“It is estimated that 40-60% of urban dwellers, or more than 130 million people, live in substandard housing. While almost all of these families lack access to basic city services and remain vulnerable due to lack of property rights, there are significant income variations. Low-cost construction technology is the only option to improve this situation.”
Low cost or affordable construction technologies and materials are often touted as a panacea in meeting the ever growing demand for rapid housing delivery in developing economies like India. From the global trends in rural to urban migration, most of the developing countries are facing an enormous service backlog and massive delivery challenges in addressing its millennium development goals in the provision of housing and shelter. With growing concern over global warming and climate change, global responsibility in the consumption and production of renewable energy becomes not only a vital necessity, but a moral imperative also.This has imposed a thrust towards the use of eco-friendly materials and sustainable architecture in both developed and developing countries. However the paradox of the third world remains; that the majority of populations remain steeped in traditional construction methods. It is up to the technocrats and engineers now to educate people and implement these technologies for construction. After all it has two fold benefits one it reduces carbon footprint and the other is it reduces the cost of construction too.
Indian construction industry is one of the largest in terms of economic expenditure, volume of raw materials/natural resources consumed, volume of materials and products manufactured, employment generated, environmental impacts, etc. Large variety of materials are manufactured and consumed in the construction industry. Production of building materials has slowly and steadily moved from highly decentralized and labour intensive methods and processes to centralized, machine-dependent industry mode. Centralized mode of production necessitates hauling of raw materials and distribution of finished materials over great distances. These activities again require expenditure of fossil fuels for transportation. Transportation of raw and finished building materials is another key issue that can contribute to cost of materials, increased energy requirements and environmental issues.
Low Cost Sustainable Building Materials
Building materials and technologies, and building practices have evolved through ages. Housing and building conditions reflect the living standards of a society. Stones, mud, thatch/leaves and timber represent the earliest building materials used for the construction of dwellings. Quest for durable building materials is an ongoing phenomenon ever since man started construction activity. Brick burning represents one of the earliest examples of using energy (other than animate energy) to manufacture durable building materials from the soil/earth. Then came the manufacture of lime and lime-based products. Burnt bricks, metal products and lime are the manufactured materials (using external energy sources) commonly used for construction by our ancestors for a very long period of time. Discovery of natural inorganic binders like pozzolanic materials lead to the use of lime-pozzolana (LP) cement for construction purposes. Experience of using LP cement paved the way for the invention of Portland cement in 1824. Portland cement and steel brought revolutionary changes in the construction practices from early part of 20th century. Then plastics and plastic products entered the construction industry.
Sustainable materials are key to limiting the impact on the ecological system. Local techniques and technology, resources and materials are a good starting point when researching or implementing projects. Housing models should determine the sustainability of the building materials through lifecycle analysis, and occupational use of building including renewable energy, water, land and use of resources. Appropriate technology goes hand in hand with the design and building materials. It should correspond to local conditions, reflect and respect climatic conditions and demand a minimum of maintenance.
Commonly Available Low Cost Sustainable Building Materials:-
The success of low cost sustainable housing lies in identification and use of low cots sustainable building materials for the work. Some of the low cost sustainable building materials are discussed as below:-
1. Tire Veneer-Vehicle tires are essential used in every part across the globe.Millions of tires are discarded annually as they wear out relatively fast. This product makes use of recycling the material in to a usable material for various types of applications.The most common application is as an environmentally responsive flooring material – resilient both indoors and out. Areas of use extend to areas such as sports and recreation,animal housing and high traffic areas outdoors – anda variety of consumer products, vibration dampeners and furniture surfaces internally. Refer Figure 1.
2. Straw and Resin Panels-These are made from agricultural waste, such as straw.A binder is applied that is made up of local resins to form insulating panels that can be easily installed under and between existing corrugated metal sheeting and lightweight corrugated iron currently being used as roofing in almost all third world countries. The technology and construction method also mitigates added casualties when the region experiences earthquakes, as heavy earthen roofs often collapse and bury those inside. With the manufacturing is able to be carried out locally with already available materials to meet the growing needs, there is an opportunity for business creation and income generation. Refer Figure 2.
