Current solar energy systems design methods mainly rely on experts developing designs on 2D flat screens using outdated CAD models. Immersive 3D design methods may democratise the design process, such that systems can be designed quickly and accurately. Therefore, in this manuscript we measure user engagement or stress levels in both a 2D and 3D immersive virtual reality environment during a solar energy systems design task. User engagement was measured by estimating a user's vital signs using a non-invasive FMCW radar. In our pilot study, four participants tried a 2D and 3D interface while their vital signs were being monitored. According to participant feedback from self-reported questionnaires, our results clearly indicate that the 3D virtual reality offers higher user engagement. These findings could have a tremendous impact on the way we develop renewable energy systems of the future.

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This study presents an ultra-wideband (UWB) radar solution for contact-free sensing and estimating human vital signs. The proposed solution uses radio frequency (RF) signals to estimate even the tiniest chest movements, including those induced by breathing and the heartbeat. Our algorithm calculates heart rate (HR) and breathing rate (BR) based on signal processing techniques. Our algorithm is validated by comparing its results against the data obtained from a medical-grade wearable sensor. In our study, the correlation between the reference sensor and radar sensor yields 98.2% accuracy in breathing rate estimation. Additionally, we measured the root mean square error (RMSE) between the reference sensor and radar sensor and found it to be 1.36.