The 6Zs target refers to the concept of a minus carbon and plus energy eco-cycle refugee house. A 37 m2 house was designed and constructed in a participatory manner in the City of Lund, Sweden. The 6Zs include: zero emissions, zero energy, zero waste, zero cost, zero indoor air pollutants and zero impact on the environment after the shelter is demolished. The key idea of this eco-cycle house is to reach net 6Zs during all stages—material extraction, building construction, operation and maintenance—until the shelter’s end of life. The main construction material is plant-based raw fibers (mainly straw and reed), which are available around the building site. This house is designed to accommodate the needs of two adults and one child. It was built with the help of 7 refugees in 11 working days through an experimental participatory urban living lab methodology. The paper discusses the 6Z design concepts and draws conclusions on the preliminary assessment of the house prototype that was built as a proof of concept. The beneficiaries of this project are not restricted to refugees but also include the majority of individuals and families seeking affordable ways of living with a low impact on the environment. The house is designed for the cold Swedish climate, but the design concept and methodological approach can be adjusted to other climates or geographical contexts.