No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Structural benefits of hempcrete infill in timber stud walls
Abstract
Hempcrete is a bio-composite mix made up of hemp shives, lime, cement and water. Extensive research has shown that it has good thermal and acoustic insulation properties, and can passively regulate humidity in a built environment. However it has low compressive strength and modulus of elasticity and so cannot be used as a direct load bearing material. It is often used as an infill material in timber stud walls. The objective of this study was to determine if the hempcrete infill has sufficient strength and stiffness to act as lateral bracing and prevent weak-axis buckling of the timber studs.Seven timber walls were constructed (both half scale – 1200 mm high; and full scale - up to 2133 mm high) with varying column dimensions. Five of the walls were infilled with hempcrete of two different densities (313 kg/m3 and 715 kg/m3). Two walls were not infilled and were baseline tests. All walls were tested in compression. It was found that high density hempcrete (715 kg/m3) not only prevents weak-axis buckling of columns but also carries some direct load. Low density hempcrete was also successful in preventing weak-axis buckling of the infilled walls. Infilled walls failed in strong-axis buckling at a load twice (for half scale walls with 38 × 89 mm columns) or four times (full scale walls with 38 × 235 mm columns) that of the unfilled walls. An analytical model (based on buckling of a strut on an elastic foundation) was proposed to predict the maximum capacity of hempcrete as a continuous lateral support for a column.
... This, too, has strong negative effects for energy bills. Anyone who lives in a modern home and has observed how easily the room temperature drops when the heating is switched off is frustrated [20] . ...
... The raw material for hempcrete will become more readily available as hemp cultivation spreads around the world and processing plants made easy [20] . If textile manufacturers can shift away from cotton and toward hemp, the hemp market can grow quickly, allowing the price of hemp shiv to remain steady. ...
Concrete one of the important building material and day by day the utilization of concrete increasing to meet the infrastructure development requirement. On one hand it is unavoidable but some alternative to be explored to reduce the global environmental impact caused by the concrete. To overcome this from the last decade the world is looking towards the fact of sustainability due to rapid industrialization. The growth in the construction industry increased the demand of concrete as construction material. This concrete produces significant amount of greenhouse emission in the environment. There is a need to find an alternative solution to minimize the greenhouse emission emitted from the concrete manufacturing plant.
... This, too, has strong negative effects for energy bills. Anyone who lives in a modern home and has observed how easily the room temperature drops when the heating is switched off is frustrated [20] . ...
... The raw material for hempcrete will become more readily available as hemp cultivation spreads around the world and processing plants made easy [20] . If textile manufacturers can shift away from cotton and toward hemp, the hemp market can grow quickly, allowing the price of hemp shiv to remain steady. ...
Construction industry is one of the main sectors contributing for the growth of countries
economy and also it is one of sector releasing huge amount of carbon emission in the
atmosphere. Several measures are taken in this sector by adopting new trends in the construction
industry with respect to the use of evolving material such as low carbon cement, fast setting
concrete, Self-healing concrete and more, has left us with a high need for research in the area of
sustainable materials. As most of the building material used in construction like concrete and
cement are high carbon dioxide emitting material that can be a hazard (in a longer run) to the
environment and people working in such buildings. To overcome this situation an alternative
sustainable material has to be used for the construction of eco-friendly buildings. Hempcrete is a
bio-composite material and also it is one of the prospective materials to reduce greenhouse gas
emissions. It can be used in Construction and Insulation activities by Hemp hurds and lime.
Hemp is the fastest growing plant and has one of the strongest plants fibers and due to its fastest
and rapid growing nature it can lock up more carbon in it. This has been used in France since the
1990s for construction of non-weight bearing insulating infill walls. A meter cube of hempcrete
has the capability to absorb 165 kg of carbon dioxide and has excellent fire resistance. Resistance
to crack under movement being the core property of hempcrete makes it most appropriate for use
in earthquake-prone areas. In this research, an initiative was taken up to check the feasibility of
hempcrete as an alternative to conventional concrete. Few feasibility studies were carried to
highlight application and access the properties of the same. The main aim to suggest the
application of hempcrete with admixture like fine aggregate and testing of its strength under
Universal Testing Machine (AIMIL) make. Though, Hempcrete does not have adequate strength
as par with the conventional concrete but can be used for the construction of substructure. It can
be concluded that it can be highly beneficial for non-load bearing structures for its property like
lightweight breathability, energy efficiency etc.
... In view of their properties, it makes sense to consider that plant-based concretes could contribute to the mechanical performance of the structure. In particular, some authors [29][30][31][32] have shown that LHC provides in-plane racking strength to the timber frame. According to Munoz and Pipet [29], the mechanical behaviour of a timber stud frame with LHC infill is enhanced compared to that with diagonal bracing. ...
... An illustration of the racking strength test and failure of timber wall is presented in Fig. 1. Another author [32] has found that hemp concrete prevents weak axis buckling of timber columns by acting as a continuous lateral elastic support. Regarding high density LHC (715 kg m À3 ), it is stated that the latter can add strength to the wall by partly contributing to its load-bearing capacity. ...
... Kenevir çimento yalıtımı çivilerin yüklü koşullar altında bükülmesini veya bükülmesini engellemeye yardımcı olacak yapısal kapasiteye sahiptir. Queen's Üniversitesinde (Kanada) yürütülen test sonuçları, 313 kg/m 3 kenevir dolgulu 610mmX1830mm ahşap dikme duvarın, kenevirin sağladığı destek nedeniyle standart bir dikme duvarın sıkıştırma yüklemesinin 3-4 katını destekleyebileceğini gösterdi(30). ...
