Climate Change and...
To calculate carbon dioxide sequestration and building energy savings provided by individual trees.
Numerical values for each tree for CO2 sequestered and energy savings (see below for details).
USDA Forest Service, Pacific Southwest Research Station, the Urban Ecosystems and Processes Team (UEP). Developed in partnership with the California Department of Forestry and Fire Protection.
Downloadable software that is programmed in an Excel spreadsheet. Currently in testing phase.
Estimating benefits of urban trees, projecting benefits of planting projects.
Data from the CTCC may not accurately reflect the rate of tree growth, microclimate, or building characteristics for every city or location within a region. Tree size and growth data are derived from trees sampled in one reference city within each of the 16 climate zones, but conditions may vary across these zones.
Tree Carbon Calculator (CTCC)
Overview & Applicability
The Tree Carbon Calculator (CTCC) developed by the Urban Ecosystems and Processes Team, provides quantitative data on carbon dioxide sequestration and building heating/cooling energy savings provided by individual trees. CTCC outputs can be used to estimate GHG (greenhouse gas) benefits for existing trees or to forecast future benefits. It is the only tool approved by the California Climate Action Reserve's Urban Forest Project Reporting Protocol for quantifying carbon dioxide sequestration from GHG tree planting projects. The CTCC is programmed in an Excel spreadsheet and provides carbon-related information for trees located in one of sixteen United States climate zones.
The CTCC is currently intended as "proof of concept" software and is in the testing phase. It is provided "as is" without a warranty. In 2011, this version will be replaced by a Web-based version with greater functionality.
Inputs and outputs
The user provides information on the climate zone (one of 16 pre-defined zones), tree species of interest, and tree size (d.b.h.) or age. Tree height can be used in place of d.b.h. for palm species. The CTCC then produces information on:
- Carbon dioxide stored in the tree due to its growth over many years
- Carbon dioxide sequestered during the past year
- Dry weight of aboveground biomass that could be utilized if the tree was removed
If trees are strategically located to shade buildings and reduce energy consumed for heating and cooling, additional inputs are needed along with those listed above. These include tree distance from building, tree direction from building, building age, and type of air conditioning/heating equipment. Default values are provided for heating emissions factors, though these can be customized. CTCC outputs then include:
- Annual energy savings in kWh of electricity (cooling) and MBtu or GJ(heating) per tree
- Carbon dioxide equivalents of these energy savings
Restrictions and limitations
Tree size and growth data are developed from samples of about 650-1000 street trees taken in one reference city for each of the sixteen climate zones. Approximately 20 predominant species were selected in each of the sixteen regional reference cities. Many of the biomass equations used to derive total CO2 stored and sequestered are derived from open-grown, city trees.
Conditions may vary within regions, so data from the CTCC may not accurately reflect the rate of tree growth, microclimate, or building characteristics for every city or location within a region. When conditions are different it may be necessary to apply biomass equations manually using adjusted tree growth data, and to perform building energy simulations with modified weather and tree data to more accurately depict effects of trees on GHGs. All equations used in are available in the help manual included with the downloaded CTCC.
Accessing the tool and additional information.
The tool can be downloaded from the CCRC website: http://www.fs.fed.us/ccrc/topics/urban-forests/ctcc/
An extensive user guide and help menu is included along with the tool once the CTCC is downloaded. The spreadsheet also provides cell-specific definitions and assistance. Additional technical assistance is available via email at email@example.com.