The EcoCab project, led by the Fraunhofer Institute for Building Physics (IBP), aimed to create a digital development platform for an autonomous, low‑energy cabin that delivers high comfort while minimizing environmental impact. The research focused on the thermal performance of the cabin, the integration of decentralized air‑treatment units, and the assessment of economic and ecological potentials of different cabin variants.
Thermal simulations were carried out with the WUFI®+ software and compared to the VEZPO model. Surface temperature predictions from WUFI®+ reached a steady state slightly later than those from VEZPO, a difference that was most pronounced in the four transient test cases. Because the VEZPO model was calibrated directly against measured surface temperatures, it showed a lower root‑mean‑square error (RMSE) and a smaller median deviation for those data. However, when the internal construction details, such as floor temperature, were considered, WUFI®+ produced more realistic results. In the air‑treatment unit (ATU) simulations, room‑level air temperatures matched reference cases with similar RMSE values, whereas relative humidity predictions exhibited higher RMSE, indicating a weaker model quality for moisture dynamics. The discrepancy was attributed to the simplified representation of the mixing zone and the heat‑recovery coil in the simulation, which could not capture cross‑flow moisture exchange or deposition within the cross‑flow heat exchanger. Surface temperature predictions across different positions showed no large outliers; wall temperatures were generally better reproduced than ceiling or floor temperatures.
The simulation framework also enabled a bio‑hygro‑thermal assessment of mold risk using WUFI® BIO. By selecting the interior surface of a structural cross‑section, the model could evaluate temperature, relative humidity, and water content over time, providing a basis for early detection of condensation and mold growth. Heat flux analysis was performed both in aggregate and per component. Solar gains were incorporated as a radiative contribution to the internal heat load. Time‑resolved heat flux data for the cabin’s test case 6.1 revealed that the main heat losses occurred through ventilation and the window door, while heat gains were dominated by ventilation and solar input during the middle of the simulation period.
Thermal comfort was evaluated with the DressMAN 2.0 tool according to DIN EN ISO 7730 and ISO 14505‑2. Equivalent temperatures at the window and bed positions were largely neutral or slightly cool, with lower leg temperatures indicating cold spots. The window area showed the most pronounced cooling effect in the winter scenario without solar gain, underscoring the importance of winter solar radiation for maintaining user comfort. Overall, the cabin’s operative temperatures were largely governed by the supply air temperature, confirming the critical role of the ATU in achieving desired comfort levels.
Collaboration among partners was essential to the project’s success. Fraunhofer IBP coordinated the research, development, testing, and demonstration activities. The German Aerospace Center (DLR) contributed ecological and social assessments, while the University of Lüneburg supplied data and analytical support. Meyer Werft (MW) provided industrial expertise and a reference cabin for benchmarking. MAC Hamburg assisted with simulation tools and data integration. The project ran through 2023, with the report number PGE‑002/2023 reflecting its completion. Funding was provided by German research agencies, supporting the joint effort to develop a sustainable, low‑energy cabin concept that balances performance, comfort, and environmental responsibility.