The building sector is one of the largest primary energy-consuming sectors and contributes substantial atmospheric emissions [1A. Kumar, and O. Singh, "Advances in the Building Materials for Thermal Comfort and Energy Saving", Recent Pat. Eng., vol. 7, no. 3, pp. 220-232.
[http://dx.doi.org/10.2174/18722121113076660005] ]. The greenhouse gases in the atmosphere are accelerating the earth’s climate change at an unprecedented rate in history [2W. Hong, Research on Corporate Environmental Responsibility in China, Research on Corporate Environmental Responsibility in China, . [E-book] Available: Bentham eBooks
[http://dx.doi.org/10.2174/97816810864771180101] ]. Greenhouse gas emissions contribute immensely to global warming [3T. Karia, and A.V. Gurumoorthy, "A Review of Progress in Calcium Looping Technology for CO2 Capture from Power and Cement Plants", Recent Innovations in Chemical, vol. 10, no. 2, pp. 74-87.
[http://dx.doi.org/10.2174/2405520410666171003161358] ]. The building and construction sector is responsible for 32% of global energy use and 19% of greenhouse gas emissions [4IPCC, "2014: Contribution of Working Group III to the 5th Assessment Report of the Intergovernmental Panel on Climate Change. 2014. International Energy Agency", Key world energy statistics, .]. For this reason, the production and use of environmental-friendly building materials are becoming more important day by day. In recent years, the use of renewable energy sources and reducing greenhouse gas emissions has become a global goal [5F. Pacheco-Torgal, "Eco-efficient construction and building materials research under the EU Framework Programme Horizon 2020", Constr. Build. Mater., vol. 51, pp. 151-162.
[http://dx.doi.org/10.1016/j.conbuildmat.2013.10.058] ].

Environmental problems such as global warming and climate change affect the design, construction and use principles of buildings. Energy efficiency and green building principles increase the demand for environment-friendly construction methods [6H. Bedlivá, and N. Isaacs, "Hempcrete – An Environmentally Friendly Material?", Adv. Mat. Res., vol. 1041, pp. 83-86.]. On a global priority scale, efforts to mitigate the impacts of climate change have focused on reducing greenhouse gas emissions within the framework of the Kyoto Protocol and Paris Agreement [7T.V. Rasmussen, E.B. Møller, and T.C. Buch-Hansen, "Extensive Renovation of Heritage Buildings - Reduced Energy Consumption and CO Emissions", Open Constr. Build. Technol. J., vol. 9, no. 1, pp. 58-67.
[http://dx.doi.org/10.2174/1874836801509010058] ]. Therefore, it has become increasingly important to consider the life cycle analysis and the total environmental impact of the construction materials in the design of environment-friendly buildings [8A. Piot, T. Béjat, A. Jay, L. Bessette, E. Wurtz, and L. Barnes-Davin, "Study of a hempcrete wall exposed to outdoor climate: Effects of the coating", Constr. Build. Mater., vol. 139, pp. 540-550.
[http://dx.doi.org/10.1016/j.conbuildmat.2016.12.143] ]. Environmental concerns about conservation of natural resources and sustainability have been a significant source of motivation for researchers to work on environment-friendly composite materials which contribute low environmental impact, long-term community benefits as well as profitability [9H.A. Khalil, A. Bhat, and A.I. Yusra, "Green composites from sustainable cellulose nanofibrils: A review", Carbohydr. Polym., vol. 87, no. 2, pp. 963-979.
[http://dx.doi.org/10.1016/j.carbpol.2011.08.078] , 10O. Kayali, M.N. Haque, and J.M. Khatib, "Sustainability and Emerging Concrete Materials and Their Relevance to the Middle East", Open Constr. Build. Technol. J., vol. 2, no. 1, pp. 103-110.
[http://dx.doi.org/10.2174/1874836800802010103] ]. Constructing with sustainable materials reduces the production costs, helps respond to planning policies and preserves our heritage [11T.H. Panzera, "New Trends of Sustainable Materials for Civil Engineering", Open Constr. Build. Technol. J., vol. 10, no. 1, pp. 379-380.
[http://dx.doi.org/10.2174/1874836801610010379] ].

Environment-friendly construction materials and methods satisfied expectations due to their low environmental impacts and renewable resources. Plant-based biomaterials are frequently used in construction due to their thermal, hygrometric and acoustic properties [12S. Amziane, and L. Arnaud, Bio-aggregate-based Building Materials: Applications to Hemp Concretes., ISTE Ltd and John Wiley & Sons, .
[http://dx.doi.org/10.1002/9781118576809] ]. Due to its high insulation and thermal properties, plant-based materials can be used as aggregate in non-structural concrete mixtures [13G. Delannoy, S. Marceau, P. Glé, E. Gourlay, M. Guéguen-Minerbe, D. Diafi, I. Nour, S. Amziane, and F. Farcas, "Aging of hemp shiv used for concrete", Mater. Des., vol. 160, pp. 752-762.
[http://dx.doi.org/10.1016/j.matdes.2018.10.016] ].

