Green Buildings-reduce resue and recycle


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Water conservation by Rainwater Harvesting systems – Treatment of waste water : Physical,Chemical and
Biological methods – Root Zone treatment - Use of recycled water.
Use of Environment friendly materials, Embodied Energy of materials, Bio degradable materials. Recycling
and Reuse of steel, Aluminium and Glass.

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Green Buildings-reduce resue and recycle

  1. 1. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 1 UNIT-4 REDUCE, RECYCLE AND REUSE 9 Water conservation by Rainwater Harvesting systems – Treatment of waste water : Physical,Chemical and Biological methods – Root Zone treatment - Use of recycled water. Use of Environment friendly materials, Embodied Energy of materials, Bio degradable materials. Recycling and Reuse of steel, Aluminium and Glass. WATER CONSERVATION BY RAINWATER HARVESTING SYSTEMS In the present scenario management and distribution of water has become centralized. People depend on government system, which has resulted in disruption of community participation in water management and collapse of traditional water harvesting system. As the water crisis continues to become severe, there is a dire need of reform in water management system and revival of traditional systems. Scientific and technological studies needs to be carried out to assess present status so as to suggest suitable mitigative measures for the revival to traditional system/wisdom. Revival process should necessarily be backed by people's initiative and active public participation. Living creatures of the universe are made of five basic elements, viz., Earth, Water, Fire, Air and Sky, Obviously, water is one of the most important elements and no creature can survive without it. Despite having a great regard for water, we seem to have failed to address this sector seriously. Human being could not save and conserve water and it sources, probably because of its availability in abundance. But this irresponsible attitude resulted in deterioration of water bodies with respect to quantity and quality both. Now, situation has arrived when even a single drop of water matters. However. " better late than never", we have not realized the seriousness of this issue and initiated efforts to overcome those problems. System of collecting rainwater and conserving for future needs has traditionally been practiced in India. The traditional systems were time-tested wisdom of not only appropriate technology of Rainwater Harvesting, but also water management systems, where conservation of water was the prime concern. Traditional water harvesting systems were Bawaries, step wells, jhiries, lakes, tanks etc. These were the water storage bodies to domestic and irrigation demands. People were themselves responsible for maintenance to water sources and optimal use of water that could fulfill their needs.
  2. 2. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 2 What is Rainwater harvesting? The term rainwater harvesting is being frequently used these days, however, the concept of water harvesting is not new for India. Water harvesting techniques had been evolved and developed centuries ago. Ground water resource gets naturally recharged through percolation. But due to indiscriminate development and rapid urbainzation, exposed surface for soil has been reduced drastically with resultant reduction in percolation of rainwater, thereby depleting ground water resource. Rainwater harvesting is the process of augmenting the natural filtration of rainwater in to the underground formation by some artificial methods."Conscious collection and storage of rainwater to cater to demands of water, for drinking, domestic purpose & irrigation is termed as Rainwater Harvesting." Why harvest rainwater ? This is perhaps one of the most frequently asked question, as to why one should harvest rainwater. There are many reasons but following are some of the important ones.  To arrest ground water decline and augment ground water table  To beneficiate water quality in aquifers  To conserve surface water runoff during monsoon  To reduce soil erosion  To inculcate a culture of water conservation How to harvest rainwater: Broadly there are two ways of harvesting rainwater: (i) Surface runoff harvesting (ii) Roof top rainwater harvesting Surface runoff harvesting: In urban area rainwater flows away as surface runoff. This runoff could be caught and used for recharging aquifers by adopting appropriate methods. Roof top rainwater harvesting (RTRWH): It is a system of catching rainwater where it falls. In rooftop harvesting, the roof becomes the catchments, and the rainwater is collected from the roof of the house/building. It can either be stored in a tank or diverted to artificial recharge system. This method is less expensive and very effective and if implemented properly helps in augmenting the ground water level of the area. Components of the roof top rainwater harvesting system The illustrative design of the basic components of roof top rainwater harvesting system is given in the following typical schematic diagram/ The system mainly constitutes of following sub components:  Catchment  Transportation  First flush  Filter
  3. 3. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 3 Catchment The surface that receives rainfall directly is the catchment of rainwater harvesting system. It may be terrace, courtyard, or paved or unpaved open ground. The terrace may be flat RCC/stone roof or sloping roof. Therefore the catchment is the area, which actually contributes rainwater to the harvesting system. Transportation Rainwater from rooftop should be carried through down take water pipes or drains to storage/harvesting system. Water pipes should be UV resistant (ISI HDPE/PVC pipes) of required capacity. Water from sloping roofs could be caught through gutters and down take pipe. At terraces, mouth of the each drain should have wire mesh to restrict floating material. First Flush First flush is a device used to flush off the water received in first shower. The first shower of rains needs to be flushed-off to avoid contaminating storable/rechargeable water by the probable contaminants of the atmosphere and the catchment roof. It will also help in cleaning of silt and other material deposited on roof during dry seasons Provisions of first rain separator should be made at outlet of each drainpipe. Filter There is always some skepticism regarding Roof Top Rainwater Harvesting since doubts are raised that rainwater may contaminate groundwater. There is remote possibility of this fear coming true if proper filter mechanism is not adopted. Secondly all care must be taken to see that underground sewer drains are not punctured and no leakage is taking place in close vicinity. Filters are used fro treatment of water to effectively remove turbidity, colour and microorganisms. After first flushing of rainfall, water should pass through filters. There are different types of filters in practice, but basic function is to purify water. Sand Gravel Filter These are commonly used filters, constructed by brick masonry and filleted by pebbles, gravel, and sand as shown in the figure. Each layer should be separated by wire mesh. Charcoal Filter Charcoal filter can be made in-situ or in a drum. Pebbles, gravel, sand and charcoal as shown in the figure should fill the drum or chamber. Each layer should be separated by wire mesh. Thin layer of charcoal is used to absorb odor if any.
