Enhancing Building Energy Flexibility Through Demand Response-Enabled Heating and Ventilation for Flexible IEQ Management

With increasing investments in renewable energy, driven by climate change and its impact on global energy security, the volatility of the energy supply-demand has grown. Energy flexibility strategies, especially within the building sector, are crucial for bridging this gap. However, the use of ventilation to achieve energy flexibility and demand-side management remains underexplored in the scientific community. Energy flexibility is the capacity of a building to manage its generation and consumption according to grid requirements, user needs, and climate conditions. This paper investigates ventilation-driven flexibility in smart retrofitted buildings using a novel Economic Rule-Based Control (ERBC) framework that modulates outdoor air and supply airflow setpoints in response to grid signals while enforcing indoor environmental quality (IEQ) constraints within the experimental setting of "HYBCELL", an in-situ testing facility at ENTPE, France. The ERBC methodology, developed in LabVIEW, integrates real-time sensor data (indoor temperature, CO2 concentration), weather data, and dynamic hourly electricity pricing signals from the French day-ahead market. The ERBC framework achieves energy flexibility through load shifting, quantified using a flexibility factor (FF) that ranges from -1 (operation exclusively during high-price periods) to +1 (operation exclusively during low-price periods). Across six monitored days in December 2025, the proposed control achieved load shifting primarily in heating, reaching a flexibility factor (FF) of up to 0.84 during high-price periods, while maintaining acceptable indoor air quality (CO2 < 900 ppm for >80% of occupied hours). Results demonstrate that heating loads are more flexible than ventilation and that both climatic conditions and price volatility influence economic savings. The findings confirm that ventilation-driven control can serve as a viable short-term flexibility measure without compromising comfort, supporting the transition toward grid-adaptive buildings.