Chapter 3

Greenhouse Curtain Systems

Benefits of Greenhouse Curtain Systems

Temperature Control/Energy Savings

Thermal curtains (or energy-saving curtains) are closed-knit or close-weave fabrics that limit heat transfer with the outdoors and retain desired heat at night and during winter days, while also preventing unwanted heat gains from the sun if used for shading during summer days. Thermal curtains are mounted to the structure of the greenhouse above the crop area and are sometimes used to cover the sidewalls inside the greenhouse to reduce nighttime heat loss in cold weather. Thermal curtain save energy in three ways. First, they trap an insulating layer of air between the curtain and the greenhouse roof. The curtain must fit tightly to trap warm air in the growing space; otherwise, warm air will rise into the attic and reduce its effectiveness. Second, they reduce the volume of greenhouse air that must be heated.

Shading

Curtain systems reduce solar radiation and help control internal greenhouse temperatures during the day. Because they’re moveable, they can be partially or fully covered as needed. Light-diffusing shade curtains may also be of open structure, with gaps in the knit or weave that freely allow airflow.

Photoperiod Control

Growing crops in a controlled environment allows the grower to manipulate photoperiods. For example, a blackout curtain system is used when growing crops such as poinsettias and chrysanthemums that are induced to flower by controlling the day length.

Light-Emission Prevention

In low-light regions (the northern United States, Canada, and northern Europe), growers often use supplemental lighting both day and night. Because of this, light emissions from a greenhouse at night can be problematic for neighbors and wildlife.

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