Straw Bale Buildings Research Articles

Strawbale buildings as carbon sinks: influence of the design and construction process on carbon emissions

Strawbale buildings as carbon sinks: influence of the design and construction process on carbon emissions

Promoting Circular Economy of the Building Industry by the Use of Straw Bales: A Review

Over the past decade, the concept of a circular economy has increasingly gained attention as a framework for guiding businesses and policymakers. Given its significant environmental impact, the building industry plays a pivotal role in the transition toward a circular economy. To address this, our review proposes a bio-based building material, specifically straw bale, which elaborates on the circularity of bio-based buildings based on the 3R principles of a circular economy: reduce, reuse, and recycle. In terms of the “reduce” principle, straw-bale buildings can reduce construction waste, the environmental impact, energy requirements, and carbon emissions. Regarding the “reuse” principle, straw-bale buildings utilize agricultural waste resources and are easily disassembled due to their prefabrication. As for the “recycle” principle, straw-bale buildings can undergo physical, biological, and biochemical conversion processes (thermochemical conversion), yielding both wooden composite boards and potential biogas and biomass fuels for electricity and heating. This study evaluates the contribution of straw packaging construction and the use of straw as a raw material, using the 3R principles to determine future research opportunities for the construction industry to achieve a circular economy. The results of this study offer circular economy solutions and interdisciplinary research insights for researchers and practitioners interested in the building environment.

A Mini-Review on Straw Bale Construction

Straw bale building construction is attracting a revived public interest because of its potential for reduced carbon footprint, hygrothermal comfort, and energy savings at an affordable price. The present paper aims to summarize the current knowledge on straw bale construction, using available data from academic, industry, and public agencies sources. The main findings on straw fibers, bales, walls, and buildings are presented. The literature shows a wide variability of results, which reflects the diversity of straw material and of straw construction techniques. It is found that the effective thermal conductivity, density, specific heat, and elastic modulus of straw bales used in construction are in the range 0.033–0.19 W/(m·K), 80–150 kg/m3, 1075–2000 J/(kg·K), and 150–350 kPa respectively. Most straw-based multilayered walls comply with fire resistance regulations, and their U-value and sound reduction index range from 0.11 to 0.28 W/m2 K and 42 to 53 dB respectively, depending on the wall layout. When compared to standard buildings, straw bale buildings do provide yearly reductions in carbon emissions and energy consumption. The reductions often match those obtained after applying energy-saving technologies in standard buildings. The paper ends by discussing the future research needed to foster the dissemination of straw bale construction.

Experimental Investigation of Two Test Setups on Straw Bales Used as Load-Bearing Elements of Buildings

The importance of green and sustainable materials in civil engineering is undeniable. Alongside modern practices that improve the properties of standard building materials, there are ways to revive forgotten techniques, including straw bale buildings. Straw bales are load-bearing structures, which are applied based on handed-down experience and lack standard approaches in testing, design, and application. Therefore, a goal ahead is to describe every aspect of the process in technical detail. The objective of this paper is to highlight practical ideas for testing straw bales on a hydraulic press machine and to provide a basic statistical investigation of the results obtained. Two basic series were prepared, one without a side barrier and the other with a side barrier. The reason for this was to delineate the limits of the real behaviour of the straw bale on the load bearing wall of the house. Due to the assumed slight embedment of adjacent bales, the real result were within these limits. The experimental plan, basic results, simplified correlations, and statistical evaluation are presented. Recommendations for a further testing and evaluation are provided. As expected, the results with and without the lateral barrier differ by almost 18% for the true strain.

