. The projected net benefits range from $17.46–$21.19 billion (2007–2031) and rise significantly over time, reaching up to $131.03 billion by 2081. Overall, the Toronto Green Development Standard is a cost-effective strategy for sustainability but must continue evolving to address changing social, economic, and environmental conditions.
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Report on the Environmental Benefits and Costs of Green Roof Technology for the City of Toronto
Authors: Dr. Doug Banting, Professor Hitesh Doshi, Dr. James Li, Dr. Paul Missios
Year: 2005
Institution / Funder: Ryerson University; prepared for the City of Toronto and Ontario Centres of Excellence – Earth and Environmental Technologies (OCE-ETech); supported by the Federation of Canadian Municipalities (FCM)
City / Country: Toronto, Ontario, Canada
System Type: Green roof
Subtype: Extensive
Scale: City
Key Findings: This study looks at what would happen if green roofs were installed across Toronto on all suitable flat roofs. The researchers calculated environmental and financial benefits at the city level, not just for individual buildings. They found that green roofs could significantly reduce stormwater runoff, lower energy use in buildings, reduce the urban heat island effect, and improve air quality. According to the summary tables, the total estimated initial municipal-level savings could reach about $313 million, with additional annual savings of about $37 million, mainly from energy savings and heat island reduction. Stormwater management produced the largest one-time savings. The study concludes that, from a city-wide perspective, green roofs provide substantial public environmental and economic benefits, supporting the case for municipal programs and incentives to encourage their installation.
An Economic Impact Assessment of the Green Infrastructure Sector in Ontario
Authors: The Delphi Group (prepared on behalf of the Green Infrastructure Ontario Coalition)
Year: 2020
Institution / Funder: Prepared by The Delphi Group for the Green Infrastructure Ontario Coalition (GIO); funded by the Greenbelt Foundation with additional financial support from Landscape Ontario
City / Country: Ontario, Canada
System Type: Green roof / Green wall
Subtype: Both / Not specified
Scale: Regional / Provincial
Key Findings: This report is not a single building-level cost-benefit study. Instead, it looks at the broader economic impact of the green infrastructure sector in Ontario, including green roofs and walls as one of seven sub-sectors. The report found that Ontario’s green roofs and walls sub-sector supported about 842 direct jobs in 2018, generated about $93 million in gross output, and contributed about $51.2 million in direct GDP. When indirect and induced effects are included, the sub-sector supported about 1,213 jobs and $88.7 million in GDP. The report explains that this sub-sector relies on a specialized supply chain that includes designers, landscapers, nurseries, plant growers, roofing contractors, and material suppliers. It also notes that green roofs and walls are growing in importance because of their role in stormwater management, climate adaptation, urban heat reduction, and greener building design, especially in urban centres like Toronto.
Life-Cycle Cost–Benefit Analysis of Extensive Vegetated Roof Systems
Authors: Timothy Carter and Andrew Keeler
Year: 2008
Institution / Funder: University of Georgia (River Basin Center, Institute of Ecology) and The Ohio State University (John Glenn School of Public Affairs); funder not specified.
City / Country: Athens, Georgia, USA
System Type: Green roof
Subtype: Extensive
Scale: District / watershed
Key Findings: This study compares an extensive green roof to a conventional flat roof using a life-cycle cost-benefit analysis. The researchers used data from an experimental green roof in the Tanyard Branch watershed in Athens, Georgia, and looked at both private and social benefits. They found that under current conditions, the green roof was about 10 per cent to 14 per cent more expensive than a traditional roof over its life cycle. However, green roofs provided important benefits, especially longer roof life, stormwater management savings, energy savings, and some air quality benefits. The study also found that if green roof construction costs dropped by about 20 per cent, the social net present value would become better than a conventional roof. Overall, the authors conclude that green roofs have strong public environmental benefits and that incentives are a good idea to encourage wider use in highly urbanized watersheds.
