Substantial and unprecedented reductions in carbon emissions are required if the worst effects of climate change are to be avoided. A major paradigmatic shift is, therefore, needed in the way heat and electricity are generated and consumed; particularly for buildings and communities. Reductions in carbon emissions can be achieved by reducing energy demand through energy efficiency improvements and by supplying the remaining energy demand with renewable energy sources. To obtain this, energy flexibility is a very important tool. Energy flexibility is necessary to manage the time deviation in supply and demand due to the large-scale integration of central and distributed energy conversion systems based on renewable primary energy resources. It is a key component of national and international transition pathways towards sustainable and resilient energy systems, where the reduction of CO2-equivalent emissions are top priorities.

In many countries, the share of renewable energy sources (RES) is increasing in parallel with an extensive electrification of the energy demand. The electrification of the demand emanates from, for instance, the replacement of internal combustion engines (ICE) cars with electric vehicles (EVs) or replacement of fossil fuel heating systems with energy efficient heat pumps. These changes, on both the demand and supply sides, impose new challenges to the management of energy systems. System operators must now design solutions to counter the increased variability and limited control of the energy supply, as well as the increased load variation over the day. Energy system electrification also threatens to exceed already strained limits in peak demand and stability (either static or dynamic). Several European urban areas have already reported that their transmission capacities have reached their limits, resulting in a lack of power capacity during peak hours.

A paradigm shift is, thus, required that shifts away from existing systems, where energy supply always follows demand, to a system where the demand side considers available supply. Therefore, flexible energy systems, where demand is responsive to supply, should play an important part in a holistic solution. These responsive systems will replace the traditional generation and distribution systems, with a fully integrated and bidirectional network capable of seamlessly incorporating distributed storage and demand response. In this context, strategies to ensure the security and reliability of the energy supply involve simultaneous coordination of distributed energy resources (DERs), energy storage and flexible loads, connected to smart electrical and thermal distribution networks.

As buildings account for approximately 40 % of the annual energy use worldwide, they must play a significant role in providing a safe and efficient operation of the future resilient energy systems. Buildings have the ability to play a central role in this transition, where consumers and “prosumers” (e.g. buildings with PV) modulate their demand/conversion/storage capacity in order to satisfy the needs of the energy networks while still ensuring good thermal indoor climate and minimal disruption to the building occupants. The flexibility can be offered either at the scale of a single building or at the scale of clusters of buildings. Energy flexible buildings and clusters rely on some form of storage and advanced control strategies to adapt their dynamic energy use to support the energy networks, which makes them inherently more resilient.

The possible energy flexibility of different buildings and how to obtain this energy flexibility have been investigated in IEA EBC Annex 67 Energy Flexibility Buildings. The concluding phase of Annex 67 has, however, revealed areas where further work is needed to ensure that energy flexibility from buildings will actually be an asset for the future energy networks. These identified areas are:

1. scaling from single buildings to clusters of buildings (aggregation);
2. energy flexibility and resilience in multi-carrier energy systems (electricity, district heating/cooling and gas);
3. acceptance/engagement of the stakeholders; and
4. business models.

IEA annex 67 has partly dealt with the above issues but further work is needed. Several IEA annexes and tasks have carried out investigations and have obtained results that will be relevant to Annex 82 – e.g.:

• EBC Annex 51 Energy Efficient Communities.
• EBC Annex 52 Towards Net Zero Energy Solar Building
• EBC Annex 54 Integration of Microgeneration and related Technologies in Buildings
• EBC Annex 58 Reliable Building Energy Performance Characterisation Based on Full Scale Dynamic Measurements
• EBC Annex 64 “LowEx” Communities - Optimized Performance of Energy Supply Systems with Exergy Principles
• EBC Annex 66 Definition and Simulation of Occupant Behaviour in Buildings
• EBC Annex 69 Strategy and Practice of Adaptive Thermal Comfort in Low Energy Buildings
• EBC Annex 70 Building Energy Performance Assessment Based on In-situ Measurements
• EBC Annex 72 Assessing Life Cycle Related Environmental Impacts Caused by Buildings
• EBC Annex 73 Towards Net Zero Energy Public Communities
• EBC Annex 74 Energy Endeavour
• EBC Annex 75 Cost-effective Strategies to Combine Energy Efficiency Measures and Renewable Energy Use in Building Renovation at District Level
• EBC Annex 79 Occupant-Centric Building Design and Operation
• EBC Annex 81 Data-Driven Smart Buildings

Other IEA Technology Collaboration Programs (TCPs): District Heating & Cooling (DHC); Energy Conservation through Energy Storage (ECES); Energy Efficient Electrical Equipment (4E); Heat Pump Programme (HPP); Demand Side Management (DSM); Photovoltaic Power Systems (PVPS); and Solar Heating & Cooling (SHC) have also obtained results or are generating useful information for Annex 82. Cooperation with relevant IEA TCP annexes and tasks will be established.

