Improved Strategy for Virtual Daily Light Integral with CO2 Supplementation in Greenhouses

Supplemental CO 2 in greenhouses can reduce the lighting required to achieve a particular yield. Systems that can also control deployable shades are very desirable for light-sensitive crops such as lettuce, which is susceptible to leaf tipburn if exposed to excess light. Four lighting control systems are compared: 1) a rule-based light and shade controller baseline; 2) a trajectory-following light and shade controller; 3) a rule-based light, shading, and CO 2 controller; and 4) a new trajectory-following light, shade, and CO 2 controller that combines the strengths of controllers 2 and 3. The primary metric used for comparison is revenue less costs for CO 2 and lighting. Differences in this metric indicate relative performance of one control system compared with another. Simulations using four different, contiguous US climates are performed, all indicating nearly twice as much improvement with the new controller over the baseline as using controller 2 or 3 alone.