Kenevir, insanlar için en önemli ve yararlı bitkilerin başında gelmektedir. İlk önce
Hindistan, Çin ve Orta Asya’da ortaya çıktığı düşünülen kenevirin, ticaret yoluyla
Mezopotamya, Mısır ve Anadolu’ya geldiği ve bu coğrafyalardan Avrupa kültürlerine geçtiği anlaşılıyor. Bazı araştırmacılar kenevirin, Neolitik Çağla birlikte insanlar
tarafından kullanıldığını iddia etmişseler de arkeolojik veriler M.Ö. II. binden itibaren
kenevirin insanlar tarafından çeşitli alanlarda kullanılmaya başlandığı kesinlik kazanmıştır.
Erken dönemlerde kenevirin daha çok gıda olarak, sağlık alanında, gemicilikte, tekstilde ve
psikoaktif alanlarda kullanıldığı anlaşılmaktadır. Ortaçağda yoğun kullanılan kenevir sanayi
devriminden sonra çok geniş alanlarda kullanılmaya başlanmıştır. Günümüzde yüksek bir
ekonomik getirisi olan endüstri bitkisi kenevirin, niteliklerinden dolayı bildiğimiz kullanım
alanlarının dışında yeni alanlarda da kullanılmaya elverişli bir bitki olduğu anlaşılmaktadır.
Bu nedenle çok geniş alanlarda kullanılmaya elverişli olan kenevir üretiminin geliştirilmesi
ekonomik olarak sadece ülkemiz için değil bütün dünya için önemli bir katkı olacaktır.
Uygun olan hemen bütün coğrafyalarda yetişebilen ve diğer endüstriyel bitkilere göre daha
az emek gerektiren bir bitki olan kenevirin, uyuşturucu ve bağımlılık yapıcı özelliğinden
dolayı insanlara zarar verebileceğinden, üretiminin kontrollü olması bir gerekliliktir.
... However, those composites cannot be directly used as a structural material, due to its low compressive strength and elastic modulus [5]. It was found that a hempcrete formulations based on hydrated lime, Portland cement, and fly ash had compressive strength well below that of concrete mixtures [21], while the rise in binder percentage and age of the mixes resulted in increasing compressive resistance [22]. It was reported that hempcrete has a resembling-ductile behaviour unlike the sudden brittle failure associated with concrete [23]. ...
The increase in environmental pollution due to large emissions from the cement industry, the need for green materials in construction industry, the increase in the amount of industrial waste that must be recycled for environmental reasons and the need for cost-effective and long-lasting building materials were the reasons to work on hempcrete. Throughout the current work hempcrete mixes are prepared using 25% wt. cement, 75% granulated blast furnace slag as binders and hemp; the natural fiber instead of the expensive synthetic fibers for the purpose of manufacturing cost effective renewable building material. Response Surface Methodology was used as a statistical tool to decrease the number of experiments and raw materials used, and to optimizing and modelling the effect of hemp/binder (0.16-0.44) and alkaline activator/binder ratio (0.41-0.69) on density and compressive strength. The results of the work revealed that the density of hempcrete decreases with increasing hemp/binder ratio and increases with increasing activator/binder ratio. Optimum density 1077.07 kg/m3 was achieved at hemp/binder ratio = 0.16 and activator/binder ratio = 0.65, while optimum compressive strength is estimated at hemp/binder ratio = 0.16 and activator/binder ratio = 0.42. Both compressive strength and density increase steadily with increasing the samples age. However, hempcrete samples cured at dry atmospheric conditions gives a compressive strength comparable with those cured in water but with higher density.
... To minimise CO 2 emissions, new forms of construction materials are emerging that combine natural fibres (biomass) with zero or low emission pozzolans (Walker and Pavia 2011). Lime Hemp Concrete (LHC) and Cement Lime Concrete (CLC) is a construction material and is a carbon-free and environmentally friendly construction material (Mukherjee and MacDougall 2013). In recent years, the use of hemp fibre as a strengthening agent in composite materials has increased in response to the growing need for recyclable, biodegradable and sustainable materials. ...
In today’s world, global warming is at its peak and the materials are being excessively used by the industry leading to an adverse effect on the environment. This made leaders all over the globe to work on halting global warming, and thus invention led to the rehabilitation of building materials made of agro-waste concrete, which has the additional benefits of carbon restoration, renewability and low embedded energy. Concrete mixes consist of agro-wastes, such as rice husk, coconut shell, wheat straw, sugarcane bagasse, maize cob, bamboo leaf, Hemp etc. In India, research on Hemp concrete has not been done so far on large scale therefore this surface new opportunity of different outcome on Hemp concrete. The purpose of this paper is to review the research on finding the self-curing properties (Hygrothermal properties), mechanical properties, and light weight properties of hemp concrete so that it can be used as a construction material, with the goal of recognizing research gaps that will guide the future research into its execution in the rapidly increasing green building industry.
Several gaps were identified in the research regarding the strength, light weight and the self-curing properties of the Hemp concrete. The article closes with a discussion of the direction and necessity of upcoming research to enhance Hemp concrete's manufacturing methods and mechanical performance in order to expand its use in the construction sector.
... The interface between straw fiber and cement in HRCC is improved and the negative effect of hemp straw fiber on hydration reaction is alleviated. [4][5][6] 。秸秆纤 维作为重要的生物质可再生材料 [7][8] ...