Research issues

An important research focus of this Annex is to expand the building energy flexibility characterization methodology developed in Annex 67 to consider clusters of buildings and multi-carrier energy systems. Expanding the scope will enable the development of a validated and standard tool for defining building flexibility services that can be used in the majority of contexts encountered by energy systems. Another research focus of the Annex is to obtain in-depth knowledge of stakeholder motivation and perceived barriers in order to develop techniques to support the uptake and use of the building energy flexibility. Based on the two above research issues, possible business cases will be investigated and recommendations for policy makers will be given.

Objectives and Limitations

The aim of the Annex is to gain important knowledge about the energy flexibility services that buildings and clusters of buildings may deliver to different types of energy networks. It is further the aim to increase the understanding of stakeholder’s motivation for utilizing such systems and the barriers preventing further participation. Constructive involvement is a key for making building energy flexibility a significant asset in resilient energy networks.

This knowledge is important when developing business cases that will utilize building energy flexibility in future energy systems. It is equally important for policy makers and government entities involved in shaping the direction of future energy systems.

Objectives

To reach the goals, the Annex focuses on the following specific objectives:

• Demonstration and further development of the Annex 67 characterization and labelling methods in order to make them commonly accepted (subtasks A and B)
• Investigation of methods for aggregation of energy flexibility from clusters of buildings both physically connected and commercially connected (not necessarily physically connected) via an aggregator (subtasks A and B)
• Investigation of the aggregated potential of energy flexibility services from buildings and clusters of buildings located in different multi-carrier energy systems (subtask A)
• Demonstration of energy flexibility in clusters of buildings through simulations, experiments and field studies (subtask A)
• Investigation of how extreme events (e.g., heat waves, drought or storms) affect the resilience of energy systems and what role energy flexible buildings, clusters of buildings and their occupants play in ensuring resilience (subtasks A and C)
• Mapping the barriers, motivations and acceptance of the stakeholders associated with the introduction of energy flexibility measures in buildings and clusters of buildings (subtask C)
• Investigation on how to include the view of the stakeholders in the development of feasible technical solutions (subtask C combined with subtask A)
• Investigation and development of business models for energy flexible services to the energy networks (subtask D)
• Recommendations to policy makers and government entities involved in the shaping of the future energy systems (subtasks C and D)

Scope and Demarcation

The Annex will mainly focus on the aggregated level of buildings in the form of clusters and communities. However, as the aggregated energy flexibility is composed of the energy flexibility of single buildings, special features of the energy flexibility of single buildings will also be investigated in order to give insight into the resulting aggregated energy flexibility.

Aggregation at its lower level is a power feeder/outlet or a small branch of a larger district heating/cooling network typically supplying power and heat to different types of buildings – e.g. residential, smaller commercial, new and existing buildings. Therefore, the energy flexibility of all types of buildings is in principle included in the focus area of the Annex. However, larger industrial buildings with production are generally outside the scope of the Annex as they often have their own feeders from the power grid and as the control of industrial production processes is different from the control of buildings. However, industrial processes may deliver waste heat to surrounding buildings or a district heating network, which require their consideration.

As energy flexibility services at an aggregated level will be investigated, it will in most cases be necessary to compare and/or include energy flexibility services supplied from buildings with energy flexibility services supplied from other technologies situated in the networks and not in the buildings. These can be larger storage facilities (both thermal and electrical), larger heat pumps in district heating networks, EV car parks with charging facilities, streetlights, etc. Here, cooperation will be established with other relevant IEA TCP annexes and tasks.

Multi-carrier energy systems (e.g., buildings supplied with more than one energy carrier from different networks), power grids, district heating/cooling and gas networks are all within the scope of the annex. The Annex will, however, mainly focus on local distribution networks including micro grids, while also considering the interaction with the central networks they are part of.

Although interoperability is mandatory when deploying energy flexibility of buildings for providing flexibility services to energy networks, this is not a direct focus area of the Annex, but will be considered where relevant.