Conference Agenda

Environmental concerns have driven the construction industry toward sustainable insulation materials. Among these, fiber-based solutions using natural fibers like barley and wheat straw are gaining attention due to their availability and good performance provided by their inherent porosity. However, optimizing their thermal performance remains challenging, especially when both material quantity and quality are altered.

Traditionally, bulk density has been the main optimization metric for fiber-based insulation, identifying the point where thermal conductivity is minimized. This study examines whether bulk density remains reliable for treated fibers or if straw content (total straw length per unit volume) is a better alternative.

Comparative experiments were conducted on untreated, unbound, and bound barley and wheat straw. For untreated straw, an optimal bulk density of 120 kg/m³ was identified. Moist heat treatment was then applied, causing mass loss while maintaining volume, reducing fiber density. This modification aimed to increase porosity and decrease pore size, potentially enhancing insulation properties.

Experiments were performed at 120 kg/m³ initial bulk density with straw contents of 92 m (barley) and 84 m (wheat). Each sample underwent three treatment cycles. Thermal conductivity was measured using a transient plane source method (0.015-0.70 W/mK range). Porosity, mass loss, and microscopic structure were also analyzed.

Results showed that moist heat treatment increased porosity, reducing thermal conductivity. However, at constant bulk density, the reduction was smaller than at constant straw content. This discrepancy arises because compressed fibers flatten, shortening heat transfer paths and partially offsetting porosity benefits. In bound composites, the presence of binders further influences thermal properties, enhancing the overall effect of the treatment.

These findings indicate that straw-based insulation can be further optimized. Focusing on straw content rather than bulk density improves thermal performance, making straw insulation more competitive with modern materials. Better efficiency and market viability ensure that straw-based insulation remains a sustainable, effective choice.

The study concludes that for treated fiber-based insulation, straw content may be a better optimization metric than bulk density. Since straw content better reflects treatment-induced structural modifications, future research should consider it for improving insulation performance.

Due to its frequent use, mass production, and low biodegradability, EPS is an ideal material for recycling. A prerequisite for polymer waste recycling is that the resulting recycled product must provide a significant and objectively measurable contribution to the environment, society, and economy.

Although low density is an advantage of EPS, it also raises concerns about the economic viability and justification of recycling due to its potential significant negative environmental impact. As a result, EPS often ends up being landfilled after a single-use application.

Among other things, EPS is used for packaging and transporting various agricultural products. Its lightweight yet durable structure protects the products from impact, moisture, and temperature changes. Due to the large quantities used in agriculture, packaging from agricultural applications was used for the production of the recycled fractions in this study.

An analysis of previous research on EPS recycling has identified inconsistencies in result interpretation. A common finding across studies is the degradation of properties; however, the state of the art research showed that conclusions remain inconclusive. Most relevant studies use bulk density as a reference parameter, providing insight into variations in tested properties.

This paper presents an overview of the mechanical properties of EPS with different proportions of recycled fractions. To emphasize economic justification and environmental sustainability, chemical recycling methods were not considered. The recycled fraction was obtained through mechanical recycling of EPS from two different sources, with each source contributing materials of two different densities. The mechanical properties of products containing recycled fractions of 10%, 15%, 20%, 30%, and 50% were tested and compared to those of a control sample made entirely of virgin expanded polystyrene (0% of recycled fractions).

Additionally, this study also examines the correlation between mechanical properties and apparent density. Given that expanded polystyrene is primarily used as a thermal insulation material in the construction industry, the study also evaluates the recycled EPS mechanical properties with accepted standard criteria for EPS applied in the construction industry.

The aim of this paper is to provide insights into the mechanical properties of recycled EPS based on a relevant number of samples, highlight gaps in current knowledge, and encourage further research in the field of EPS recycling and its future applications. It will be shown in this research that there is the feasibility of use of recycled EPS for application in the construction industry.

The study aimed to analyze the basic properties of polystyrene thermal insulation products made from recycled materials, with the help of laboratory tests. In addition to the heat conduction property, tests were performed based on the compressive force, water absorption and dimensional stability parameters for 10% compression. The utilization of secondary raw materials recycled from demolition and construction waste in the circular economy can be fully realized if the products' basic properties meet the minimum requirements prescribed by the relevant product standards. Based on the results, it is possible to set further directions for product development.

