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In the face of growing demands for efficiency, sustainability, and intelligent control, building technology and its tasks for smart city development are constantly evolving. Digital twins play a pivotal role here: they make it possible to digitally map, monitor, and optimize complex buildings and their technical systems. Using these virtual models, energy processes can be analyzed, maintenance can be planned proactively, and operating costs can be sustainably reduced. In the process, the physical and digital worlds merge into a dynamic overall system that makes buildings and cities smarter, more resource-efficient, and more user-friendly. In this article from the Building Perspectives series, we take a look at the various approaches to digital twins in different regions, caught between global challenges and regional realities, in smart city projects and smart buildings.
Digital Twin in Salesforce Tower: Innovation and Sustainability
The Salesforce Tower, the defining landmark on San Francisco’s skyline, stands not only for architectural highlights but also for technological revolution: the application of a digital twin is changing the way this impressive skyscraper is built, operated, and used. At 326 meters and 61 stories, the Salesforce Tower is not only one of the tallest buildings in the western US but also a pioneer in intelligent building management. The digital twin is a virtual, dynamic replica of a real object and digitally maps all relevant physical and functional properties—from architecture and building services to daily operations. Through real-time connectivity with sensors and data sources, a constantly updated reflection of the real building is created. The Salesforce Tower uses a digital twin to manage the complexity of its operation and set new standards in sustainability, user comfort, and efficiency. Even during the construction phase, the model was used for planning, simulation, and logistics. After completion, the digital twin is now the heart of building management.
The digital twin of Salesforce Tower is linked to thousands of sensors that continuously deliver data on temperature, air quality, occupancy, elevator status, energy consumption, and more. This real-time data allows for monitoring the condition of every single component and acting proactively.
For example, the system detects unusual vibrations in an elevator shaft or increased CO2 levels in a conference room. The maintenance team receives automated alerts on mobile devices, can locate faults, and take targeted action—often before users even notice any issues. Predictive maintenance thus ensures maximum availability and reduces unexpected downtime and costs.
A central goal of Salesforce Tower is to be one of the most sustainable office buildings worldwide. The digital twin is central to this: detailed analyses of energy and water consumption, lighting control, and air conditioning enable continuous optimization. Simulations help assess various scenarios in advance, such as the use of renewable energy or peak loads.
With the help of the digital twin, ventilation, heating, and lighting systems can be controlled as needed. Sensors on windows and façades measure sunlight and outside temperature so that the system automatically adjusts shading and air conditioning. This reduces energy consumption and operating costs while shrinking the carbon footprint.
Implementing and maintaining a digital twin in a skyscraper like Salesforce Tower is complex. Large amounts of sensitive data must be processed in real time, securely stored, and analyzed. Investments in IT infrastructure and data security are just as necessary as training personnel to use and further develop the systems. Within the building, the digital twin ensures maximum efficiency, sustainability, and an outstanding user experience and is a prime example of how digital twins will shape the planning, operation, and reuse of commercial properties globally in the future—making a vital contribution to intelligent, sustainable, and livable cities. The following examples illustrate how the use of digital twins extends beyond individual buildings to entire cities and regions.
Klagenfurt: Digital Twin Helps Achieve Climate Goals
The city of Klagenfurt is part of the EU Cities Mission 2030 and aims to be climate neutral by 2030. As in many other countries, municipal administrations in Austria collect and update data extensively. However, more data does not necessarily mean more knowledge, and the collected and curated data is seldom shared, analyzed, or made practically available. The challenge was to network and involve all urban stakeholders and create a space where all information is easily accessible and editable. To meet this challenge, the city of Klagenfurt, together with industry partners, developed a data-driven, AI-based solution using remote sensing, aerial imagery, photogrammetry, and municipal geodata—a solution that serves residents, city decision-makers, local trades, and industry alike.
