## 1 Introduction
### Technology for Sustainable Building Environment (SBE)  
Artificial Intelligence (AI), the Internet of Things (IoT), and Digital Twins (DT) are interconnected technologies that enhance decision-making, automation, and system optimization across various domains [8; 11; 12]. AI refers to the development of algorithms and systems that enable machines to perform tasks that typically require human intelligence, such as learning, reasoning, and problem-solving [13; 14; 15]. IoT involves a network of physical devices embedded with sensors, software, and connectivity, allowing them to collect and exchange data over the internet. DT, on the other hand, are virtual replicas of physical systems or objects that use real-time data from IoT devices to simulate, monitor, and analyze the performance of their physical counterparts based on AI analysis [11; 16; 17]. The relationship between these technologies is synergistic: IoT provides the data streams necessary to create and update DT, while AI analyzes this data to predict behaviors, optimize performance, and automate decisions, making these technologies a powerful combination for enhancing efficiency and innovation across industries [18; 19; 20].  
AI, DT, and IoT can significantly enhance the sustainability, efficiency, and resilience of the building environment. IoT devices embedded within buildings collect real-time data on energy usage, temperature, humidity, occupancy, and equipment performance, creating a comprehensive digital ecosystem. This data feeds into DT, which serves as dynamic, virtual replicas of the physical building, enabling constant monitoring, simulation, and optimization of building systems [21; 22; 23]. AI processes this data, analyzing trends and predicting future behaviors to optimize energy consumption, automate lighting, heating, and cooling systems, and improve overall resource efficiency. In addition, AI-powered DT can simulate different scenarios, such as occupancy patterns or equipment failures, to identify potential inefficiencies and suggest proactive maintenance measures. Together, these technologies create smarter, more sustainable buildings that adapt in real-time to changing conditions, contributing to reduced energy consumption, lower carbon emissions, and improved occupant comfort and safety [22; 24; 25].  
Figure 1: Sustainable building environment (SBE) technologies [7; 8].  
Figure 2 illustrates the integration of IoT-enabled physical buildings and Digital Twins, emphasizing a bi-directional communication loop between physical and digital assets. The physical building, equipped with IoT sensors, actuators, and systems, continuously collects real-time data (RTD) such as environmental conditions, equipment performance, and energy consumption and exchanges this data with the DT. AI analyzes the RTD and develops predictive analytics and simulations for DT using real-time computing (RTC). The DT serves as a virtual replica, performing real-time data analysis, fault detection, simulation forecasting, and interactive communication for predictive operations and optimization. The controllability aspect refers to IoT-enabled smart controls, which act on the insights provided by the DT to adjust building systems, improve operational efficiency, and integrate facilities management (IFM) throughout the building's lifecycle. IFM refers to improving the efficiency, effectiveness, and sustainability of managing buildings and infrastructure. It involves leveraging technologies such as AI, IoT, and automation to optimize operations, reduce costs, and improve occupant experiences [26]. This continuous feedback loop allows for condition-based monitoring and lifecycle process improvement, ensuring the building remains adaptive, efficient, and optimized.