August 16


Trees and “Heat Islands”

By clientsite

August 16, 2016

It sure has been a hot and dry summer at ArborTech’s yard here in Springfield. The neighborhood kids are playing in sprinklers, dogs are panting, and our crews are looking forward to air conditioning at the end of the work day! It’s safe to say that the Springfield metro area can be brutally hot during the summer. Many of us living and working in urban areas don’t realize that we are on a “heat island.” This is the condition where urban areas are warmer than the surrounding countryside, during the heat of summer, due to more human activity; large amount of heat absorbing surfaces such as buildings and parking lots; plus a lower percentage of vegetation in these areas. Any type of vegetation including trees, shrubs, and turf grass can reduce temperatures in these heat islands.

A few minutes after this tree was planted, a worker sat down in a shaded spot to enjoy his lunch.

The cooling effect that plants have is accomplished in two ways. The obvious one is shade. Shaded surfaces in the urban environment are much cooler than surrounding exposed areas. It’s no wonder that a shady parking space on a sunny day is in high demand! The other plant contribution to cooling is through Evapotranspiration. Evapotranspiration is a process in which plants release water vapor threw tiny pores in their leaves. This can reduce the air temperature during peak summer heat in dense urban centers.

To limit the impact of temperature extremes, it’s important to consider a number of factors. The most important is the angle of the sun. A tree planted on the west side of a house will provide shade during the hottest part of the day and will have more impact than one on the south side. Trees planted on the south side should have a canopy large enough to shade part of the structure. Deciduous trees (ones that lose their leaves annually) are recommended because they provide shade in the summer months and allow the sun to provide solar heating during the winter.

This mature oak, west of the home, provides enough shade to block the sun for most of the day. This reduces the amount of energy needed to cool the home.

It’s worth noting that trees planted close to buildings should be resilient in storms, with good structure and strong wood characteristics (contact an ArborTech Arborist if you have concerns about a tree near your home). As for shade, dense foliage has more impact. A tree, such as a Sugar Maple or Linden, provides deep shade, while a Honey Locust offers light, partial shade due to smaller leaf size.

Plants are most effective at cooling (actually limiting heat gain) when they shade windows and hard surfaces such as walls, roofs, and pavement. These surfaces would otherwise absorb, hold and slowly release heat from the sun. Shading the air conditioning unit itself is also beneficial, increasing its efficiency. If space is limited, shrubs, tall grasses and small trees all can contribute to shading.

Right now, as I’m writing this blog, it’s 93 degrees here at the ArborTech yard. It’s hot and I’m thankful to be enjoying the AC after a day working out in the field. I’m also thankful for all of the urban trees in the Springfield metro area that are contributing to the reduction of heat right now. Without them, who knows how hot it would be! As for your home, if you have questions about how trees and shrubs could benefit your energy usage, our Certified Arborists can assist you in choosing the right plantings for your landscape. To schedule a consultation, please call (413) 525-0060 or contact us online.


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