5 Tips For A More Energy-Efficient Greenhouse

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Scott Longfellow, owner of Longfellow’s Greenhouses in Manchester, Maine knows a thing or two about dealing with cold winters. With two acres of greenhouse production, he also deals with many of the same issues of finding ways to conserve energy that other small to mid-size growers do.

Longfellow offered several tips for finding energy improvements that can benefit your greenhouse operation during heating season – and in the summer too.

1. Get an energy audit. Longfellow had one performed as part of a USDA grant process, but recommends doing an audit whether it’s required or not. “You’ll find a whole list of things you’re not paying attention to,” he says. “It cost us about $1000 and it was money well spent.”

2. Adjust your boiler temperatures in the summer. “You don’t want to shut it down, but there’s no need to keep the boiler running at 210-220 degrees all summer long,” he says. Longfellows dials theirs down to the 150-160 degree range and saves on fuel costs in the process.

3. Calibrate your thermostats. “Ours haven’t been calibrated nearly as well as they should be. When we checked, one was nearly 9 degrees off. One area was providing more heat than the crop required and another was running much cooler than the computer thought and the plants weren’t growing as quickly as they should have been,” he says. “You might have some high-tech equipment, but it always needs your attention.”

4. Inspect all of your vents before winter arrives. Look for bent flaps and openings that aren’t closing tightly. “We regularly find vents that aren’t closing all the way, even though it appears they are if you don’t look closely. You can lose a ton of heat through that gap,” Longfellow says.

5. Install insulation along the sidewalls. “We installed two feet of blueboard along the sidewalls and sealed the area where the board rested on the concrete with silicone. We also sealed the top with aluminum tape, although that didn’t last so well so we’re looking for a replacement for that. The guys who did the installation said they were amazed how cold it was down there,” he says.

Richard Jones is the group editor for Greenhouse Grower and Today's Garden Center magazines.

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