In the future, the high share of renewable energy sources in electrical power and district heating grids will force the transition from a purely demand-oriented energy production (“generation on demand”) to a production-oriented demand respectively consumption (“consumption on demand”). This is also rational and necessary for the promotion of more accurate direct use of short-term predictable yet not time-controllable renewable energy production from e.g. wind or solar power, as well as solar thermal systems. It will relieve the grids and storage requirements likewise.

This adaptability of buildings to currently available energy supplies, their “energy flexibility” in respect with load balancing of the grid, is hard to quantify at this point in time. Indicators and a methodology for quick characterization of a building regarding such flexibility do not exist. The potential for energy flexibility in buildings is determined by factors like heat storage capacity of building components, quantities and sizes of thermal storage tanks and batteries, quantities and type of electrical devices and consumers such as heat pumps, the specifically utilized control systems, and similar. Intelligent use of related equipment enables to shift peak loads and discharge the grids at the right time. In this sense, buildings could be intelligent “prosumers” (consumers AND producers of energy). The aim of the Annex is to evaluate, analyze and characterize this future role of energy-flexible buildings integrated in renewable energy systems.

Since „Energy Flexibility of Buildings“ is a relatively new topic within the building and energy research community, a methodology and terminology for characterization of energy flexibility will be developed. For this purpose, the potential contribution of direct load control (load management or demand-side management – DSM, also called demand response), active thermal storage technologies incl. thermal storage of building components, optional on-site energy production, and control concepts for energy flexibility will be analyzed, simulated and tested. Related concepts will be tested in operating buildings or building clusters, and user motivation and acceptance in this context will be studied. A book detailing the “Principles of Energy Flexibility” will be published by the international experts at the end of this project. Diverse events and publications will complement the activities in the Annex.