References

The i-Tree Planting Calculator is designed to help you estimate the long-term environmental benefits from a tree planting project. The focus is on greenhouse gases, but many co-benefits are included. This tool relies on species growth equations and other geographic parameters that are generalized from city, county, state, and climate region data.

Tree effects on energy use are calculated using the methods detailed in the USDA Forest Service publication, "Carbon Dioxide Reduction Through Urban Forestry: Guidelines for Professional and Volunteer Tree Planters (PSW-GTR-171)." Trees' effects on buildings from shade, evapotranspiration, and wind speed reduction (windbreak) are calculated using an applied reduction factor based on tree type, height, azimuth, and distance from the home. Shade and evapotranspiration effects are set to zero when trees are beyond 18 meters (approximately 60 feet) from defined building footprints. Windbreak effects on use are set to zero when trees are at a distance from the building equaling 35 times the tree height or greater (see: Heisler, G.M. and D.R. Dewalle. 1988. Effects of Windbreak Structure on Wind Flow. Agriculture, Ecosystems and Environment. 22/23:41-69). Because reduction factor calculations are based on data for the United States, these values for other countries should be regarded as approximations.

Stormwater
The stormwater values were derived from county-based i-Tree Eco runs for the conterminous United States using 2010 data.
(see: i-Tree Eco Precipitation Interception Model Descriptions)
Carbon
Carbon dioxide sequestration values are derived from species-based biomass equations. Carbon dioxide avoided values are estimated by converting the savings to pounds of avoided carbon emissions. Values (kWh and Mbtu) are converted to carbon dioxide using state-based EPA E-grid conversion values.
The carbon dioxide dollar value is based on the average central value estimate of the social cost of carbon as calculated by the 2015 Interagency Working Group on Social Cost of Carbon for the United States Government.
(see: Technical Update of the Social Cost of Carbon for Regulatory Impact Analysis ­ Under Executive Order 12866).
Air Quality
Air pollutant removal and associated health benefit values were derived from county-based i-Tree Eco runs for the Conterminous United States using 2010 data. (see: Tree and forest effects on air quality and human health in the United States.)
Air pollutant avoided resource units and monetary values for air quality benefits come from the following sources and are adjusted for inflation using the Produce Price Index (see: Bureau of Labor Statistics Producer Price Indexes):
Abbreviation Benefit Description Transmission Rate - Fuel Transmission Rate - Electricity Monetary Value
CO Carbon Monoxide EPA E-grid, 2009 Leonard Academy, 2011 Murray, 1994*
NO2 Nitrogen Dioxide EPA E-grid, 2009 EPA E-grid, 2009 BenMap, 2010
PM10 Particulate Matter Less Than 10 Microns EPA E-grid, 2009 Leonard Academy, 2011 Murray, 1994*
SO2 Sulfur Dioxide EPA E-grid, 2009 EPA E-grid, 2009 BenMap, 2010
VOC Volatile Organic Compounds EPA E-grid, 2009 Leonard Academy, 2011 IMPACT, 2008

*Murray, F.J., L. Marsh. and P.A. Bradford. 1994. New York State energy plan, vol. II: issue reports. New York State Energy Office, Albany, NY. Values adjusted based on Produce Price Index. Note: In Canada, median US transmission rates were used and monetary values for CO and PM10 were sourced locally.

For more detailed information on urban and community forest assessments, please continue exploring the i-Tree website.

Acknowledgements

i-Tree Planting was developed with support and resources from the following organizations:

  • California Urban Forest Council
  • Urban Ecos
  • The California Department of Forestry & Fire Protection
  • The Davey Tree Expert Company
  • The US Forest Service

For technical questions about this tool, contact i-Tree support.