Physical properties of straw bale and its effect on building energy conservation and carbon emissions in different climatic regions of Iran

Straw has been used as a building material for many centuries, and due to its outstanding physical properties such as great thermal and acoustical insulation, energy efficiency and low embodied carbon emission, it has become more popular within the last decade. In this study, first the physical properties of straw bale such as apparent density, thermal conductivity, short-term water absorption and compressive strength are measured through laboratory tests. Based on experimental data, Inventory of Carbon & Energy (ICE) database and using EnergyPlus software, the energy performance and carbon emissions of three different types of straw bale buildings in four climatic regions of Iran are evaluated, and the results are compared to that of a conventional building in the same climates. The results show that using straw bale as a construction material, the energy consumption of buildings will reduce up to about 83.12%. Additionally, it was observed that the straw bale buildings, can decrease embodied carbon up to 76% compared to the conventional buildings.

Hygrothermal performance, energy use and embodied emissions in straw bale buildings

Straw bale is a low embodied energy and technically acceptable thermal insulation material. As per today, there is a lack of standardized technical data on utilizing straw bale in building construction, while the existing research studies rather focus on limited specific experimental or computational scenarios without summarizing in an organized way the behaviour of straw bale construction under different climate conditions and assembly configurations. This comparative study presents systematically the hygrothermal and energy performance of straw bale buildings with different exterior cladding and finishing mortar or sheathing board, exposed in various representative climates. The findings provide an insight into the optimal selection of materials and furthermore highlight the importance of climate adaptation of straw bale wall constructions. Overall, straw bale buildings show robust hygrothermal performance, when properly designed, and achieve very low energy use at a minimum of embodied emissions.

Physical Properties of Straw Bales as a Construction Material: A Review

Straw bale buildings provide significant benefits in terms of costs, human health, and environmental sustainability. Several studies in different regions have underlined the remarkable properties of straw bales as insulating and construction material; however, to the authors’ knowledge, there are no reviews published on this topic. The main objective of this paper is to provide a better understanding of straw bale systems, focusing on durability and thermal and acoustic insulation properties. To this end, previous tests and studies on straw bale buildings around the world were reviewed, comparing their results, assessing where research currently stands, and identifying the aspects that need to be further investigated. Results from previous tests have highlighted their ability to achieve excellent living comfort and encouraged their use. Guidelines for the characteristics to be achieved during the baling process are now required. Combining straw bale walls with a render or any type of high-density layer can improve both the thermal and acoustic properties of straw bale constructions. Finally, a quantitative assessment of the most significant properties, such as thermal resistance and acoustic insulation, is necessary to reduce the gap between straw bales and traditional building materials.

Construction and monitoring of experimental straw bale building in northeast China

Straw bale buildings have the potential reduce the environmental impact of construction. Although the technique has been introduced into northern China more than a decade ago, the construction method and potential problems within straw bale walls have not been fully understood in existing research. Following an analysis of existing straw bale construction both in north China and worldwide, this paper proposes modifications to the straw bale construction details currently used in north China. The modifications involve in-fill raw material, toe-up design and lime render application. These modifications were incorporated into an experimental building constructed in north China, and after having been monitored for 12 months, the modified construction details were critically assessed. The data demonstrate that rice straw bale walls are resistant to agents of decay and offer reduced construction time and cost than standard wall construction in north China. The construction method has the potential to become a mature construction system in the Chinese market in the future offering significant benefits both in construction and operational cost and in environmental impact.

Straw bale construction in northern China – Analysis of existing practices and recommendations for future development

Straw bale buildings in China have been mainly limited to rural farm houses and self-builders. An expansion of straw-bale construction into main-stream medium-rise buildings has the potential to make a significant contribution to the reduction of both embodied and operational carbon in China as well as removing a major source of pollution. As a response, there has been the construction of straw bale buildings, however these buildings have several issues, resulting in the limited adoption of the technology.This paper makes recommendations for future straw bale design in northern China based on an inspection of existing buildings. The issues identified with existing construction details were subjected to computational simulation analysis which identified shortcomings in existing practice and proposes revisions to design detail in order to accommodate the environmental conditions in northern China. The paper provides a unique insight into current straw bale practice in northern China and proposes a practical and environmentally sound solution to the pollution crisis in this region.

