GREEN TECHNIQUES IN BUILDING CONSTRUCTION (CONCEPT) Hema. C, Assistant professor, Department of Civil engineering, Bharath University

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1 ABSTRACT GREEN TECHNIQUES IN BUILDING CONSTRUCTION (CONCEPT) Hema. C, Assistant professor, Department of Civil engineering, Bharath University Green buildings refer to a structure and using the process that is environmentally responsible and resource efficient throughout the building s life-cycle. Constructing and operating building requires enormous amounts of energy, water and materials and creates large amounts of waste. Where and how they are built affects the ecosystem around us in countless ways. To avoid these problems green buildings are constructed. "A green building uses less energy, water and natural resources, creates less waste and is healthier for the people living inside compared to a standard building." There is a rapidly expanding market for green building materials. Green building provide suitable environment by controlling solar radiation temperature, energy efficiency, water conservation using domestic treatment plant and indoor air quality. The main aim of green buildings is to reduce the environmental impact of new buildings. The sustainability in the environment can be well achieved by reducing the energy emission and consumption by the buildings. Sustainability means using the energy efficiently. Green Building refers to a structure that is environmentally responsible and resource-efficient throughout a building's life-cycle. Solar panels and Photo voltaic cells are used to produce efficient energy. Green buildings are also known as Green construction or Sustainable buildings. The best technique that is adapted to this type of buildings is Rat-Trap Bond Wall technique. Green buildings are highly efficient buildings when compared to conventional buildings. The different types of waste produced in the conventional buildings are much reduced in these types of buildings. Green building ISSN: Page 27

2 provides several benefits over other buildings. Economic, ecological and environmental benefits are most important in these buildings. INTRODUCTION: Green building standards focus on making residential and commercial buildings more environmentally friendly, sustainable and healthier for their occupants. Many builders and designers are implementing green building standards into their designs to create buildings that use environmentally friendly materials where are highly energy efficient and have excellent air quality. The basic principles of sustainable design or green design as it is popularly known, are to aim for maximum resource conservation, to enhance efficient utilization of nonrenewable resources by adopting efficient systems, and to maximize use of renewable forms of energy as well as to recycle and reuse resources. These principles need to be applied throughout the building life-cycle e.g. during the site planning and development stage, building planning and construction, and building operation and maintenance. GREEN BUILDING is one that incorporates the use of clean and renewable energy, efficient use of water and use of recycled or recyclable materials, and provides for healthy indoor air quality. Buildings are responsible for 40 per cent of the world's energy consumption. The green building concept helps to conserve energy. Today the world requires high performance, low energy buildings offering long-term sustainability. GREEN FEATURES: It includes natural lighting in the building, which results in substantial savings in energy consumption. Insulated walls and double-glazed glass windows for lower energy consumption. A green lawn around the building improves the quality of air inside the building premises. Use of non-toxic house-keeping materials - green seal approved products. Natural manure for plants such as neem-based pesticides. Water recycling. SUSTAINABLE FEATURES: Buildings achieve a 50% reduction in energy use and purchase their electrical power from a renewable energy supplier. The building incorporates many energy-conserving features: a well insulated building shell energy efficient window systems ISSN: Page 28

3 supplemental passive solar heating extensive use of natural ventilation and day lighting. ECO-FRIENDLY BUILDING: Phenomenal growth in the construction industry depends upon exhaustible resources. Production of building materials leads to irreversible environmental impacts. Using ecofriendly materials is the best way to build an ecofriendly building. Rat-Trap bond wall technique is provided in these types of buildings. RAT TRAP BOND WALL: It is a cavity wall construction is a modern technique that offers unique combination of strength lightweight thermal and sound insulation fix resistance and resistance to water penetration and reduction in the quantity of bricks required for masonry work. The main features of Rat-trap bond wall are: Strength is equal to standard 10" (250mm) brick wall, but consumes 20% less bricks. The air medium or cavity created in between the bricklayers helps in maintaining a good thermal comfort inside the building. This phenomenon is particularly helpful for tropical climate of South Asian and other countries. As the construction is done by aligning the bricks from both sides with the plain surfaces facing outwards, plastering is not necessary except in a few places. The finished surface is appealing to the eye from both internally & externally, Buildings up to two stories can easily be constructed with this technique. Mr. Laurie Baker has pioneered this type of construction and had built such houses more than 40 years ago without having any signs of distress till now. ISSN: Page 29