  4. 4. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 4 PVC- Pipe filter This filter can be made by PVC pipe of 1 to 1.20 m length; Diameter of pipe depends on the area of roof. Six inches dia. pipe is enough for a 1500 Sq. Ft. roof and 8 inches dia. pipe should be used for roofs more then 1500 Sq. Ft. Pipe is divided into three compartments by wire mesh. Each component should be filled with gravel and sand alternatively as shown in the figure. A layer of charcoal could also be inserted between two layers. Both ends of filter should have reduce of required size to connect inlet and outlet. This filter could be placed horizontally or vertically in the system. Sponge Filter It is a simple filter made from PVC drum having a layer of sponge in the middle of drum. It is the easiest and cheapest form filter, suitable for residential units.
  5. 5. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 5 METHODS OF ROOF TOP RAINWATER HARVESTING Storage of Direct use In this method rain water collected from the roof of the building is diverted to a storage tank. The storage tank has to be designed according to the water requirements, rainfall and catchment availability. Each drainpipe should have mesh filter at mouth and first flush device followed by filtration system before connecting to the storage tank. It is advisable that each tank should have excess water over flow system. Excess water could be diverted to recharge system. Water from storage tank can be used for secondary purposes such as washing and gardening etc. This is the most cost effective way of rainwater harvesting. The main advantage of collecting and using the rainwater during rainy season is not only to save water from conventional sources, but also to save energy incurred on transportation and distribution of water at the doorstep. This also conserve groundwater, if it’s being extracted to meet the demand during rains. Recharging ground water aquifers Ground water aquifers can be recharged by various kinds of structures to ensure percolation of rainwater in the ground instead of draining away from the surface. Commonly used recharging methods are:- a) Recharging of bore wells b) Recharging of dug wells. c) Recharge pits d) Recharge Trenches e) Soak ways or Recharge Shafts f) Percolation Tanks Recharging of bore wells Rainwater collected from rooftop of the building is diverted through drainpipes to settlement or filtration tank. After settlement filtered water is diverted to bore wells to recharge deep aquifers. Abandoned bore wells can also be used for recharge. Optimum capacity of settlement tank/filtration tank can be designed on the basis of area of catchement, intensity of rainfall and recharge rate as discussed in design parameters. While recharging, entry of floating matter and silt should be restricted because it may clog the recharge structure. "first one or two shower should be flushed out through rain separator to avoid contamination. This is very important, and all care should be taken to ensure that this has been done."
  6. 6. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 6 Recharging of dug wells Dug well can be used as recharge structure. Rainwater from the rooftop is diverted to dug wells after passing it through filtration bed. Cleaning and desalting of dug well should be done regularly to enhance the recharge rate. The filtration method suggested for bore well recharging could be used. Recharge Pits Recharge pits are small pits of any shape rectangular, square or circular, contracted with brick or stone masonry wall with weep hole at regular intervals. to of pit can be covered with perforated covers. Bottom of pit should be filled with filter media. The capacity of the pit can be designed on the basis of catchment area, rainfall intensity and recharge rate of soil. Usually the dimensions of the pit may be of 1 to 2 m width and 2 to 3 m deep depending on the depth of pervious strata. These pits are suitable for recharging of shallow aquifers, and small houses.
  7. 7. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 7 Recharge Trenches Recharge trench in provided where upper impervious layer of soil is shallow. It is a trench excavated on the ground and refilled with porous media like pebbles, boulder or brickbats. it is usually made for harvesting the surface runoff. Bore wells can also be provided inside the trench as recharge shafts to enhance percolation. The length of the trench is decided as per the amount of runoff expected. This method is suitable for small houses, playgrounds, parks and roadside drains. The recharge trench can be of size 0.50 to 1.0 m wide and 1.0 to 1.5 m deep. Soak away or Recharge Shafts Soak away or recharge shafts are provided where upper layer of soil is alluvial or less pervious. These are bored hole of 30 cm dia. up to 10 to 15 m deep, depending on depth of pervious layer. Bore should be lined with slotted/perforated PVC/MS pipe to prevent collapse of the vertical sides. At the top of soak away required size sump is constructed to retain runoff before the filters through soak away. Sump should be filled with filter media. Percolation tanks Percolation tanks are artificially created surface water bodies, submerging a land area with adequate permeability to facilitate sufficient percolation to recharge the ground water. These can be built in big campuses where land is available and topography is suitable. Surface run-off and roof top water can be diverted to this tank. Water accumulating in the tank percolates in the solid to augment the ground water. The stored water can be used directly for gardening and raw use. Percolation tanks should be built in gardens, open spaces and roadside green belts of urban area.
  8. 8. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 8 Do's and Don’ts Harvested rainwater is used for direct usage or for recharging aquifers. It is most important to ensure that the rainwater caught is free from pollutants. Following precautionary measures should be taken while harvesting rainwater:-  Roof or terraces uses for harvesting should be clean, free from dust, algal plants etc.  Roof should not be painted since most paints contain toxic substances and may peel off.  Do not store chemicals, rusting iron, manure or detergent on the roof.  Nesting of birds on the roof should be prevented.  Terraces should not be used for toilets either by human beings or by pets.  Provide gratings at mouth of each drainpipe on terraces to trap leaves debris and floating materials.  Provision of first rain separator should be made to flush off first rains.  Do not use polluted water to recharge ground water.  Ground water should only be recharged by rainwater.  Before recharging, suitable arrangements of filtering should be provided.  Filter media should be cleaned before every monsoon season.  During rainy season, the whole system (roof catchment, pipes, screens, first flush, filters, tanks) should be checked before and after each rain and preferably cleaned after every dry period exceeding a month.  At the end of the dry season and just before the first shower of rain is anticipated, the storage tank should be scrubbed and flushed off all sediments and debris.