3. Flax Insulation- Flax is a plant native to the region extending from the eastern Mediterranean to India and China, and was once extensively cultivated in Egypt – today flax fibers are amongst the oldest fiber crops in the world. The fiber has is soft, flexible, stronger than cotton but not as elastic. Natural insulation can be made from 100% flax fibers by matting them together into a non-woven process and then utilizing their properties for insulation in lofts or wall cavities. Refer Figure 3.
4. Wood Fiber Insulation-Wood fiber insulation panels are made from 100% pulped wood fiber with no added harmful chemicals or materials, using the dry manufacturing process there is no water treatment necessary and energy costs are low. There are various types of wood fiber insulation for different uses and purposes – floor and roof insulation and internal/external wall insulation. The thermal conductivity values range from 0.04 – 0.05 W/mK. They protect against cold in the winter and heat in the summer. Refer Figure 4.
5. Warmcel-Warmcel is an insulating material. These are basically cellulose fibers extracted from 100% recycled newspaper with natural mineral additives that make it insect, rodent and fire resistant. It consumes minimal energy to manufacture, is non-toxic and can be disposed up without any biodegradability problems. Refer Figure 5.
6. Corkoco- These are a panel made of combination cork and bioecologic coconut fiber, mainly used for acoustic insulation. The performance is specialized in providing acoustic insulation and insulation – for installation in attics, gaps, between rooms or apartments. Refer Figure 6.
7. Thermafleece- Thermafleece is an alternative type of home insulation, for applications in roofs, walls and floor construction. Only 14% of embodied energy is used in comparison to common fiberglass insulation. The material is intended for use as an insulator in home construction. The material is made from wool, offering a naturally higher fire resistance than cellulose and plastic insulates. Refer Figure 7.
8. Natural touch cotton fiber insulation – This insulation is made of different type of composite, offering excellent performance qualities with regards to heating and sound absorption for residential applications. The material comes in rolls, and is applied directly to walls, roofs and floors in homes. The insulation contains 85% post-industrial recycled natural fibers, most of which are sourced from denim manufacturers giving the blue color. Refer Figure 8.
9. Rice husk ash/ Pozzolanas- Pozzolanas are materials containing reactive silica and/or alumina, which in their own right have little binding ability. Yet, when mixed with lime and water it will set and harden like cement. They are important ingredients in alternative cement compounds, making a significant contribution towards low-cost materials. Rice husks are a large by product one ton is produces per five ton of rice paddies, and it is estimated that 120 million tons of husk could be available annually on a global basis. Rice is a major crop in many third world countries including China and the Indian sub-continent, South-east Asia and in some regions of Africa and South America. Weight for weight, rice husk contains an energy value about half that of coal, and is therefore an important energy source, though it must be consumed close to natural production as transportation is a very unviable option. Only 20% of its weight may be utilized as a pozzolana. The success of using rice husks depends on the self-construction of individual ovens. With the ovens, this method would be sufficient and successful, making rice husk ash an affordable and sustainable alternative to cement.
10. Recycled materials in concrete- Though this is a very good sustainable concept owing to its environmental and cost advantages yet there is limited development and research regarding the inclusion of waste or industrial by-products in the makeup of concrete building materials. One risk of incorporating recycled materials into the compound is a lack of homogeneity and the chance of contamination that in general lower the quality of the product. There is evident opportunity for further engineering and research testing of new cement products containing waste, focusing on durability and the binding capability crucial for their viability.
11. Concrete canvas- Concrete canvas is exactly what its name says – canvas impregnated with concrete power. With a wide range of applications, it is an extremely valuable solution to both short term emergency response and long term installations. The material is a 3-dimensional fiber matrix containing a specially formulated dry concrete mix.
12. Magnesium oxide cement- Magnesium oxide cement is often referred to as ‘eco-cement’ as it has been engineered to incorporate a large proportion of waste materials while retaining highly durable qualities for construction. Magnesium deposits are found worldwide and cover roughly 8% of the earth’s surface and phosphates are available from rock, animal wastes and fermented plants. Depending on where they are mined, magnesium oxide and magnesium choloride cements require only 20-40% of the energy required to produce Portland cement. Magnesium-based cements are proven exceptional in promoting the health for occupants of homes in which they are used as the prime building material. Refer Figure 9.