North America
Integrating Cost-benefits Analysis and Life Cycle Assessment of Green Roofs: A Case Study in Florida
Authors: Lan Yao, Abdol Chini, and Ruochen Zeng
Year: 2018
Institution / Funder: M.E. Rinker, Senior School of Construction Management, University of Florida
City / Country: Florida, United States of America
System Type: Green Roof
Subtype: Not specified
Scale: Educational Building
Key Findings
The case study utilizes an educational building situated at the University of Florida comparing white roofs to green roofs. The study utilizes a cost-benefit analysis to consider additional initial and maintenance costs of green roofs versus their benefits due to avoided stormwater management fees, reduced energy consumption cost, reduced energy consumption, and social cost of carbon living. Benefits are defined by LCA in comparison to white roofs, demonstrating that the installation of green roofs will decrease GWP, acidification potential, HH particulate, and total primary energy. It is important to note that the study explicitly mentions its focus on monetary values and therefore the subsequent exclusion of factors such as improvement in air quality, increased property value, and using green roofs as recreational spaces. Furthermore, the software AIE, which is used in this study to measure the effect of a green roof on a building’s life cycle environmental impact, demonstrates assumptions within the software. The case study concludes that a green roof is less cost-efficient than a conventional white roof due its high initial costs and follow-on maintenance costs.
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Benefit-Cost Analysis of Stormwater Green Infrastructure Practices for Grand Rapids, Michigan, USA
Authors: Erik E. Nordman, Elaine Isely, Paul Isely, Rod Denning
Year: 2017
Institution / Funder: Grand Valley State University & West Michigan Environmental Council
City / Country: Michigan, United States of America
System Type: Green Roof
Subtype: Not Specified
Scale: City
Key Findings
In this case study costs are evaluated using the Net present value formal which is usually employed to test the profitability of an investment. The study discusses six different types of Green Infrastructure to determine if their utilization would save costs regarding the management of stormwater. It is evaluated that a green roof has the highest present value cost of all the practices surveyed. The net benefits are negative using mid-range installment costs, however $119.48/m^2 is the break even point, meaning under certain circumstances that enable low-cost installment, the green roof could be cost efficient. In Grand Rapids, where the study is conducted, many installed green roofs are in place to achieve LEED certification. A green roof can contribute up to 5 to 23 points toward the 40 points needed for basic LEED certification. The LEED premium which can range from $5.70 - $10.01/m^2/year, can lead to extra earnings or the owner that could be invested back into the green roof.
Economic Benefits for Green Roofs: A Case Study of the Skaggs Pharmacy Building, University of Utah
Authors: T. Wu, R.E. Smith
Year: 2011
Institution / Funder: Office of Sustainability, University of Utah
City / Country: Utah, United States of America
System Type: Green Roof
Subtype: Extensive
Scale: Building
Key Findings
This case study refers to the Skaggs Pharmacy Building situated on the University of Utah campus. The implementation of a green roof would provide multiple benefits, including reduction of the Urban Heat Island (UHI) effect, contributions to community urban living, preservation of wildlife habitat, earning LEED certification points, and increasing overall building marketability. While many of these benefits are difficult to quantify in monetary terms, they strengthen the case for green roof adoption. Among the quantified benefits, electricity savings for space cooling accounted for the largest return on investment segment. The potential implementation of a green roof on the Skaggs Pharmacy Building would require an initial investment of approximately $300,000, with an estimated break-even period of 27 years, making a green roof a better advisable investment than a black roof or a reflective roof.
Europe
Case Studies on Financing Green Roofs: The Ignition Project
Authors: Not individually listed in the brief, produced by The Ignition Project
Year: Not clearly listed in the brief (references use 2020 price)
Institution / Funder: The Ignition project / Ignition Nature-Based Solutions Evidence Base; supported by partners shown on the brief including Greater Manchester, Urban Innovative Actions (UIA), and the European Regional Development Fund.