  9. 9. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 9 WASTEWATER TREATMENT METHODS Wastewater treatment consists of applying known technology to improve or upgrade the quality of a wastewater. Usually wastewater treatment will involve collecting the wastewater in a central, segregated location (the Wastewater Treatment Plant) and subjecting the wastewater to various treatment processes. Most often, since large volumes of wastewater are involved, treatment processes are carried out on continuously flowing wastewaters (continuous flow or "open" systems) rather than as "batch" or a series of periodic treatment processes in which treatment is carried out on parcels or "batches" of wastewaters. While most wastewater treatment processes are continuous flow, certain operations, such as vacuum filtration, involving as it does, storage of sludge, the addition of chemicals, filtration and removal or disposal of the treated sludge, are routinely handled as periodic batch operations. Wastewater treatment, however, can also be organized or categorized by the nature of the treatment process operation being used; for example, physical, chemical or biological. Physical, Chemical and Biological Wastewater Treatment Methods – TERMINOLOGY Physical Sedimentation (Clarification) : This water treatment process used to settle out suspended solids in water under the influence of gravity. Screening: This water treatment process used to trap and remove the floating matter such as paper, wood etc. by using automated mechanically raked bar screens. Aeration: This Water aeration process is used for water bodies that suffer from anoxic conditions, usually caused by adjacent human activities such as sewage discharges, agricultural run-off, or over-baiting a fishing lake. Aeration can be achieved through the infusion of air into the bottom of the lake, lagoon or pond or by surface agitation from a fountain or spray-like device to allow for oxygen exchange at the surface and the release of noxious gasses such as carbon dioxide, methane or hydrogen sulfide. Filtration: This water treatment process is used at the end to remove remaining suspended particles and unsettled floc. Chemical Chlorination:This is a method of treatment which has been employed for many purposes to disinfect or destruct the pathogenic organisms and to prevent water from decomposition. Ozonation: In this process O3 is used, Which is an unstable molecule gives up one atom of Oxygen providing a powerful oxidizing agent which is toxic to most waterborne organisms. Neutralization: The neutralization process can be performed for the industrial wastewater containing acidic substances (acidic) or base (alkaline) that need to be neutralized before discharge of water into the waste water treatment process. Coagulation: Coagulation is one of the most important physio-chemical reactions used in water treatment. The precipitation of ions (heavy metals) and colloids (organic and inorganic) are mostly held in solution by electrical charges. By the addition of ions with opposite charges, these colloids can be destabilized; coagulation can be achieved by chemical or electrical methods. The coagulant is added in the form of
  10. 10. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 10 suitable chemical substances. Alum [Al2(SO4)3.18H2O] is such a chemical substance, which has been widely used for ages for wastewater treatment. Adsorption: This is the physical adhesion of chemicals on to the surface of the solid. The effectiveness of the adsorbent is directly related to the amount of surface area available to attract the particles of contaminant. The most commonly used adsorbent is a very porous matrix of granular activated carbon. Ion Exchange: This technique has been used extensively to remove hardness, and iron and manganese salts in drinking water supplies. It has also been used selectively to remove specific impurities and to recover valuable trace metals like chromium, nickel, copper, lead and cadmium from industrial waste discharges. The process takes advantage of the ability of certain natural and synthetic materials to exchange one of their ions. Biological Aerobic: Under aerobic (O2 ) conditions bacteria rapidly consume organic matter and convert into CO2 .The following treatment methods come under this method.  Activated Sludge Treatment Methods  Trickling Filtration  Oxidation Ponds  Lagoons  Aerobic Digestion Anaerobic: This is a bacterial process of domestic sewage in septic tanks which normally retain the sewage from one day to two days reducing B.O.D by about 35 to 40 percentage. The following treatment methods come under this method.  Anaerobic Digestion  Septic Tanks  Lagoons Physical treatment methods Include processes where no gross chemical or biological changes are carried out and strictly physical phenomena are used to improve or treat the wastewater. Examples would be coarse screening to remove larger entrained objects and sedimentation (or clarification). In the process of sedimentation, physical phenomena relating to the settling of solids by gravity are allowed to operate. Usually this consists of simply holding a wastewater for a short period of time in a tank under quiescent conditions, allowing the heavier solids to settle, and removing the "clarified" effluent. Sedimentation for solids separation is a very common process operation and is routinely employed at the beginning and end of wastewater treatment operations. While sedimentation is one of the most common physical treatment processes that is used to achieve treatment, another physical treatment process consists of aeration -- that is, physically adding air, usually to provide oxygen to the wastewater. Still other physical phenomena used in treatment consist of filtration. Here wastewater is passed through a filter medium to separate solids. An example would be the use of sand filters to further remove entrained solids from a treated wastewater. Certain phenomena will occur during the sedimentation process and can be advantageously used to further improve water quality. Permitting greases or oils, for example, to float to the surface and skimming or physically removing them from the wastewaters is often carried out as part of the overall treatment process.