The Klagenfurt Digital Twin is a web application with various functionalities and a strong focus on sustainability. The 3D model is based on thousands of images taken during two extensive flights over the city, as well as other collected sensor data. With the help of AI, the digital twin maps the total area of properties with various land use categories to better understand how land is used in the city. The 3D model is publicly accessible and offers laypeople an easy-to-use and fully functional 3D geographic information system. It shows how valuable individual green spaces are for the urban climate and provides initial information for assessing whether photovoltaic and solar thermal systems can be installed on building surfaces. Even the shadow cast by each individual tree is calculated, thus determining the solar energy potential of every house and business in Klagenfurt. A study quantifying the positive environmental effects of the digital twin now shows impressive results: savings of 14,000 tons of CO2 emissions for each year the digital twin is in operation.
The digital twin is also used for evidence-based simulation studies in building and urban planning when evaluating the benefits of measures in planning scenarios beforehand. The new technology is used not only for new construction projects but also for Klagenfurt’s historic center, providing the basis for monument protection and preservation.
“This project is a significant step into the future of our city. It shows how we can use digital technologies to make Klagenfurt smarter, more efficient, and more livable.”
Genoa: Digital Urban Planning Amidst the Historic City Center
While sustainability is the focus in Klagenfurt, those responsible in Genoa faced entirely different tasks. The “Le Strade Nuove” and the system of the Palazzi dei Rolli in Genoa have been UNESCO World Heritage Sites since 2006 and illustrate the historical significance of the city. At the same time, Genoa faces challenges such as pollution, mass tourism, and climate change, which require a sustainable approach to its architectural heritage. To address these tasks, the city administration relies on innovative technologies and has implemented an extensive Urban Digital Twin project.
Urban planning in Genoa is complex, as various departments must coordinate and historical structures must be preserved. Since 1985, the city has been building a digital city model with the help of START 4.0, a competence center supported by the Italian Ministry of Economic Development that promotes digital innovation in the context of Industry 4.0.
The “OverUnderGround” project integrates ground-penetrating radar, BIM, and point clouds to precisely capture both above- and underground infrastructures. In this way, the interplay of historic buildings and modern technology becomes more manageable, and the planning of water resources and monument protection is improved. As early as 2025, urban planners were able to use initial 3D models showing above- and underground structures seamlessly. The digital twin not only helps with infrastructure projects but also with tourism management and heritage protection. Real-time data makes it possible to manage visitor flows and environmental impacts in a targeted manner.
The vision goes even further: in the future, IoT sensors are to feed data on water levels and environmental changes directly into the digital city model, enabling proactive urban management. Genoa thus demonstrates how history and digital future merge in a smart city.
Canton of Zug: Digital Twin in 3D
With the “Digital Zug” strategy, the Canton of Zug pursues ambitious goals for further digitalizing the administration and developing modern services. Through ZugMap, the canton’s publicly accessible geoportal, users can access extensive official geoinformation. While this data was previously only available in 2D, cooperation with Hexagon and the use of modern technologies have enabled access to a digital 3D twin of the Canton of Zug since May 2025. ZugMap, the existing public geoportal of the Canton of Zug, was chosen as the basis for the digital twin in 3D because a wealth of geodata is already united in digital form in this application. These include road and path maps, all types of boundaries, digital cadastral data, zoning plans, and environmental data including water information. The objective was to make the diverse data within the digital twin understandable, visually appealing, and interactively accessible to the public in 3D.
At the start of the project, the entire canton area was comprehensively surveyed using hybrid LiDAR and aerial photography. Additionally, three buildings were scanned with drones. For special use cases, interior shots were also taken in four selected buildings. The geodata can be accessed together with further information at the click of a button. Most data is available either as a direct download or can be integrated as a geoservice into existing systems.
In the field of building culture education, the Office for the Preservation of Monuments, for example, supported the development of use cases and provided additional, general data on the objects recorded in the study. This opens up interesting possibilities, for example, for the communication of building culture, which also requires reflective guidance. This calls for innovative forms of cooperation between politics, administration, business, civil society, and research, as well as improved (digital) communication and participation tools.
Conclusion
The examples from San Francisco, Klagenfurt, Genoa, and the Canton of Zug impressively demonstrate how digital twins are shaping the future of buildings and cities. They enable not only sustainable and efficient management but also create transparency, participation, and innovation across national borders. Digital twins are thus a decisive building block for intelligent, livable, and future-proof urban development.
