The Fraunhofer spin-off C3RRO offers web-based apps for energy-efficient building planning, based on a multi-physics simulation model. Building physics calculations on different temporal & spatial scales can evaluate energy needs & certify building components to prevent damage. Cloud-based technology shortens simulation times & allows for collaborative projects. C3RRO’s mission is to contribute to a carbon-free future through energy-efficient buildings that enhance health & well-being.