Analysis of the Occurrence of Thermal Bridges in Several Variants of Connections of the Wall and the Ground Floor in Construction Technology with the Use of a Hemp–Lime Composite

Abstract

This article analyses the connection of the two types of floors on the ground (floors on joists and self-supporting floors), with the external wall made of a hemp–lime composite for the occurrence of thermal bridges. Several factors that may affect the heat transfer in the junction were taken into account: the level of the floor on the ground, the wall thickness, the thermal conductivity of the composite, and the location of the timber frame construction. The technology of using hemp and lime is relatively new, and there is a lack of such analyses in the literature. The two-dimensional (2D) heat-transfer in the described construction joints was analyzed based on the finite-element method with the use of the THERM 7.4 software. The results were presented as averaged and linear thermal transmittance coefficients dependent on the above mentioned factors. The possibility of surface condensation was also checked. The differences in the values of the thermal transmittance of the junction between the two variants of ground floors reached around 0.13%–1.67% and the values of linear thermal transmittance factor reached approximately 2.43%–10.13%. The junctions with the highest floor level showed a decrease in the thermal transmittance value by about 3.00%–5.77% and in the linear thermal transmittance, by about 21.98%–53.83%, compared to the junctions with the lowest floor level. Calculations showed that almost all analyzed junctions are free from surface condensation causing mould growth, because the minimum temperature factors f0.25 were higher than 0.78 (except for junctions with the lowered floor levels). The junction with a floor on the timber joists showed better thermal parameters than the junction with a self-supporting floor in each of the analyzed variants. By increasing the level of floor insulation, it is possible to limit the thermal bridges and improve the thermal properties of the junction.

Influence of Hemp Shives Size on Hygro-Thermal and Mechanical Properties of a Hemp-Lime Composite

“…Hemp dusty fractions and dust originating from the ground, due to the larger specific surface area compared to the recommended shives fractions, increase the demand for water and binder during the preparation of the composite mix. The consequence of using a larger amount of binder is, therefore, an increase in the value of the composite thermal conductivity [1,15]. There is a risk that the dusty fractions absorb water that is needed for the crystallization process of the lime particles or the hydration process of the hydraulic components of the binder.…”

The Heat Conductivity Properties of Hemp–Lime Composite Material Used in Single-Family Buildings

“…Note that the literature related to hemp-lime composites discusses a lot of other important properties of the material. The compressive strength is one of the more common tests performed, as we can see by the number of papers by Cazacu et al [32], Kremensas et al [33], Brzyski et al [22,34], or Li et al [35]. As we can see from the information presented in these papers, the compressive strength results obtained in those researches have different values, which vary up to 20% in some cases depending on the mixture type.…”

Wettability of Asphalt Concrete with Natural and Recycled Aggregates from Sanitary Ceramics

“…Depending on the properties that characterize them, the obtained products can be used as additives in building materials, mainly in composites. The waste aggregates from agricultural production are a good example, which may be used as fillers in cement–lime composites, improving the thermal insulation of building barriers [ 10 ]. Waste processing is highly important [ 11 ]; therefore, the ongoing research aimed at optimizing the recycling process and improving its efficiency is mainly focused on the possibility of reusing the greatest possible amount of wastes, the production, transport, storage, and disposal of which are significant issues [ 12 , 13 , 14 , 15 , 16 ].…”