Alternative and sustainable building materials and ... and sustainable building materials . and technologies in Auroville . L. ... cement and lime using coal , ... this project, of approximately ...

Download Alternative and sustainable building materials and ...  and sustainable building materials . and technologies in Auroville . L. ... cement and lime using coal , ... this project, of approximately ...

Post on 27-Mar-2018




2 download

Embed Size (px)


<ul><li><p>Alternative and sustainable building materials </p><p>and technologies in Auroville LIBERATO ALIBERTI </p><p> Tirocinio svolto presso: AUROVILLE DESIGN CONSULTANTS (C.S.R) Tutor universitario: PROF. GIORGIO SERINO, PROF. DONATELLA MAZZOLENI Tutor aziendale: SUHASINI AYER </p><p>Abstract. La crisi energetica globale non pu pi essere a lungo ignorata. Notevole quantit di energia viene spesa nei processi di produzione di materiali e componenti per l'edilizia nonch nella pratica delle costruzioni. Lo scopo di questo lavoro quello di valutare materiali e tecnologie, alternative e sostenibili, nel campo delle costruzioni nel contesto del sud dell'India. La questione tecnologica stata affrontata non come questione specifica e neutrale, ma come una parte del "senso" e del "valore" ecologico del costruire e dellabitare. Sono stati esaminati ventiquattro casi studio, progetti realizzati nell'ecovillaggio sperimentale di Auroville (Tamil Nadu). Attraverso un'analisi di tali progetti sono state individuate e descritte specifiche tecnologie che denotano bassi valori di embodied energy, ottimizzazione delluso di materiali (anche non convenzionali) e di risorse locali. Secondo tali parametri, le tecnologie e i materiali analizzati rappresentano una alternativa sostenibile per quel particolare contesto economico, sociale ed ambientale. </p><p>1. Global context Today the Earth has a population of seven billion people and we are adding one billion more every 15 years. Consequently there is an increasingly amount of lands getting urbanized with accompanied increase in consumption of energy in the construction sector. </p><p>Human actions are increasing the concentrations of greenhouse gases in the atmosphere, reducing heat loss to deep space, and increasing global temperatures. The Carbon dioxide (CO2) causes 50% of the current greenhouse effect. It is growing exponentially as shown in fig.1, we see also </p></li><li><p>Liberato Aliberti </p><p>2 </p><p>how today the production of cement contributes to such emissions (Arvind, 2001). </p><p>This alarming demographic growth combined with the global energy crisis has been a major trigger for the sensitization to ecological concerns in our lifestyle, our habits, our environment and more generally on the future of our planet. In recent years, climate change, air pollution, depletion of natural resources and biodiversity, waste generation, depletion and pollution of water resources became global issues that require urgent actions to be taken. </p><p>A great quantity of CO2 is emitted into the atmosphere throughout the life-cycle of a building from the production of building materials, to the construction of a building itself, the occupation period, renovation, possible rehabilitation and its final demolition. </p><p> Fig.1 . CO2 emissions </p><p> Some authors estimate that almost 50% (including 5% for building </p><p>construction) of total energy costs in the developed countries is used for building practices (heating, cooling lighting of buildings) and construction (Joseph &amp; Tretsiakova, 2010). </p><p>The construction industry is also one of the major sources of pollution. Therefore the contribution of building industry to global warming can no longer be ignored. </p><p>2. Indian Context </p></li><li><p>Alternative and Sustainable Bauilding Materials and Technologies in Auroville </p><p>3 </p><p>Indian population has almost tripled over the last 50 years. The demographics of India are inclusive of the second most populous country in the world, with over 1.21 billion people (2011 census), more than a sixth of the world's population, India is projected to be the world's most populous country by 2025 surpassing China. </p><p>Today, Indian rural population is around 70%. Demand for residential buildings is increasing every year. The Housing and Urbanization scenario predicts that over the next 40 years the urban population will increase from 30% to 50% with a huge increase in new constructions, especially in small towns with less than 500000 inhabitants. </p><p>In India the construction industry is the largest after agriculture. From about 20% to 25% of India's total national energy demand is generated by the manufacturing materials required in the building sector (Arvind, 2001). The construction industry is one of the major sources of pollution. Construction-related activities account for quite a large portion of CO2 emission. </p><p>India generates about 1,35 bt of CO2 which is nearly 5% of total world emission (Nilanjan, 2008). India is a signatory to the Kyoto Protocol, so reduction in this emission through alternative technologies and practices is necessary and will be beneficial to the problem of global warming. </p><p>3. Energy in building constructions Modern building constructions consume energy in different phases: manufacturing of