  11. 11. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 11 In certain industrial wastewater treatment processes strong or undesirable wastes are sometimes produced over short periods of time. Since such "slugs" or periodic inputs of such wastes would damage a biological treatment process, these wastes are sometimes held, mixed with other wastewaters, and gradually released, thus eliminating "shocks" to the treatment plant. This is call equalization. Another type of "equalization" can be used to even out wide variations in flow rates. For example, the wet well of a pump station can receive widely varying amounts of wastewater and, in turn, pump the wastes onward at more uniform rates. Chemical treatment Methods These methods consist of using some chemical reaction or reactions to improve the water quality. Probably the most commonly used chemical process is chlorination. Chlorine, a strong oxidizing chemical, is used to kill bacteria and to slow down the rate of decomposition of the wastewater. Bacterial kill is achieved when vital biological processes are affected by the chlorine. Another strong oxidizing agent that has also been used as an oxidizing disinfectant is ozone. A chemical process commonly used in many industrial wastewater treatment operations is neutralization. Neutralization consists of the addition of acid or base to adjust pH levels back to neutrality. Since lime is a base it is sometimes used in the neutralization of acid wastes. Coagulation consists of the addition of a chemical that, through a chemical reaction, forms an insoluble end product that serves to remove substances from the wastewater. Polyvalent metals are commonly used as coagulating chemicals in wastewater treatment and typical coagulants would include lime (that can also be used in neutralization), certain iron containing compounds (such as ferric chloride or ferric sulfate) and alum (aluminum sulfate). Certain processes may actually be physical and chemical in nature. The use of activated carbon to "adsorb" or remove organics, for example, involves both chemical and physical processes. Processes such as ion exchange, which involves exchanging certain ions for others, are not used to any great extent in wastewater treatment. Biological treatment methods These methods use microorganisms, mostly bacteria, in the biochemical decomposition of wastewaters to stable end products. More microorganisms, or sludges, are formed and a portion of the waste is converted to carbon dioxide, water and other end products. Generally, biological treatment methods can be divided into aerobic and anaerobic methods, based on availability of dissolved oxygen. The purpose of wastewater treatment is generally to remove from the wastewater enough solids to permit the remainder to be discharged to a receiving water without interfering with its best or proper use. The solids which are removed are primarily organic but may also include inorganic solids. Treatment must also be provided for the solids and liquids which are removed as sludge. Finally, treatment to control odors, to retard biological activity, or destroy pathogenic organisms may also be needed. While the devices used in wastewater treatment are numerous and will probably combine physical, chemical and biological methods, they may all be generally grouped under six methods: 1. Preliminary Treatment 2. Primary Treatment 3. Secondary Treatment 4. Disinfection
  12. 12. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 12 5. Sludge Treatment 6. Tertiary Treatment Degrees of treatment are sometimes indicated by use of the terms primary, secondary and tertiary treatment. Tertiary treatment, properly, would be any treatment added onto or following secondary treatment. Preliminary Treatment At most plants preliminary treatment is used to protect pumping equipment and facilitate subsequent treatment processes. Preliminary devices are designed to remove or cut up the larger suspended and floating solids, to remove the heavy inorganic solids, and to remove excessive amounts of oils or greases. To effect the objectives of preliminary treatment, the following devices are commonly used:  Screens -- rack, bar or fine  Comminuting devices -- grinders, cutters, shredders  Grit chambers  Pre-aeration tanks In addition to the above, chlorination may be used in preliminary treatment. Since chlorination may be used at all stages in treatment, it is considered to be a method by itself. Preliminary treatment devices require careful design and operation. Primary Treatment In this treatment, most of the settleable solids are separated or removed from the wastewater by the physical process of sedimentation. When certain chemicals are used with primary sedimentation tanks, some of the colloidal solids are also removed. Biological activity of the wastewater in primary treatment is of negligible importance. The purpose of primary treatment is to reduce the velocity of the wastewater sufficiently to permit solids to settle and floatable material to surface. Therefore, primary devices may consist of settling tanks, clarifiers or sedimentation tanks. Because of variations in design, operation, and application, settling tanks can be divided into four general groups:  Septic tanks  Two story tanks -- Imhoff and several proprietary or patented units  Plain sedimentation tank with mechanical sludge removal  Upward flow clarifiers with mechanical sludge removal When chemicals are used, other auxiliary units are employed. These are:  Chemical feed units  Mixing devices  Flocculators The results obtained by primary treatment, together with anaerobic sludge digestion as described later, are such that they can be compared with the zone of degradation in stream self-purification. The use of chlorine with primary treatment is discussed under the section on Preliminary Treatment.
  13. 13. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 13 Secondary Treatment Secondary treatment depends primarily upon aerobic organisms which biochemically decompose the organic solids to inorganic or stable organic solids. It is comparable to the zone of recovery in the self- purification of a stream. The devices used in secondary treatment may be divided into four groups:  Trickling filters with secondary settling tanks  Activated sludge and modifications with final settling tanks  Intermittent sand filters  Stabilization ponds The use of chlorine with secondary treatment is discussed under the section on Secondary Treatment Disinfection- Chlorination This is a method of treatment which has been employed for many purposes in all stages in wastewater treatment, and even prior to preliminary treatment. It involves the application of chlorine to the wastewater for the following purposes:  Disinfection or destruction of pathogenic organisms  Prevention of wastewater decomposition -- (a) odor control, and (b) protection of plant structures  Aid in plant operation -- (a) Sedimentation, (b) trickling filters, (c) activated sludge bulking  Reduction or delay of biochemical oxygen demand (BOD) While chlorination has been commonly used over the years, especially for disinfection, other methods to achieve disinfection as well as to achieve similar treatment ends are also used. Among the most common is the use of ozone. In view of the toxicity of chlorine and chlorinated compounds for fish as well as other living forms, ozonation may be more commonly used in the future. This process will be more fully discussed in the section on disinfection. Sludge Treatment The solids removed from wastewater in both primary and secondary treatment units, together with the water removed with them, constitute wastewater sludge. It is generally necessary to subject sludge to some treatment to prepare or condition it for ultimate disposal. Such treatment has two objectives -- the removal of part or all of the water in the sludge to reduce its volume, and the decomposition of the organic solids to mineral solids or to relatively stable organic solids. This is accomplished by a combination of two or more of the following methods:  Thickening  Digestion with or without heat  Drying on sand bed -- open or covered  Conditioning with chemicals  Elutriation  Vacuum filtration  Heat drying  Incineration
