**2. Background**

Buildings play undoubtedly a crucial role within a sustainable and fossil-free energy system. Whilst the focus on the single entity is hugely relevant in order to develop highly efficient materials, structures and system, the enlargement of the perspective to bigger entities can be crucial to leverage the full potential of connected systems. Especially in dense urban environments, buildings cannot only be viewed as detached elements, but must be perceived within a wider neighborhood in their urban morphological and societal context. Resilient urban development thus sets a particular focus on concepts for sustainable, efficient, and green districts [17]. The de-carbonization of the energy systems will heavily rely on the widespread integration of RES. But since demand and supply can be deeply asynchronous, demand response managemen<sup>t</sup> and storage potentials must be implemented to match the scale of renewables. Energy grids can provide the required transfer for electrical and thermal energy. Whilst on the building level infrastructure considerations are mostly dependent on the already existing infrastructure on a particular building site, planning on a district scale offers a broader range of options. In addition to larger urban or regional networks, small-scale infrastructure, such as district heating or cooling networks, can be included at this scale.

#### *2.1. Regulative Background and Current Developments on the SRI*

Within the latest revision of the EPBD the regulators also foresee a Smart Readiness Indicator (SRI) that rates a building to use information and communication technology (ICT) to adapt the operation of the building to the needs of the occupants and the grid [9]. As a support mechanism, the European Commission has funded a study to provide a coherent methodology for the assessment of the SRI for the member states [10]. After the publication of the original findings in 2018, the consortium subsequently started a stakeholder consultation process to review the applicability of their proposal. This process included the review of a series of topics, including cost and cost-benefits, climatic specificities, scoring system and testing. They also implemented two expert topical stakeholder working groups focused on SRI value proposition and implementation as well as SRI calculation methodology. The findings of the process and adaptations have been summarized in the interim report of the Second Technical Support Study on the Smart Readiness Indicator for Buildings [11]. Related to their Task 1 on the technical support for the consolidation of the definition and the calculation methodology of the SRI, the study concludes that the proposed SRI methodology builds on assessing the smart readiness service in a building. These services improve the performance of the building in regard to energy efficiency, responds to user requirements and support the interaction with the grid. The proposal includes both a

simplified and detailed assessment method and the overall methodology has also been tested on 112 test cases [11]. Compared to the initial study, the revised version after the consultation process has not significantly changed other than refinement of the indicators as outlined above. The methodology still relies heavily on qualified assessors and thus on a subjective and quantitative approach. The latest report states that the reliability of and trust in the experts to deliver the scheme will be a key success factor and that high-quality training will be required [11]. It should also be noted that the methodology relates mostly to the electricity demand (as outlined under point 3 in the reference stated above) and does not equally consider flexibility in thermal demand.

Whilst the implementation of the EPBD is up to the individual member states, the Concerted Action on Energy Performance of Buildings Directive (CA EPBD), which is funded under the European Unions' Horizon 2020 program, aims at exchanging knowledge and best practices in the field of energy e fficiency amongs<sup>t</sup> the European member countries [18]. Subsequently the SRI and potential methodologies associated with its integration into national building codes will also most likely be discussed within this working group. As the CA EPBD also publishes country reports on the status of the implementation of the EPBD in the member states, it remains to be seen how the SRI methodology as proposed in the above study will be applied throughout Europe.

Nevertheless, it is clearly understood, that the Energy Performance certificates (EPCs), which are an inherent part of the EPBD play a crucial role in transforming the building market and that the directive as such already has been shown to be an e ffective policy [19,20]. Education and training as well as interdisciplinarity are essential cornerstones in driving the EPBD forward to improve the performance of buildings [21]. The EPCs should ideally provide easily accessible data on building performance and can support the identification and subsequent refurbishment of underperforming buildings [22]. The recently added SRI can also serve as a useful source of information to enhance public awareness on the smartness of a building, however similarly to the EPC, it is key that the indicator is easy to use, transparent and based on reliable data.

The discussion of the regulatory background shows, that policy related to the assessments of buildings are both highly relevant, but there is an evident need for easily applicable and reliable tools that provide an objective assessment. Currently, this aspect is still mostly missing within the context of the SRI.