Building envelopes influence the hygrothermal behavior, energy efficiency, comfort and indoor air quality in the building. The hygroscopic property depends on the thermal conductivity, heat capacity, absorption curve and vapour permeability of the materials. It has been observed that it is possible to use hygroscopic materials in buildings with low energy [14F. Collet, J. Chamoin, S. Pretot, and C. Lanos, "Comparison of the hygric behaviour of three hemp concretes", Energy Build., vol. 62, pp. 294-303.
[http://dx.doi.org/10.1016/j.enbuild.2013.03.010] ]. Various efforts have been made to examine innovative energy-saving materials that combine appropriate structural performance and thermal insulation properties [15C. Balocco, and G. Petrone, "Efficiency of Different Basic Modelling Approaches to Simulate Moisture Buffering in Building Materials", Open Constr. Build. Technol. J., vol. 10, no. 1, pp. 561-574.
[http://dx.doi.org/10.2174/1874836801610010561] ]. After Künzel's [16M. Künzel Hartwig, Simultaneous heat and moisture transport in building components: one- and two-dimensional calculation using simple parameters., IRB Verlag: Stuttgart, .] study of hygroscopic building materials, many researchers focused on evaluating hygrothermal properties and modelling in hygroscopic porous materials.

Hemp-based concrete called hempcrete is advantageous for the construction sector compared to traditional materials with low environmental impact and high hygroscopic behavior [17F. Collet, S. Pretot, J. Chamoin, and C. Lanos, "Hydric characterization of sprayed hempcrete", Fourth international building physics conference, pp. 15-18.]. Hempcrete provides many significant environmental benefits an amount of CO₂ sequestrated by hemp in its lifespan is much than the production of CO₂ during hempcrete production, transportation and construction phase [18M.P. Boutin, and C. Flamin, Examination of the environmental characteristics of a banked hempcrete wall on a wooden skeleton, by lifecycle analysis: feedback on the LCA experiment from 2005.Bio-aggregate-based Building Materials., John Wiley & Sons, Inc., pp. 289-312.
[http://dx.doi.org/10.1002/9781118576809.ch9] ]. A recent review studied by Ingrao et al. [19C. Ingrao, A.L. Giudice, J. Bacenetti, C. Tricase, G. Dotelli, M. Fiala, V. Siracusa, and C. Mbohwa, "Energy and environmental assessment of industrial hemp for building applications: A review", Renew. Sustain. Energy Rev., vol. 51, pp. 29-42.
[http://dx.doi.org/10.1016/j.rser.2015.06.002] ] concluded that hempcrete is useful with its hygric and thermal properties and also using hempcrete in buildings leads to reduced environmental impacts of the building’s life-cycle. As a result, hempcrete offers both environmental and construction opportunities, which can help to deliver sustainable solutions.

Hemp and hempcrete were used as keywords in the literature search. For this literature review, papers published in the last decade were selected, and a few older studies were included to examine the hempcrete in all aspects. It has been thoroughly researched to investigate the relevance of resources to the subject. Publications such as journals, books, chapters and reports scanned for this review were obtained from Science Direct, Springer Link and Taylor & Francis, etc. databases. To evaluate the literature for relevance, answers to the following questions are needed:

• What is hemp?
• What are the properties of hemp?
• What is hempcrete?
• How is hempcrete produced?
• What are the application areas of hempcrete?
• What are the benefits of hempcrete to the environment?
• What are the physical and mechanical properties of hempcrete?
• What is the cost of hempcrete?

Hemp is a plant with a wide range of uses, a source of fiber, and seed oil used worldwide. Hemp can reach at least 2 meters of height and is a versatile plant especially grown for industrial purposes [19C. Ingrao, A.L. Giudice, J. Bacenetti, C. Tricase, G. Dotelli, M. Fiala, V. Siracusa, and C. Mbohwa, "Energy and environmental assessment of industrial hemp for building applications: A review", Renew. Sustain. Energy Rev., vol. 51, pp. 29-42.
[http://dx.doi.org/10.1016/j.rser.2015.06.002] ]. It has been used in paper, textile and rope making for thousands of years and it is also used in the automotive, furniture and construction industries today [20A. Tewari, "Hemp–A Sustainable Building Material", Journal of Civil Engineering and Environmental Technology, vol. 5, pp. 327-332.]. Archaeological remains found in China revealed that hemp was the first plant to be cultivated between 4000 and 6000 years ago [21N.I. Vavilov, Origin and geography of cultivated plants., Cambridge University Press: Cambridge, .].