4 In R.C.C. framed structures, the filler walls can be made of rat-trap bond. Due to lesser load on the base of the walls, the width of foundation is also decreased, resulting in a saving of about 8% on use of bricks, cement and sand in foundation and plinth. There is reduction in cost of the wall by 25%, as with conventional English bond (9 thk wall) 350 bricks are required per cu. m whereas in Rat-trap bond only 280 bricks are required and also the reduced number of joints reduces the mortar consumption. SITE PLANNING AND DESIGN OF GREEN BUILDINGS: Development of a site for building purposes requires disruption and disturbance of existing natural systems. The most sustainable and environment sensitive development is one that requires very minimal site disturbance. Resource conservation measures pertaining to site planning should entail minimum disturbance and depletion. Some recommended measures to achieve efficient site planning are given below. Preserve and protect vegetation and soil from degradation during construction. Reduce hard paving. Enhance site lighting efficiency and avoid light trespass / light pollution. A) Preserve and protect vegetation and soil from degradation during construction: Preservation and protection of existing vegetation, particularly mature trees, is highly recommended. This is done by avoiding cut and fills in the root zones, delineating and fencing the drip line of all trees or a group of trees. Trees should also protect against damages from carving, nailing, fires or heat emitting construction activity. The top soil, in most cases, is the most nutrient rich layer that supports vegetative growth. Topsoil removal and preservation should be mandatory for projects with site area greater than 10000sq.m. The preserved topsoil should to be re-laid for vegetative growth through a suitable process, after ensuring its nutrient contents as per laid out codes and standards. Suitable measures such as contour ISSN: Page 30

5 trenching, mulching to prevent soil erosion and runoff should also be taken. B) Reduce hard paving: Hard paved parking lots, pathways, plazas and courts should be minimized. Hard paved areas enhance imperviousness of the sit and generate a heat island effect, which causes a sharp microclimate temperature rise. By reducing penetrability of the site, hard paving also lowers the localized aquifer recharge potential. Dark colored and constructed surfaces absorb solar energy and radiate it back when the ambience is cooler. So, typically one find a sharp temperature rise in built urban areas than in green areas. Thus, design strategies should look at a combination of soft and hard landscape, use of pervious paving, use of light colored surfaces with higher solar reflective index, shaded hard paved surfaces. Planting trees and bushes adequately also help to minimize the heat island effect. such as sidewalks, parking lots, roads, community gathering spaces, landscaped areas and for security purposes. It must be carefully designed to avoid waste and nuisance. It must address a few basic standards such as- it should avoid over luminance; it should be properly shielded to avoid light pollution; the optical control of light is also critical. Light pollution can be defined as waste light emanating from building sites that produces glare and adversely affects the environment. Waste light does not contribute to increased night time safety, utility or security and needlessly consumes energy. Light pollution can also potentially disrupt biological c cycles in plants, animals, including humans. C) Enhance site lighting efficiency and avoid light trespass / light pollution: Site lighting is mainly used to illuminate connections between buildings and support facilities ENERGY EFFICIENCY: ISSN: Page 31

6 One of the primary requirements of a green building is that it should have optimum energy performance and yet should provide the desirable thermal and visual comfort.energyefficiencycan be maximized by utilizing materials components, and systems that help reduce energy consumption in buildings and facilities. To increase the efficiency of the building envelope, they may use high-efficiency windows and insulation in walls, ceilings, and floors. Another strategy, passive solar building design, is often implemented in low-energy homes. In addition, effective window placement can provide more natural light and lessen the need for electric lighting during the day. Solar water heating further reduces energy loads. Onsite generation of renewable energy through solar power, wind power, hydro power, or biomass can significantly reduce the environmental impact of the building. MATERIAL EFFICIENCY: Efficient use of building materials & land apart from the reduction in initial costs will also result in lowering the overall life cycle cost. Building materials, components and systems found locally or regionally which saves energy and resources in transportation to the project site. Select materials that can be easily dismantled and reused or recycled at the end of their useful life. Building materials typically considered to be 'green' rapidly renewable plant materials like bamboo and straw, lumber from forests certified to be sustainably managed ecology blocks, dimension stone, recycled stone, recycled metal, and other products that are non-toxic, reusable, and renewable. The EPA (Environmental Protection Agency) also suggests using recycled industrial goods, such as coal combustion products, foundry sand, and demolition debris in construction projects. Building materials should be extracted and manufactured locally to the building site to minimize the energy embedded in their transportation. Brick Waste &waste cement mortar are re used. Steel & empty cement bags were sold to local vendors for recycling. WATER EFFICIENCY: Reducing water consumption and protecting water quality are key objectives in ISSN: Page 32

7 sustainable building. -water may be minimized by utilizing water conserving fixtures such as ultra-low flush toilets and low-flow shower heads. Point of use water treatment and heating improves both water quality and energy efficiency while reducing the amount of water in circulation. INDOOR AIR QUALITY (IAQ): IAQ can be affected by microbial contaminants (bacteria), gases (including carbon monoxide, radon and volatile organic compounds), particulates, or any mass or energy stressor that can induce adverse health conditions. Indoor air is becoming an increasingly more concerning health hazard than outdoor air. Indoor Air Quality (IAQ) is enhanced by utilizing materials that meet the following criteria: Low or non-toxic: Materials that emit few or no carcinogens, reproductive toxicants, or irritants as demonstrated by the manufacturer through appropriate testing. Moisture resistant: Products and systems that resist moisture or inhibit the growth of biological contaminants in buildings. Systems or equipment: Products that promote healthy IAQ by identifying indoor air pollutants or enhancing the air quality. It can be accomplished by utilizing materials that meet the following criteria: Natural, plentiful or renewable:materials harvested from sustainably managed sources and preferably have an independent certification (e.g., certified wood) and are certified by an independent third party. Resource efficient manufacturing process: Products manufactured with resourceefficient processes including reducing energy consumption, minimizing waste (recycled, recyclable and or source reduced product packaging), and reducing greenhouse gases. Recycled Content: Products with identifiable recycled content, including post industrial content with a preference for post consumer content. Resource availability: Building materials, components, and systems found locally or regionally saving energy and resources in transportation to the project site. WASTE REDUCTION: Green architecture also seeks to reduce waste of energy, water and materials used during construction. During the construction phase, one goal should be to reduce the amount of material going to landfills. Well-designed buildings also help RESOURCE EFFICIENCY: ISSN: Page 33