  14. 14. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 14  Wet oxidation  Centrifuging Tertiary and Advanced Wastewater Treatment Tertiary treatment is the next wastewater treatment process after secondary treatment. This step removes stubborn contaminants that secondary treatment was not able to clean up. Wastewater effluent becomes even cleaner in this treatment process through the use of stronger and more advanced treatment systems. Tertiary treatment technologies can be extensions of conventional secondary biological treatment to further stabilize oxygen-demanding substances in the wastewater, or to remove nitrogen and phosphorus. Tertiary treatment may also involve physical-chemical separation techniques such as carbon adsorption, flocculation/precipitation, membranes for advanced filtration, ion exchange, dechlorination and reverse osmosis. ROOT ZONE TECHNOLOGY Root zone technology is a low energy, low maintenance and natural approach to treat domestic sewage. The process is a clean, economic and eco-friendly method used as an alternative to conventional systems. What are Root zone Filters? Root Zone filters are type of constructed wetlands commonly known as subsurface flow wetland. Root Zone Treatment System are planted filter-beds consisting of sand / gravel/ soil. This Technology was developed in 1970’s in Germany and is successfully running in different countries, mainly in Europe, India and America. The process incorporates the self-regulating dynamics of an artificial soil eco-system. How Root Zone Filters work? Root Zone System uses ecological principles, which simulate the natural processes for treatment of wastewater. It is a live, self-cleaning biological filter. It removes disease organisms, nutrients, organic loads and a range of other polluting compounds. The breakdown of contaminants and the treatment of wastewater are achieved by the controlled seepage of the waterborne pollutants through a root-zone of plants. Organic pollutants are broken down as a food source for the extraordinary variety of microorganisms that are present in the soil and plants. Other contaminants like heavy metals are fixed in humic acid and Cation exchange bonds in the soil or mineral substrate in which these plants are rooted. The complexity of microbial life forms and the powerful reaction in the Root zone of the plants result in cleansing capacity that adapts to change in a very dynamic way. Root zone treatment systems have self-contained engineered ecosystems that utilize particular combinations of plants, soil, bacterial and hydraulic flow systems to optimize the physical, chemical and micro-biological processes present within the root zone. Technical Background and Details The design of system depends upon the specific wastewater or sludge characteristics and the required level of treatment. Consequently every application has a custom design according to effluent, flow rates and location. The approach of wastewater treatment in Root zone filters is similar to conventional biological, chemical and mechanical treatment plants, but the difference is that the processes are integrated in a nature-based design which at the same time has buffer capacity to absorb shock loading.
  15. 15. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 15 The system consists of  Properly designed treatment tank  Graded filling material  Acclimatized, aerobic, anaerobic & facultative bacteria  Acclimatized & selected indigenous plants. The wastewater is collected from existing septic tank overflows and brought to a suitable site. On the site, a pit of requisite dimension is made. The clarified sewage from the septic tank is made to pass through the Root Zone pit. The length and breadth of the pit depends on the volume of the wastewater to be treated per day. The pit is lined by sealing with low Density Polypropylene sheets or rolls. If necessary, other types of civil structure can be made into the treatment tank. The pit is filled layer by layer with layered media of adequate porosity. The supporting medium is planted with special acclimatized plants, which form an association with the bacteria and the medium in such a way that the combination gives an effective sewage treatment system. Within a few days the bacterial cultures and the plants establish themselves to cover the entire medium. This system then becomes operative and remains functional for many years with almost zero maintenance. The wastewater interacts with the filling media and the bacteria present in the rhyzosphere of the acclimatized plants. The interaction results in removal of impurities like BOD, COD, Suspended solids etc. The aerobic and facultative bacteria in the Root zone System are supplied with oxygen by the network of root system of the acclimatized plants. While the anaerobic ones thrive away form the roots. Organic matter is converted to carbon dioxide & water. The sludge is mineralized and the suspended matter is filtered and sedimented in- situ. As a result we get treated water out of the system. Selection of Plant Species Following list of species can be tried :  Phragmites austrails (reed)  Phragmites Karka (reed)  Arundo donax (Mediterranean reed)  Typha latifolia (cattail)  Typha augustifolia (cattail)  Iris pseudacorus  Schoenopletus lacustris (bulrush)  Canna species Application of Root Zone Treatment Technology 1. Treatment of domestic wastewater especially for small towns, village resorts, hotels, hostels, etc. is easily possible & affordable because it involves low capital, operation & maintenance cost. 2. RZTS can also treat Biodegradable Industrial Effluents specially effluents from agro based industries. 3. RZTS Technology can be applied in Urban Watershed Management (UWM) by treating the open nullah in decentralized way and receiving the treated waste either for irrigation or dilution purposes.
  16. 16. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 16 4. A trial project of Root Zone Treatment Technology is underway at Titagarh Generating Station, CESC limited WHAT CAN RECYCLED WATER BE USED FOR? Recycled water can be used for almost any use, as long as it is treated to a level to make it fit for that intended purpose from a health and environmental perspective . However, the cost of treatment may make reclamation uneconomical for some uses.  washing clothes  flushing toilets  watering lawns, gardens and vegetable patches  washing cars on grassed areas  fighting fires  filling ornamental ponds and water features ( Water in ponds or water features may need to be changed regularly as algae may grow due to the nutrients in the recycled water) Other possible uses include:  Groundwater recharge  Municipal landscapes  golf courses and recreational parks.  Environmental flows and wetlands  Industry  Washing and cooling in power stations and mills.  Agriculture It is now also possible for advanced treatment technology to produce safe drinking (potable) water. In several countries wastewater is recycled for potable reuse via groundwater injection (e.g. Water Factory 21(Groundwater Replenishment system) in Orange County, California, USA) or where it is added directly to surface reservoirs (e.g. NEWater, Singapore).