AN ALTERNATIVE APPROACH TO BUILDING CONSTRUCTION: NATURAL BUILDING TECHNIQUES

Concerns about the environment around the world are increasing in recent years. As a countermeasure to these concerns, interest in natural building techniques has begun to increase because of the high environmental, social and economic costs of existing construction methods and the potential for natural structures to be a solution to the problem of sustainable living. With natural building techniques it is possible to construct buildings with materials and techniques that are ecologically sound, culturally sensitive, based on local resources and skills, and affordable to local residents. Adobe buildings, cob buildings, earthbags, rammed earth buildings, straw bale buildings, earthships are among the construction techniques utilized for this purpose. In this article, natural building techniques are introduced in a general framework. Increasing usage of natural construction techniques that have the potential to be a solution to the environmental problems in the world by the construction professionals and the construction sector, and supporting developments with research, supporting volunteers, who will take steps in this field, with government policies, and increasing the interest of the users and their awareness should be regarded as a necessity. Keywords: natural buildings, earth buildings, straw bale buildings, earthships

A RESEARCH ON THE PERCEPTION OF ARCHITECTURE STUDENTS ABOUT STRAW-BALE BUILDINGS

Although straw-bale construction has been used for thousands of years, currently doesn‟t attract considerable attention by professional architects and students. The reason behind this is assumed to be the prejudices and lack of knowledge about straw-bale buildings. In the scope of this research understanding candidate architects point of view on the preference criterias that are effective about choice of straw-bale construction is aimed. For this purpose, among 214 students of private university (in Turkey) in 2015-2016 academic year, 100 students were selected through simple random sampling and the survey was conducted. The results show that according to the candidate architects, the properties such as its being compatible to nature, harmless to human health, recyclable and low-cost are the main positive qualities of straw-bale construction, whereas lifetime, structural properties and fire resistance are still calling into question. This study demonstrates that straw bale construction techniques, which have the potential to solve environmental problems, need to be given more attention in the architecture educational. Keywords: Straw-bale construction, preference criterias, architecture students

Analysis of the parameters affecting the mechanical behaviour of straw bales under compression

Straw bale construction is a building technique that has excellent thermal performance and limited impact on the environment. Improving knowledge of the mechanical properties of straw bales is important to understand the behaviour of straw bale buildings, especially in case of natural calamities, where straw bales may carry mechanical load and act as a “surviving cell”. The results of extensive tests conducted on bales of different materials are presented. The influence of the material, bale density, bale orientation, baling process and loading rate on the mechanical properties of straw bales was investigated. Force-displacement curves obtained from monotonic compression tests were analysed and relationships between the mechanical properties of straw bales and their geometry and density were determined. Continuous measurements of bales lateral displacement allowed Poisson's ratio to be calculated and, using a simple model, the strain to which bale strings are subjected during loading was estimated. Young's modulus was shown to mainly depend on the square of the density, while no influence of the loading rate and of strings pre-tension was observed. The Poisson's ratio did not remain constant during loading and it exhibited a different trend depending on the orientation of the bales. Moreover, it was observed that for flat bales a rearrangement of the straw fibres during loading occured and the maximum strings strain remained limited. Strings strain reached higher values for on-edge bales instead, and strings bursts occured more frequently.