... Nevertheless, according to results and perceiving observations from literature, it can be assumed that anisotropic mechanical behaviour applies to other bio-aggregates composites manufactured using external compaction/vibration or projection techniques. Although used as a non-load bearing infilling material, LHCs contribute to the mechanical performance at the structural scale for the in-plane racking resistance [88][89][90][91]. Investigations on the shear strength of LHCs were conducted at the material scale, using an adapted triaxial testing equipment [92] and a special shear box test [72,93]. ...
Bio-based building materials are composites of vegetal particles embedded in an organic or mineral matrix. Their multi-scale porous structure confers to them interesting thermal, hygroscopic and acoustic properties. These performance properties have spurred research on these materials as alternative building materials with low embodied energy. This review contains a comprehensive critical analysis of mechanical, thermal, and acoustic properties of bio-based building materials with a particular focus on the interactions of various constituents and manufacturing parameters. Alkali-activated binders are reviewed for their potential use in high strength bio-based composites. A detailed physico-chemical characterisation of the aggregates and compatibility analysis allow a comprehensive understanding of fundamental phenomena affecting mechanical, thermal, and acoustic properties of bio-based building materials. A wide range of biomass materials is available for building composites, and hemp shives remain the most prevalent bio-aggregate. In the context of England, the farming of industrial hemp remains limited, due in part to the long, costly licencing process and the abandonment of processing subsidy as part of the EU common agricultural policy in 2013. On the other hand, Miscanthus (elephant grass) is a perennial, low-energy, and well-established crop in the England which is gaining interest from farmers in the South West region. Its development aligns with actual agricultural, land management and environmental policies with potential to fuel innovative industrial applications. This review performs a critical assessment of the performance of bio-based materials in an attempt to identify potential frameworks and opportunities to develop building insulating materials from miscanthus.
... The term bio-aggregate concretes refers to the mixture of binders (lime, clay, plaster, and cement) and natural fibers (hemp, straw, flax, bamboo, and animal hairs) [1]. In this context, the use of eco-friendly concrete such as hempcrete [2], wood-concrete [3], papercrete [4], and mud-concrete [5] has been growing considerably. Hempcrete is most widely used in the field of green construction owing to its remarkable environmental quality as a non-CO2 producer [6,7]. ...
Construction materials made of renewable resources have promising potential given their low cost, availability, and environmental friendliness. Although hemp fibers are the most extensively used fiber in the eco-friendly building sector, their unavailability hinders their application in Iraq. This study aimed to overcome the absence of hemp fiber in Iraq and develop a new sustainable construction material, strawcrete, by using wheat straw and traditional lime as the base binder. A comparable method of developing hempcrete was established. The experimental program adopted novel Mixing Sequence Techniques (MSTs), which depended on changing the sequence of mixed material with fixed proportions. The orientation of the applied load and the specimen's aspect ratio were also studied. The mixing proportion was 4:1:1 (fiber/binder/water) by volume. Results showed that the developed strawcrete had a dry unit weight ranging from 645 kg/m3 to 734 kg/m 3 and a compressive strength ranging from 1.8 MPa to 3.8 MPa. The enhanced physical and strength properties varied with the MST and loading orientation. The properties of the developed hempcrete were compared with those of strawcrete.
... Hempcrete insulation possesses the structural capacity to help restrain the studs from bending or buckling under loaded conditions. Results of tests conducted at Queen's University in Canada showed that a 610 mm  1830 mm timber stud wall with 313 kg/m 3 hempcrete infill could support three to four times the compressive loading of a standard stud wall due to the support that hempcrete provides to the timber stud in weak axis bending (Mukherjee and MacDougall, 2013). ...
The growing concerns surrounding the rising carbon emissions have impelled the leaders around the world to make efforts to prevent catastrophic manifestations of climate change and global warming. This has led to the resurrection of vegetal concrete building materials using biomass, which have the added benefits of carbon sequestration apart from low embodied energy and renewability. Vegetal concretes are made up of an organic or inorganic binder, and biomass originating from agro-forestry industries such as rice husk, straw bale, hemp, kenaf, cork, and so on. Hemp concrete, a variety of vegetal concrete has been widely researched and is arguably one of the most researched building materials in current times. This paper presents a review of the state-of-the-art of hemp concrete research, with a view to identifying research gaps that shall guide future research for its implementation in the fast-growing green buildings industry. The reviewed aspects of hemp concrete include properties of hemp relevant to construction, binder characteristics, mechanical properties, durability, hygric and thermal properties, environmental credentials, manufacturing processes, and current applications. Several research gaps with regards to the hydraulicity of the binder, strength and durability, and fire resistance of hemp concrete were identified. It was also established that hemp concrete has very low embodied carbon and embodied energy, making it ideal for green building applications. The paper ends with a discussion outlining the need and direction for future research on improving the manufacturing processes and mechanical performance of hemp concrete for wider adoption by the construction industry.
... Hempcrete is a more elastic material in comparison to traditional building materials and can allow walls to sustain lateral earthquake motion. 28 Hempcrete is a so-called zero carbon material but also acts as a carbon sink for the lifetime of the building, providing an environmentally safe and green home for its dwellers. ...
In April of 2015, a 7.6 magnitude earthquake struck the Kathmandu Valley at the center of Nepal. Within the following year, Kathmandu was struck by a 7.3 magnitude earthquake and multiple aftershocks. The initial earthquake caused the deaths of 8,856 people, injured 22,309, and affected eight million more. Many agencies around the world came together to fund reconstruction efforts as part of Nepal and a Multi-Donor Trust Fund (MDTF). The MDTF conducted an Earthquake Housing Damage and Characteristics Survey (EHDC) which led to the creation of Nepal Rural Housing Reconstruction Program (NRHRP), which sought to reconstruct earthquake-resistant homes. The NRHRP developed a homeowner-driven grant process and established the National Reconstruction Authority (NRA) to distribute housing reconstruction grants to families. Those grants were to be paid out via three tranches, each after the completion of a specific construction phase.
