Temperature and humidity profiles in passive-house building blocks

In recent decades many studies have focused on the thermal performance of massive and lightweight constructions of energy-efficient houses. Surprisingly, temperature and humidity profiles have been addressed relatively rarely, despite the fact that they can influence the living conditions, the lifetime of the construction materials, as well as the energy efficiency of the house and consequently the environment as well. In the present study we compare different lightweight building blocks and the associated temperature and relative-humidity profiles. The studies were performed on residential as well as test passive houses. Small differences in the building blocks were identified as having a large influence on the performance of the building. The structural elements should be placed in such a way as to prevent shear forces due to humidity differences. It has been proven that ventilated wooden facades, in comparison with classical façade plaster, protect the building blocks from high thermal loads. Last but not least, the use of vapor barriers instead of vapor retarders and a lack of moisture-buffering materials led to a higher indoor relative humidity, as well as higher moisture loads on construction that could have an impact on the durability of a building and also on the energy performance of the house.

► Choice of building materials and building blocks influences living conditions.
► Vapor retarders and moisture-buffering materials maintain indoor comfort.
► Building blocks can be designed in a way to prevent large humidity differences.
► Ventilated wooden facades protect building blocks from high thermal loads.