In this paper we present results of our investigation into the relationship between urban microclimate and the local density of tree cover as measured in Sacramento California. These results were obtained through analysis of data collected in a two-month long monitoring program with automatic weather stations installed at 15 residential locations throughout the city. Measured wind speeds showed a highly negative correlation with respect to tree cover. Daily peak air temperatures showed significant variation often differing from site to site by 2 to 4°C (-3.5 to 7°F). A complex interaction between several competing factors is discussed leading to the conclusion that additional tree cover may actually increase urban air temperatures on synoptically cool days. It is suggested that this does not have a significant adverse affect in terms of overall summer urban cooling load. This is supported by an integrated analysis of the temperature data which yielded preliminary estimates indicating that residential cooling load (as measured by cooling degree days) may decrease by 5 to 10% per 10% increase in tree cover. Shortcomings of this experiment are briefly discussed and suggestions are provided for future experiments.
Sailor , David J, Leo Rainer, and Hashem Akbari. “Measured Impact of Neighbourhood Tree Cover on Microclimate .” Lawrence Berkeley Laboratory, Energy & Environment Division
Source: University of California Berkeley
Publication Date: August 1992