Saving Energy in Greenhouses By Dr. Claudio Pasian OSU Department of Horticulture & Crop Science Energy cost is high on the worry list of several greenhouse growers in the MidWest these days. Some growers have locked in prices that are reasonable -- given the present energy market circumstances. However, even the best deal reported by my contacts represents a high plant production cost. To counteract this, growers have to conserve energy every way possible. The National Greenhouse Manufacturers Association (www.NGMA.com) outlines these tasks in the brochure, "Energy Conservation" which addresses the question, "What are some inexpensive improvements with short term payback?" This brochure is available online, free by registering at the NGMA website. Your goal is to be as efficient as possible. Achieving this goal will require careful management of all or most of the items on the NGMA checklist below. Insulate pipes, foundation walls and north walls Use light reflective materials on inner greenhouse surfaces such as ground covers, north walls, post and benches Close up fan housings with insulated covers Caulk and seal all air leaks Clean, service, adjust all louvers and vent systems and check to ensure they seal properly when closed Make sure exhaust fans, pad and fan systems are in good working order Use poly liners to reduce heat loss and increase the RH factor in cold winter months Concentrate crops and shut unused greenhouses Plant later and grow warmer or plant earlier and grow cooler Check control settings for accuracy and proper temperature sensors placement (usually at the top of the crop canopy) Service and adjust boilers and unit heaters Make sure thermal curtain systems are working properly and are in good repair Isolate propagation areas from growing zones - only heat the areas you currently need Maintain clean glazing surfaces Reduce boiler water temperature in warmer weather In colder months, use the lowest heating set points and the highest cooling set points possible Use split day/night temperatures where possible Allow climate temperatures to rise naturally late in afternoon to reduce energy demands at night In addition, the NGMA recommends making some retrofits to your greenhouses: Thermal curtain installation or retrofit If you capture CO2 from your boilers, consider heat storage options Automated control systems can produce more consistent climates while minimizing energy inputs Reposition heating pipes Replace boilers and unit heaters with higher efficiency models Retrofit fan cooling systems with higher efficiency equipment Other questions I hear often from growers when energy cost are high: Can I grow my crops cooler? Can I lower the temperature of my greenhouses at night? My answer to these questions is: Yes and no. It depends on the crop and how you grow it. I will address this issue next month. Stay tuned!