# Autonomous Cyber-Physical Systems Enabling Smart Positive Energy Districts
## 3 Emerging Technologies Enabling Positive Energy Districts
### Cyber-Physical Systems  
CPSs are essential to develop smart PEDs and support the production of sustainable and efficient urban environments. CPSs are important for enabling, managing, and optimizing PEDs. CPSs are \"_complex multi-layered feedback systems that combine computing resources and interaction with the physical environment using sensors and actuators_\" [32]. By integrating physical energy infrastructures with digital calculations, real-time control of distributed energy, and storage and communication, CPSs enable (i) monitoring, detection, and mitigation of disturbances; (ii) efficient and resilient operation of energy systems at the district level; and (iii) defense against cyber-attacks, secure state estimation, and control. They also stimulate stakeholder participation (a fundamental feature of successful PEDs) through their data sharing platforms for data sharing and community participation. CPSs in energy are applied in areas such as smart grids, renewable energy integration, microgrid control, energy storage management, and efficient power system operation, enhancing efficiency, reliability, and sustainability. CPSs contribute to energy-aware environments through the integration of energy consumption data into software development processes [32]. CPSs combine complex physical network systems and cyber systems to optimize energy utilization and to enhance the functionality of smart grids and urban infrastructures. Recent developments in information and ICT and embedded system design have enabled the adoption of CPSs in practical applications. An example is the change of traditional energy grids into smart grids which utilize \"_a two-way communication system for information transformation, power generation, and distribution_\" [33], via the use of real-time advanced monitoring, communication, and control systems. Hence, CPSs support smart grid technologies, facilitating advanced energy management, microgrid control, and protection, which are crucial for PEDs to operate efficiently and sustainably [33]. A specific case study, namely the Aspen Smart City project in Vienna, Austria [34], can be mentioned, due to the use of CPSs to link monitoring in real time, intelligent control, and decision-making for optimizing energy performance. CPSs enable PED outcomes via demand response (consumption shift during peak hours or low renewable generation), real-time optimization (reducing energy losses by controlling when to consume, store, or feed energy back to the grid), user interaction (residents access dashboards to monitor usage and receive suggestions regarding how to reduce consumption), and fault detection and maintenance (detection of equipment performance irregularities activates alerts or maintenance requests). CPSs used in the Aspen project include the following:  
1. _Building Energy Management Systems (BEMS)_ connected via CPSs to manage heating, cooling, and lighting according to real-time data, and to optimize energy use by adaptive control while comfort levels are maintained. 2. _Smart meters and IoT sensors_ that collect environmental data, such as temperature, humidity, and occupancy, and monitor energy generation and consumption in real time across buildings. 3. _Renewable Energy Integration Platforms_ managing energy flows dynamically depending on demand and supply. A central CPS is used to collect data from solar PV panels on rooftops. 4. _Smart Grids and Decentralized Energy Storage_ (e.g., batteries) are managed by CPSs to store excess energy (e.g., solar power). Demand is estimated by predictive algorithms and grid behavior is adjusted accordingly. 5. _Digital Twins_ are used as virtual models of the physical district to simulate scenarios for energy optimization. CPSs enable real-time feedback loops to update the digital twin with live data.