Analysis of Thermal Parameters of Hemp Fiber Insulation

Gaujēna, Baiba; Agapovs, Vladislavs; Borodiņecs, Anatolijs; Strelets, Ksenia

doi:10.3390/en13236385

Cited by 25 publications

(16 citation statements)

References 22 publications

(26 reference statements)

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“…Due to the rising energy consumption of buildings (residential/commercial), increased prices of fossil fuels and its effect on global warming, energy saving through the use of thermal insulation is regarded as an effective and efficient method [ 5 , 6 ]. Efficient thermal insulation is a highly relevant topic [ 7 , 8 , 9 ], as highlighted by the fact that in the EU the heating of living space corresponds to the main use of energy in houses (64% of total energy consumption in houses) [ 10 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

Thermophysical Properties of Larch Bark Composite Panels

et al. 2021

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The effects of using 100% larch bark (Larix decidua Mill) as a raw material for composite boards on the thermophysical properties of this innovative material were investigated in this study. Panels made of larch bark with 4–11 mm and 10–30 mm particle size, with ground bark oriented parallel and perpendicular to the panel’s plane at densities varying from 350 to 700 kg/m3 and bonded with urea-formaldehyde adhesive were analyzed for thermal conductivity, thermal resistivity and specific heat capacity. It was determined that there was a highly significant influence of bulk density on the thermal conductivity of all the panels. With an increase in the particle size, both parallel and perpendicular to the panel´s plane direction, the thermal conductivity also increased. The decrease of thermal diffusivity was a consequence of the increasing particle size, mostly in the parallel orientation of the bark particles due to the different pore structures. The specific heat capacity is not statistically significantly dependent on the density, particle size, glue amount and particle orientation.

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Section: Introductionmentioning

confidence: 99%

Thermophysical Properties of Larch Bark Composite Panels

et al. 2021

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“…With the carbon sequestration considered in the calculations, the embodied carbon content of a building construction insulated by natural thermal insulations can achieve negative carbon emissions compared to artificial insulations such as mineral wool, expanded polystyrene, or polyurethane foam. This is possible because cellulose-based insulations′ embodied carbon contents are lower than those of artificial insulations [ 7 ] due to their composition or lower densities. In addition, carbon is locked in the natural insulations for the service life of the building; hence, it is sequestered [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

“…Such materials are, among several other used natural alternatives such as bark, cellulose, hemp, kenaf, flax, feathers, sheep wool, or wood fibers [ 7 , 19 , 20 , 21 ], the natural vegetable fiber-based thermal insulations that are gaining ground in the construction market [ 22 ] because demand for green building materials is rising sharply [ 23 ]. Among natural fibers, one of the most researched materials is the use of straw bales as building materials [ 24 , 25 ] because of their low thermal conductivity and high specific heat capacity, and hence low thermal diffusivity and good thermal insulation capability, especially with fibers randomly oriented and perpendicular to heat flow, and low environmental impact if the straw bale selection used for the straw-based building is suitable [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer in Straw-Based Thermal Insulating Materials

2021

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An analytic-empirical model was developed to describe the heat transfer process in raw straw bulks based on laboratory experiments for calculating the thermal performance of straw-based walls and thermal insulations. During the tests, two different types of straw were investigated. The first was barley, which we used to compose our model and identify the influencing model parameters, and the second was wheat straw, which was used only for validation. Both straws were tested in their raw, natural bulks without any modification except drying. We tested the thermal conductivity of the materials in a bulk density range between 80 and 180 kg/m3 as well as the stem density, material density, cellulose content, and porosity. The proposed model considers the raw straw stems as natural composites that contain different solids and gas phases that are connected in parallel to each other. We identified and separated the following thermal conductivity factors: solid conduction, gas conduction in stem bulks with conduction factors for pore gas, void gas, and gaps among stems, as well as radiation. These factors are affected by the type of straw and their bulk density. Therefore, we introduced empirical flatness and reverse flatness factors to our model, describing the relationship between heat conduction in stems and voids to bulk density using the geometric parameters of undisturbed and compressed stems. After the validation, our model achieved good agreement with the measured thermal conductivities. As an additional outcome of our research, the optimal bulk densities of two different straw types were found to be similar at 120 kg/m3.

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“…Thermal insulation produced from more natural raw materials requires less energy than is produced from artificial raw materials. According to [ 18 ], the thermal conductivity of hemp insulation is comparable with other insulation materials, but the energy consumption required for producing is three times lower than that needed for extruded polystyrene.…”

Section: State-of-artmentioning

confidence: 99%

Assessment of Mechanical and Thermal Properties of Hemp-Lime Mortar

Parcesepe

Masi

Lima³

et al. 2021

Materials

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The use of renewable and natural materials characterized by the low environmental impact is nowadays a key issue for the sustainable development of the construction industry. For this reason, the interest for natural fibers, to be used as reinforcement in composites as an alternative to other fibers, is continuously growing. In this paper, the use of hemp for reinforcing lime mortar used as plaster is considered with a multidisciplinary approach, taking into consideration the structural and thermal performance. Natural fibers have several advantages compared to industrial ones, such as low cost, low environmental impact, biodegradability, renewable nature. Moreover, these can show remarkable mechanical performance in relation to specific weight, and sometimes, as in the case of hemp fibers, these can improve the thermal insulation capacity of the plaster. However, the experimental results on the mechanical features are still lacking, especially to assess their durability, and the variability of thermal parameters with the mechanical characteristics. Therefore, this paper proposes an experimental program, developed at Laboratory of Materials and Structures (LAMAS) of the University of Sannio (Italy), aimed at investigating the main mechanical properties (compression strength, flexural strength) of lime mortar reinforced by hemp fibers and subjected to various environmental exposures and aging processes. The characterization is completed with the measurement for the produced samples of the thermal conductivity by means of the standardized guarded hot plate technique.

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Analysis of Thermal Parameters of Hemp Fiber Insulation

Cited by 25 publications

References 22 publications

Thermophysical Properties of Larch Bark Composite Panels

Thermophysical Properties of Larch Bark Composite Panels

Heat Transfer in Straw-Based Thermal Insulating Materials

Assessment of Mechanical and Thermal Properties of Hemp-Lime Mortar

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