Economic Scheduling Strategies for Climate Management in a Venlo-Type Rose Greenhouse Under Time-of-Use Tariffs and CO2 Supplementation Costs

Abstract

Greenhouse cultivation plays an important role in supporting stable and high-quality horticultural production by providing controlled environmental conditions under variable outdoor climates. However, regulating temperature, humidity, CO2 concentration, and light requires substantial energy and resource inputs, resulting in high resource consumption and operating costs. This study presents a dynamic optimization framework for the coordinated operation of heating/cooling, ventilation, CO2 injection, and shading in a Venlo-type rose greenhouse to support resource-efficient and cost-effective operation while maintaining the greenhouse climate variables within prescribed environmental bounds. Three strategies are formulated and compared under identical operating conditions: electricity consumption minimization (ECM), electricity expenditure minimization (EEM), and operating cost minimization (OCM). For the baseline winter day, ECM achieved the lowest electricity consumption of 1954.29 kWh. EEM increased electricity consumption by 26.05% but reduced electricity expenditure by 9.06% compared with ECM, demonstrating the effect of tariff-responsive scheduling. By jointly considering electricity and CO2 supplementation costs, OCM reduced CO2 supplementation to 1.302 t and the total operating cost to R 5550.41, representing reductions of 69.31% and 63.05% compared with ECM and EEM, respectively. For the baseline winter day and under the adopted controller settings, OCM showed 70.86% lower electricity consumption and a 69.69% lower total operating cost than the representative rule-based controller. Over seven consecutive winter days, OCM achieved a lower CO2 supplementation and total operating cost than EEM. Additional evaluations under contrasting winter weather conditions showed that operating costs were strongly weather dependent, while the prescribed environmental constraints were maintained. Sensitivity analysis further showed that the total operating cost was more responsive to variations in electricity price than to variations in CO2 price. These results demonstrate the potential of coordinated economic scheduling to improve resource efficiency and reduce greenhouse operating costs.