City / Country: Greater Manchester, England, United Kingdom (with case studies from Stockport Interchange and Unicorn Grocery in Chorlton)
System Type: Green roof
Subtype: Both
Scale: Building
Key Findings: This brief shows that green roofs can be financed more effectively when their full benefits are counted, rather than just their upfront cost. In the Stockport Interchange case, a planned accessible blue-green roof was found to offer £116,000 in capital cost savings compared to a storm attenuation tank, along with £14,100 per year in wastewater charge savings. In the Unicorn Grocery retrofit case, the green roof cost about the same as standard insulation at the time of installation but provided added benefits such as energy savings, longer roof life, wastewater charge discounts, biodiversity value, and recreational space. The brief estimates annual energy savings of about £1,070, a £1,237 yearly wastewater charge discount, and lower annualized replacement costs because the roof membrane lasts much longer. Overall, the study argues that green roofs can make good financial sense when benefits like drainage savings, insulation, property value, and roof longevity are included in the business case.
Cost-Benefit Analysis of Green Roofs in Densely Built-up Areas
Authors: Šárka Konašová
Year: 2019
Institution / Funder: Czech Technical University in Prague; supported by CTU Student Grant Competition
City / Country: General urban (densely built-up) areas; Czech Republic / EU context
System Type: Green roof
Subtype: Both (Extensive and Intensive analyzed separately)
Scale: Building
Key Findings: This study compares the costs and benefits of installing green roofs in dense urban areas. It looks at both private benefits (like longer roof lifespan, energy savings, higher property value, and possible tax reductions) and public benefits (like better air quality, reduced flooding, cooler cities, and improved biodiversity). The results show that green roofs are more expensive to install than regular roofs, but private benefits such as longer roof life and increased property value can sometimes justify the extra cost. When public environmental benefits are added, green roofs clearly provide more overall benefits than costs. However, the study concludes that private financial returns alone are not always strong enough to motivate building owners without supportive policies or incentives.
Cost-benefit analysis of Green Roofs in Urban Areas: Case Study in Helsinki
Authors: Väinö Nurmi, Athanasios Votsis, Adriaan Perrels and Susanna Lehvävirta
Year: 2013
Institution / Funder: Urban Ecology Research Group at the University of Helsinki and funded by Regional Council of Uusimaa
City / Country: Helsinki, Finland
System Type: Green Roof
Subtype: Intensive
Scale: City
Key Findings
The study discusses the economic benefits and costs of thin, lightweight green roofs with minimal maintenance requirements in Helsinki, Finland. Benefits were evaluated through categories of membrane longevity, storm-water management, scenic and healthy benefits, energy savings, increased urban diversity, noise insulation and emission regulation. Moreover, the study concluded that the cost of a green roof was over two times more expensive than a bitumen roof, which was used as a reference roof. However, it is argued that a higher implementation rate would drive down the cost level resulting in public benefits and therefore would be considered a good investment. As currently the private benefits are not high enough to justify a green roof installation for a private decision maker, the rate of implementation can be expected to stay low.
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Public Versus Private Incentives to Invest in Green Roofs: A Cost Benefit Analysis for Flanders
Authors: Karla Claus, Sandra Rousseau
Year: 2012
Institution / Funder: Hogeschool-Universiteit Brussel
City / Country: Flanders, Belgium
System Type: Green Roof
Subtype: Extensive
Scale: Regional
Key Findings
The case study explores the implementation of green roofs in Flanders, Belgium, concluding that the construction of an extensive green roof is socially desirable. It should be noted that the benefits of increased fire protection, decrease of urban temperature, increased biodiversity and esthetics could not be expressed in monetary terms, hence their exclusion in the study. Furthermore, a key deciding factor is that the life span of a green roof is twice that of classic roof coverings. Moreover, its study states that it can be expected that environmental benefits from greening cities will increase even more due to climate change. In addition, green roofs might mitigate the impact of some predicted consequences of climate change such as more intense precipitation and extreme weather events. Private incentives alone are insufficient to encourage green roof investment, despite social benefits exceeding social costs. Therefore, subsidies are justified and likely to improve overall welfare, as demonstrated by Rotterdam’s €25/m² subsidy program and similar policies in Flanders.