Hemp stands out with its wide availability, low irrigation and fertilizing needs. It is also one of the fastest-growing plants in the world; 4 meters of height can be reached in 4 months with minimum fertilization and irrigation [22R. Deitch, Hemp: American history revisited: the plant with a divided history., Algora Pub.: New York, ., 23C. Gross, and P. Walker, "Racking performance of timber studwork and hemp-lime walling", Constr. Build. Mater., vol. 66, pp. 429-435.
[http://dx.doi.org/10.1016/j.conbuildmat.2014.05.054] ]. Hemp can be produced efficiently in any geography with its drought-resistant and very low fertilization demand [24A. Bourdot, T. Moussa, A. Gacoin, C. Maalouf, P. Vazquez, C. Thomachot-Schneider, C. Bliard, A. Merabtine, M. Lachi, O. Douzane, H. Karaky, and G. Polidori, "Characterization of a hemp-based agro-material: Influence of starch ratio and hemp shive size on physical, mechanical, and hygrothermal properties", Energy Build., vol. 153, pp. 501-512.
[http://dx.doi.org/10.1016/j.enbuild.2017.08.022] ]. The hemp plant is resistant even to -6 °C and the best-growing temperature is in the range of 15 °C and 27 °C. While the annual precipitation amount of 200-300 mm is sufficient during the growth phase, hemp production is very efficient in well-drained natural and alkaline soil [25H. Burczyk, L. Grabowska, J. Kołodziej, and M. Strybe, "Industrial Hemp as a Raw Material for Energy Production", J. Ind. Hemp, vol. 13, no. 1, pp. 37-48.
[http://dx.doi.org/10.1080/15377880801898717] , 26J. Fike, "Industrial Hemp: Renewed Opportunities for an Ancient Crop", Crit. Rev. Plant Sci., vol. 35, no. 5-6, pp. 406-424.
[http://dx.doi.org/10.1080/07352689.2016.1257842] ].

Due to its low protein content, it is not consumed by insects and moths; therefore, pesticide use is not required, which is harmful to the environment. Hemp has a woody core surrounded by strong and long fibers, and it is processed to obtain shiv and fiber. Seeds and shiv have commercial value, but the most valuable part of hemp is fiber [27A. Arrigoni, R. Pelosato, and G. Dotelli, "Hempcrete from cradle to grave: the role of carbonatation in the material sustainability", ]. Shiv constitutes 40% to 60% of the weight of the hemp stalk and can be used as an animal bed or as an aggregate in biocomposites [28R.D. Valle-Zermeño, J. Aubert, A. Laborel-Préneron, J. Formosa, and J. Chimenos, "Preliminary study of the mechanical and hygrothermal properties of hemp-magnesium phosphate cements", Constr. Build. Mater., vol. 105, pp. 62-68.
[http://dx.doi.org/10.1016/j.conbuildmat.2015.12.081] ].

The biggest hemp producers in Europe are France, Germany, the UK and the Netherlands, respectively. Production quantities vary depending on the supply but differ from year to year. While hemp was produced in an area of 11300 hectares in 2009 in France, this figure decreased to 5400 hectares in 2011 [29" Directorate General for Agriculture and Rural Development of the European Commission, Agriculture in the European Union – statistical and economic information", Report, .]. China is the biggest hemp producer country in the world. Globally, 52.4% of hemp was produced in Asia, 40.6% in Europe and 7% in America in 2017 on a global scale [30E. Kurtuldu, and Ö.E. İşmal, "Sürdürülebilir Tekstil Üretim Ve Tasarımında Yeniden Değer Kazanan Lif: Kenevir", Süleyman Demirel Üniversitesi Güzel Sanatlar Fakültesi Sanat Dergisi, vol. 24, pp. 694-718.].

Hempcrete is a mixture created with plant-based aggregate called shiv and binder in very variable proportions. The porous structure of hemp shiv provides deforming capacity, sound absorption and hygrothermal transferability [36S. Amziane, and M. Sonebi, "Overview on Biobased Building Material made with plant aggregate", RILEM Tech. Lett., vol. 1, p. 31.
[http://dx.doi.org/10.21809/rilemtechlett.2016.9] ]. Early assumptions were to using cement as a binder, but recent researches are about using other binders such as lime and pozzolana to improve the performance of hempcrete. Hempcrete produced with cement or lime provides much better hygrothermal behavior than conventional concrete depending on component proportions and wall, floor, or roof application [28R.D. Valle-Zermeño, J. Aubert, A. Laborel-Préneron, J. Formosa, and J. Chimenos, "Preliminary study of the mechanical and hygrothermal properties of hemp-magnesium phosphate cements", Constr. Build. Mater., vol. 105, pp. 62-68.
[http://dx.doi.org/10.1016/j.conbuildmat.2015.12.081] ].

