A Discussion on Winter Indoor Hygrothermal Conditions and Hygroscopic Behaviour of Plasters in Southern Europe

Abstract

In Southern European countries, due to the specific climate, economy and culture, a permanent heating practice during winter is not widely adopted. This may have a significant effect on the performance of indoor coating materials, typically tested considering hygrothermal conditions in the range of 33–75% relative humidity (RH) and 20–25 °C, which are common in continuously heated buildings. In this study, the indoor climate of four bedrooms located in Lisbon, Portugal, was monitored under operational conditions. Based on the data monitored in the case studies, characteristic ranges of indoor hygrothermal conditions were defined and compared to those considered in standard test procedures. In addition, numerical simulations were adopted to compare the hygroscopic performance of four plasters under operational conditions observed on-site. Results show that the four rooms, intermittently heated or unheated, do not provide comfort conditions over 50% of the wintertime, with temperatures lower and RH higher than the ones recommended by the standards. The MBVs resulting from simulations (under operational conditions) are qualitatively in agreement with the MBVs obtained under standard testing conditions. Nonetheless, future studies are recommended to evaluate if standard tests are quantitatively representative of the hygroscopic performance of coating materials in the Southern European scenario.

Re-thinking Indoor Humidity Control Strategies: The potential of additive manufacturing with low-carbon, super hygroscopic materials.

“…The use of a 4cm full-volume geopolymer layer leads to a reduction of up to 70% in the discomfort hours and up to 95% in the annual intensity of discomfort. For the same covered areas, a full-volume layer of geopolymer composite offers higher [20], [29], [35], [91], and (e) environmental impact in the materials and components considered in the study. benefits than the 3D-printed tiles.…”

“…Porous, hygroscopic building materials offer a chance for passive regulation of indoor relative humidity, with no need for operational energy. They can absorb moisture from the indoor environment when humidity gets higher, and release it when the air gets drier [20]. This type of behaviour is particularly studied for spaces that are subjected to the effects of intermittent sources of indoor moisture, such as spaces with temporary human occupation e.g., bedrooms, offices and public spaces [21]- [24].…”

“…Figure 2 -Results of Hygrothermal and Environmental analyses on the 3D-printed geopolymer composite, in comparison to earth and limecement plasters: (a) open porosity, dry density, vapour resistance factor, capillary water absorption, thermal conductivity and secific heat capacity, (b) sorption isotherm, (d) MBV of materials considered in the study and of materials in literature[20],[29],[35],[91], and (e) environmental impact in…”

Hygroscopicity and Morphology of Bio-Based Boards—The Influence of the Formulation

“…As hazelnut-shell-based and A. donax-based boards have demonstrated interesting hygroscopic behavior [29,30], which can be useful to passively contribute to indoor comfort [50], reducing energy consumption [51], the present study mainly considered this property. The contribution of each material was investigated by testing them individually and in composites.…”