During 2017, an international collaborative effort began among four parties: Hiroshima University (HU); Tribhuvan University (TU); Nepal’s Alternative Energy Promotion Center(AEPC); and the Lyndon B. Johnson School of Public Affairs(LBJ) of the University of Texas at Austin (UT). The team investigated the challenges and opportunities for reconstruction of homes in rural areas damaged by the 2015 earthquake in and around the hinterland of Kathmandu Valley, Nepal. Within the context of a university course, students began by studying alternative building technologies(ABTs) being implemented in Nepal by local nongovernmental organizations(NGOs). When project members visited Nepal in March 2017, they interviewed rural residents to identify barriers to home reconstruction. During a field study, the students also met with local governmental officials and NGO representatives.
This report describes students’ field investigation in Nepal, background research on alternative building technologies (ABTs)for home reconstruction, and recommendations developed from consultation with stakeholders and technical advisors. The first chapter starts with the earthquake and its associated damage and describes the response of the Government of Nepal (GON) and the international community in forming the MDTF, the NRHRP, and the NRA. The second chapter discusses different alternative building technologies (ABTs) considered by the GON, including bamboo, hempcrete, rammed earth, Compressed Stabilized Earth Brick (CSEB), earthbags, and modified conventional housing. Each section describes the type of building style, its construction, materials and labor required, estimates of construction time (if available), costs, and a brief section on comparative advantages and disadvantages.
The third chapter describes the 2017 field study in Nepal, included the locations of the field study and interviews and discussions with local NGOs, the governmental agencies, and local residents. The research group sought to learn whether a lack of affordable and appropriate building methods could explain why many villagers still live in temporary shelters. Village residents discussed barriers to housing reconstruction unrelated to the type of home being built. The final chapter presents conclusions from 2017 field study observations of the three villages. Researchers found four common barriers to reconstruction: the cost of transportation and materials; insufficient reconstruction incentives; grant processes with many procedural barriers to funding; and the need for consistent interaction of the community with governmental agencies. One suggestion is to evaluate the home reconstruction program to assess its procedures and outcomes. A second suggestion is for Nepal to enhance the number and authority of mobile teams of professionals to assist villagers seeking to reconstruct homes.
... walls, failing at more than twice the load as compared to unfilled timber walls (Mukherjee, 2012). ...
With the alarming global increase in carbon emissions and its implications, the need for carbon neutral or carbon negative technologies is of utmost importance and urgency. Cellulose aggregate concrete (CAC) or bio-aggregate concrete has not only the multi-benefits of low density, better thermal insulation and low embodied energy, it can also make use of industrial wastes such as fly ash, slag, etc. One such CAC is called hemp concrete, which is a composite made of hemp shiv and lime based binder. Hemp is one of the world's earliest cultivated crops and has a variety of applications including construction. This paper discusses various properties and applications of hemp and hemp concrete such as mechanical performance and durability, with a focus on its carbon sequestration ability and carbon negativity, and the current research interest as well as its possible contribution towards solution of climate change problems.
... It was found that the addition of hemp fiber resulted in a high performing construction material. [3] But is hemp really an environmentally friendly material? This paper explores answers to this question, using both published literature and on site experience. ...
In the last decade, society has been looking at sustainability of construction. The pressure for improved construction methods also leads to the search for new materials. One possible material with suitable technical properties based on renewable resources is hemp fibre concrete – hempcrete.Hempcrete is a construction material made from hemp fibres, lime and water. This composite breathes, as well as having good thermal and acoustic-insulation properties. The paper provides an overview of international literature and its relevance to New Zealand (where hempcrete has already been used) and the Czech Republic (where the first hempcrete house is under construction).A life cycle analysis of hempcrete will be used to examine its ecological footprint, especially in reducing carbon dioxide emissions. The construction in 2014 of a New Zealand house provides data which can be used to model performance in both countries. The preliminary results suggest that hempcrete offers both environmental and construction opportunities which can help to deliver sustainable housing solutions.
The demand of high quality of strength mingled with the superior standards and durability leads to development of new carbon sequestration panels.[1] It is a comparatively new material and can be treated as a special type of carbon sequestration panels (csp).It differs from normal (csp) in three aspects – the fibre content, lime matrix and method of production[2]. It is made by infiltrating lime slurry into a number of panels preplaced and packed tightly in the moulds since, its possesses tremendous durability, superior heat energy engrossment, adequate stiffness, including numerous extra salutary characteristics, precast vetticrete panels command spacious scope of architectural construction works wherever huge heat energy-based ingredients are wanted[3]. A unique principal goal of this investigation determines how much co,co2 absorbed and how much strength it gains periodically. of slurry infiltrated fibrous pozzolanic lime panels with multi-scale of vetiver fibre. The existing study strives to examine the carbon sequestration behavior from vetticrete panels. The organic additives fibres used for this study is crimped type of different length 0.5cm and 1cm with 8% by volume. Development of ultrahigh strength of more than 100 MPa compressive strength slurry for the preparation of vetticrete panels[4]. The work on this study evaluates the mechanical properties of the vetticrete panels like carbon sequestration, compressive strength, heat proof[5].