The proper mix design of hempcrete differs according to application in the building. A small amount of binder is used for interlocking shivs in roof insulation; however higher amount of binder is required for the wall since higher mechanical properties are expected in the wall. The highest proportion of binder is used to obtain the highest mechanical properties in floor application [37T. Colinart, P. Glouannec, and P. Chauvelon, "Influence of the setting process and the formulation on the drying of hemp concrete", Constr. Build. Mater., vol. 30, pp. 372-380.
[http://dx.doi.org/10.1016/j.conbuildmat.2011.12.030] ].

Similar to conventional concrete, it can be produced in 3 different methods [38R. Bevan, and T. Woolley, Hemp lime construction: a guide to building with hemp lime composites., IHS/BRE Press: Bracknell, Berkshire, UK, .]: producing as prefabricated blocks, moulding in place and spraying. Each method has its advantages and disadvantages. In the on-site moulding method, long drying time is required. The spraying method is a quick method, provides short drying time and lower density. On the other hand, the prefabricated production is the fastest method [39M. Golebiewski, "Hemp-Lime Composites in Architectural Design", Kwartalnik Naukowy Uczelni Vistula, vol. 4, pp. 162-171.].

Remarkable physical properties are explained by the unique variable-sized pores of hempcrete, micropores in the shives, mesopores formed by the air inside the mixture matrix and macropores between the shives in the matrix [40P. Faure, U. Peter, D. Lesueur, and P. Coussot, "Water transfers within Hemp Lime Concrete followed by NMR", Cement Concr. Res., vol. 42, no. 11, pp. 1468-1474.
[http://dx.doi.org/10.1016/j.cemconres.2012.07.007] ]. The presence of macro and mesopores is associated with the low compaction ability and the difficulty of compressing shiv with a density of 50 to 100 kgm^-3 [41S. Elfordy, F. Lucas, F. Tancret, Y. Scudeller, and L. Goudet, "Mechanical and thermal properties of lime and hemp concrete (‘hempcrete’) manufactured by a projection process", Constr. Build. Mater., vol. 22, no. 10, pp. 2116-2123.
[http://dx.doi.org/10.1016/j.conbuildmat.2007.07.016] ]. The porosity ratio of hempcrete is considered to be approximately 80% [42C. Lanos, F. Collet, G. Lenain, and Y. Hustache, Formulation and implementation.Bio aggregate based Building Materials., John Wiley and Sons publisher, pp. 117-152.
[http://dx.doi.org/10.1002/9781118576809.ch4] ]. The chemical properties of hemp are presented in Table 1 [43D. Sedan, C. Pagnoux, A. Smith, and T. Chotard, "Mechanical properties of hemp fibre reinforced cement: Influence of the fibre/matrix interaction", J. Eur. Ceram. Soc., vol. 28, no. 1, pp. 183-192.
[http://dx.doi.org/10.1016/j.jeurceramsoc.2007.05.019] ].

Table 1
Chemical properties of hemp [43D. Sedan, C. Pagnoux, A. Smith, and T. Chotard, "Mechanical properties of hemp fibre reinforced cement: Influence of the fibre/matrix interaction", J. Eur. Ceram. Soc., vol. 28, no. 1, pp. 183-192.
[http://dx.doi.org/10.1016/j.jeurceramsoc.2007.05.019] ].

Despite its insulation and hygroscopic advantages, hempcrete has high water absorption as a disadvantage. The use of excessive water in the mixture extends the hardening and drying time, which is not suitable in modern constructions. Moreover, its highly porous structure and strong capillarity effect absorb water up to 5 times its weight. Excessive use of water increases the drying time up to several months, but it is not an acceptable time on an industrial scale [44B. Seng, C. Magniont, and S. Lorente, "Characterization of a precast hemp concrete block. Part II: Hygric properties", J. Build. Eng., vol. 24, .100579
[http://dx.doi.org/10.1016/j.jobe.2018.09.007] ]. Considering that there is water exchange between the shiv and the paste, therefore, it is not possible to optimize the mixing water [40P. Faure, U. Peter, D. Lesueur, and P. Coussot, "Water transfers within Hemp Lime Concrete followed by NMR", Cement Concr. Res., vol. 42, no. 11, pp. 1468-1474.
[http://dx.doi.org/10.1016/j.cemconres.2012.07.007] ].

In the experimental studies conducted, the density of hempcrete was obtained between 300 and 600 kgm^-3 depending on the mixing proportions. Hempcrete, which has the lowest porosity rate of 65% [45S. Allin, Building with Hemp., SEED Press: Kenmare, .], has a thermal conductivity of 0.07 to 0.2 Wm^-1K^-1 at 23 ° C, 50% relative humidity (RH) [46F. Collet, Caractérisation hydrique et thermique de matériaux de Génie Civil à faibles impacts environnementaux, .]. The acoustic absorption coefficient was obtained from 0.5 to 0.9 [47V. Cerezo, Propriétés mécaniques, thermiques et acoustiques d’un matériau à base de particules végétales: approche expérimentale et modélisation théorique, .].

