The relationship between tree shading and summertime home energy consumption has long been a topic of interest, and has been the subject of many simulations and small-scale studies. A recent study, led by Geoffrey Donovan, United States Department of Agriculture (USDA) Forest Service, and David Butry, confirmed what previous studies had determined: Trees shading the west and south sides of houses reduce summertime energy consumption considerably. Butry and Donovan’s study is unique in that it uses real electrical billing data on a large scale. While others had monitored one house, or a few houses, Donovan and Butry monitored 460 different houses located in Sacramento, California, making this the largest, most comprehensive study on the relationship between tree shading and home energy consumption to date. The pair collected data in the summer of 2007. They used aerial photography to collect data on the trees surrounding the 460 houses based on three factors: crown size, distance from the house, and aspect relative to the house. They then collected electrical billing data from the Sacramento Municipal Utility District and water use data from the city of Sacramento. They found that trees providing shade on the west and south sides of the houses reduced summertime ...