Energy Flexibility Realization in Grid-Interactive Buildings for Demand Response: State-of-the-Art Review on Strategies, Resources, Control, and KPIs

The increasing penetration of renewable energy into the grid has given rise to an emerging challenge of maintaining the supply–demand balance. Conventional supply-side regulation is now insufficient to maintain this balance, necessitating flexible resources from the demand side to address this challenge. Buildings, as important energy end-use consumers, possess abundant flexible resources and can play a significant role in responding to grid dispatch via demand response. Therefore, grid-interactive buildings (GIBs) have garnered widespread attention. This technology coordinates the scheduling of distributed renewable energies, energy storage, and adjustable loads via advanced control methodologies, leading to the reshaping of building load profiles to enhance grid flexibility. However, the realization of energy flexibility in GIBs has not yet been comprehensively identified in the literature. To narrow the knowledge gap, this review compared GIBs with other technologies of building energy management to highlight the distinct features of GIBs. Additionally, the flexible energy strategies of GIBs were explored, combined with flexible resources within buildings, and the feasible pathways for these strategies were also addressed. Based on the scheduling scenarios in GIBs, the performance characteristics of various control methodologies were compared and analyzed. Finally, an evaluation framework for GIBs was established. This review will facilitate the shift of buildings from traditional energy consumers to flexible resources that actively respond to the grid and provide critical support for the grid stability and reliability.