The Le’ Colaz system redefines construction and renovation by integrating innovative tools, products, and techniques to enable adaptable, circular, and sustainable building practices. Inspired by “LEGO bricks,” its modular framework combines bio-based and recycled materials with advanced snap-fit components, designed for seamless assembly, disassembly, and reuse. This approach significantly improves the adaptability of buildings and building units to new uses, ensuring optimal utilization of indoor spaces and enhancing living and working conditions. By embedding principles of circular economy and life-cycle optimization, Le’Colaz extends the service life of buildings and increases the reuse and recycling of building elements, reducing waste and resource consumption. The system incorporates two cutting-edge digital platforms: the Internet of Materials Module (IoM²), which uses IoT sensors and digital product passports to monitor component performance, enabling predictive maintenance and informed decisions on reuse or recycling, and the Internet of Building Brain (IoB²), powered by Large Language Models (LLMs), which optimizes renovations, regional component reuse, and compliance with regulatory frameworks. Together, these tools facilitate dynamic adaptations to changing user needs and environmental conditions while promoting best practices for design for adaptability, reuse, and deconstruction. The system’s effectiveness is validated through simulation-based assessments and Living Labs in Athens and Trondheim, demonstrating measurable gains in energy efficiency, circularity, and adaptability. By fostering awareness and innovation in sustainable construction, Le’ Colaz sets a new standard for circular, resource-efficient buildings. Through its modular design, digital intelligence, and life-cycle optimization, it delivers measurable improvements in adaptability and resource efficiency, paving the way for a circular and future-proof built environment.