Designing of the module envelope of a hybrid modular building to meet the passive house standards in Luxembourg

To face the challenges of climate change, new buildings need to be further greener while being able to ensure a minimum comfort to the tenants. Nonetheless, extensibility and flexibility could be added to buildings. In this context, the architect jointly with the team of this research project have designed a hybrid modular construction called “slab building” which is composed of a permanent concrete structure and several removable wooden modules. A module offers 27m² of living space but larger housings can be realized by combining two up to four modules. The aim of this paper is to design the walls of the modules to meet the criteria of nZEB. The thicknesses of the studied thermal insulations, namely rock wool, wood wool, polyurethane and aerogel, have been determined in accordance with the passive house requirements in Luxembourg. The embodied energy of the building materials has also been considered in the designing of the modules. Steady state calculations revealed that a wall thickness of 40 cm, comprising 31cm of insulation is sufficient but according to the LCA outcomes, there is no environmental benefit in having the modules comply with the AAA energy class requirements at reasonable wall thicknesses.