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Northern Research Station
One Gifford Pinchot Drive
Madison, WI 53726
(608) 231-9200
(608) 231-9544 TTY/TDD

Urban Natural Resources Stewardship

This research is no longer active. 
If you’d like additional information, please contact the project leader of this unit.

Tree Influences on Human Comfort

[image:] A visual design module in OUTCOMES permits tree shade patterns to be plotted for any latitude and longitude and date and time.  Tree crowns are assumed to be ellipsoidal in shape. Research Issue

Trees modify air temperature, solar and thermal radiation exchanges, wind, and humidity of the air, and all of these influence human comfort.  For urban forest planning, the tree influences on comfort and health of people should be taken into account.  Because trees interact with the physical environment in so many ways, the assessment of tree influences on human comfort and health is complex.  It is especially difficult to predict tree influences over the course of a season with a typical weather pattern.  Such predictions could be possible with computer programs to calculate the influence of trees on environmental factors and the effect of these factors on human comfort.  Such computer programs should be easily understood and straight forward to use so that they would be helpful for urban foresters and other planning professionals.

Our Research

Our research aims to measure and derive models of tree influences on the climatic factors solar radiation, wind, and air temperature and then to develop computer programs to predict the climatic factors on human comfort.  Studies on tree influences on the total spectrum of solar radiation were completed some years ago (Heisler 1985: 1986).  Some Forest Service research on urban tree influences on wind speeds has shown large reductions in wind speed in both summer and winter (Heisler 1990: HeislerGrimmond et al. 1994).  We have developed preliminary computer programs to predict human-comfort and evaluate the impact of trees on comfort.  The first program, called OUTCOMES (OUTdoor COMfort Expert System), was a Windows® program that was written with the goal of providing an easy to use interface and ample on-screen help.  OUTCOMES shows the shade pattern of a tree and calculates a human comfort index considering the full range of weather variables, the density of a tree that shades a person, and other features of the surrounding neighborhood.

Expected Outcomes

We expect to provide computer programs that will aid in urban forest planning by permitting easy assessment of tree shade patterns and the influence of multiple climatic factors on human comfort.  

Research Results

The current version of OUTCOMES is available for evaluation and comment.  This version provides an estimate of human thermal comfort in one location and for one time for each run of the program.

For advanced users, we also developed a "batch" version of OUTCOMES that can input a file with weather data for any number of times and predict comfort at one location for all of the times with a single run of the program. OUTCOMES Batch is especially intended to work with Typical Meteorological Year data that is available free for 239 cities in the United Sates and Puerto Rico. OUTCOMES Batch was originally devised by Yingjie Wang to test the algorithms in OUTCOMES, and modules are included to do systematic sensitivity analyses and Monte Carlo analyses of the effect of input errors. To use OUTCOMES Batch, download the OUTCOMES Batch.zip file and extract the contents to a directory or folder of your choosing. The Readme.pdf file, which is included in the .zip file, will explain use of the program. Reports of either successful or unsuccessful use of either of the OUTCOMES programs, and suggestions for improvement will be appreciated; contact Gordon Heisler.

Heisler, G. M. and Y. Wang, 2002: Applications of a human thermal comfort model. Fourth Symposium on the Urban Environment, Norfolk, VA, American Meteorological Society, Boston, MA, 70-71.

Heisler, G. M., S. Grimmond, R. H. Grant, and C. Souch, 1994: Investigation of the influence of Chicago's urban forests on wind and air temperature within residential neighborhoods. Chicago's Urban Forest Ecosystem: Results of the Chicago Urban Forest Climate Project, E. G. McPherson, D. J. Nowak, and R. A. Rowntree, Eds., USDA Forest Service, Northeastern Forest Experiment Station, 19-40.

Heisler, G. M., 1990: Mean wind speed below building height in residential neighborhoods with different tree densities. American Society of Heating, Refrigerating, and Air Conditioning Engineers Transactions, 96, 1389-1396.

Heisler, G. M., 1986: Effects of individual trees on the solar radiation climate of small buildings. Urban Ecology, 9, 337-359.

Heisler, G. M., 1985: Measurements of solar radiation on vertical surfaces in the shade of individual trees. The Forest-Atmosphere Interaction: Proceedings of Forest Environmental Measurements Conference, Oak Ridge, TN, Reidel, 319-335.

Research Participants

Principal Investigator

Research Partners

  • Lee P. Herrington, Professor, SUNY College of Environmental Science and Forestry
  • Yingjie Wang, during his work on this project, PhD candidate, SUNY College of Environmental Science and Forestry

 

Last Modified: 10/03/2019

About this Research Area
Featured Product

[image:] OUTCOMES software opening screenOUTCOMES software shows the shade pattern of a tree and calculates a human comfort index considering the full range of weather variables, the density of a tree that shades a person, and other features of the surrounding neighborhood.

 

Heisler, G. M. and Y. Wang, 2002: Applications of a human thermal comfort model. Fourth Symposium on the Urban Environment, Norfolk, VA, American Meteorological Society, Boston, MA, 70-71.

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