Optimization on Fresh Outdoor Air Ratio of Stratum Ventilation for Both Targeted Indoor Air Quality and Maximal Energy Saving

Stratum ventilation is widely recognized for its efficiency in maintaining good indoor air quality. However, the non-uniform CO2 distribution within a stratum-ventilated room is challenging in achieving intended indoor air quality levels. This chapter introduces an optimization method to identify the optimal ratio of fresh outdoor air that minimizes energy consumption while maintaining indoor air quality of stratum ventilation. A model is developed to estimate the CO2 concentration in the breathing zone by incorporating the CO2 removal efficiency within the breathing zone and mass conservation principles. The model facilitates the quantification of ventilation parameters based on varying ratios of fresh outdoor air, intending to achieve targeted indoor air quality. Energy performance assessments of the air-conditioning system are conducted using building energy simulations. Experiments show that the developed model for CO2 concentration in the breathing zone achieves a mean absolute error of 1.9%. The effectiveness of the proposed optimization approach is demonstrated using TRNSYS, leading to a 6.4% reduction in energy consumption for the air-conditioning system with stratum ventilation. This optimization method has significant potential for enhancing indoor air quality and energy efficiency for other ventilation modes.