An Evaluation of WUFI-Bio to Predict Mold Growth in Straw Bale Walls in Japan

The greatest challenges facing straw bale building in Japan, and many other countries with high humidity and precipitation, are moisture and the susceptibility of straw to microbial decay. WUFI-Bio, developed by the Fraunhofer Institute for Building Physics, is a computer program that assesses the risk of mold growth in buildings based on measured or computed climatic conditions. Researchers in Japan have monitored the hygrothermal conditions of six straw bale buildings in Japan and evaluated the risk of mold growth based on an interstitial temperature and relative humidity guideline. The purpose of the present study is: (one) reevaluate the potential for mold growth in the six buildings using WUFI-Bio and (two) evaluate the accuracy of Holzhueter and Itonaga′s interstitial temperature and relativity guideline vis-à-vis WUFI-Bio. As a result of the study, the potential for mold growth was found to vary by structure. Buildings utilizing rainscreens were found to have a lower risk of mold growth. Holzhueter and Itonaga′s interstitial temperature and relativity guideline was found to over exaggerate the potential for mold growth. Also, although Holzhueter′s guideline does indicate a potential for mold growth, the number of hours above the guideline alone is not a sufficiently accurate indication of severity.

Feasibility Study on the Promotion and Application of Straw Bale House in Northern Rural Areas in China

With the accelerated pace of new rural areas construction in northern China, people have a higher requirements in terms of houses’ quality and function. At the same time, the backward construction methods and developing with the wind blindly has also led to a rapid growth in resource consumption. In order to better meet the requirements of hot comfort, energy saving and environmental protection properties of rural houses in northern areas. Based on the research methods including investigation, mathematical statistics, documentation, and logical analysis, combining with the residential problems in northern rural areas, and the superiority of straw bale house, and the favorable conditions for straw bale buildings. This article identified the feasibility of straw bale housing construction in the northern countryside, and draw the conclusion that the excellent economy, simple construction methods and good energy efficiency of straw bale house will be accepted by the majority of farmers friend.

Straw bale: A Waste from Agriculture, a New Construction Material for Sustainable Buildings

Since the beginning of the 21st century, straw-bale buildings are reappearing in the world; however, their thermal performances were not thoroughly investigated up to now. The purpose of this study is to analyze thermal behavior and energy performance of a straw-bale building in Switzerland. Using Pleiades+Comfie Software, building designs have been studied to understand the best way to mitigate overheating risks due to the low heat capacity of straw. Thermal-dynamic results and Life Cycle Assessment conclude that straw bale buildings can be a sustainable alternative in the energy evolution of building construction, due to its low embodied energy and excellent thermal performance.

Straw Bale: An Innovative Sustainable Material in Construction

It is around 10 years that the straw buildings have reappeared on the Europe construction market. Often self-built, these buildings sometimes made only with straw bales and soil aroused interest for their energy and sustainability performance. As there is no feedback existing on this kind of “alternative” construction, it is necessary to verify if straw bale buildings performances can meet today's energy requirements. The purpose of this study is to analyze different aspects of the thermal and energy performance of these buildings using the example of ECO46, an administrative load bearing straw bale building in Lausanne (Switzerland). The conductivity and heat capacity of the straw material were investigated through literature review to find a range of possibilities. Subsequently a dynamic thermal model was created, using the extracted thermal properties, by means of Pleiades+Comfie software. The model was calibrated against two sets of measurements in summer and winter. The results permit to compare the consumption of this building with some standard administrative Swiss buildings. Finally, life cycle assessment (LCA) of ECO46 using SimaPro software was carried out to show the evolution of energy consumption from a building constructed in 1975 to the current construction and to evaluate the main environmental impacts of straw bale building. The result shows that straw bale buildings could be a sustainable solution in the future of construction for its low embodied energy level and its excellent thermal performance if it is well built.

Hygro-Thermal Behaviour of Timber Frame Straw Bale Construction as an Energy Efficient Building Technology