4.1. Physical and Mechanical Properties

The physical properties of hempcrete are relatively low thermal conductivity, medium-low density, very high specific heat, strong thermal insulation and thermal mass, which provide building comfort and prevent sudden heat changes [48R. Walker, and S. Pavia, "Moisture transfer and thermal properties of hemp-lime concretes", Constr. Build. Mater., vol. 64, pp. 270-276.
[http://dx.doi.org/10.1016/j.conbuildmat.2014.04.081] , 49A. Shea, M. Lawrence, and P. Walker, "Hygrothermal performance of an experimental hemp–lime building", Constr. Build. Mater., vol. 36, pp. 270-275.
[http://dx.doi.org/10.1016/j.conbuildmat.2012.04.123] ]. The lack of a heat bridge and airtightness prevents heat losses. The hygroscopic feature that provides vapor permeability to the material ensures that the humidity in the building is in the comfort of microclimate [50A. Evrard, "Sorption behaviour of Lime-Hemp Concrete and its relation to indoor comfort and energy demand", ]. Various parameters affect the mechanical properties such as binder type, curing conditions, production method and moulding [51C. Niyigena, S. Amziane, A. Chateauneuf, L. Arnaud, L. Bessette, F. Collet, C. Lanos, G. Escadeillas, M. Lawrence, C. Magniont, S. Marceau, S. Pavia, U. Peter, V. Picandet, M. Sonebi, and P. Walker, "Variability of the mechanical properties of hemp concrete", Materials Today Communications, vol. 7, pp. 122-133.
[http://dx.doi.org/10.1016/j.mtcomm.2016.03.003] ]. Binder type, shiv/binder ratio (S/B), water/binder ratio (W/B) curing conditions, physical and mechanical results of experimental studies of hempcrete are presented in Table 2. These experimental studies have been selected because they conducted with different binders, different shiv ratios and different cure conditions to be able to see the various properties of hempcrete.

Table 2
Binder type, S/B, W/B, curing conditions, physical and mechanical results.

4.1.1. Hygric Property and Heat Conductivity

The energy efficiency of buildings depends on the hygrothermal behavior of the materials used in the building envelope. Despite its low mechanical properties, hempcrete is an environmentally-friendly material that provides very good thermal and acoustic properties with high porosity and low density [53S.C. Some, A.B. Fraj, A. Pavoine, and M.H. Chehade, "Modeling and experimental characterization of effective transverse thermal properties of hemp insulation concrete", Constr. Build. Mater., vol. 189, pp. 384-396.
[http://dx.doi.org/10.1016/j.conbuildmat.2018.08.210] ]. Good thermal and hygric properties are attributed to the very high porosity of the shiv aerogel structure [24A. Bourdot, T. Moussa, A. Gacoin, C. Maalouf, P. Vazquez, C. Thomachot-Schneider, C. Bliard, A. Merabtine, M. Lachi, O. Douzane, H. Karaky, and G. Polidori, "Characterization of a hemp-based agro-material: Influence of starch ratio and hemp shive size on physical, mechanical, and hygrothermal properties", Energy Build., vol. 153, pp. 501-512.
[http://dx.doi.org/10.1016/j.enbuild.2017.08.022] ]. The high open porosity of hempcrete enables the transfer of thermal mass since pores are interconnected [59D. Samri, Analyse physique et caractérisation hygrothermique des matériaux de construction: approche expérimentale et modélisation numérique, .].

Evrard and Herde [60A. Evrard, and A. De Herde, "Bioclimatic envelopes made of lime and hemp concrete", Proceeding of CISBAT, pp. 1-6.] reported that the small amount of moisture in hempcrete positively affects the thermal performance of the material and slows down the rapid heat flow when the sudden temperature changes, taking into account a phase change between liquid and vapor. Dhakal et al. [56U. Dhakal, U. Berardi, M. Gorgolewski, and R. Richman, "Hygrothermal performance of hempcrete for Ontario (Canada) buildings", J. Clean. Prod., vol. 142, pp. 3655-3664.
[http://dx.doi.org/10.1016/j.jclepro.2016.10.102] ] determined that hempcrete is able to heat up in a short time because of its high thermal inertia and maintains the temperature for a long time when the ambient temperature decreases. Collet et al. [14F. Collet, J. Chamoin, S. Pretot, and C. Lanos, "Comparison of the hygric behaviour of three hemp concretes", Energy Build., vol. 62, pp. 294-303.
[http://dx.doi.org/10.1016/j.enbuild.2013.03.010] ] stated the hempcrete water vapor permeability of approximately 2.5 × 10−11 kgm-1s-1Pa-1 and moisture buffer value of 2.15 gm-2%RH. Minguela [61A.F. Minguela, "Bio-Composites to Tackle UK Built Environment Carbon Emissions: Comparative Analysis on Load-Bearing Capacity, Hygroscopic and Thermal Performance of Compressed Earth Blocks with Addition of Industrial Hemp Waste", Open Constr. Build. Technol. J., vol. 11, no. 1, pp. 395-412.
[http://dx.doi.org/10.2174/1874836801711010395] ] observed that the thermal conductivity of earth blocks had been largely reduced after the addition of fine hemp shiv. Piot et al. [8A. Piot, T. Béjat, A. Jay, L. Bessette, E. Wurtz, and L. Barnes-Davin, "Study of a hempcrete wall exposed to outdoor climate: Effects of the coating", Constr. Build. Mater., vol. 139, pp. 540-550.
[http://dx.doi.org/10.1016/j.conbuildmat.2016.12.143] ] reported that using a water-absorbing exterior coating or plaster increases the thermal conductivity of the hempcrete wall. Another risk of using a water-absorbent coating is the growth of mold just below the coating.