To maintain the thermal comfort, buildings consume about 40% of the total energy produced in most of the countries. Thus, they are one of the largest contributors to the global greenhouse gas emissions and the associated climate change. Emissions from the built environment originate from three sub-sources: construction, operation, and demolition. To reduce the embodied energy of construction materials, operation energy of buildings, and energy required to dismantle the buildings at the end of their life cycle, the use of materials made from crop residues and agroforestry wastes seems to be a viable option. Lightweight concrete made of crop residues such as hemp, jute, sisal, flax, nettle, and pigeon pea in the form of aggregates is also called “vegetal concrete.” These aggregates are embedded in a cementitious matrix. Few examples of vegetal concrete are lime hemp concrete, cork-cement composites, lime stabilized straw bale, flax-lime concrete, and cement straw boards/panels. Because of their source, these biomass-based building materials are considered to be carbon negative. In addition, carbon sequestration takes place during various stages of their lifespan. The other advantages with vegetal concretes are their excellent thermal insulation property and a favorable hygrothermal behavior that improves thermal comfort and thereby reduces energy consumption in buildings. This chapter reports the availability and suitability of various crop residues, the types of vegetal concrete being developed, the carbon footprint of vegetal concrete materials, and their impact on energy consumption in buildings throughout the three phases: construction, operation, and demolition. Comparisons with other applications for crop residues are also drawn, and the second-order effects of manufacturing and application of vegetal concrete are discussed in the chapter.
Hemp concrete is obtained from the mix of hemp shiv, water and a mineral binder (which can be itself a mixture of different binders).
In the Climate Change Act of 2008 the UK Government pledged to reduce carbon emissions by 80% by 2050. As one step towards this, regulations are being introduced requiring all new buildings to be ‘zero carbon’ by 2019. These are defined as buildings which emit net zero carbon during their operational lifetime. However, in order to meet the 80% target it is necessary to reduce the carbon emitted during the whole life-cycle of buildings, including that emitted during the manufacture of materials and components, and during the processes of construction, refurbishment and demolition. These elements make up the ‘embodied carbon’ of the building. This paper reviews the existing European and UK standards, methodologies, databases and software tools for the estimation of embodied energy and carbon of buildings.While there is currently no legislation requiring the calculation of embodied energy in buildings, voluntary standards are being developed by the European Committee for Standardisation Technical Committee 350 (CEN/TC 350). Based on BS EN ISO 14040 and BS EN ISO 14044, these define a four stage process-based life cycle assessment method to calculate the embodied energy in construction, with a compulsory ‘product’ stage and optional further stages for ‘construction’, ‘use’ and ‘end of life’. A further voluntary specification for the assessment of the life-cycle greenhouse gas emissions of goods and services, PAS2050, was introduced in the UK in 2008. It too uses a process-based assessment the environmental impact of a building calculated through this method can therefore be seen as the sum of the environmental impacts of the products and processes that have created the building.Other Life Cycle Assessment methodologies have been developed in this area, including input-output (I-O) and hybrids of process and input-output. The environmental impact of a building defined by an input-output based assessment in contrast to that by a process-based method, is seen as a proportion of the total impacts of the different economic sectors which have created the building. The I-O approach therefore inherently assigns responsibility for environmental impacts to a particular industrial sector. Process-based methods are more specific to the construction product, and more accurate within the limited boundaries used. However they omit the supporting services necessary for construction, including finance, insurance, government and organisational administration and all related office buildings. While I-O assessment overcomes the problems with process assessment by considering a complete system boundary, the assumptions of homogeneity and proportionality in particular limit its use for comparison of impacts from individual products. For the purposes of designing a low embodied energy building, the I-O approach is too broad-brushed and generic to be helpful. The hybrid approaches attempt to overcome the limitations of both the process and the I-O methods.There is some existing embodied carbon and embodied energy data. However, due to the lack of current regulations and the inherent complexity and diversity of the area, the available data are varied in scope and application. There are three main sources of data:1. There are several databases which include embodied energy and carbon of standard building materials and components. Some of these are construction sector-specific, while others contain more general product data. These provide data for the ‘cradle to factory gate’ phase of the embodied energy. Manufacturers are also starting to develop their own Environmental Product Declarations (EPDs) which include this data, and several of these are publicly available.2. Both commercial and in-house software tools have been developed to calculate whole life-cycle embodied energy for buildings and infrastructure projects. This is known as ‘cradle to grave’ assessment.3. Detailed life cycle assessments of specific buildings, including housing developments and individual dwellings, have also been carried out by academic researchers.A review of the research literature shows a wide range for the calculated embodied energy. This range in reported figures is due to the use of diverse product data arrived at through different LCA methodologies, different boundaries and often for specific manufacturers, which are therefore non-comparable; different calculation methodologies for the LCA of the whole building; and different building construction and designs. Perhaps most crucially, in spite of the likelihood of an underestimation by current analysis methods, the results show that embodied energy and carbon of buildings can be a very significant absolute value, as well as an increasingly high proportion of the whole life energy and carbon.The existing databases and much of the literature provide data for the product stage (stage 1) of the process – that is for the embodied energy and carbon in the building materials. However there is less, very limited, data available for composite components such as windows, for services components and for innovative materials and products. There is also a particular shortage of data across the construction sector in the energy used and carbon emitted during transport to site (part of stage 1 in prEN 15804), stages 2 (construction), 3 (in use) and 4 (end of life). The commercial and in-house analysis tools also vary in the databases they use, in their LCA methods and in the boundaries assumed in analysis.Taking each of the missing calculations in turn, the calculation of the reduced impacts of transport to site of local construction materials will inform and support the European standard BS EN 15643 parts 3 and 4, which considers the social and economic sustainability of construction works.Some construction projects last for several years and have hundreds of workers on site carrying out energy intensive activities. The accurate prediction of energy use and carbon emissions during standard site operations for stage 2 of the life cycle is therefore a fundamental part of the calculation for whole life embodied energy. Separately