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"Think global, act local" as said by Tony Arnel in his recent meeting of Tackling Global Climatic Change highlights the intensity of need for global green awareness and climate change which is a consequence of much emitted green house gases, have attracted the attention of researchers at a alarming rate. The reason being that building fabric uses around 32% of world's resources, 40% of global energy and generates 30% of global green house gases. (Miller.J, September,2010)
India, having around 2.1% of world's land and supporting 17% of world's population, has extended its hands for contributing in spreading awareness and tacking this problem of carbon emission. (Demographics of india)
IGBC, which is Indian Green Building Council, founded in 2001, which collaboration and support of LEED, has established sets of criteria's which demonstrates the green construction rating system. As of February 2010, for different types of building typologies,IGBC has developed the following green building rating systems :
LEED India for New Construction
IGBC Green Homes
IGBC Green Factory Building
LEED India for Core and Shell
According to the basic principles practiced in IGBC green building rating system, much of the hassle generated is not from the new production, but managing the existing commodities. India is among those countries who have always given a strategic position to stratification. Be it the social stratification of society in terms of work or be it recycle and replenish of mother earth. (Indian Green Building Council)
POINTS ALLOTMENT BY IGBC
MR Prerequisite 1 Storage & Collection of Recyclables
MR Credit 1.1 Building Reuse:Maintain 75% of Existing Walls, Floors and Roof
MR Credit 1.2 Building Reuse:Maintain 100% of Existing Walls, Floors and Roof
MR Credit 1.3 Building Reuse: Maintain 100% of Shell + 50% of Non-Shell
Construction Waste Management
MR Credit 2.1 ,Divert 50% from Disposal
MR Credit 2.2 Divert 75% from Disposal
MR Credit 3.1 5%
MR Credit 3.2 10%
MR Credit 4.1, 5% (post-consumer + 1/2 post-industrial)
MR Credit 4.2, 10% (post-consumer + 1/2 post-industrial)
MR Credit 5.1, 20% Manufactured Regionally
MR Credit 5.2 , 50% Extracted & Manufactured Regionally
Regional Materials of building material
MR Credit 6 Regional Materials, 5% of Building Materials
MR Credit 7, 50% of Wood based Materials
(Leed India,Green Building rating System, 2007)
Today, in this modernised world, when national economy are guided by big It factors, a proven fact of this country is much of the local section, earn their livelihood by recycling and managing the resources... so the "kabariwala" ( the junk collector), markets like nayi sarak,
New Delhi, Exemplifies this fact.
EVOLUTION OF BUILDING MATERIALS IN INDIA
Evolution of building practice has happened through ages. Housing and building conditions have always been the mirror of the standard of living of a society. If noted, long back, the earliest civilizations alike Harappa and Mohenjo-Daro demonstrates quite a high level of excellence in construction methodology in terms of technique as well as the materials used to build a range of buildings categorising them according to their importance in the society.
Existing examples of the historical period along with the excavation studies shows that construction materials used then were consists of mud, thatch/ leaves, timber, stones which are not only most environmental friendly materials but also sustainable to the extent that we can find their traces in today's date also. All this would have a result of careful study, analysis and application of the properties these materials posses. (Reddy, 2004)
Further evolution in material industry, use of brick and lime stone took a strategic position in building industry, which took the industry to the next level of sophistication where mankind started to experiment not only the methods of construction but also with the preparation of materials. Discovery of natural inorganic binders like pozzolian materials lead to the use of lime-pozzoland cement for construction purposes.
In today's construction, the commonly used construction materials like bricks, cement, steel, aluminium, plastic products, paints and polished stones contains high level of embodied energies and cost of transportation. Along with this, the consumption of natural materials, recycling and safe disposal are also the factors which contribute to today's un-sustainable construction environment. (Reddy, 2004)
So today, in manufacturing the basic building elements like bricks, cement, aluminium and construction steel, the total energy expenditure comes out to be 164 X 10 8 GJ per annum (2004), accounting for 22% green house gas emissions- contribution by construction sector. (Reddy, 2004)
So when it came to experiment and explore the new more sustainable materials, it became a mandate to understand the philosophy on which we have based ourselves till now for our survival. According to Hindu mythology, there have been five elements of harmonious living. When dealt with care, these elements can enlighten or destroy the balanced surrounding environment.
Space, which is called Akasha, is boundary less, defines the essence of our being. Optimising the use of space allow nature to become a seamless of our lives and vice versa. So, dealing with the building fabric becomes a issue of concern. Making the building breathable, encouraging more exchange of air, will eventually creates a healthy environment admits urban sprawl.
Air, Vayu,... associates with saying, " each time we breathe in air, we breathe in life". Using natural building material alternatives will allow building to breathe, thereby making the occupants feel the association with nature.