In the case of pore size and total porosity decrease, the thermal conductivity increases as the density of hempcrete increases. With the increase of density, the heat transfer interface becomes more connected. The moisture trapped in the pores gives the hempcrete thermal mass [62E. Latif, M. Lawrence, A. Shea, and P. Walker, "Moisture buffer potential of experimental wall assemblies incorporating formulated hemp-lime", Build. Environ., vol. 93, pp. 199-209.
[http://dx.doi.org/10.1016/j.buildenv.2015.07.011] ]. Gourlay et al. [63E. Gourlay, P. Glé, S. Marceau, C. Foy, and S. Moscardelli, "Effect of water content on the acoustical and thermal properties of hemp concretes", Constr. Build. Mater., vol. 139, pp. 513-523.
[http://dx.doi.org/10.1016/j.conbuildmat.2016.11.018] ], in the study in which the amount of water examines the effect of thermal and acoustic properties, found that, as the water content increases, the thermal conductivity increases and the acoustic properties remain constant.

4.1.2. Density, Durability and Acoustic Absorption

The density of hempcrete is dependent on the quality and quantity of materials used, shiv size and porosity, and compaction energy [51C. Niyigena, S. Amziane, A. Chateauneuf, L. Arnaud, L. Bessette, F. Collet, C. Lanos, G. Escadeillas, M. Lawrence, C. Magniont, S. Marceau, S. Pavia, U. Peter, V. Picandet, M. Sonebi, and P. Walker, "Variability of the mechanical properties of hemp concrete", Materials Today Communications, vol. 7, pp. 122-133.
[http://dx.doi.org/10.1016/j.mtcomm.2016.03.003] ]. In the wall applications, the density of hempcrete can be found between 400 and 500 kgm^-3 by on-site pouring method, while the density of hempcrete can be obtained as 200 to 250 kgm^-3 by spray method. It is possible to obtain a density of 600 to 1000 kgm^-3 when a higher proportion of binder is used, while the amount of shiv remains the same [64T-T. Nguyen, V. Picandet, S. Amziane, and C. Baley, "Influence of compactness and hemp hurd characteristics on the mechanical properties of lime and hemp concrete", Eur. J. Environ. Civ. Eng., vol. 13, pp. 1039-1050.
[http://dx.doi.org/10.1080/19648189.2009.9693171] ]. Ohmura et al. [65T. Ohmura, M. Tsuboi, and T. Tomimura, "Estimation of the Mean Thermal Conductivity of Anisotropic Materials", Int. J. Thermophys., vol. 23, pp. 843-853.
[http://dx.doi.org/10.1023/A:1015423708823] ] reported that hempcrete has better strength and high density with good compaction.

Hempcrete produced using lime binder undergoes carbonization for several years due to its lime content and transforms into limestone and gives strength to the structure and micro bonds in the structure matrix. This strength gain over the years shows the increasing durability over time [66T. Jami, S. Karade, and L.P. Singh, "Hemp Concrete – A Traditional and Novel Green Building Material", International Conference on Advances in Construction Materials and Structures, pp. 1-8.].

Open porosity provides high permeability and acoustic absorption [67P. Glé, E. Gourdon, and L. Arnaud, "Acoustical properties of materials made of vegetable particles with several scales of porosity", Appl. Acoust., vol. 72, no. 5, pp. 249-259.
[http://dx.doi.org/10.1016/j.apacoust.2010.11.003] ]. Kinnane et al. [68O. Kinnane, A. Reilly, J. Grimes, S. Pavia, and R. Walker, "Acoustic absorption of hemp-lime construction", Constr. Build. Mater., vol. 122, pp. 674-682.
[http://dx.doi.org/10.1016/j.conbuildmat.2016.06.106] ] concluded that hempcrete has better sound absorption properties than conventional concrete, and physical parameters such as porosity ratio and density do not affect acoustic absorption. In addition, hempcrete using a lime binder has been found to have better acoustic absorption than hempcrete produced using Portland cement.

