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Submitted to: Greenhouse Product News
Publication Type: Trade Journal Publication Acceptance Date: 9/1/2014 Publication Date: 10/1/2014 Citation: Boldt, J.K. 2014. A novel approach to reduce greenhouse energy costs. Greenhouse Product News. 24(10):14-22. Interpretive Summary: Irradiance, temperature, and carbon dioxide (CO2) are three environmental parameters growers can control during greenhouse production to alter crop growth, quality, and timing. Significant costs are incurred every year, especially during winter and early-spring production, to heat and light the greenhouse in order to provide optimal growing conditions for plant growth and development. Small changes to the growing environment have the ability to greatly impact the bottom line. An approach that has the potential to reduce energy-related production costs without sacrificing plant quality is presented. The effect of growing plants for one or more days per week in a "reduced energy" greenhouse (55 °F day/50 °F night, ambient irradiance, and an energy curtain pulled to reduce heating costs) relative to growing them continuously at "normal" growing conditions (72 °F day/65 °F night, ambient irradiance, and supplemental lighting on cloudy days) is discussed. It was observed that growing plants for one or two days per week in a reduced-energy environment results in a minimal decrease in plant growth or delay in flowering, except in angelonia (a cold-insensitive plant). Growing plants for up to four days per week in a reduced-energy environment will result in a finished plant of acceptable quality, but reductions in growth and delays in flowering will occur. Growers and producers will need to weigh the reduction in energy costs with costs associated with an increase in production time to see if it is a viable option for their greenhouse operation. Virtual Grower, a decision-support software tool, can help growers estimate their heating and lighting costs. Technical Abstract: Irradiance, temperature, and carbon dioxide (CO2) are three environmental parameters growers can control during greenhouse production to alter crop growth, quality, and timing. Significant costs are incurred every year, especially during winter and early-spring production, to heat and light the greenhouse in order to provide optimal growing conditions for plant growth and development. Small changes to the growing environment have the ability to greatly impact the bottom line. An approach that has the potential to reduce energy-related production costs without sacrificing plant quality is presented. The effect of growing plants for one or more days per week in a "reduced energy" greenhouse (55 °F day/50 °F night, ambient irradiance, and an energy curtain pulled to reduce heating costs) relative to growing them continuously at "normal" growing conditions (72 °F day/65 °F night, ambient irradiance, and supplemental lighting on cloudy days) is discussed. It was observed that growing plants for one or two days per week in a reduced-energy environment results in a minimal decrease in plant growth or delay in flowering, except in angelonia (a cold-insensitive plant). Growing plants for up to four days per week in a reduced-energy environment will result in a finished plant of acceptable quality, but reductions in growth and delays in flowering will occur. Growers and producers will need to weigh the reduction in energy costs with costs associated with an increase in production time to see if it is a viable option for their greenhouse operation. Virtual Grower, a decision-support software tool, can help growers estimate their heating and lighting costs. |
