New Castle greenhouse pulls curtains for energy savings

By Suzie Romig
Clean Energy Economy News

Employees at Dwyer Greens & Flowers near New Castle were busy in November 2010 hanging curtains, but don’t think linen sheers or silk drapes.

Photo courtesy Wadsworth Control Systems

These curtains are made of high-tech, reflective, climate control fabric manufactured in Sweden, and they are huge: 30 feet wide and 132 feet long. They are installed to save energy in greenhouses in summer and in winter.

Dwyer Greens manager Kristine Edge said she hopes the 11 sections of curtains will cut electricity and propane bills in the company’s large greenhouse by 30 percent. The automated system will reflect heat on hot summer days and hold in heat during winter in the plastic-walled greenhouse.

“It will definitely change our greenhouse environment for the better. The more precisely you can control that environment, the healthier your plants are going to be,” said Edge, who earned a biology degree from the University of Colorado at Boulder. “Less stress on plants increases plant vigor, decreases water use and leads to less disease and insect problems on the plants.”

Dwyer Greens & Flowers owner Lynn Dwyer decided to pursue the curtain project after enrolling in the Garfield Clean Energy Challenge for Business program being offered by CLEER: Clean Energy Economy for the Region through the Garfield New Energy Communities Initiative. Dwyer, who founded her company in 1997, already uses solar hot water and solar electric systems to help heat and power the greenhouse operation.

Dwyer and Edge knew about the benefits of greenhouse energy curtains, and a walk-through energy audit conducted at the greenhouse by Craig Tate, commercial energy efficiency manager for Holy Cross Energy, confirmed the strategy. In a collaborative effort, Edge, Tate and CLEER Energy Coach Rob Morey researched the automated curtain systems of different manufacturers to see what would work best at the New Castle greenhouse.

By combining a WE CARE rebate offered by Holy Cross Energy for the automated curtain controls with the $5,000 rebate bonus from the Garfield Clean Energy Challenge for Business, Dwyer benefitted from a sizeable offset on the $14,000 price tag for the curtains and associated design fees. The staff at Dwyer Greens will be installing the curtains.

The curtains are fitted in between the roof trusses in the greenhouse. In winter, the automated controls can be set to open the curtains during the day for solar gain and to be closed at night to create a smaller volume of space to be heated. The curtains reflect the stored heat back down to the plants instead of being trapped near the ceiling or lost through the thin roof. In summer, the operation can be reversed, helping keep the greenhouse from overheating.

Edge said the company uses huge exhaust fans to keep the greenhouses cool in the summer, and she predicts the curtain system could save up to $500 per year in resulting electricity costs. She said winter propane use for heating could be reduced by $5,000 per year.

Installation of the lightweight curtains should also conserve soil moisture in the greenhouse, cutting water demand and the energy needed to pump water up to the greenhouse site. The efficiency upgrade should increase worker comfort levels and reduce staff time for hand watering in the greenhouse. Edge also expects that healthier plants will also need less of the organic pesticides used in the operation.

“It’s all about controlling your environment, and that curtain is definitely going to play a huge role in that,” Edge said.

Edge knows from experience. She previously worked in greenhouses in Rifle, where the installation of energy curtains led to healthier plants during the western Colorado summertime when the sun’s intensity is stressful for greenhouse plants.

Installation consultant Roger Weakland, owner of Greenhouse Environmental Services in Denver, said energy curtains have been around for years, and the technology continues to improve. He said the technology could also be used for skylights in office buildings or garden seating areas in restaurants.

The Dwyer Greens installation includes an upgraded computerized system that controls the greenhouse environment such as heating, cooling, lighting and the energy curtains. The system also can feed information to an off-site computer for remote monitoring. The equipment is distributed by Wadsworth Control Systems in Arvada.

“It conserves energy tremendously because it only allows the equipment to run when it should rather than when a person has time to go over and turn it on or off,” Weakland said.

More information about energy curtains is available at www.wadsworthcontrols.com, or contact Roger Weakland, Greenhouse Environmental Services, at roger@ghses.com.