13. Fly Ash Technology – Flash Bricks
Fly ash is a fine, toxic powder produced as a byproduct from coal-burning power plants. In India alone, approximately 100 million tones are generated per year, while 200 million tones are produced in China. The Indian Government took action in 2005, requiring 25 percent of the fly ash to be used in the manufacturing of clay bricks for construction within a 50 km radius of the original coal plant source. Bricks can be manufactured entirely from waste fly ash, formally referred to as Flash Bricks. The manufacturing process traps any harmful chemicals to reduce generated greenhouse gases. The materials properties include being 28 percent lighter and 24 percent stronger than comparable clay bricks. A separate aggregate called Flashag, a concrete can be made that is 22 percent lighter and 20 percent stronger than standard products. Refer Figure 10a and 10b.
14. Cannabrick- Cannabrick is derived from the cannabis plant – using the woody inner core as a material element for construction. This part of the plant is free of THC and used primarily for construction in the housing sector. Performance is excellent against fire and water, as silica leached from the soil through the plant, combined with unabsorbed lime makes a chemical bond similar to cement – and cannabis cement requires lime.
15. Syndecrete- Syndecrete is a version of concrete that uses natural minerals and recycled materials as aggregate. Fly ash is also part of the compound, an environmental material that conserves natural resources and prevents the production of typical concrete contents by resourcing waste from coal production. There are a variety of domestic applications – tiles, sinks, countertops and slabs. The manufacturing process utilizes fly ash. This method requires less water and gives better durability and workability when compared to typical concrete. Refer Figure 11.
16. TX Active- TX Active is also known an‘pollutant-eating’ cement. It is a photocatalytic cement that works to reduce organic and inorganic pollutants present in the air. A case study illustrates the Milan example, where if by 15% of the visible urban surfaces was a material containing TX Active, it would cause an approximate reduction in pollution by 50%. Scientific laboratory results have shown that three minutes of sun exposure is sufficient to obtain a reduction of polluting agents up to 75%. Refer Figure 12.
17.Bendable Concrete –Its is a new type of concrete and is developed by the University of Michigan. The fiber-reinforced bendable concrete is 500 times more resistant to cracking, and weighs 40 percent less. The compound is made up of 2 percent fiber, designed for maximum flexibility. The costs and overall emissions are estimated to be lower as a result of its long lifespan. Refer Figure 13.
18. Grancrete – Grancrete is a spray applied to Styrofoam walls, of which it adheres to and cures within 15 minutes. With properties proven to perform better than concrete, such as it being stronger, fire resistant, able to withstand both tropical and sub-freezing temperatures and ideal for a range of geographic locations, this is ideal for the construction of low-cost housing. Grancrete makes use of the natural resources such as soil and ash found in nearly every village, it is made of 50 percent sand or sandy soil, 25 percent ash and 25 percent binding material – the binding material consisting of magnesium oxide and potassium phosphate, with the latter being a biodegradable element in fertilizer. After two days of training on how to control and calibrate the machinery, the house may be fully assembled in another two day period. Refer Figure 14.
19. Earth blocks –Burnt brick production requires approximately huge energy. The brick industry in India produces 22% of the CO2 emissions by the construction sector and requires about 27% of the energy used in building material production. The production of simple earth blocks only requires around one thousand of the energy needed to fire bricks, and even in cases where earth is stabilized with cement it is no more than a sixth per kg of material. Refer Figure 15.
20. Ecobrique – The Ecobrique is a French revolution in brick making by vBc 3000. It is a ceramic product made from partially dried sewage sludge by incorporating waste treatment plant residue in the clay matrix. The lightweight material is just as durable as the traditional counterpart – being fired in traditional kilns or rotary furnaces. Throughout this process, the organic matter creates porosity and expansion in the material, this is where it lightens and gives good properties of heat insulation and soundproofing. Refer Figure 16.