4.1.3. Mechanical Properties

Amziane and Arnaud [12S. Amziane, and L. Arnaud, Bio-aggregate-based Building Materials: Applications to Hemp Concretes., ISTE Ltd and John Wiley & Sons, .
[http://dx.doi.org/10.1002/9781118576809] ] reported that hempcrete produced with low dose binder shows very weak mechanical properties and deformation is very high. The mechanical performance of hempcrete, produced with a high dose of binder, increases and tends towards the performance of the binder.

Bourdot et al. [24A. Bourdot, T. Moussa, A. Gacoin, C. Maalouf, P. Vazquez, C. Thomachot-Schneider, C. Bliard, A. Merabtine, M. Lachi, O. Douzane, H. Karaky, and G. Polidori, "Characterization of a hemp-based agro-material: Influence of starch ratio and hemp shive size on physical, mechanical, and hygrothermal properties", Energy Build., vol. 153, pp. 501-512.
[http://dx.doi.org/10.1016/j.enbuild.2017.08.022] ] investigated the effect of hemp shiv size on mechanical and thermal conductivity; it was obtained that increasing the rate of 0-5 mm shivs from 15% to 30% increased hygroscopic properties while increasing the shiv proportion, decreased mechanical properties. Arnaud and Gourlay [52L. Arnaud, and E. Gourlay, "Experimental study of parameters influencing mechanical properties of hemp concretes", Constr. Build. Mater., vol. 28, no. 1, pp. 50-56.
[http://dx.doi.org/10.1016/j.conbuildmat.2011.07.052] ] found that the curing conditions, the water used, the type of binder, the length and width of the shiv affect the compressive strength of hempcrete.

4.1.4. Cost and Benefit Performance

The cost of hemp varies depending on the country to be used. Due to low bulk density, hempcrete has high transport and high storage costs. For example, hemp shiv was imported from the Netherlands, for the hemp house to be built in New Zealand with high transport costs [6H. Bedlivá, and N. Isaacs, "Hempcrete – An Environmentally Friendly Material?", Adv. Mat. Res., vol. 1041, pp. 83-86.].

The cost per square meter of a house built with traditional materials in the UK is £ 478, while a hemp house has a cost per square meter of £ 526. The cost of the hemp wall is £ 194 per square meter [69T. Yates, Final report on the construction of the hemp houses at Haverhill, SuffolkBuilding Research Establishment, Watford, report, pp. 209-717.]. Hemp wall is 64% more costly than walls made with traditional materials [70B. Yassine, K. Ghali, N. Ghaddar, G. Chehab, and I. Srour, "Effectiveness of the earth tube heat exchanger system coupled to a space model in achieving thermal comfort in rural areas", Int. J. Sustain. Energy, vol. 33, no. 3, pp. 567-586.
[http://dx.doi.org/10.1080/14786451.2012.762776] ]. To compare, the hempcrete market in France has grown by 400% in the past 10 years [71R. Rhydwen, Building with Hemp and Lime..https://www.votehemp.com/wp-content/uploads/2018/09/building_with_hemp_and_lime.pdf], where French farmers sell hemp shiv €80 per tons [72P. Bouloc, S. Allegret, L. Arnaud, D.P. West, and G. Cousquer, Hemp industrial production and uses., CABI: Wallingford, .
[http://dx.doi.org/10.1079/9781845937935.0000] ].

On the other hand, advanced building envelopes reduce the use of heating and cooling systems and reduce annual energy costs by reducing energy needs [73L.D.D. Harvey, "Reducing energy use in the buildings sector: measures, costs, and examples", Energy Efficiency, vol. 2, no. 2, pp. 139-163.
[http://dx.doi.org/10.1007/s12053-009-9041-2] ]. Using hygroscopic materials as building envelopes reduces the use of heating systems by 7 to 8% and cooling systems by 10 to 30%. Moisture buffering property and high thermal inertia of hempcrete provides at least 10% total energy saving, which reduced energy costs [74M. Leskard, "A sustainable storage solution for the Science Museum Group", Science Museum Group Journal, vol. 4, no. 4, .-76O. Kinnane, G. McGranaghan, R. Walker, S. Pavia, G. Byrne, and A. Robinson, "Experimental investigation of thermal inertia properties in hemp-lime concrete walls", Proceedings of the 10th Conference on Advanced Building Skins, Economic Forum, pp. 942-949.].

