As summer approaches, we know the snows of winter will give way to heat and humidity, as well as high energy costs to keep our farm homes and structures cool.
Before Dutch elm disease took nearly every American elm tree from our farm in the 1970s, our old farm home and barns were shaded by huge, stately American elms. These trees shaded the south and southeast faces of our house from the hottest of the summer sun, but in the winter, they allowed filtered sunlight to reach the house and still give us a little warming through the windows and on the surface of the siding.
When we were forced to cut these dying giants down as they declined from disease, it made a big difference in summer temperatures inside our house.
For agricultural purposes, we usually talk about the benefits of tree plantings around the farmstead in the terms of windbreaks or shelterbelts. Windbreak plantings have their benefits in the summer, but they truly shine when they protect our farms and livestock yards from wind velocity in the winter.
We must remember that shade trees, too, serve an important role around farm homes and structures — including barns, shops and livestock holding yards and facilities — but their useful purpose is exhibited in the heat of summer.
If you think about the transmission of sunlight in the hot summer months, you recognize that single-pane glass surfaces in windows transmit about 90% of the sunlight received perpendicular to the surface. While the sunlight can pass through the windows, the heat produced by the light cannot escape from inside the home or barn, for instance.
In addition, heat can be conducted through the outer surfaces of farm buildings to produce heat inside those structures. If you’re working in a metal, non-insulated shop on a hot summer afternoon, you know this is true.
That’s why shade trees strategically planted around farm homes and buildings can reduce the transmission of sunlight through windows and the conduction of sunlight on outer building surfaces during the hot midday in the summer.
According to Penn State University Extension research, interior temperatures in a mobile home without air conditioning, but shaded by trees, were 20 degrees F less than an unshaded mobile home during the hottest part of the day.
In addition, maximum temperatures in the shaded trailer occurred up to three and a half hours later than at the unshaded site. That way, interior cooling of the shaded trailer to a level that would be tolerable by humans happened much sooner at the shaded site in the evening.
Shade trees often are overlooked in the farmstead forest, but their benefits are real, no matter if they are planted around a farm home, barns or corrals. They not only can save cooling costs in the summer months, but also can provide wildlife habitat and aesthetic beauty to the agriculture operation.