Due to an increasing request for ecological building constructions, in particular straw bale buildings, a research in this regard has been performed at the Vienna University of Technology. Straw bale construction is a new rediscovered building technology, which is an alternative to conventional construction technologies. The aim of this study is caring out of hygro-thermal simulation of a straw bale wall construction to design as efficiently as possible straw bale house. The choose of other construction elements for a thermal analysis (appropriate wall, roof and a base plate construction), was based on an extensive literature researche. For the examination of the building a timber frame construction has been selected. The straw bales in this construction were plastered inside with clay plaster and externally with a combination of lime and clay plaster. The roof structure was designed as a green roof and insulated with straw bales. The base plate was also insulated with straw bales. To check the thermal behavior of the structures described above were thermal bridges calculated using a FEM program. The hygrothermal behavior was calculated with HAM4D building physic software, developed on the department for Buildings Physics and Sound Protection on Vienna University of Technology. Ecological and economic evaluation of straw bale construction was carried out with reference to the data from the literature. The performed thermal (with COMSOL) and the first hygrothermal calculations (with HAM4D Software) have demonstrated a very favorable performance of the proposed building components. The achieved low U-values ​​of the components allow the construction of passive houses. The use of self-build-service in the construction process can reduce construction costs significantly. The use of ecological materials such as: straw, clay and wood allows a low cost recycling of building materials.

Architect Werner Schmidt's Straw-Bale Construction

Werner Schmidt (Trübbach, Switzerland, 1953) is one of the most interesting contemporary 'green' architects, particularly experienced in straw-bale building. His accomplishments include now 20 straw-bale buildings of which 14 at least partially load-bearing. This paper extracts some essential principles from his work and explains in detail his technological solutions. This is the result of a thorough analysis, carried on during the preparation of a monograph. The success of his approach derives from many factors, among which: - Schmidt's training as a mason. In contrast with many fellow architects, his designs are rooted in practicality and feasibility. Moreover, he actively participates to the construction work. - His holistic vision of ecological building: straw bales are chosen because of the overall advantages they offer. Preferably, he adopts a modified 'Nebraska' technique, using high-density 'jumbo bales' forming more than 120 cm thick walls. This rather unique method assures rapidity of construction, and allows to solve a number of criticalities associated with 'small bale' building. - Not seeking the highest possible performances lets to focus economic and technical efforts on few elements that really need to be state-of-the-art. The envelope can be built with simple techniques, while parts that need be built precisely (stairs, cooking implements, baths, etc.) can be prefabricated. Schmidt's work shows that high ecological consideration can be coupled with convincing architectural results. The quality of his buildings in terms of energy performance, living value, and beautiful form constitutes a good practice promoting new ways to 'green' architecture.

House Embodied Energy and Zero Energy Building Concept

Seeking to mitigate climate change it is impossible to avoid radical changes in construction sector, because it accounts for 40% of primary energy use for buildings operation in Europe and other countries. Production of building materials also affects climate change and environment quality. The concept of zero energy building (ZEB) emphasizes energy efficiency, energy saving and renewable energy use during the operation of buildings and it is a necessary step in changing the present situation. Nevertheless there are more possibilities for improving building sector sustainability. The article presents analysis of embodied energy reduction using straw bales and other local materials for wall construction. Estimations have shown that replacing a structural component as bricks with local wood, and thermal insulation material - stone wool with straw bales, it is possible to reduce embodied energy and embodied carbon of a wall more than 7 times. Pressed straw being a building material with good thermal properties, straw bale buildings could meet the passive houses standard or help fulfilling the concept of zero energy building without additional harm to the nature of extra thermal insulation use.

An experimental study on shrinkage of earth plaster with natural fibres for straw bale buildings

In this paper, a series of laboratory tests on shrinkage of plaster materials are presented. The plaster materials consist of cohesive soil, sand and different natural fibres. Three types of fibres, wheat straw, barley straw and wood shavings, were used as reinforcement in the tests. The shrinkage behaviour of earth plasters was studied by laboratory tests for different compositions and under different curing conditions. The specimens of plaster material were dried under a constant temperature of 30, 50 and 70°C, respectively. The effect of the following factors on shrinkage was investigated: temperature, soil composition, fibre type and fibre content. It was established that shrinkage crack formation decreases with increasing fibre content and increases with increasing soil content. In general, it was also found that lower curing temperature and higher fibre content are to be preferred to improve the performance of earth plasters.