Fire, agni, primal, represents passion: greeting homes with locally available- low impact materials like soil- stabilized blocks, shows a belief in the possibility of preserving the energy cycle for eternity. "And no, these choices do not imply, recreating the past of returning to a simpler time, on a contrary, we are investing in forward looking future- compatible lifestyle".
Water, Jala, the elixir of life, takes many forms- rain, lake, river and oceans. "It is known to chart its own way, overcoming all obstructers with patience and persistence". Rain water harvesting and water entrained walls, water walls are some solutions to look forward to.
Earth, Bhoomi, is our planet, our mother- an intrinsic to our existence. The closer to it, the better future we endeavour. (Earth, 2009)
All the materials used in making of several building constituents have sustainable and greener solutions.( Appendix A). But if a building has to be considered as a process, then a systematic analysis of behaviour of substructure and super structure becomes mandatory. It is essential to look for greener material solutions for structure of the building( bamboo reinforced concrete),masonry used in the building(foundation and wall), and the roofing material.
With the materials, it is worth analysing the contribution of planning and construction technology for a more sustainable approach. Planning a small water pond in the surrounding of a built fabric, helps in generation of convection current and thereby cooler air circulation happens in the whole building fabric. This lowers down the ambient temperature to a considerable extent. (Green Solution Magazine, 2008)
The cavity wall insulation improves thermal efficiency and performance of a building by cutting down direct loss of heat or coolness within a building. A gap of 50 millimetres in brick masonry, treated with chemical additives can make a building wall perform much better as a thermal insulator thereby incorporating thermal mass properties. (Entries, 2010)
Bamboo reinforced concrete versus steel RCC (Reinforced cement concrete) construction
Concrete is a composite construction material having cementitious components like cement, gravels, and sand, when mixed with optimum amount of water, gives a semi liquid pourable material with high compressive strength but weak in tension.
To cater to its weakness, materials like steel bars and bamboo reinforcement are used. The combination of these makes the resulting component workable for both compressive as well as tensile forces.
The convention way of reinforcement is steel bars.
Mechanical properties of steel reinforcement:
â€¢ Typical reinforced concrete mix of Mpa 28 exhibits a compressive strength of 4,000 psi. (Wikipedia, 2010)
â€¢ Modulus of elasticity for all grades of steel is taken as Es = 2.9 x 10 6 psi
Bamboo is a light weight alternative solution to steel reinforcement at much low cost and energy consumption. It has a potential to replace steel in light construction as the tensile element in concrete design.
Availability of the material
Bamboo has a potential to grow on marginal and degraded land, elevated ground, along field bunds and river banks. It can also adapt to most climatic conditions and soil types.
Also it has a capability to act as a soil stabilizer, an effective carbon sink and helping to counter the greenhouse effect.
A good cultivation of bamboo is done in North Eastern States, the Western Ghats, Chattisgarh,M.P. and Andaman Nicobar Islands. (Bamboo for Intergrated Rural Development)
One of the facts to be considered is that bamboo which is grown in valleys are somehow less in strength when compared to bamboo grown on slopes. Also the quality and strength od bamboo varies with type of soil they are grown into. Bamboos which are grow in poor and dry soils are observed to be more solid and non- fibrous as compared to those grown in rich soils.
Mechanical Properties which make bamboo a successful reinforcement material:
Ultimate compressive strength: 8,000 psi
Allowable compressive stress : 4,000psi
Ultimate tensile strength: 18,000psi
Allowable tensile stress: 4,000 psi
Allowable bond stress: 50
Modulus of elasticity: 2.5x106
Criteria to be kept in mind for the selection of bamboo for structural purposes:
â€¢ The bamboo should have pronounced brown colour which ensures that the plant is at least three years old.
â€¢ Larger diameter bamboos should be preferred
â€¢ Avoid using whole culms of green, unseasoned bamboo.
â€¢ Avoid bamboos with cuts as they increase the moisture content within the fibres, may result in quick decay of the bamboo
The feasibility to use bamboo as a reinforcing material was first experimented at the U. S. Army Engineer Waterways Experiment Station in 1964. (Brink, 2000)
Structural Characteristics of Bamboo
Bamboo is a strong and versatile material which is renewable as well as environment-friendly. One of the unique characteristics of bamboo as a material is its strength both in tension and compression. To note, the tensile strength of the bamboo remains constant but the compressive strength increases as the member grows older. (ADAMS, 1998)
Bamboo to be used as a structural member:
Preparation of bamboo has to be taken special attention as it is an organic material and has a tendency to rot.
To split a bamboo, rather than using a sharp knife, a dulled knife is used in order to ensure that every fibre is intact. The middle cut fibres makes the bamboo weak. For seasoning; it is recommended to sun dry the bamboo for around 3 to 4 weeks before taking it in use as a structural member.
