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The APPA Tree Benefits Estimator Was Designed to
Help You
This Web-based application will help APPA member utilities
quantify and track the benefits of planting shade trees.
It estimates the amount of energy savings (KWh saved),
capacity savings (KW saved) and carbon and CO2 sequestration
(lbs) resulting from mature trees planted in urban and
suburban settings. The Tree Benefits Estimator can be
used by those who have no formal background in urban
forestry or Demand Side Management (DSM) utility practices.
Tracking the Benefits of Tree-Planting Efforts is
Necessary
One of the greatest challenges facing public power today
is environmental stewardship. It is increasingly important
that public power utilities not only take steps toward
local environmental improvements, but measure the effectiveness
of their efforts. The measurements are important to
local communities in understanding how they can control
their environmental future and the cost of doing so.
It is also important for utilities to be able to measure
environmental impacts that in the future may be reported
to state and federal governments on a voluntary or mandatory
basis.
What You Need to Know About the Estimator
The Tree
Benefit Estimator, developed by Sacramento Municipal
Utility District (SMUD), was based on the experience
of the SMUD's Shade Tree program. In developing this
simplified and easy-to-use method for estimating the
tree planting benefits, broad assumptions have been
made regarding trees' impact on direct shading benefits,
impacts of indirect or evapotranspiration effect, heating
penalty in winter months, tree growth rates and tree
survival rates. As a result, this method may yield less
precise results than a more tailored approach. Staff
from the Center for Urban Forest Research, Pacific Southwest
Research Station, USDA Forest Service, University of
California, Davis, have reviewed the Tree Benefits Estimator.
What You Need to Know About Your Trees
1. the tree species;
2. the direction your tree faces (for trees planted
next to buildings);
3. the distance between the tree and the building
that is being shaded;
and,
4. the age of the tree from the tree planting date.
Items to Consider
To take into account different climate zones, you will
need to input information on whether the utility has
a substantial summer cooling load (which would then
estimate 100% of the energy and capacity benefits),
or small summer cooling load (which would then estimate
50% of the energy and capacity benefits) or no summer
cooling load (which would then provide no energy and
capacity benefits). However, regardless of whether a
utility has any summer cooling load, the method will
estimate carbon and CO2 sequestration values for the
specified tree species.
The methodology is based on the "standard" nursery raised
trees which are typically sold in 5-gallon containers,
and which are usually 1 inch in diameter at the tree
base (1 foot above the ground). (SMUD Shade Tree program
has experienced that 5-gallon container trees will grow
quickly and catch up with the larger 15-gallon container
trees within the next couple of years and thus the methodology
applies for both 5- and 15-gallon container trees.)
This methodology assumes that the standard (5 gallon)
trees are "0" age when planted.
The age of the tree from the planting date will then
determine the tree growth rate factor and the tree survival
rate factor, which will in turn determine together the
level of benefits for any year between 1 and 30. In
other words, the combination of the tree growth rate
and the tree survival rate will determine the final
multiplier factor that will estimate the appropriate
level of tree benefits for any year. In order to estimate
tree benefits for any tree age (between age 1 to 30
years), you will need to enter the age of the tree from
the tree planting date and the estimator will automatically
multiply the energy, capacity and carbon sequestration
benefit values of MATURE trees with the appropriate
Tree Growth and Survival Rate FACTOR. Additional manual
calculations are NOT needed.
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