One Engineer’s Fight for Energy Efficiency in CEA

Gretchen Schimelpfenig entered the energy space fighting climate change one utility bill at a time. As senior energy engineer at Energy Resources Integration, she aims to save energy and reduce the cost of operating buildings.

She originally started working on university buildings, data centers, and hospitals. Throughout those experiences she learned a lot about HVAC and lighting, which encouraged her to tackle the energy challenges plaguing the controlled environment agriculture (CEA) industry.

Since she first joined the industry in the 2010s, when CEA was picking up steam in the U.S., Schimelpfenig started creating policies and programs that aimed to make indoor agriculture more efficient.

“I didn’t realize how much energy was used in CEA until I started working in large-scale greenhouse construction,” Schimelpfenig says. “I wanted to look into how better HVAC and lighting solutions could keep that in check.”

This has been her primary focus for the last 10 years. In that time, she’s helped growers optimize their operations by making smarter energy-focused decisions.

Knowing What to Look For

When she first walks into a CEA facility to perform an energy audit, Schimelpfenig evaluates the organization, the control system, and the equipment installed.

1. Organization: Getting a feel for the facility’s overall health helps Schimelpfenig determine what the grower’s budget could be for improvements. “If it’s an older facility, for example, low-cost quick fixes that could make a big difference for them to keep equipment running efficiently,” she says.
2. Control system: How data is monitored and how many people are responsible for operating controls are also key. “Whether they use a tablet, central computer, or their phone, automation matters because it can save energy,” Schimelpfenig explains.
3. Equipment: Lastly, she looks at the unit heaters, boilers, lights, and other pieces of equipment that are high energy users. “I’ll look at the make and model to get an estimate of how much energy is being used by those systems,” she says. “Then I’ll go back to my desk and use that information to make some energy models to calculate potential savings.”

Once she completes her first walkthrough, Schimelpfenig addresses the most prominent energy opportunities in the operation.

Common Greenhouse Energy Opportunities

Here are the most common drivers behind energy costs that Schimelpfenig encounters across CEA operations:

1. High-pressure sodium (HPS) lights. Some growers still use HPS lights over LED lights, which can account for 75 – 90% of electricity bills for greenhouses.
2. Thermal Curtains. Growers may not use energy curtains or have ones that are outdated and in need of repair. By failing to use or upgrade them, they’re unknowingly driving up their energy costs. “The latest climate screens are a great way to save energy on heating,” she says. “Growers can tailor the environment for shade during the day and retain heat at night.”
3. Automation. Lighting controls are one of the main things Schimelpfenig focuses on when evaluating a CEA operation. Using sensors to automate supplemental lighting operation saves energy in every climate. “If growers are using timers for scheduled control, there is almost always savings if you move to a sensor-based system,” Schimelpfenig says.

While updating these parts of a CEA system is important, it can get expensive—and fast. For that reason, growers should take return on investment (ROI) into account before making any energy upgrades to make sure they tackle the right project first.

Taking ROI Into Account

The importance of ROI varies from operation to operation.

Larger greenhouse operations can tolerate longer payback periods, even if it takes seven to 10 years. However, that’s not the case for small growers with lower profit margin crops—they often need to see ROI within three to five years.

“When I do energy audits at greenhouses, I can usually get a sense of the payback period we’re talking about,” Schimelpfenig says. “If I see a lot of newer equipment, I might assume this facility has been able to do these replacements and they’re not deferring their maintenance.”

This indicates that the facility can schedule equipment replacements in advance instead of waiting for a failure to occur before replacing it.

For operations that can only afford to update their equipment when it’s absolutely necessary, Schimelpfenig encourages them to explore on-bill financing. This gives small-scale growers the option to pay energy upgrades off on their energy bill instead of putting capital into it.

“Some folks need loans, and they can’t make ROI work without one,” she explains. “This year, I’m looking at projects that have shorter payback periods because the cost of energy is only going up.”

Energy Efficiency in Action

Since 2024, Schimelpfenig has worked on a large energy efficiency greenhouse project in Idaho. Setting May 2026 as a completion date, the project will cost approximately $1.8 million. But, since it was built with energy efficiency in mind, it will receive about $200,000 in rebates.

Those rebates have helped shorten the payback period.

“My work is quantifying those energy savings because of the measures we took,” she says. “That’s what energy engineering comes down to sometimes—being the translator for energy upgrades, proving to the utility that they work, and making sure the grower gets the support they need to do the efficient thing.”

She set out to fight climate change one bill at a time. Ten years in, she’s still at it, and continues to make a difference with every grower she works with.

Tags: cea, energy efficiency, greenhouse production