4.1.5. Life Cycle Assessment

Environmental assessment has been a core task for construction projects due to the rising recognition of environmental sustainability [77P. Wu, J. Wang, W. Shou, and X. Wang, "“BIM-Integrated Life Cycle Assessment in Environmental Analysis – Current Status and Future Development” ", Integrated Building Information Modelling, Bentham Science Publishers, pp. 224-239. [E-book] Available: Bentham eBooks]. Life cycle assessment is a scientific assessment method to promote recourse saving and environmental protecting behavior [78J. Shi, Z. Liu, H. Zhang, Q. Jiang, and T. Li, "Life Cycle Assessment: State of the Art and Future Perspectives", Recent Pat. Mech. Eng., vol. 8, no. 3, pp. 211-221.
[http://dx.doi.org/10.2174/2212797608666150729231737] ]. The environmental impact of construction materials extends from the extraction of its raw materials to the management of the waste generated by its demolition [79M.V. Montes-Delgado, D. Monterde Pereira, and P. Villoria Sáez, "Approach to the Use of Global Indicators for the Assessment of the Environmental Level of Construction Products", Open Constr. Build. Technol. J., vol. 5, no. 1, pp. 141-148.
[http://dx.doi.org/10.2174/1874836801105010141] ]. According to the life cycle analysis, which is a method of evaluating the effects associated with the use of resources and all the effects of hempcrete on the environment, from the extraction of resources to the production of materials by measuring and evaluating, the lime binder used hempcrete has a beneficial effect on the environment [80B. Guinée Jeroen, Handbook on life cycle assessment: operational guide to the ISO standards., Kluwer: Dordrecht, ., 81S. Pretot, F. Collet, and C. Garnier, "Life cycle assessment of a hemp concrete wall: Impact of thickness and coating", Build. Environ., vol. 72, pp. 223-231.
[http://dx.doi.org/10.1016/j.buildenv.2013.11.010] ]. The use of hempcrete ensures that the energy used in buildings is reduced by 12-17%. In addition, the production and use of the lime hempcrete wall have a reverse effect on climate change; as the thickness of the lime hempcrete wall increases, the reverse effect on climate change increases [82A. Arizzi, G. Cultrone, M. Brümmer, and H. Viles, "A chemical, morphological and mineralogical study on the interaction between hemp hurds and aerial and natural hydraulic lime particles: Implications for mortar manufacturing", Constr. Build. Mater., vol. 75, pp. 375-384.
[http://dx.doi.org/10.1016/j.conbuildmat.2014.11.026] ].

The use of hemp in construction is promising to radically reduce the carbon footprint of buildings [83F. Pittau, F. Krause, G. Lumia, and G. Habert, "Fast-growing bio-based materials as an opportunity for storing carbon in exterior walls", Build. Environ., vol. 129, pp. 117-129.
[http://dx.doi.org/10.1016/j.buildenv.2017.12.006] ]. Approximately 1.8 tons of CO₂ are sequestrated for 1 ton of shiv used [84N. Cherrett, Ecological footprint and water analysis of cotton, hemp and polyester., Stockholm Environmental Institute: Stockholm, .]. Approximately 1000 liters of shiv is used for one cubic meter of hempcrete and approximately 180 kg of CO₂ is locked on the 1m³ hempcrete wall. Depending on the CO₂ emitted for the production of binders and the recarbonation of lime, 18 kg CO₂ is sequestrated to one cubic meter of hempcrete [85M. Pervaiz, and M.M. Sain, "Carbon storage potential in natural fiber composites", Resour. Conserv. Recycling, vol. 39, no. 4, pp. 325-340.
[http://dx.doi.org/10.1016/S0921-3449(02)00173-8] ].

Considering the results in this study, hempcrete has not only a positive influence on the environment, global warming and climate change; it also provides comfort in the buildings. Excellent hygrometric behavior leads to indoor air quality and a comfortable indoor microclimate at the same time. Hempcrete exhibits low thermal conductivity, low density, low strength, high absorptivity and high moisture buffer capacity. The increased interest of researchers makes hempcrete more useful by obtaining more practical knowledge.

Hempcrete is ensuring a building envelope, which can be used in the wall, roof and floor. Although the water content in the hempcrete production cannot be standardized, mixture proportions should be calculated properly according to the application area, so as to avoid unexpected results.

Hempcrete production and use were inadequate until now in Turkey. Regulations should be created to promote hempcrete use in the buildings and contractors should be encouraged. Hemp plant, which has a lot of industrial use areas, will contribute to the production of new products and new technological developments.

Hemp is a suitable plant for growing in environments other than extreme desert climates and high mountain regions. The best growing conditions for hemp, however, are warm-weather areas with well-drained soil rich in organic material. Therefore, hemp agriculture should be expanded. Therefore, hemp plants can be cultivated in wide geography of the world.

Regulations should be created to promote hempcrete use in the building's construction and contractors should be encouraged. It is to be expected that researches related to hemp will increase in the coming period and used in the development of new products and technologies.