Socioeconomic Feasibility of Green Roofs and Walls in Public Buildings: The Case Study of Primary Schools in Portugal
Authors: Catarina Almeida, Inês Teotónio, Cristina Matos Silva, Carlos Oliveira Cruz
Year: 2021
Institution / Funder: Portuguese Foundation for Science and Technology, research project GENESIS
City / Country: Lisbon, Portugal
System Type: Green roof, Green wall
Subtype: Extensive green roof, green facades, living walls
Scale: Primary School Building
Key Findings
The study evaluated the potential financial, economic and socio-environmental impact of the implementation of green roofs and green walls in two primary schools located in Lisbon, Portugal. It is concluded that ten green scenarios are all feasible, benefit-cost ratios varying from 3.01 to 34.99. Moreover, the study states that it was not possible to forecast some benefits that stem from green roofs and green walls due to the lack of data and studies regarding this topic, hence most of these indirect benefits were not considered for the case studies under evaluation. Lastly, the study states that it is crucial to note that results depend on local and market conditions, project characteristics and other external factors.
Asia
Thermal Insulation and Cost Effectiveness of Green-Roof system: An Empirical Study in Hong Kong
Authors: Vivian W.Y. Tam, Jiayuan Wang, Khoa N.Le
Year: 2016
Institution / Funder: Australian Research Council, Australian Government
City / Country: Hong Kong
System Type: Green Roof
Subtype: Both
Scale: Buildings
Key Findings
The study found that green roof applications are not widely adopted in Hong Kong. The key benefit of the implementation of green infrastructure would be the improved visual aesthetic value of the buildings. Further benefits include better air quality and the reduction of urban heat-island effect. Nevertheless, the respondents stated that they are not interested in investing into a green roof and rather believe that the government and other stakeholders should take the lead in promoting this. The case studies further showed that green roofs can improve thermal insulation by up to 3.4 degrees. This performance is heavily influenced by soil depth and plant type, as deeper soils enhance moisture retention. Higher capital investment corresponded with better insulation outcomes. Similar results across cases are likely due to Hong Kong’s consistently high humidity, which supports plant growth and thermal efficiency.
Benefit–Cost Analysis of Green Roof Initiative Projects: The Case of Jung-gu, Seoul
Authors: Eunha Shin and Heungsoon Kim
Year: 2019
Institution / Funder: Department of Urban Planning and Engineering, Hanyang University, Seoul, South Korea; the study states that it received no external funding.
City / Country: Jung-gu, Seoul, South Korea
System Type: Green roof
Subtype: Extensive
Scale: District
Key Findings: This study tests whether green roof initiative projects in Jung-gu, Seoul are economically worthwhile by comparing five scenarios over a 20-year period. The analysis includes six cost items and eight benefit items, such as construction, maintenance, stormwater management, air quality improvement, cooling energy savings, rooftop lifespan, and social benefits like better urban aesthetics and comfort. The results show that the 100% green roof application scenario was the only one with benefits clearly greater than costs, with a benefit–cost ratio of 1.174. The more realistic partial-application scenarios had benefits–cost ratios just below 1, meaning they were close to being economically feasible but did not fully exceed costs under current conditions. The study concludes that green roof projects in Seoul can be economically viable under specific conditions, especially if installation costs fall and policy support continues.
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Cost-Benefit Analysis of the Green Deck Development
Authors: Dr. Mark S.C. Hsu
Year: 2023
Institution / Funder: Department of Civil and Environmental Engineering; the report studies the Green Deck proposed by The Hong Kong Polytechnic University (PolyU). A specific outside funder is not clearly identified in the excerpted report.
City / Country: Hung Hom, Hong Kong, China
System Type: Green roof / urban green deck
Subtype: Not specified
Scale: District / Neighborhood
Key Findings: This study evaluates the proposed Green Deck over the Hung Hom transport corridor using a full social cost-benefit analysis. It includes both tangible costs and benefits like construction cost, operating cost, visitor spending, and property value increases, and intangible benefits like air pollution reduction, carbon sequestration, runoff reduction, noise reduction, temperature reduction, health benefits, and travel time savings. The study finds that the project is economically feasible from a social perspective, with a benefit-cost ratio of 1.35, a positive net present value of about HK$3.33 billion, and an internal rate of return of 5.5 per cent, which is higher than the 4 per cent discount rate used. The largest benefits come from visitor expenditure, property value gains, and health and well-being improvements. The report also finds that the project’s results are most sensitive to the number of visitors, so attracting users is important to making the project worthwhile.