The search for environmentally friendly insulation materials is a paramount issue in green buildings. This work examined organic materials of marine origin (algae and plants), including Sargassum and Posidonia oceanica, for their high acoustic performance and low environment impact, being naturally abundant organic raw materials and, in most cases, a waste product. Storms hit the beaches, dropping these seaweeds creating accumulations, which are regularly removed and thrown into dumpsters.

The reason for the interest in these materials is their fibrous and highly porous nature, through which sound can be effectively lowered in intensity. The sound absorption coefficients have been measured in lab tests and vary with density: for Posidonia oceanica (with an average density of 120 kg/m³), the sound absorption coefficients vary between 0.7 and 0.9, and for Sargassum (with an average density of 150 kg/m³), between 0.6 and 0.8, depending on the frequency and sample thickness, respectively.

In addition to the acoustic performance, these materials show a rather good thermal insulation. Thermal conductance under the equivalent density conditions considered for the sound analysis was determined by means of the Hot Disk technique. For a density of 120 kg/m³, a thermal conductivity value of 0.051 W/mK was determined for Posidonia oceanica and 0.050 W/mK for Sargassum at a density of 150 kg/m³. These results show that, even with different filamentous structure, both species are characterised by equivalent thermal performance, with minimal variation in density and material composition.

The observations verify that Sargassum and Posidonia oceanica can be a viable alternative to conventional insulation materials, both for high thermal-acoustic performance and ecological sustainability. The optimal density of the samples plays a key role in balancing thermal insulation and sound absorption, opening new pathways to the use of zero-impact raw materials in buildings.

Fibrous insulating materials represent a relatively specific group of materials whose structure is often very difficult to define. From the point of view of reaction to fire and combustion, these materials are mostly described from a macroscopic point of view and evaluated on the basis of standard tests carried out to determine reaction to fire in accordance with EN 13501-1 and related test standards. However, the research work carried out at Brno University of Technology seeks to describe the combustion of these materials from a different perspective at the microscopic level and to use some principles from the field of building physics to describe the heat process in more depth and to parameterise it by key properties of the fibrous material, so that the fire response of these types of composites can be estimated at the design stage and better optimised when developing them. This paper describes the initial phase of the research work, the formulation of the basic models and the initial results of the experimental tests.

New Zealand's housing crisis has worsened issues like affordability, high energy use, and poor living conditions. Many homes in the country struggle with inadequate insulation, making them cold and damp, which has significantly increased energy consumption in the residential sector. Recent studies emphasise the significance of materials exhibiting low thermal conductivity, such as FRP, for enhancing energy performance and occupant comfort. FRP panels exhibit low thermal mass while providing high thermal regulation and significant load-bearing capacity. While there is extensive research on the thermal performance of materials like timber and steel, there is a lack of information about how FRP wall panels perform in New Zealand’s climate, which presents a significant gap in building design and energy efficiency strategies. This research focuses on evaluating the thermal transmittance of a novel FRP wall panel system in residential buildings. Each panel has three cavities separated by the stiffeners, where the cavities are filled with insulation, letting a moderate air gap for thermal regulations and heat storage. This research primarily focuses on examining the gap between the designed performance and the actual performance of the wall panel by using field monitoring to measure heat flux, temperature changes, and thermal transmittance. K-type thermocouples and heat flux plates were installed on northwest external walls. Data were collected through pico loggers and U-value kits between October 2024 and January 2025. The results indicate that the FRP panel system effectively controls heat transfer, with the cavity serving as thermal storage to enhance indoor comfort. The cavity progressively releases the heat it stores into the indoor environment after sunset, which assists in maintaining a stable temperature throughout the night. This mechanism results in indoor air temperatures ranging from 19 to 25 °C for most of the time, reducing the need for heating or cooling. These findings show the potential of FRP panels to improve energy efficiency and reduce energy consumption by enhancing thermal comfort, implying that they could serve as a viable alternative to existing building systems in New Zealand while also contributing to global sustainable building standards.