In general, it's a good idea for farmers to look at energy use on their farm every five years and consider opportunities to reduce energy consumption, says Don Day, energy extension associate for University of Missouri Extension.
However, the need for an energy audit may vary from farm to farm, Day said. For example, if you already had an energy audit conducted on your farm, even if it was five or more years ago, it will continue to provide accurate information regarding potential energy savings until you make changes that affect energy usage.
"A new audit may also be in order if energy prices change or there is an additional energy alternative that a farmer is considering using that was not addressed initially," he said.
Changes in energy prices can alter payback periods, he added. "We have seen changes in the relative prices of energy sources over the past few years that will change what fuel a farmer might use." However, he notes, it generally doesn't pay to change the type of fuel you are using unless a piece of equipment such as a furnace or an engine needs to be replaced.
Day offers some additional recommendations to help farmers decide when they need an energy audit on their farm: