Lower Building Energy Demands

Green infrastructure such as street trees and green roofs helps reduce heat island effects and shade building surfaces. As a result, less energy is needed to cool and heat buildings. As the climate changes, U.S. and global temperatures are continuing to rise, leading to higher summer residential energy use. For low-income households that already spend a greater percentage of their income on energy costs,ⁱ increased home energy needs are disproportionately challenging. Reducing building energy demands can help lower energy costs and improve resiliency.

Explore the sections below to learn more about using green infrastructure to reduce building energy demands and find resources on implementation.

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Using Green Infrastructure to Reduce Building Energy Demands
Resources
References

Using Green Infrastructure to Reduce Building Energy Demands

Vegetative cover and green roofs can provide temperature control benefits that help decrease building energy needs. Find tips for implementing these strategies below. To learn more about green infrastructure and heat in urban areas, visit the Reduce Heat Islands page.

Consider Trees an Asset for Your Community

Trees and vegetative cover can lower ambient air temperatures, especially in urban areas, through shading, windbreak, and evapotranspiration.ⁱⁱ This, in turn, lowers the amount of energy needed to provide air conditioning in summer months. Communities can take several actions to prioritize and contribute to community green spaces, including:

Planting trees in or around stormwater control features like curbside planters and bioswales to amplify the cooling and shading capability of spaces already dedicated to water quality. Planting should only occur in accordance with the overall design of the green infrastructure approach.
Including tree planting as part of regular capital improvement projects (e.g., street upgrades or road maintenance).
Partnering with tree-focused nonprofits to encourage residential or street-tree volunteer planting or canopy mapping events.
Providing residents with access to tools and resources to plant trees for maximum energy efficiency.

Incentivize Green Roof Construction

Green roofs can greatly reduce the amount of energy needed to keep the temperature of a building comfortable year-round.ⁱⁱⁱ They insulate against extensive heat loss in the winter and heat absorption in the summer. A study published by the National Research Council of Canada found that an extensive green roof reduced daily energy demand for air conditioning in summer months by over 75 percent.^iv Green roof temperatures can be 30 to 40 °F lower than those of conventional roofs and can reduce citywide ambient temperatures by up to 5 °F.^{v, vi} (Learn more on EPA's Using Green Roofs to Reduce Heat Islands webpage.) A 2017 study found green roofs can reduce roof heat flow by 80 percent and that the green roofs require 2.2 to 16.7 percent less energy consumption than conventional roofs during summers, with similar results in winters.^vii

Communities can implement private development incentives to encourage community investment in green roofs. For example, the Ecoroof Program in Portland, Oregon, reimburses private property owners $5 per square foot of green roof created. It also provides resources and technical assistance to small businesses interested in entering the green roof industry.

Estimate Cooling and Energy Efficiency Benefits

Publicly available tools, such as the U.S. Forest Service's (USFS's) iTree modeling suite, can help estimate the benefits of urban forestry and tree planting. For example, the Mid-America Regional Council partnered with USFS to quantify multiple benefits from the existing tree canopy in the Kansas City, Missouri, area. They used iTree to map existing canopy concentrations in the region and estimate the value of energy efficiency gains in buildings.

Resources

Reports and Studies:

Filho, W.L., F. Wolf, R. Castro-Diaz, C. Li, V.N. Ojeh, N. Gutierrez, G.J. Nagy, S. Savic, C.E. Natenzon, A.Q. Al-Amin, M. Mauna, and J. Bonecke. (2021). Addressing the urban heat islands effect: A cross-country assessment of the role of green infrastructure. Sustainability, 12(2), 753. Retrieved May 5, 2023.
Ko, Y. (2018). Trees and vegetation for residential energy conservation: A critical review for evidence-based urban greening in North America. Urban Forestry & Urban Greening, 34:318–335. Retrieved May 5, 2023.
Mahmoodzadeh, M., P. Mukhopadhyaya, and C. Valeo. (2020). Effects of extensive green roofs on energy performance of school buildings in four North American climates. Water, 12(1), 6. Retrieved May 5, 2023.
Mutani, G., and V. Todeschi. (2020). The effects of green roofs on outdoor thermal comfort, urban heat island mitigation and energy savings. Atmosphere, 11(2), 123. Retrieved May 5, 2023.

Tools:

AVoided Emissions and geneRation Tool (AVERT) — Developed by EPA's Office of Air and Radiation to help estimate the emissions benefits of energy efficiency and renewable energy policies and programs.
Energy Resources for State, Local, and Tribal Governments — EPA's State and Local Climate and Energy Program offers free tools, data, and technical expertise about energy strategies—including energy efficiency, renewable energy, and other emerging technologies—to help state, local, and tribal governments achieve their environmental, energy, and economic objectives.
Green Roof Energy Calculator — Developed by Green Roofs for Healthy Cities, the University of Toronto, and Portland State University to compare the annual energy performance of a building with a green roof and the same building with either a conventional or a highly reflective roof.
iTree — A USFS analysis tool for urban forest managers that uses tree inventory data to quantify the dollar value of annual environmental benefits (e.g., energy conservation, air quality improvement, carbon dioxide reduction, stormwater control, property value increase).

References

U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. Low-income community energy solutions. Retrieved December 1, 2022.
Huang, J., H. Akbari, and H. Taha. (1990). The wind-shielding and shading effects of trees on residential heating and cooling requirements. ASHRAE Winter Meeting; American Society of Heating, Refrigerating and Air-Conditioning Engineers; Atlanta, Georgia, February 11–14. Retrieved May 5, 2023.
Liu, K., and B. Baskaran. (2005). Thermal performance of extensive green roofs in cold climates (pdf). National Research Council Canada. Retrieved May 5, 2023.
Liu, K., and B. Baskaran. (2005). Thermal performance of extensive green roofs in cold climates (pdf). National Research Council Canada. Retrieved May 5, 2023.
General Services Administration. (2011). The benefits and challenges of green roofs on public and commercial buildings (pdf). Retrieved December 1, 2022.
Santamouris, M. (2014). Cooling the cities – A review of reflective and green roof mitigation technologies to fight heat island and improve comfort in urban environments. Solar Energy, 103, 682–703. Retrieved May 5, 2023.
Besir, A.B., and E. Cuce. (2018). Green roofs and facades: A comprehensive review. Renewable and Sustainable Energy Review, 82, 915–939. Retrieved May 5, 2023.