Western Pennsylvania greenhouse operators gathered at Gumto Greenhouses on February 25th to tour the operation and to learn about energy efficiency.
According to Ciolkosz, the key to energy conservation is in eliminating unnecessary waste by using high efficiency equipment, turning things off when not in use, and re-using energy when practical.
Energy efficiency measures not only reduce energy use and cost, but in many cases they can also improve growing conditions in the greenhouse--a double benefit. While there are many high-cost ways to reduce energy use, the evening's presentation focused on low-cost and no-cost measures that growers can implement.
The top ten easy steps for improving greenhouse efficiency are:
10. Tune the Control System. If you have timers for lighting or thermostats for heating and ventilation, make sure that they are set properly to minimize wasted energy. It is surprising how often thermostats or computer control systems can get out of whack, resulting in equipment that is operating when it shouldn't.
9. Upgrade Your Motors. When it comes time to replacing a motor, choosing a "high efficiency" model often boosts motor efficiency 5-10%. Three phase motors are more efficient than single phase. Don't buy more motor than you need; ideally a motor should run at 80-100% of its full load.
8. Clean Your Fans. Dirt and dust on the fan blades lower the efficiency of the fan, while gunk on the ventilation louvers creates gaps for cold air to get in. Keeping your fans clean can improve fan efficiency by as much as 10-15%.
7. Upgrade Your Lighting. Replace low efficiency light sources such as incandescents with higher efficiency sources such as compact or tubular flourescent, or metal halide. Keeping lamps clean can make a big difference in light output, as well. Install precision controls such as occupancy sensors for people lighting, and computer controls for plant lighting.
6. Upgrade Your Fans and Screening. Use high efficiency fans, and make sure that the brand of insect screening you use isn't causing undue drag on fan performance. If it is time to replace your fans, make sure you shop around, and find out the "ventilation efficiency ratio" of all models that you are considering.
5. Insulate the North Wall. You won't lose very much usable light, but you will cut down on heat loss.
4. Insulate the Perimeter. Insulation should be installed around the bottom of a greenhouse during its construction. This should reach at least two feet, and preferably three feet, below the soil line. If the greenhouse will be used only for bench production, insulation can be extended up the walls of the greenhouse without a loss of useful light.
3. Seal the Fans. Heat loss around fans can be considerable. If light leaks around the fan, you can be sure that heat will be leaking out the same cracks. Some greenhouse operators have even installed roll-up fan covers to seal the leaks when the fans are not in use.
2. Add a Thermal Screen. If your irrigation system and your budget allow, consider a thermal screen as a very effective way to trap escaping heat.
1. Tighten Up the House. And last but not least, grab a caulk gun and seal up miscellaneous holes, gaps and cracks wherever you find them in the greenhouse.
With an investment of a little bit of time, attention and money, you can really improve your bottom line by eliminating unnecessary energy waste.