An in-depth analysis assessing urban tree cover and its impact on residential building energy use in the coterminous United States estimates a reduction of 38.8. million MWh or $4.7 billion in electricity use and 246 MMBtus or $3.9 billion in heating use annually. The estimated collective reduction in national residential energy use attributable to trees is 7.2%.
Nowak, David J., Nathaniel Appleton, Alexis Ellis, and Eric Greenfield. (2017). Residential building energy conservation and avoided power plant emissions by urban and community trees in the United States. Urban Forestry & Urban Greening 21: 158-165. https://doi.org/10.1016/j.ufug.2016.12.004