This document describes a modular and mobile building system. The building modules are designed with modularity and mobility in mind, allowing endless combinations. Each 6x3x3m metal module has a lifetime warranty and can be assembled and separated as needed. Modules connect through various connection types and can be installed manually or by crane at the construction site. The modular design allows the buildings to meet Passivhaus energy efficiency standards with an energy consumption of less than 15 kW/m2/year.