building materials and components, transport materials, construction of the buildings, maintenance during the building's life span, demolition process of buildings as well as in the recycling of their parts. </p><p>The primary use of energy is in the production of the building material, the basic energy use in the form of thermal energy: bricks and tiles using firewood, cement and lime using coal , steel using coking coal as the fuel, etc.. Table 1 lists typical building materials in South India and their energy content per unit of measurement (Jagadish et al., 2007). . </p><p>Material </p><p>Unit </p><p>Energy per unit MJ </p><p>Type of Energy </p><p>Burnt brick One brick 3,75 4,5 Coal/ Wood/ Rice Husk Cement 1 kg 5,85 Coal + Electricity Lime 1 kg 5,63 Coal/ Wood Lime + Fly 1 Kg 2,33 Coal/ Wood </p></li><li><p>Liberato Aliberti </p><p>4 </p><p>Ash Steel 1 Kg 42 Coal + Electricity Aluminium 1 Kg 236,8 Electricity Glass 1 Kg 25,83 Electricity Polyester 1 litre 220 Petroleum + Electricity GFRP 1 Kg 100 Petroleum + Electricity Mangalore Tile 1 tile 5,0 - 15 Firewood/ Coal </p><p> Tab.1 . Energy in common building materials </p><p> The table shows that some common building materials are energy </p><p>intensive and also often produced by non-renewable energy sources. Alternative building technologies can be used for minimising the </p><p>embodied energy in buildings (~50%) by optimizing the use of common materials but also through the introduction of alternative materials (Jagadish &amp; Venkatarama, 2001). Examples of buildings using alternative building technologies are widely present in Auroville (South India). </p><p> 4. Auroville </p><p>Auroville is a township located near Puducherry in the state of Tamil Nadu, South India. Auroville was founded in 1968 by The Mother (Mirra Alfassa) as an urban experiment to develop a society based on human unity and higher consciousness. Actually Auroville has about 2200 permanent resident more than 40 different nationalities. Auroville represents a valid response, a living lab, an exemplary model not only for India. Since its founding, as an experimental city, Auroville has been the site of numerous innovations in architecture and building construction, combining local materials, ecological solutions and cost-effective techniques of construction. </p><p>Starting mid-nineties there were good results in the applied research particularly in ferrocement technology for roof and interior fittings as well as compressed earth blocks for load bearing structures. Some of the buildings constructed won considerable design awards and significant grants-in-aid from agencies that support such innovations (Mandeen, 2004). Among these projects, the most representatives were Visitor Center and Mirramukhi school, through these projects it was provided the opportunity to demonstrate and promote the rich potential of alternative technologies such as appropriate building technologies, land reclamation and afforestation, renewable energies, water management and waste </p></li><li><p>Alternative and Sustainable Bauilding Materials and Technologies in Auroville </p><p>5 </p><p>recycling techniques etc. Visitor Center won International Award (Hassan Fathy, Architecture for the poor), it was designed by Suhasini Ayer architect and it was built with the technical support of Earth Institute. In this project, of approximately 1200 square meters, particular emphasis was put on the use of earth as a building material and precast (in situ) elements. </p><p>The following study was done by analyzing a series of projects that have been built over the past fifteen in Auroville. The research covers 24 study cases where a systematic analysis of the building materials and technological solutions for each construction elements has been done. </p><p>5. Alternative building materials and technologies Among various materials and technologies used in the 24 projects analyzed, only those that represent a real sustainable alternative, considering the particular social context, environment and climate, have been set out below (tab. 2). </p><p>Foundations Stabilised rammed earth foundation Composite foundation </p><p>Walling Rammed earth wall Walls with CSEB (Compressed Stabilised Earth Blocks) Walls with CSEB interlocking Cavity walls using Rat-Trap Bond Technology </p><p>Pillars and columns Composite columns Plaster Stabilised earth plaster Beams Composed beams cast in U CSEB blocks </p><p>Composed RCC cast in ferrocement elements Floors Terracotta filler slab </p><p>RBCS (Reinforced Brick Concrete Slab) Precast ferrocement elements Terracotta jack arch </p><p>Roofs Piched roofs with precast concrete rafters Vault with terracotta interlocking tubes Nubian technique for vault and dome in CSEB </p><p>Recycled materials Some materials and elements </p><p>Tab.2. Alternative technologies </p></li><li><p>Liberato Aliberti </p><p>6 </p><p>Alternative is used here to denote not only the non-common building practices with respect the predominant and/or conventional practices but also for other aspects such as: </p><p>a) Reducing energy demand b) Using local resources c) Replacement materials or technologies to make up for the </p><p>unavailable d) Using materials and technologies not included in the Indian </p><p>Standard Codes. Alternative construction