Detailed assessment of hybrid ventilation control system in a mixed-mode building in cold climate

This paper investigates a hybrid ventilation control method for a mixed-mode office landscape in a cold climate, i.e. Norway. The mixed-mode building utilizes a hybrid ventilation system that combines natural ventilation through automatic window opening with a balanced mechanical ventilation system controlled by demand control ventilation (DCV) method. For natural ventilation, the windows consist of two parts: the upper part which is openable and the lower part that is not openable and equipped with external solar shading. From a control point of view, the article elaborates a control algorithm for the proposed hybrid ventilation based on various parameters including outdoor air temperature, indoor air temperature, CO₂ level, maximum air change per hour (ACH), operation schedules, and heating/cooling setpoints. The simulation results obtained from the hybrid ventilation and mechanical ventilation cases are compared based on thermal comfort, CO₂ level, and energy savings. The primary results show that the proposed hybrid ventilation control method can satisfy the thermal comfort and CO₂ level requirements while reducing the energy use for fan and ventilation cooling by approximately 55% and 45%, respectively. While the impact on energy consumption for space and ventilation heating is negligible.