Verifiable and Sovereignty-Aware Data Access for Digital Twins in Smart Energy Communities

Digital Twins (DTs) are becoming central to services
in smart cities and energy communities, but their value depends
on data streams whose integrity, accessibility and sovereignty
must be jointly guaranteed across heterogeneous and indepen
dently governed sources. Existing platforms typically address
only one or two of these properties, preventing DT services
from simultaneously verifying data authenticity and enforcing
provider-specific data locality and hosting constraints within a
single deployment. This paper presents a data platform that
provides accessibility through a polyglot data lake handling
time series, semi-structured documents and relational records,
consolidated by an interoperability layer into knowledge graphs
aligned with a shared ontology and reached through a single
authenticated entry point. Data-location sovereignty is preserved
by three federated hosting regimes designed to accommodate
different provider requirements regarding data location and
platform deployment. Integrity is delivered by a Distributed
Ledger Technology Interface (DLTI) that groups records into
batches, anchors the Merkle root of each batch on a permissioned
ledger, and keeps a proof of inclusion for each record off
chain, allowing the DT to verify any individual record without
reprocessing entire datasets. Validation on two smart energy
communities in Aalborg and Coimbra tests all three layers under
different sovereignty regimes and confirms end-to-end ingestion,
verifiable access and interactive exploration.