Trees of any variety are ideal additions to any landscape, providing natural beauty and oxygen, shade for energy efficiency and UV protection, tree houses, fruit, nuts and flowers. A tree's shade factor is a technical term that refers to the overall amount of sunlight blocked by the tree—and knowing this information can help you understand how much shade your tree will provide, and also help with measurements for tree spacing and planting. Keep in mind, though, key factors when calculating the shade factor of trees for your landscape.
Figure out the crown spread of your tree, which refers to the tree branches' average area. Use the measuring tape to measure the most narrow and widest points of the spread, then average them out to get the tree's crown spread.
Figure out the height of your tree, as accurately as possible with a clinometer, a tool used in forestry (available at your local hardware or gardening store, such as Lowe's or Home Depot). This device calculates distances and angles to estimate an item's height (in this case, the tree). Depending on the type of clinometer you choose, follow the directions exactly.
Include variables such as tree health, leaf type and variety, seasons and region. For example, trees in the northern United States will always cast longer shadows then places that are far south, because of the sun's angle.
Combine the estimated shade length of the tree with the crown spread to calculate the tree's overall shade factor.