  17. 17. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 17 MATERIALS General Building materials choices are important in sustainable design because of the extensive network of activities such as extraction, processing and transportation steps required for making a material, and activities involved thereafter till building construction and even thereafter. These activities may pollute the air, soil and water, as well as destroy natural habitats and deplete natural resources. One of the most effective strategies for minimizing the environmental impacts of material usage is to reuse existing buildings. Rehabilitation of existing building, their shell and non-shell components, not only reduces the volume of solid waste generated and its subsequent diversion to landfills but also the environmental impacts associated with the production, delivery and use or installation of new building materials. The use of rapidly renewable materials, recycled materials minimizes the adverse impact of natural resource consumption in the manufacture of new building materials. The use of local materials supports the local economy and reduces the negative impact of transportation. Environmental Concerns and Human Health and Safety Aspects related to Building Materials Increased demand for building materials creates a major and diversified impact on the environment. Excessive extraction of raw material diminishes non-renewable natural resources very rapidly. Even during some extraction process, waste is generated whose disposal may pose problems. Sometimes extraction processes may also affect the wildlife. Transportation of building materials from one place to another is also a major indirect factor leading to harmful effects. During manufacturing or processing of some materials like plastic, harmful gases are generated, which are dangerous for human health and environment. There are many frequently used building materials like reconstituted wood products, paints, glues, carpet and upholstery, which may release gases, fumes, etc, from the chemical components used, even long after the installation. These volatile organic compounds (VOCs) affect the environment and human health and may cause headaches, dizziness, respiratory problems and even major diseases in human and other living beings. Minimizing Green House Gas (GHG) Emission Construction sector in the country is a major consumer of energy resulting in the largest share of CO2 emissions in the atmosphere. Cement, steel and bricks, the largest and bulk consumption items in the construction industry, are contributors of large CO2 emissions. It is estimated that close to a tonne of CO2 is emitted during the production of every tonne of cement, resulting in very high GHG emission. Similarly, concrete, which is a very widely used construction material has very high GHG emission. Minimizing the consumption of such conventional materials which may contribute to substantial GHG emission, by using alternative materials and alternative methods and techniques can considerably reduce energy and CO2 emissions. Building Material An ideal sustainable building material is not only environment friendly, causes no adverse impact on health of occupants, is readily available, can be reclaimed, can be recycled and is made from renewable raw material, but also uses predominantly renewable energy in its extraction, production and transportation. Practically, this kind of ideal material may not be available, hence when selecting sustainable materials, it may be best to choose materials which fulfill most of these criteria.
  18. 18. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 18 Life Cycle Assessment (LCA) of Building Materials LCA of building materials intends to assess the potential environmental impacts at every stage in the life cycle of a material– right from the raw material sourcing, processing, manufacturing and finishing, up to the product installation, maintenance and ultimately reuse/recycle/demolition. It is a tool to determine the environmental suitability of any building material for a thorough understanding of the environmental impact and the improvement which can be employed at every stage of a material, so as to make a decision for its selection after evaluation of criteria such as embodied energy, performance and durability. LIFE CYCLE OF A BUILDING MATERIAL A description of life cycle analysis with respect to various relevant criteria is given below: a) Embodied energy - Embodied energy is an important factor to be considered in the life cycle assessment of a material. Minimizing embodied energy means minimizing the impact on the environment. In any building construction use of materials with low embodied energy should be considered. Table gives classification of building materials based on their energy intensity and gives the comparative embodied energy for a few building materials. Sl No. Category of material Energy intensity (Range) (GJ/t) Examples i) Very High energy >50 Aluminium, stainless steel, plastic, copper, zinc. ii) High energy 5-50 Cement, steel, glass, bitumen, solvents, cardboard, paper and lead. iii) Medium energy 1-5 Lime, gypsum plaster board, burnt clay brick, burnt clay brick from improved vertical shaft kiln, soil cement block, aerated block, hollow concrete block, gypsum plaster, concrete block, timber, wood products, particle board, medium density fiber board, cellulose insulation, in-situ concrete. iv) Low energy <1 Sand, aggregate, fly ash, cement stabilized earth block, straw bale, bamboo, stone. CLASSIFICATION OF MATERIALS BASED ON ENERGY INTENSITY
  19. 19. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 19 b) Resource reuse and upgradation – It includes saving a material from disposal and utilizing it by renovating, repairing, restoring, or generally improving the appearance, performance, quality, functionality, or value of a product. Efforts should be made to reuse existing, previously occupied buildings – including the structure, envelope and elements, after removing or replacing the elements which have risk of failure/contamination during construction or occupancy. Upgradation of systems should be done in the areas of energy and water efficiency where the previously installed systems are not environment friendly or efficient. c) Recycled content – To reduce the demand for virgin materials, effort should be made to use the products with identifiable recycled content, including from those coming from industrial and post-consumer utilization, with a preference for the later. d) Reusable or recyclable – Effort should be made to select materials that can be easily dismantled and reused or recycled at the end of their useful life. Consider installation techniques which allow easy dismantling and reuse of materials. e) Natural, plentiful – Effort should be made to use materials which are bio-based and naturally harvested from sustainably managed sources. f) Bio-degradable – Consider using materials which are bio-degradable so that they can be harmlessly disposed at the end of their life cycle. g) Indigenous or locally available – Effort should be made to use building materials, components, and systems which are found locally or regionally, saving energy and resources for transportation of materials to the project site, which in turn reduces environmental impacts. h) Rapidly renewable material – Effort should be made to use materials which replenish substantially faster than traditional extraction demand (for example, timber which can be planted and harvested in less than a 10-year cycle) to reduce the demand for limited/finite resources. i) Materials compliant with clean air and clean water – Effort should be made to select those materials that emit few or no carcinogens, reproductive toxicants, VOCs, etc. Such materials that enhance the indoor environment quality and consume less water, do not cause water contamination, pollution as well as help in reducing water consumption should be considered for use. MATERIALS AND RECOMMENDED SUSTAINABLE ALTERNATIVES Cement concrete Concrete is a strong, durable material and provides good thermal mass to buildings. However, manufacture of cement used in it is a high energy-intensive process and source of pollution, requiring also, high energy for its transportation due to centralized production. Extraction and mining of aggregates also result in natural habitat destruction or deforestations. Following are the recommended alternatives to conventional concrete:
  20. 20. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 20 a) Use of pozzolanas and other mineral admixtures for cement replacement in cement concrete and other cement matrix products 1) Use of fly ash and slag in cement concrete – Pozzolanas like fly ash or ground slag may be used to replace certain percentage of ordinary portland cement in cement concrete in accordance with the good practice [11(3)] or cement manufactured by using mineral admixtures like fly ash or ground slag may be used, in accordance with the good practice. 2) Rice husk ash (RHA) – Rice husk ash, a waste from rice industry, is pozzolanic in nature and may be used for part replacement of cement in accordance with the good practice [11(3)]. 3) Ready mixed concrete (RMC) – RMC provides opportunity for use of pozzolanas and slag in greater quantities while maintaining strict quality control. Also, there are advantages of RMC over conventional concrete such as reduction noise and dust pollution, apart from better quality control. Preference may be given to use of RMC if the RMC manufacturing plant is nearby. The manufacture, quality control delivery, etc of RMC shall be done in accordance with the good practice [11(4)]. 4) Geopolymer concrete – It is made with fly ash, ground granulated blastfurnace slag (GGBS), fine aggregates and coarse aggregates and catalytic liquid system (CLS). This concrete uses no Portland cement and utilizes waste products. It has good resistance to chloride penetration and acid attack. However, geopolymer concrete is a future sustainable material option as it is in development stage. It could be designed and developed for a specific use in a project for which specialist literature may be referred. 5) Other cement concrete mix and products/cement matrix products/lime-pozzolana mixtures – Various cement concrete mix and products, other cement matrix products, lime-pozzolana mixtures, etc, used in buildings having waste based mineral admixtures such as fly ash and slag may be produced or used. The requirements of such products and for their utilization shall be in accordance with accepted standards and good practice [11(5)] which also includes list of accepted standards for mineral admixtures for use in such products as may be applicable. b) Use of recycled aggregate- Crushed concrete are most common form of recycled aggregates which should be considered for use in concrete. The recycled concrete aggregate should be intended to offer the same level of strength and durability as conventional aggregate from natural resources. In the concrete mix, both virgin aggregate from natural resources and recycled aggregate may be mixed with hydrated cement paste. Such mix may have reduced specific gravity and increased porosity compared to concrete using similar virgin aggregate from natural sources. It is recommended that recycled aggregate be batched in a pre-wetted and close-to-saturated surface dry condition. Recycled aggregate may be used in concrete for bulk fills, bank protection, base/fills of drainage structures, pavements, sidewalks, kerbs and gutters, etc. Up to 30 percent of natural crushed coarse aggregates can be replaced by the coarse recycled concrete aggregate, in fresh concrete. This percentage can be increased up to 50 percent for pavements and other areas which are under pure compression. Also refer good practices [11(3)]. For quality requirements for other/artificial aggregates such as cinder as fine aggregate, in line, broken burnt clay bricks as coarse and fine aggregates, artificial light weight aggregates, etc, reference may be made to the accepted standards[11(6)].
  21. 21. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 21 c) Precast/prefabricated/partially prefabricated concrete elements – Precast concrete can be used in construction in the form of building elements which are assembled at site and made monolithic by pouring in-situ concrete. The products are manufactured by casting concrete in a reusable mould or form which is then cured in a controlled environment, transported to the construction site, and erected at place. Precast concrete elements break the structural span into smaller segments resulting in reduced steel requirement. Precast concrete roofing techniques like plank and joist roofing system, ferrocement roofing channels, precast arch panels, precast waffle units, L-panels are among roofing systems which may have comparatively less embodied energy than conventional RCC roof. d) Use of light weight concrete 1) Preformed foam concrete – Preformed foam concrete may be considered for use for the levelling of floors, sprayed onto horizontal surfaces or in hollow cavities as light weight filler. 2) Ferrocement – Ferrocement is a thin cement mortar laid over wire mesh (which acts as reinforcement). It uses minimal material (particularly steel) which is reduced compared to conventional RCC. e) Use of light weight aggregates in concrete – These are usually used in masonry blocks, slabs or floor beam units which are relatively strong. Light weight blocks help to reduce structural loading of building. These may be foamed blast furnace slag, bloated clay aggregate, sintered fly ash aggregate, cinder aggregate, etc. Mineral insulating aggregate in concrete like light expanded clay, pumice and expanded perlite have the lower moisture absorption coefficient, and are therefore best suited to products used for insulation. Fossil meal and exfoliated vermiculite, perlite or slag due to very high moisture absorption coefficient is preferred for high temperature equipment insulation. If artificial lightweight aggregate is used for making lightweight concrete, the same shall be in accordance with the accepted standard [11(6)]. f) Commonly used masonry concrete blocks: 1) Solid and hollow concrete blocks – Hollow concrete block masonry uses lesser concrete as compared to solid concrete blocks and provides better thermal insulation due to cavity. Filling of the cores with concrete or concrete with steel reinforcement offers much greater tensile and lateral strength to structures, wherever required. 2) Autoclaved cellular (aerated) concrete blocks – These are made by mixing fly-ash, lime, cement and gypsum, with foaming agent like aluminium powder which gives them the lightweight and good insulation property. These are lightweight blocks which can be useful to reduce dead load on structure, particularly of high rise buildings. 3) Lightweight concrete blocks – These blocks are lightweight and manufactured like normal concrete blocks using light weight aggregates. 4) Preformed foam cellular concrete blocks – These have considerably better thermal insulation properties than normal concrete which is as high as 0.1W/m²k for densities of approximately 650 kg/m3. 5) Concrete stone masonry blocks – Precast concrete stone block masonry which uses recycled stone is a viable option. It can be made with waste stone pieces which could be locally available, and lean cement concrete. These blocks may be specially useful in places where there is scarcity of good quality clay required for burnt clay brick manufacture. The design mix of concrete blocks can also be done using fly ash as replacement of certain percentage of cement by volume. The concrete blocks shall be in accordance with the accepted standards [11(7)] and masonry construction using these blocks shall be in accordance with good practice [11(8)].
