New Heat Extremes

by Michael N. Hofman

One of the aspects of climate change AND increased energy efficiency is how these two elements affect the landscape. There is quite a bit of information about how new high efficiency windows collect and redirect heat (see the great article by the National Association of Home Builders which follows: “Sunlight Reflected from Double-Paned Low-E Windows, and Damage to Vinyl Siding and Other Materials”, which centers in on the damage to vinyl siding. One sentence stands out in this report: “The heat from double-paned low-e window reflected sunlight has been measured in excess of 200 degrees Fahrenheit at its point of focus….” We have seen a similar result in several of the yards in which we installed artificial grass which showed signs of burning with our infrared thermometer. Artificial grass is a great medium to understand the impact of this issue because it doesn’t move, is a stable material and therefore will show any issues quite clearly. There’s also an interesting news clip about the same problem:

We’ve found that these points are usually identifiable as a band across the grass area (photo attached). We’ve found that in the Bay Area this high temperature usually occurs when there are east- or south-facing high efficiency windows which are in close proximity to the area. While deterioration of the artificial glass is certainly important, of greater importance is the accumulation of so much heat in a localized spot in the garden. We’ve sometimes seen plant deterioration (or even discoloration in structures) but didn’t previously ascribe these impacts to the focused heat. If your children are playing in the area, might they get burned if staying in the same location for any period of time? We hope not, but consider that the grass burning is a “canary in a coal mine” in this case. Luckily a solution exists in the form of a window film which will mitigate the reflection of heat away from the windows.

In addition to reflective heat from windows, we’ve also seen that even placing metal on the artificial grass (such as containers or metal furniture) has the potential to scar the grass and other items in the garden as well, especially in east-facing yards with good sun exposure in the morning. This means that over time it’s important to make sure that such material doesn’t end up staying in your garden area or else it might create scarring. If you find you have a significant problem, creating more shade with a permanent structure (such as an arbor which will break up the sun’s rays) or a movable structure (such as an umbrella) might be a good solution.