Water proofing of the bamboo is the next step to avoid bamboo to decay and swell when concrete is gaining its strength. A brush coat or dip coat of asphalt emulsion , latex, coal tar, dilute varnish, and water-glass (sodium silicate) coatings are preferred.
While placing the bamboo, it should not be placed less that 1-1.5 inches from the concrete surface. Attempt should be taken to break the vertical nodal joints wherever possible in alternate courses. Also a welding effect at every joint will tie the concrete particles to the bamboo in a better matter. For the erection of the wall or column, the fastener should embed at least 10 times the diameter of the bamboo, in order to ensure safe standing.
Wall and foundation construction
Fly ash bricks (flyash+sand+lime) solutions in comparison to fired clay bricks, cement concrete block and stone.
FLY ASH ALTERNATIVE
What is it?
"Fly ashÂ is one of the residues generated inÂ combustion, and comprises the fine particles that rise with the flue gases". (Wikipedia). According to the statistics given by press information Bureau, Government of India (2004), "In India, pulverized fly ash is a residue resulting from combustion from grounded coal or lignite.As noticed, the quantity of fly ash is continuously increasing as the power generation is being augmented. The ash generation has increased from 40 million tons in 1993-94 to 100 million tons during 2002-03 and is expected to reach 175 million tons by 2012". (India)
Fly-Ash Bricks are an environment friendly cost saving building product.
Significant features attributing to fly ash brick are:
Low water absorptionÂ
Less consumption of mortar
Low energy consumption
No emission of green house gases.
(Fly ash Brick )
Properties of Fly ash
Compressive Strength : Avg. 6 N / Sq.mm. ( As against 3.5 N/Sq. mm for handmade clay bricks )
230x150x80 mm ( Weight about 5.0 to 5.20 kgs. )
230x110x75 mm ( Weight about 3.4 to 3.60 kgs. )
Water Absorption : 8-12 % ( As against 20 to 25% for Clay Bricks)
Cement : Birla Super Cement OPC 53 Grade
Thermal Station Fly Ash
Crushed Sand / Stone Dust
Efflorescence : Nil
Density : 1700 Kg/m3
(Technical data, Fly ash Bricks India)
Since, there is much less impact of environmental conditions and they are capable of remaining static, the ensure longer life of the building is ensured. Sine these bricks show much less variation in their shape and size, there is a consistency in the quality, and the workability.
Hence, the wastage of the material is least unlike traditional clay bricks. Also, there is no wastage while getting transported and handling.
Why to use it?
As compared to conventional bricks, the fly ash bricks show a consistent strength three times more.
The ratio of strength to weight is about 3- 4 times as compared to burnt clay bricks) (Fly ash Brick )
How to use them?
Since they are as good solution as the other building materials are, with the additional properties mentioned above, these can be used as load bearing walls, party walls, interior walls and exterior walls.
"Ministry of Environment and Forests has made use of fly ash bricks mandatory within 100 km radius of coal or lignite based thermal power plants. CPWD has already used 88 lakh fly ash bricks during 2003-04 in their construction projects and also encouraging more use of such bricks/blocks."
The sourcing of this material has another story to itself. TARA, which is a leading organisation working towards sustainable technology, takes the initiative and supplies the equipment as well as the knowledge for their production. Estimating the material quantification: As per TARA estimations, to make 12,000 tiles per month, the amount to material required will be:
160 cement bags
10 cu.m of sand
5 cu.m of aggregate
two skilled staff and five workers.
This whole mechanism not only generates a better roofing material but also generate employment and skill expansion scheme. (Alternatives, Technologies)
Alternatives to Ferrous / non-ferrous sheets, tiles, thatch
The conventional materials used as a roofing material comprises of clay and concrete roof tiles. But the limitation with them is their limited lifespan and their pores development due to acid rains, pollution. According to the study done by J lowther and sons, "Erosion is also accelerated when wet tiles freeze and thaw during the winter. The increase in weight of soaked tiles adds further stress to the roof shortening its life expectancy". (Roofs coating)
On the other hand, the ferrous constituent roofing materials like SI, GI sheets have massive embodied energy in terms of manufacturing as well as in transportation.
A greener solution for this situation is micro concrete roofing tiles. Validated by Building Materials and Technology Promotion Council (BMTPC), Government of India and is promoted by Development Alternatives and TARA (Technology and Action for Rural Advancement), MCR have higher durability and more aesthetic value. As a cost effective and extremely versatile material, MCR are now widely used in cost effective housing schemes, workplaces, restaurants and poultry farms. (Alternatives).
The preparation of MCR tiles calls for carefully controlled mix of cement, sand, fine stone aggregate and water.
Advantages of MCR over other roofing materials are that they are highly cost effective with easily installation mechanism. As they are lighter that other roofing materials, they require less understructure. In additional to this they have a life span comparable to concrete. They can be coloured and painted to the choice of the user. It also helps in reducing heat gain within a building.