the development of off-site construction systems has been heralded as a ‘sustainable’ solution; this can only be verified with the development of an accurate ‘carbon costing’ method for both on-site and off-site construction activities, enabling the accurate comparison of different techniques and materials. Furthermore there is a lack of general data on the carbon and energy savings to be made by site management operations such as reuse of subgrade rather than the import of new materials.While ongoing maintenance and repair can be considered as part of the operational energy requirements, as suggested by the Strategic Forum for Construction (SFfC) [15], the impacts of major retrofit and refurbishment works form part of stage 3 of the whole life embodied impacts of a building. A clear understanding of the service life of individual components is necessary for these to be calculated.Finally there is limited data on the energy used by demolition, reuse and recycling processes at the end of life of a building. While these may be less important for building types with a long expected lifetime such as UK housing, it is a key element of short expected lifespans such as stadia, where design approaches are often required to consider deconstruction and reuse of components.In conclusion, it is essential to measure the whole life embodied energy and carbon of buildings, as well as their operational energy and carbon emissions. The comprehensive development of a robust methodology, and a deeper understanding of its limitations, is a necessary prerequisite for this. Various initiatives to develop and collate data and tools and make them freely available are still in their infancy, and these should be encouraged by the construction industry. It is hoped that the forthcoming standardisation of EPDs should ensure that all manufacturers produce equivalent information for their products within a few years. However the diversity of products used within construction will mean that the LCA of individual buildings will remain complex.This review will guide the future development of a consistent and transparent database and software tool to calculate the embodied energy and carbon of buildings within the specific context of the UK. The research is being carried out as part of a project led by BLP Insurance, and with the support of the Technology Strategy Board and the Engineering and Physical Sciences Research Council (EPSRC).In the Climate Change Act of 2008 the UK Government pledged to reduce carbon emissions by 80% by 2050. As one step towards this, regulations are being introduced requiring all new buildings to be ‘zero carbon’ by 2019. These are defined as buildings which emit net zero carbon during their operational lifetime. However, in order to meet the 80% target it is necessary to reduce the carbon emitted during the whole life-cycle of buildings, including that emitted during the processes of construction. These elements make up the ‘embodied carbon’ of the building. While there are no regulations yet in place to restrict embodied carbon, a number of different approaches have been made. There are several existing databases of embodied carbon and embodied energy. Most provide data for the material extraction and manufacturing only, the ‘cradle to factory gate’ phase. In addition to the databases, various software tools have been developed to calculate embodied energy and carbon of individual buildings. A third source of data comes from the research literature, in which individual life cycle analyses of buildings are reported. This paper provides a comprehensive review, comparing and assessing data sources, boundaries and methodologies. The paper concludes that the wide variations in these aspects produce incomparable results. It highlights the areas where existing data is reliable, and where new data and more precise methods are needed. This comprehensive review will guide the future development of a consistent and transparent database and software tool to calculate the embodied energy and carbon of buildings.
STM International's Subcommittee E06.71 on sustainability, part of Committee E06 on performance of buildings, is responding to a fast-growing market demand for 'green building' and 'sustainable development'. This market interest is expressed in developed as well as developing countries. The three primary considerations for sustainability are environmental, economic and social. The building industry is one of the United States' largest industries and annually it accounts for an estimated 9 million jobs.
The demand of traditional building materials such as straw, hemp, lime, and unfired clay for construction purposes have increased considerably in the UK because of their environment friendly properties. The development of these materials in modern construction processes is being led by the BRE Centre in Innovative Construction Materials at the University of Bath, the UK. Earth building methods such as cob and rammed earth involve low energy costs than wall construction, while straw bales are less expensive and provide high degree of thermal insulation through thick walls. Architects of White Design Associates and Integral Structural Design engineering consultancy have also developed the use of prefabricated modular straw bale (ModCell) panel construction in the UK, which maintains the benefits of straw bales while using the modern construction methods. The use of hemp and hydraulic lime in a composite light-weight material, hemcrete or hemp-lime, also is a unique innovation and has great future potential.
The Haliburton 4C's Food Bank and Thrift Store building, shown in Figure 1, was designed and built in June through August 2005. The structure combines an impressive variety of sustainable design options, while meeting specific functional and financial goals. The vision for the building was for it to serve as a working food bank and thrift store, while being a demonstration of the applicability of various alternative building materials and design options for a public building located in a very traditional neighbourhood. The Haliburton 4C's (Christian Concern Community Centre) is a non-profit, charitable collaboration of four Haliburton Churches that work to provide food and second-hand clothing for members of the community who require moderate support. The food bank and the Lily Ann second-hand clothing store are the two main components of the operation, with the clothing store providing funding for the food bank. A partnership was created between the 4C's and the Sustainable Building Design & Construction Program of Sir Sandford Fleming College. The goal was to create a cost-effective and sustainable home for the Haliburton 4C's group. The use of alternative building materials and design techniques has traditionally been limited to private residences, with public use restricted to a small number of projects utilizing only a few of the many sustainable building options available. The reason for this is a general lack of knowledge in the area of sustainable design and construction, and a false belief that sustainable construction leads to a structure that is not aesthetically pleasing, and has limited functionality. One goal of the 4C's project was to showcase sustainable building in a public structure, and thus to dispel the negative perceptions that may exist regarding alternative building. This goal was achieved, in conjunction with the needs of the Haliburton 4C's group, and the requirements of the Sir Sandford Fleming Sustainable Building Design and Construction Program. In this paper, the conceptual design for the building is outlined, with an emphasis on describing the sustainable and unique wall design, which included the use of hemp bale construction, earthen plasters, and an earthbag stacked footing. In order to obtain building code approval, testing of the proposed wall system was required. This was carried out at Queen's University in Kingston, Ontario. Further testing was carried out to better understand the structural performance of some of the materials used in the building design.
