Energy-Efficient Building Design in Real-Time Simulation

Screenshot from Beyond: The solar radiation and the available window area must b
Screenshot from Beyond: The solar radiation and the available window area must be taken into account when setting the thermostat. Image source: ISDS - TU Graz

An interdisciplinary team at TU Graz is revolutionising the design of sustainable buildings. The advantages and disadvantages of different construction measures are visualised in real time using VR simulation.

Next-generation energy services are designed to help a building’s end users understand and visualise the benefits of new energy-efficient technologies or thermal refurbishment measures. This includes the control of heating and cooling, lighting and ventilation. In order to make this possible, Christina Hopfe, head of the Institute of Building Physics, Services and Construction at Graz University of Technology (TU Graz) has brought together TU Graz colleagues from the fields of virtual reality, machine learning, building performance simulation and the Internet of Things in the BEYOND project. The result is a virtual reality environment in which users can change the physical parameters of a building and experience the effects of this change in real time. This enables them to design an energy-efficient building at realistic costs or to improve the energy efficiency of an existing one. The project’s focus also aligns with TU Graz’s ongoing sustainability initiatives, including its goal to be carbon neutral by 2030.

Visual and acoustic feedback

In the BEYOND simulation, participants change the properties of a building or room in a virtual environment and receive additional guidance through light signals, notes and audio hints. This is supplemented by haptic and audio feedback on the positive and negative effects of these changes. When it comes to insulating a wall, for example, it is not only the wall structure and materials used that are relevant, but also the costs incurred. Having larger windows, for example, provides more daylight, which has been shown to generally have a positive effect on people indoors. But glazing components typically have higher heat transfer coefficients leading to greater energy losses during the colder periods of the year compared to an insulated fašade. Conversely, glazing can also harvest solar gains, which can effectively turn windows into radiators. This has advantages in winter, but can also lead to overheating in summer. Understanding the competing pros and cons occurring within a building and making them visual, and even visceral, to the building end-users is one of the great attributes of Beyond.

The clear feedback helps users to better understand the advantages and disadvantages of different building measures. This makes this application valuable for architects, planners and owners, but also for end users and students, who can use BEYOND as an interactive teaching tool to better understand the topics of building physics and building behaviour. In order to meet the requirements of different users, the parameters and boundary conditions of a building can be changed at varying levels of detail. "What-if" questions such as "What happens if the outside temperature increases by three degrees Celsius or what if the type or position (inside versus outside) of the insulation layer is changed?" can be analysed, in addition to technical questions, such as the change in energy consumption with increased or decreased heating or cooling setpoints.

Combination of three technologies

The BEYOND project is unique in that it combines three technologies and methods. In addition to a virtual reality environment, machine learning and building performance simulation are used to process, visualise and forecast changes in the building data. For this purpose, mathematical models fed with relevant data points - so-called surrogate models - and forecasting methods are used to provide data that make it possible to visualise the actual effects of planning interventions in real time. The third element is the integration of IoT platforms and sensor networks for bidirectional real-time communication between the building and its users.

Building stock largely inefficient

To bring these technologies together, three core research teams worked together on an interdisciplinary basis. In addition to the Institute of Building Physics, Services and Construction, teams from the Institute of Interactive Systems and Data Science and the Institute of Software Technology were also involved at TU Graz. EAM Systems GmbH and EnAlytics i.G. were on board as project partners.

"The BEYOND project deals with an interdisciplinary topic that is emerging at the edge of building physics, data science and virtual reality," says Christina Hopfe. "It is a topical area for research which is underpinned by the energy crisis, the climate crisis and the rapidly changing demands on our energy systems. Energy-efficient buildings play an important role on the path to climate neutrality, as the building stock in the EU is still energy-intensive and predominantly inefficient - it is responsible for 40% of final energy consumption and around 36% of CO2 emissions. For the first time - nationally and internationally - BEYOND enables the connection of VR technology with real buildings, as well as real-time communication and simulation. This allows direct virtual interaction with real buildings and their energy services."

From Christina Hopfe’s point of view, this awareness is of central importance to changing energy-related behaviour, especially one’s own, and reducing profligate energy consumption - and thus for achieving the climate targets. She explains further: "The EU aims to be climate neutral by 2050, and this means transforming the entire built environment to achieve net-zero greenhouse gas emissions. Renewable energy is part of that solution, but energy services such as predictive maintenance, demand-side management or model-predictive control have an important role to play in reducing the energy demand of buildings whilst transforming buildings into active, intelligent players in higher-level energy systems."

This project is part of the research center Graz Center of Sustainable Construction as well as the Fields of Expertise I nformation, Communication and Computing , and Sustainable Systems , two of the university’s five scientific research foci.

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