Research was performed into the use of hemp shive as a fast-growing and carbon-storing agricultural waste material in the production of particleboard for the construction industry. Hemp shives were acquired and prepared for board production with the use of milling and sieving to reach two target groups with 0.5 mm to 2 mm and 2 mm to 5.6 mm particle size ranges. The cold pressing method was used to produce hemp boards with Kleiberit urea formaldehyde resin as a binder. The boards were made as 19 mm thick single-layer parts with a density range of 300 ± 30 kg/m3, which qualifies them as low-density boards. Exploratory samples were made using milled hemp fibers with higher density. Additional components such as color pigments and wood finishes were added to test improved features over raw board samples. Tests were performed to determine moisture contents, density range, structural properties, and water absorption amounts. Produced board bending strength reached 2.4 MPa for the coarser particle group and thermal conductivity of 0.057 ± 0.002 W/(mK). The results were compared with existing materials used in the industry or in the development stage to indicate options of developed board applications as indoor insulation material in the construction industry.

Phase change materials (PCMs) are now widely known as potential additives for building insulation materials to provide a thermal mass effect that helps conserve energy and maintain a comfortable indoor temperature. Therefore, the study presented in this paper focuses on an experimental investigation of the specific heat capacity and thermal conductivity of hemp shive mixed with PCMs. Industrially manufactured organic PCM-S50 received from MikroCaps Ltd. (Slovenia) has been used to further enhance respective properties of the product samples. The experimental boards were made from hemp shive by directly mixing 5% encapsulate PCMs into the mass. Cold pressing was used to manufacture the boards with Kleiberit urea formaldehyde resin glue as a binding agent. The experimental boards were made as 25 mm thick single-layer parts with a density of 300 ± 20 kg/m3, which qualify them as low-density boards. By adding nanocapsules during the board manufacturing process, the heat capacity is increased by 62%. Based on the great potential of using latent heat, it becomes a possible solution for the development of new technologies related to the automatic regulation of an indoor microclimate.

<p class="R-AbstractKeywords"><span lang="EN-US">Energy and raw material costs, an increase in environmental pollution, greenhouse gas emissions, global warming, depletion of fossil raw materials stimulate to seek and study alternatives to the synthetic fibers and products made of them for full or partial replacement. Renewable raw materials, including natural fiber sources, are the future of storage resources with a variety of positive effects on both the planet ecosystem and the living and working environment, and the energy consumption of delivering the required functionality. One of the most important energy-saving types is to reduce energy consumption in buildings by insulating them.</span></p><p class="R-AbstractKeywords"><span lang="EN-US">For Latvian conditions suitable crops are historically grown flax and hemp. Within the framework of the studies, hemp stems are being used. Hemp compared with flax, are less suffering from diseases and less damaged by pests, so hemp cultivation is practically free from use of chemical pesticides and herbicides reducing the risk to the ecosystem.</span></p><p class="R-AbstractKeywords"><span lang="EN-US">One of the most frequently mentioned industrial hemp raw materials positive qualities are their very wide use, practically all plant parts can be used in production of different products. This work explores the possibilities and technologies within the Latvian grown hemp stems to work into board materials with insulation capability.</span></p><p class="R-AbstractKeywords"><span lang="EN-US">Hemp fibers/shives mix boards can fulfill the main function of insulation materials, i.e., to reduce the transmission of heat, because they have a porous structure and low density. Material thermal insulation properties affect physical and structural properties of compounds. Cost effective particles board samples from chopped hemp stems with three types of adhesives and different thicknesses were produced and their thermal conductivity evaluated. The technologies applied and test results will be discussed in the paper. </span></p>

Abstract. The initial research describes a new type of fiber boards for the furniture interior design, developed in cooperation with ATB (Leibniz-Institute for Agricultural Engineering) by using a new method of raw materials preparation and specific production technologies of ATB. The main raw materials are aerobically aged hemp stalks. The samples are made of hemp chips with a long preservation time and fastened together with the UF glue. Specimens are 8 mm thick and correspond to a medium-density fiberboard, fitting standard EN622. Due to the fact that nonveneered material can be used only in non-load-bearing constructions, material improving technologies were studied, such as increase of board density, increase of glue percentage, partially substitution of wet-preserved hemp chips with a dry hemp and/or wooden chips to equalize moisture content of obtained mixture. The particular article describes how the new material is veneered with the oak veneer obtaining three-ply composite board with the improved mechanical properties that allows to use these boards in a load-bearing constructions. Tests are performed with the veneered material to determine such parameters as static bending strength (MOR), modulus of elasticity in static bending (MOE), swelling in thickness and hardness.

Over the past few decades, climate change and the search for renewable energy sources have become hot topics within the research community. About 30% of the world's energy consumption is in the heating and cooling sector of residential buildings. Such materials can reduce the temperature variations, leading to an improvement in human comfort and decreasing at the same time the energy consumption of buildings. This paper assesses the integration of a microencapsulated phase change material (PCMs) with organic composite phase change as the core material and melamine-formaldehyde as the shell in hemp shive intended for building indoor wallboard. Paraffin waxes are cost-effective and have moderate thermal energy storage density but low thermal conductivity and, hence, require large surface area. Commercial manufactured organic PCM-S28 with a 25-29°C melting point received from MikroCaps Ltd. (Slovenia) has been used. The experimental boards were made using cold pressing technology and with 10% Kleiberit Urea Formaldehyde resin (UF) glue as a binding agent. The experimental boards were made 25 mm thick with a density of 310 ± 20 kg/m3 that qualify them as low-density boards. By adding 5% nanocapsules during the board manufacturing process, the heat capacity is increased by 28%.