Hemp-lime is an insulating low carbon dioxide material that is produced from sustainable natural resources. The use of hemp-lime within the construction industry is a relatively recent development. Currently within the UK hemp-lime is used to form solid wall insulation in conjunction with structural timber studwork. Current design practice generally assumes that the hemp-lime does not contribute towards the structural capacity of the wall. This paper details research that has been undertaken to establish the compressive load enhancement provided to timber studs by encasement in hemp-lime. Laboratory testing was carried out on timber studs with and without hemp-lime and the results compared. It was found that the hemp-lime significantly increases the compressive capacity of the studs and prevents buckling from occurring.
The concepts of green building and sustainable construction have received tremendous interest in North America in the past decade, as shown by the growth in the numbers of L.E.E.D.™ certified projects (Kibert 2005). Parallel to this has been a growing interest in natural, vernacular, or traditional building materials and techniques. Examples of these include straw bale construction and rammed earth construction. From an environmental point of view, these materials offer a low embodied energy and low embodied carbon alternative to conventional building materials such as concrete and steel (Woolley 2006, Walker 2007). In the case of straw bale construction, use is made of a waste material with excellent insulation properties. Other benefits of many natural materials include their ability to passively regulate humidity in a building, reduced toxicity, high thermal mass, and biodegradability at the end of life (Walker 2007). There remain many barriers to the use of natural building materials in the mainstream construction industry, including a lack of scientific data to quantify their true performance (Woolley 2006) and lack of experience by the mainstream construction industry in using these materials. This leads to the perception that these materials are low-tech and have poor performance. This perception, however, is changing. There is a growing body of research that is quantifying the performance of natural building materials and showing that they can compete with conventional building materials. There are also some excellent recent examples of the integration of natural building materials in mainstream construction projects. This paper describes three natural building material products that have been successfully integrated into mainstream construction projects in the United Kingdom: straw bale panels by ModCell; a hemp-lime composite called hemcrete and marketed by Tradical; and, rammed earth and unfired clay bricks. The information in this paper is based on interviews and site inspections undertaken by the author during February 2008. Some of the research supporting the use of these products will be described. Finally, some lessons and cautions for the use of these products in North America will be discussed. A caveat regarding the limitations of this paper is in order. This paper does not claim to be an exhaustive review of natural building materials and their performance. Other references should be consulted for more details on thermal or fire performance, for example.
The building industry accounts for up to 40% of the earth's energy usage from material extraction through building operation; housing constitutes roughly 30% of energy use in North America. Owners and consumers are looking for more efficient building systems that would decrease this use of energy. The material chosen to construct the structure of a building has the potential to reduce the building's initial environmental impact and its life cycle energy use. However, this is rarely considered during conceptual design. Sustainable construction materials that have low embodied energy include earthen construction and straw bale construction. However, these materials are not widely accepted alternatives in North America because they are included only in select building codes in North America and around the world. In this paper, an extensive review of the current construction practice of sustainable construction materials is summarized. Durability concerns and limitations of the methods of construction are discussed, and areas of future research are identified. DOI: 10.1061/(ASCE)MT.1943-5533.0000241. (C) 2011 American Society of Civil Engineers.
The Building for Environmental and Economic Sustainability (BEES) tool implements a rational, systematic technique for selecting cost-effective green building products. The technique is based on consensus standards and designed to be practical, flexible, and transparent. The Windows-based decision support software, aimed at designers, builders, and product manufacturers, includes actual environmental and economic performance data for 24 building products across a range of functional applications. BEES measures the environmental performance of building products using the environmental life-cycle assessment approach specified in the latest versions of ISO 14000 draft standards. The approach is based on the belief that all stages in the life of a product generate environmental impacts and must be analyzed. The stages include raw material acquisition, manufacture, transportation, installation, use, and waste management. Economic performance is measured using the ASTM standard life-cycle cost method. The technique includes the costs over a given study period of initial investment, replacement, operation, maintenance and repair, and disposal. Environmental and economic performance are combined into an overall performance measure using the ASTM standard for multiattribute decision analysis.
The Centre for Excellence is being designed as a highly innovative, two–storey multi-purpose facility that will provide essential trades and technology training and professional development to students in British Columbia, Canada and beyond. The building will support a syllabus with a focus on sustainable building technologies and processes, and the development and application of alternative and renewable energy. Design work and construction will be completed in time for the building to open in April 2011. The Centre for Excellence will also host an incubator organization to provide tenancy space for start–up innovation and research companies specializing in sustainable technologies. This building project is unique from a number of perspectives. It is aimed at attaining the highest standard of sustainable building design, namely the Living Building Challenge. Further, the building itself will become an essential element of the educational programs that will reside there, mainly focused on building trades and engineering technologies. In addition, the Okanagan Research Innovation Centre will be incorporated into the building, providing opportunities for start–up companies to develop and prototype new green technologies in a supportive and synergistic environment. Finally, this building is being constructed in the somewhat challenging climatic regime of the Okanagan region of Canada. The most important element of this project is that is will demonstrate that the Living Building Challenge is achievable at a cost comparable to conventional building design. The paper will focus on how this ambitious goal will be attained along with the numerous unique aspects that have been incorporated into the building design.
