We get many questions about autoclave energy savings. This isn’t surprising: Research labs generally use three to four times more energy that similar-sized office spaces. The primary culprits: Devices responsible for heating or cooling, “always-on” equipment, and anything with a 3-phase power supply. So if you’re looking to cut your lab’s energy (not to mention water!) bill, your autoclave is a good place to start.

But we see many “energy saving” features being advertised that have little hope of making a real dent in your energy bill. For example, autoclave size and orientation has less impact on your autoclave’s energy consumption than you might assume. Top-loading and front-loading units of the same size generally have comparable heating demands. In many cases, an autoclave has to more than double in size (regardless of orientation) before it bumps up to a larger heater.

Similarly, load type and size often has little impact on energy efficiency. According to technicians in our London production facility, sterilizing a small fluid load (e.g., racks of test tubes) requires roughly the same amount of energy as sterilizing larger fluid loads (e.g., 500mL bottles of saline solution)—even though the large fluid load cycle is slightly longer. For that matter, a 30-minute waste load—although twice as long as a 15-minute fluid load—requires only about 15 to 20 percent more energy. And vacuum cycles—which can significantly bump up water consumption, depending on the style of vacuum used—have very little impact on energy consumption overall.

What Really Impacts Autoclave Efficiency

In the end, there are two major factors contributing to your steam sterilizer’s high energy consumption:

The steam source and the chamber shape.

In short, for a given working volume, the most efficient autoclave will always have a cylindrical pressure vessel and in-chamber steam generation. In our next post, we’ll dive into the debate with a bit more detail.