11:30am - 11:45am
Hygric Performance of New Building Components for Vertical Green Gardens
České vysoké učení technické v Praze, Czech Republic
The newly developed box-like panel lightweight element for vertical greenery was designed and built at University Centre for Energy Efficient Buildings of the Czech Technical University in 2020. A test site for testing green facade components is operated since spring 2021. Test samples differ in shape, arrangement of functional layers, water distribution means and irrigation patterns. The article presents and discusses measured data at selected test samples during growing season in year 2021. Physical quantities, such as surface temperature of plants, moisture content and matric potential of growing substrate, water inflow and outflow, and ambient boundary conditions, were recorded.
11:45am - 12:00pm
Mold Growth on Spruce and Pine Samples in Steady State Conditions - Time for the First Signs and Maximum Coverage
1Czech Technical University in Prague, Faculty of Civil Engineering, Department of Building Structures; 2University Centre for Energy Efficient Buildings, Třinecká 1024, 273 43 Buštěhrad, Czech Republic
ood is a material that is environmentally friendly and has minimal carbon impact. The durability of wood depends on ambient environmental conditions. This article deals with mold growth on wood samples under constant relative humidity (75 %; 87 %; 95 % RH) and temperature (23 °C). Pine and spruce samples with surfaces oriented along the three principal anatomical directions of wood were prepared. The occurrence of mold was studied by regular microscopic observations. The mold consortium was a mixture of Penicillium sp., Aspergillus sp., and Alternaria sp.
The first signs of mold growth on pine were observed after 7 days for 87 % RH and 12 days for 95 % RH, regardless the surface orientation. Molds on spruce began to grow in 12 to 26 days at 95 % RH in dependence on surface orientation: at first on tangential surface, then on transversal surface, and finally on radial surface. The lower relative humidity of 87 % resulted in a shorter germination time: 7 days for tangential and radial surfaces, and 21 days for transversal surface.
12:00pm - 12:15pm
Analyses of the Geometrical Properties of Fine Recycled Aggregates
KU Leuven campus Bruges, Belgium
The acquisition of fine natural aggregates (FNA) for use in cement-based materials on the one hand and the lack of applications for fine recycled aggregates (FRA) on the other hand, are two serious environmental problems that can be solved simultaneously by replacing FNA by FRA. However, the high water absorption and geometrical properties of FRA pose some significant challenges. The geometrical properties of FRA can be quantified based on their flakiness, angularity, surface roughness, aspect ratio, eccentricity, and circularity. Both fine mixed recycled aggregates and fine recycled concrete aggregates were collected from several recycling companies in Belgium to test the variability in geometrical properties. In addition, FRA produced with various crushing methods were compared to assess the influence of the crushing method on the geometrical parameters. Each sample was sieved and subdivided in several fractions to determine and compare the relation between aggregate size and the geometrical properties of FRA. This paper discusses the geometrical properties of several types of FRA using 3D Laser Scanning Microscopy (KEYENCE VK-X1000), Optical Microscopy, the Hausner ratio and the Angle of Repose. All test results were compared with FNA (natural sand) as a reference. The results of this work provide a clear understanding of the extent, influencing factors and variability of the geometrical properties of FRA. The new insights into the properties of FRA set the next step towards a higher sustainable materialmanagement by the use of this secondary raw material in high-end applications.
12:15pm - 12:30pm
The Potential Use of Giant Reed from Portugal as a Thermal Insulation Material
University of Minho, Portugal
The construction sector plays an important role in climate change. Thus, there is a pressing need to construct buildings that reduce heat losses, use natural and local materials, exploit renewable sources and ensure high comfort levels with a minimum environmental impact. Reed, considered carbon-neutral and a carbon dioxide sink material, has been used for centuries for diverse uses. Its properties and high availability made it a popular building material, as seen in Portuguese vernacular architecture. Knowing the properties of the reed is a crucial step to ensure successful heritage conservation, optimising these materials, and developing innovative solutions. This paper studies the potential of using giant reed from different Portuguese regions as a thermal insulation material. Giant reed board prototypes (15 x 15 x 5 cm, about 235 kg/m3) were built. Their thermal performance was tested in a hotbox, according to ASTM C1363 19. The results show that the giant reed harvested on the northern coast of Portugal has better thermal performance than reeds from other regions. However, regardless of the region of the country where the giant reed was harvested, it has a satisfactory thermal resistance (Re ≥ 0.30 (m2.ºC)/W), allowing its use as a thermal insulation material in the buildings.
12:30pm - 12:37pm
Acoustical Aspects of Replacing Traditional Materials in Building Elements with Renewable and Recycled Ones
1University Centre for Energy Efficient Buildings of Czech Technical University in Prague, Czech Republic; 2Faculty of Civil Engineering, Czech Technical University in Prague, Czech Republic
Building elements, especially partitions, floors and external walls significantly affect indoor acoustic comfort. Their ability to reduce noise transmission from neighbouring rooms or from outdoors depends on the element composition and the building materials used. In Central Europe, the heavyweight masonry or concrete walls and slabs are typical elements both for family and residential buildings. However, increasing popularity of lightweight multi-layered structures is noticeable. This creates new opportunities for the gradual replacement of traditional materials with renewable and recycled ones, both for load-bearing components and for fillings and other layers of building elements. This paper introduces such design changes in relation to acoustics, particularly airborne sound insulation. The greatest attention is paid to the replacement of masonry and mineral wool insulation with timber and wood fibres. The overview is supplemented by examples of low-energy house external wall and timber wall with recycled infill whose sound insulation has been determined by measurements in the acoustic laboratory.
12:37pm - 12:44pm
Natural Materials in Building Construction - Annual Evaluation
University of Zilina, Slovak Republic
The construction industry's focus on a low-carbon economy will result in the need for a deeper examination of natural-based building materials. From an environmental point of view, the benefits of these materials are undeniable. However, it is necessary to consider their shortcomings in other areas of design in terms of building thermal engineering. This article observes and evaluates a wall designed for a wooden building with almost zero energy demand in year-round operation and subsequent assessment in confrontation with a different composition, seemingly more advantageous in thermal resistance and humidity regime. These assemblies are under long-term examination within the pavilion research of the KPSU of the University of Žilina in laboratory conditions from the interior side. At the same time, they are exposed to the realistic boundary conditions of the external environment. The paper includes an environmental assessment of two compositions, variating in the used material. The research shows that the wall composition of natural materials is more advantageous from an ecological perspective and can also show favourable effects in terms of temperature and relative humidity regulation.