The article describes cardboard as a building material and in the context of sustainability. Paper and cardboard are generally regarded as eco-friendly or ‘green’ materials. However the paper production is energy-intensive therefore the sustainability of cardboard as a building material should be looked upon from different points of view such as embodied energy of the final building element, recyclability and thermal insulation which influences the operational energy of the building. The meaning of the sustainability in the building industry is given at the beginning. Next the information about paper as a building material is provided. The last part of the article consist of comparison of three examples of emergency architecture, where paper and cardboard were used as a main building materials.