technologies bring down the embodied energy </p><p>level associated with production of building materials by lowering use of energy-consuming materials. This embodied energy is a crucial factor for sustainable construction practices (Venkatarama, 2004). </p><p>Embodied energy is defined as the amount of energy required to produce a building material and energy consumption during building construction. It consists in energy required for: Procuring the raw material including all the processes involved Transformation of the raw material into finished product for use </p><p>including packaging for transport Handling and safe disposal of all the waste produced during the </p><p>manufacturing process Transportation raw material to the processing plant and the finished </p><p>product to the supplier / retailer and end user Assembly into the building </p><p>Steel, cement, glass, aluminium, plastics, bricks, etc. are energy-intensive materials, commonly used for building construction and generally these materials are transported over great distances. </p><p>A typical example of reducing energy cost extensively tested and used in Auroville is the Earth Technology that uses locally available materials; they have very low embodied energy and generate very little waste. So an important aspect for saving energy and cost is procuring materials in the local area to minimize transportation and maximize the use of local materials and resources. </p><p>It provides also the alternatives to replace technologies or materials not available in the place. A case in point concerns the question of timber. In fact good quality timber used in building construction is in short supply in India and very often it is imported from Malaysia and Australia. Considering this problem of shortage of wood in this area, an alternative </p></li><li><p>Alternative and Sustainable Bauilding Materials and Technologies in Auroville </p><p>7 </p><p>approach is replacing timber to ferrocement or concrete. So, in some project we shall see that instead of the traditional wooden trusses, ferrocement or reinforced concrete slender beams are used as modern reinterpretation (Majumdar, 2001). This is perhaps a good short term strategy alongside a strong undertaking for the recovery and reuse of old items and wooden structures per new buildings to allow for forests recover in the sub-continent. Finally, alternatives because most of these technologies are not included in the Indian Codes. The following are some of the most representative alternative technologies analyzed. </p><p>5.1. Wall with CSEB blocks. Stabilized Earth Blocks are manufactured by compacting raw earth mixed with a stabilizer such as cement or lime under a pressure of 20 - 40 kg/cm2 using manual soil press. In Auroville, CSEB are stabilized with 5% cement and has an average dry compressive strength of 50 kg/cm2 (5 Mpa) and a wet compressive strength of 25 kg/cm2. The water absorption is around 10%. Country fired bricks have an approximate dry compressive strength of 35 kg/cm and have a 12% water absorption rate. The Auroville Earth Institute has designed manual presses for CSEB. In Auroville, CSEB present several advantages compared to the local country fired bricks: Walls made of CSEB and stabilized rammed earth are always usually </p><p>cheaper than fired bricks. The initial embodied energy of CSEB produced on site with 5 % </p><p>cement is ~ 4 times less than the local country fired bricks: CSEB produced on site with 5 % cement = 1,112.36 MJ/m3; Country fired bricks = 4,501.25 MJ/m3 </p><p> The strength of these blocks is most of the time higher than the local country fired bricks. </p><p>5.2. Composite columns and beams cast in CSEB blocks. This technique is extensively used in Auroville since 1995. Round hollow CSEB blocks are used for columns, U-shaped CSEB blocks for beams. The blocks are used as lost shuttering, but they also help the compressive strength of the elements. This is a mixed technology that aims to reduce the use of reinforced concrete and use local resources like the earth with significant advantages in terms of embodied energy. </p><p>Columns. Two types blocks have been designed: the round block 240 and the round block 290. These blocks allow for a reinforced with cement concrete core. Both types of blocks are laid with a cement sand mortar CSM 1: 3 of 1 cm thickness. The steel rods do not exceed 1.5 m high, as it </p></li><li><p>Liberato Aliberti </p><p>8 </p><p>is difficult to slide down the blocks if the steel bars are the entire height of the column. Beams. U-shaped CSEB are composed with reinforced cement concrete. Reinforcements vary with the span, but the rod diameter cannot exceed 12 mm for the Auram blocks 290 &amp; 295 and 16 mm for the Auram blocks 240 &amp; 245. The concrete cast in the U shape is normally 1 cement: 2 sand: 4 gravel . The vertical mortar in between the U blocks is cement sand mortar CSM 1: 3 of 1 cm thickness. Three types of beams have been developed: Single height beams (only 1 U block), Double height beams (2 U blocks in opposite 1directions) and Triple height beams (1 U blocks downwards, 1 plain block in the middle, 1 U block upwards). </p><p>5.3. Precast ferrocement elements. Although ferrocement is not strictly a 'sustainable' technolo...</p></li></ul>


View more >