Multiple Countries
Economic Benefits and Costs of Green Roofs
Authors: Haibo Feng and Kasun N. Hewage
Year: 2018
Institution / Funder: Published as a chapter in Nature Based Strategies for Urban and Building Sustainability by Elsevier; specific funder not stated in the chapter excerpt provided.
City / Country: Not one specific city; draws on examples from multiple places including Ottawa, Toronto, British Columbia, Germany, Singapore, China, New York, and Tokyo.
System Type: Green roof
Subtype: Both
Scale: Building / Urban policy overview
Key Findings: This chapter reviews the economic benefits and costs of green roofs by combining evidence from many previous studies. It explains that green roofs create private benefits such as lower heating and cooling costs, longer roof membrane life, better sound insulation, aesthetic value, and possible LEED certification advantages, while also creating public benefits such as stormwater reduction, better air quality, urban heat island mitigation, and increased biodiversity. The authors show that public benefits are much larger than private benefits: over a 40-year period, the estimated net present value of private benefits is $135.9–195.8/m², while public benefits are $478.7–751.7/m². Lifecycle costs range widely depending on roof type and market conditions, from $42.3–978.8/m². The chapter concludes that green roofs can often pay for themselves over their lifespan, especially when public benefits are included, and argues that governments should support them through incentives, rebates, tax credits, or policy requirements because private owners alone do not capture most of the value.
Economic Benefits and Costs of Green Roofs
Authors: Geeta Ganesh Malewar
Year: 2022
Institution / Funder: Published in the International Journal of Advances in Engineering and Management (IJAEM); no specific funder or institutional sponsor is listed in the article.
City / Country: Not one specific city or country, the article draws on examples from multiple places including Canada, the United States, Singapore, China, and Germany.
System Type: Green roof
Subtype: Not specified
Scale: Building / Urban policy overview
Key Findings: This article reviews the main private and public economic benefits of green roofs rather than studying one single project. It explains that private benefits include lower heating and cooling costs, longer roof membrane life, sound insulation, aesthetic value, and possible LEED-related financial advantages. Public benefits include reduced stormwater runoff, improved air quality, mitigation of the urban heat island effect, more biodiversity, and job creation. The article states that green roofs often have high upfront costs, but over their lifespan they can provide financial and environmental returns, with one section noting payback periods of about 6.2 to 6.6 years in some cases. It concludes that green roofs can become more cost-effective over time, especially when wider social benefits are considered, and argues that governments should support them through incentives such as tax breaks, rebates, and low-interest loans.
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Eleanor Chong is a second-year student at the University of Toronto, studying at the Daniels Faculty of Architecture, Landscape, and Design. Originally from Singapore, she is pursuing a degree in Architecture with a minor in Urban Studies. To get in contact, email her at eleanor.chong@mail.utoronto.ca
Madison Munro is an Architecture and Urban Studies student at the University of Toronto. She is interested in exploring how urban design, as a broader framework, informs her architectural design process, especially in relation to sustainability, public space, and the social life of cities. Find her on LinkedIn here: http://www.linkedin.com/in/madison-munro
Ann-Sophie Raedler is a student at University of Toronto, pursuing a major in architecture and a minor in urban studies. Through an urbanism course, she had the opportunity to volunteer with Green Roofs for Healthy Cities, where she valued the chance to contribute to an active organization, exploring their work and learning about their role in advancing sustainable urban design. This experience has inspired her to continue to explore sustainable design, particularly interested in the integration of green roofs within architectural design. To get in contact, email her at annsophiee.r@gmail.com
Steven W. Peck, GRP, GRIMP, Honorary ASLA has been a passionate bird watcher for decades and enjoys learning about the natural world and the lessons it has to share. He is the founder and president of Green Roofs for Healthy Cities, the Editor of The Living Architecture Monitor and currently the President of the World Green Infrastructure Network.
