Today our region of the county will experience a partial solar eclipse. Not far to our north, they will experience a full solar eclipse. You’ve probably seen or heard others discussing what is going on astronomically, but I want to address whether or not you’ll see any energy savings during the eclipse. The short answer is “yes” with a slightly longer answer being “but not much.”
The biggest energy savings from the eclipse could come from a reduction in solar load on a building. If it is a sunny day and your roof is suddenly in shade, your air conditioner will no longer have to work as hard to reject the heat that builds up from the sun’s rays hitting your building. If your building is already shaded by trees, you won’t see much change. Consider how hot an attic is during a sunny afternoon afternoon versus the early morning. A lot of that heat is due to the sun hitting your roof rather than the outside temperature.
Ambient temperatures can also drop between 5 to 15 degrees during a solar eclipse which would reduce the amount of heat transferred between the outside and inside of your building. Heat transfers more quickly when the difference in temperature between two surfaces is higher. If the inside of your building is 75 °F and the outside is 100 °F, energy transfer into the house will be much higher than if the outside temperature is only 85 °F.
Unfortunately for your energy bill, the benefits of an hour or so of nighttime during the day will most likely be insignificant. Either way, know that while you are outside viewing the eclipse, your building is enjoying a nice short break in the shade.