21. Accoya Wood – Accoya is a new type of wood species, well researched with repeatedly demonstrated high performance qualities. The technical properties of the wood have been improved based on a process of acetylation, studied by scientists for more than 75 years. The process alters the actual cell structure of the wood by transforming free hydroxyl groups into acetyl groups – hydrogen, oxygen and carbon already present in all wood types. Refer Figure 17.
22. Dakota Burl – Dakota Burl composite is a unique bio-based material, which exhibits the same aesthetic qualities of traditional burled woods. The material is created from an agricultural fiber and sunflower hulls and can be worked using standard woodworking tools. The material is primarily for interior use, such as tables and counters, cabinetry, furniture and similar architectural applications. Refer Figure 18.
Benefits of Using Low Cost Sustainable Building Materials
The environment friendly building materials are composed of renewable, rather than non-renewable resources. Use of these materials provides the following benefits.
1. Resource Efficiency – benefits like high recycled content, naturally available, efficient manufacturing processes, locally available, high salvage potential, reusable and highly durable.
2. Indoor Air Quality – Selection of the materials with benefits like low/ non-toxic, minimum emissions, low VOC content, moisture resistant and healthfully maintained.
3. Energy Efficiency – Selection of the materials with benefits like reduction in energy consumption in buildings and facilities etc.
4. Water conservation – Selection of materials with benefits like reduction in water use in buildings and conserve water in landscape areas.
5. Affordability – Is considered to compare the eco-friendly building materials to conventional materials within a defined percentage of the overall budget of the building.
Apart from the above benefits, using these materials have the following advantages also:
– These have similar or low price compared to conventional building materials when total life cycle cost is assessed
– These does not exhaust the existing supplies of finite materials
– These materials save energy and reduce harmful emissions
– These materials helps in reducing environmental degradation
– These materials are encouraged by building promotion council, so planning/ building permissions are easy to get
– Since they are less harmful to occupants, they make healthier and safer buildings
Table Below shows conventional building materials vs sustainable building materials.
While many sustainable building materials and technologies do cost more, it has been demonstrated that many green strategies and technologies actually cost the same and some even cost less than traditional “not-so-green” technologies.By blending the right mix of green technologies that cost less with green technologies that cost the same or slightly more, it is possible to have a very green building project that costs the same as a conventional one.Often the key to a cost effective green building and site design lies within the interrelationships and associated cost and performance trade-offs that exist between different building systems.
It is understandable that economic growth leads to rise in income but this has led to even faster rise in property prices leaving it unaffordable for majority of population. Affordable housing is expected to have a positive impact by improving basic quality of life. While the concept of affordable housing seems to be a simple solution to current housing woes, its execution remains complicated due to the unclear policy framework. To make affordable housing work in India, it would require “will” from all the stakeholders by slightly adjusting their interests towards a wider social cause. The first step towards making low cost housing should be making available low cost sustainable building materials for common people. Government and research institutes and construction companies should join in to bridge the gap between common people and such techniques. As more companies and clients become environmentally aware and request the specification of sustainable low cost building products in their facilities and as natural resources are depleted, manufacturers will respond to increased demand and the necessity to develop such sustainable products.
“The future looks green for low cost sustainable building materials as they contribute towards a more sustainable future on our resource limited mother earth”
– ICAEN 2004, Sustainable Building Design Manual, Volume 2, The Energy & Resources Institute (TERI), New Delhi
– National Building Code (NBC) of India 2005, Bureau of Indian Standards (BIS), New Delhi
– Manual on norms & standards for environmental clearance of large construction projects, Ministry of Environment & Forests (MoEF), Government of India, New Delhi.
– GRIHA 2008, National Rating System – Green Rating for Integrated Habitat Assessment (GRIHA), Ministry of New & Renewable Energy (MNRE), Government of India and The Energy Resources Institute (TERI), New Delhi
– Eco Housing Assessment Criteria 2006, International Institute of Energy Conservation (IIEC), Mumbai
– Guide for sustainable building design, Ministry of Non-conventional Energy Sources (MNRE), Government of India and The Energy Resources Institute (TERI), New Delhi
– The Construction Specifier
– Other Internet Source and all Original Manufacturers and Patent Holders.