8 reduce the amount of waste generated by the occupants as well, by providing on-site solutions economic buildings. and environmental performance of To reduce the impact on wells or water treatment plants, several options exist. "Grey water", wastewater from sources such as dishwashing or washing machines, can be used for subsurface irrigation, or if treated, for non-potable purposes, e.g., to flush toilets such as compost bins to reduce matter going to landfills and wash cars. Rainwater collectors are used for similar purposes. Centralized wastewater treatment systems can be costly and use a lot of energy. An alternative to this process is converting waste and wastewater into fertilizer, which avoids these costs and shows other benefits. By collecting human waste at the source and running it to a semi-centralized biogas plant with other biological waste, liquid fertilizer can be produced. Practices like these provide soil with organic nutrients and create carbon sinks that remove carbon dioxide from the atmosphere, offsetting greenhouse gas emission. BENEFITS OVER OTHER BUILDINGS: Green buildings provide several benefits over other buildings. Buildings have an enormous impact on the environment, human health, and the economy. The successful adoption of green building strategies can maximize both the Cost Savings: Energy and water efficient designs reduce monthly utility bills. Health & Safety: Proper ventilation and low or non-toxic materials and finishes contribute to a safer, healthier home. Added Value: Use of durable green materials, lower operating costs, and healthier indoor air quality can increase a building's market value. Ecological Benefit: Making environmentally responsible choices when building helps reduce pollution while protecting forests and wildlife. Environmental Benefit: Reduce impact on the environment. Economic Benefit: When compared to conventional buildings green buildings are more economic and cheap in cost. OCCUPANT HEALTH AND SAFETY: Recent studies reveal that buildings with good overall environmental quality can reduce the rate of respiratory disease, allergy, asthma, sick building symptoms, and enhance worker performance. Choose construction materials and interior finish products with zero low emissions to improve indoor air quality. Many building ISSN: Page 34

9 materials and cleaning/maintenance products emit toxic gases, such as volatile organic compounds (VOC) and formaldehyde. These gases can have a detrimental impact on occupants' health and productivity. Provide adequate ventilation and a high-efficiency, in-duct filtration system. Heating and cooling systems that ensure adequate ventilation and proper filtration can have a dramatic and positive impact on indoor air quality. Prevent indoor microbial contamination through selection of materials resistant to microbial growth, provide effective drainage from the roof and surrounding landscape, install adequate ventilation in bathrooms, allow proper drainage of air-conditioning coils, and design other building systems to control humidity. GOALS OF GREEN BUILDINGS: Operational Savings: Green buildings consume at least % less energy and % less water than a conventional building. This comes at an incremental cost of about 5-8 %. The incremental cost gets paid back in 3-5 years time. Daylights & Views: Working in environment with access to daylight and views provides connection to the exterior environment. This has a soothing effect on the mind. Various studies prove that the productivity of people who have access to day lighting and views is at least % higher. Air Quality: Green buildings are always fresh and healthy. The green buildings use interior materials with low volatile organic compound (VOC) emissions. A typical office building would require purging of fresh air which provides a fresh ambience inside the building. ADVANTAGES: Provide a healthier and more comfortable environment Improve long-term economic performance Incorporate energy and water efficient technologies Use recycled content materials in their construction Reduce construction and demolition waste Include renewable energy technologies Improve indoor air quality Reduce environmental impact DISADVANTAGES: While homeowners who live close to larger cities may have no difficulty finding green building materials, the selection may be scarce in other areas. Many materials may require special ordering, which could increase the cost. In addition, some materials ISSN: Page 35

10 may only be available through orders, which will include a cost for shipping and handling. Since some green building projects encourage the use of recycled and found materials, time may become a disadvantage. Finding the needed materials may take extra time that the builder and/or homeowner doesn't have for the project. CONCLUSION: Although new technologies are constantly being developed to complement current practices in creating greener structures, the common objective is that green buildings are designed to reduce the overall impact of the built environment on human health and the natural environment. Sustainability in building construction is very important now-days, since the earth is becoming non-green. Now-a-days everyone is looking for the concept Go Green.This can be achieved by lowering the energy demand and consumption of materials, utilizing the reusable or recyclable products in a holistic way which will eventually offer an economic and cost effective sustainable living environment. REFERENNCES: ISSN: Page 36