Abstract The first half of the Review focuses on the impacts and risks arising from uncontrolled climate change, and on the costs and opportunities associated with action to tackle it. A sound understanding of the economics of risk is critical here. The Review ...
The effect of using different binding agents in combination with hemp shives and fibres in Lime–Hemp Concrete (LHC) building material was examined. LHC is a light composite building material with building lime as binding agents and hemp (Cannabis sativa) as a renewable raw material from agriculture. Contemporary LHC only uses the woody core part of the hemp, the shive. However, using both hemp shives and fibres may improve the mechanical strength, eliminating the need for a fibre separation process.
The aim was to elucidate the feasibility of using the entire fragmented hemp stalk in an LHC, and to determine some important material properties such as compressive strength, splitting tensile strength, water sorption and frost resistance. LHC with varying inclusions of the lime-based binders were tested, as were five mixes using the binding agents hydrated lime, hydraulic lime, and cement.
Specimens were cured for 12 weeks at room temperature and 40 days in a carbonation room (4.5 vol% CO2), and tested for mechanical properties, water sorption and frost resistance. Using both shives and fibres in LHC may be advantageous for countries such as Sweden where facilities for separating hemp from shives are not commercially available.
Timber column design methods have now to take account of a body of research work on timber properties from in-grade tests and on strength considerations using notions of stressed volume. This paper gathers results from this body of work and proposes a design formula for timber columns which is convenient to use and represents true behaviour. It includes, in particular, a material strength effect related to the length of the column. The proposed formula has been incorporated into the new Canadian code “Engineering design in wood.” Key words: timber, buckling, columns, design, size effects.
Combined bending and axial loading is often encountered in lumber and timber members. Existing design methods are based on studies carried out many years ago, and are no longer appropriate because they do not recognize that wood with defects behaves in compression as a nonlinear ductile material and in tension as an elastic brittle material subject to size effects.This paper summarizes the findings of a comprehensive investigation into the behaviour of lumber subjected to eccentric axial loading, which was carried out at two Canadian universities. The study included analytical modelling and an extensive experimental program using full-size lumber.The results of the investigation have been used in this paper to propose improved design methods, using design charts and approximate formulae for in-plane behaviour. The discussion is extended to general loading cases and biaxial behaviour. Input information required for the design process is also discussed.
Concrete blocks, made of a mixture of lime and hemp shives (also called “hemp hurds”), have been manufactured by a recently developed projection process. Lime carbonatation kinetics is determined by X-ray diffraction. Density measurements are made within blocks, and thermal and mechanical properties are measured (flexural strength, compression strength and hardness). The main observations are moderate density variations within a given block, and an influence of the projection distance on density. Both thermal conductivity and mechanical properties increase with the mortar density, which is well described by existing theoretical models. Compression tests induce a compaction, or densification, of the material.
Mechanical and Thermal properties of hemp mortars and wools: experimental and theoretical approaches
- L Arnaud
Arnaud, L. Mechanical and Thermal properties of hemp mortars and wools: experimental and
theoretical approaches. Proceedings of the third International symposium, bioresource, hemp and
other fibre crops, Germany: Wolfsburg: 2000.
Innovative building material based on line and hemp particles: From ecological and technical interests
- L Arnaud
- D Samri
Arnaud, L. and Samri, D. Innovative building material based on line and hemp particles: From
ecological and technical interests. International conference on Sustainability in the Cement and
Concrete Industry, Lillehammer, Norway, September 16-19, pp. 580-592, 2007.
Hemp and lime composites in sustainable construction
- I Pritchett
I. Pritchett, Hemp and lime composites in sustainable construction, Convention on Non-Conventional Materials, NOCMAT 2009 Proceedings, 2009, Bath, England.
ASTM D143 -09 for Small Clear Specimens of Timber
- P A Usa
ASTM D143 -09 for Small Clear Specimens of Timber, P.A,USA 2010.
ASTM D 1621 -Standard Test Method for Compressive Properties of Rigid Cellular Plastics-Determination of Compression Properties
ASTM D 1621 -Standard Test Method for Compressive Properties of Rigid Cellular Plastics-Determination of Compression Properties. P.A,USA 2008
The Wales Institute for Sustainable Education(WISE): Non-conventional materials in Mainstream Construction
- R Harris
- J Shanks
- T Hodsdon
- Borer
Harris. R., Shanks. J., Hodsdon. T., Borer., The Wales Institute for Sustainable
Education(WISE): Non-conventional materials in Mainstream Construction. Proceedings of the
11 th International Conference on Non-conventional Materials and Technologies (NOCMAT
2009)6-9 September 2009, Bath, UK.
Structural Behavior of Timber
- B Madsen
Madsen, B., Structural Behavior of Timber. Timber Engineering Ltd., First Edition, 1992.
Wood Design Manual 2005-A complete reference for wood design in Canada-Canadian Wood Design Council
- D J White
- W A Take
- M Bolton
White, D. J., Take, W. A, and Bolton, M. D, Soil deformation measurement using particle image
velocimetry (PIV) and photogrammetry. Geotechnique 53, No. 7, 619-631,2003.
Wood Design Manual 2005-A complete reference for wood design in Canada-Canadian Wood
Design Council.