Strategically placed trees around your building can reduce your energy bills. 

According to the Environmental Protection Agency, trees in an urban areas make hot summer days in cities bearable.

While concrete and buildings tend to reflect heat, thereby increasing temperatures, shade created by trees, in combination with the water vapor they release, can reduce peak temperatures by as much as 20–45°F (11–25°C) compared to unshaded areas. 

When shade is cast on an office buildings, the internal temperatures of those buildings can drop by 8 or 10°F.  Some estimates say the shade from a single tree can save the same amount of energy it takes to power 10 room-sized air conditioners for 20 hours a day.

In the winter, trees provide important windbreaks around buildings to reduce heat loss by as much as 50%, lowering heating costs and energy consumption.