  22. 22. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 22 Burnt clay bricks and tiles Bricks are made of clay which is abundant and generally sourced locally. They are durable and provide thermal mass to buildings. They are used for applications such as wall masonry, cladding, flooring and roof tiling. In many cases bricks can improve the indoor climate by regulating and stabilizing moisture levels. Clay building waste being inert, its disposal has no detrimental effects on the environment. Exceptions are coloured and pigmented brick and ceramic tiles containing heavy metals, fire proof bricks containing soluble chrome and bricks from chimneys which have absorbed large amount of aromatic hydrocarbons during their life span. These products have to be separated and disposed off by following special precautions. The burnt clay products have high durability, and these have high potential for their reuse as the energy needed to remove and clean up old material only represents approximately 0.5 percent of the energy required for the manufacture of new bricks and tiles. However, the recovery for reuse of bricks is facilitated if a weak or medium-strength mortar has been used. Ceramic tiles or expanded clay pellets cannot be recycled and have to be usually more down-graded for uses such as for use as fill. Clay tiles and bricks can be broken up and used as fill, and aggregate in concrete in accordance with the good practice [11(3)].. Brick and clay manufacturing is a medium to high energy-intensive and polluting process depending on the firing temperatures and type of kilns used in firing. Preference should be given to locally manufactured bricks and tiles to reduce transportation energy. The vertical shaft brick kiln technology which substantially reduces both the embodied energy and resultant emissions from brick production may be used. The consumption of energy in the kilns can be reduced considerably by the use of bricks with different firing temperatures, in different parts of the building. The following other types of bricks may also be used as sustainable alternatives: 1) Hollow/perforated bricks – These types of bricks save the amount of material used and provide better thermal insulation due to the presence of air cavities. These bricks when provided with reinforcements, can be used for structural applications and also in the form of filler blocks to replace concrete in the tensile zone. 2) Low and medium-fired bricks – Clay bricks which are burnt between 350 °C to 500 °C are low-fired bricks, and bricks burnt at slightly higher temperature like 500 °C to 800 °C are medium-fired bricks. Low- fired bricks are highly absorbent and hence recommended for use in internal walls or inner layer of external cavity walls (where they act as a moisture regulator), etc. The medium-fired bricks although comparatively more durable, may be used in similar applications as above. 3) Burnt clay flyash bricks – They are lower in embodied energy, provide better thermal property as compared to conventional burnt clay bricks and also utilize flyash, an industrial waste product. 4) Flyash lime bricks – These are flyash based and use bricks lime as the binder, along with accelerator in required proportion. These have good thermal properties. These are mostly used as masonry units and as fillers in pre-fabricated floor slabs. 5) Red mud burnt bricks – Red mud is a waste product from aluminium extraction industry. It contains mainly oxides of aluminium, iron and titanium. Red mud and flyash partly replace clay in these bricks. The alumina content gives a nice red tone to the brick. They have high compressive strength and are suitable for all types of construction. The presence of 4 to 5 percent of alkali in red mud also results in better plasticity and better bonding in these bricks. 6) Lato bricks – These are strong bricks (south western region of India) made of laterite soil mixed with cement or lime, and are moulded under pressure instead of being fired.
  23. 23. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 23 Glazing Glass is a high embodied energy mineral material. Its usage is in skylights, windows, glazing systems, flooring, infill panels for doors. Glass helps to get in natural daylight to interior spaces and provides views. Glazing if not chosen and positioned in a building properly may lead to lot of heat ingress/egress. Glass shall be selected with high recycled content and shall be so sized as to minimize wastages. The most commonly used glazing material in openings is glass, though recently polycarbonate sheets are being used for skylights. The primary properties of glazing that impact energy use are: a) Visible transmittance (affecting daylight), b) Visible reflectance (affecting heat and light reflection), c) Thermal transmittance or U value (affecting conduction heat gains), d) Solar heat gain (affecting direct solar gain), e) Spectrum selectivity (affecting daylight and heat gain), f) Glazing material, and g) Glazing colour (affecting the thermal and visual properties of glazing systems). Use of insulated glazing units (IGU) may be considered in appropriate cases. IGU are hermetically sealed, multiple pane assemblies consisting of two or more glazing layers held and bonded at their perimeter by a space bar typically containing a desiccant material. The glazing used in IGUs may be clear, tinted or coated or reflective. The spacer serves to separate the panes of glass and to provide a surface for primary and secondary sealant adhesion. As heat transfer at the edge of the IGU is greater than its centre, the choice of material for spacer is critical to the performance of IGU. The hermetically sealed space between glass panes may be filled with air or other alternatives such as argon and krypton. While selecting a glazing, attention should be given to the following: 1) Selecting between dual pane and single pane glazing. 2) Selecting a spectrally selective glazing. 3) Balancing the conflict between glare and light. 4) Trading off window size and glazing selection. 5) Dark glass not necessarily providing good solar control. 6) Not depending on glazing alone to reduce heat gain and discomfort. 7) Selection of frame for glazing. 8) Varying the selection of facade, if possible.
  24. 24. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 24 Embodied energy demystified Posted by Avikal Somvanshi in Down to Earth. Appliances consume energy to operate, but materials used in the construction of buildings consume energy, too. Embodied energy, or EE, is the sum of all energy used in the construction process— right from extraction of raw materials, manufacture of products to their transportation and incorporation in buildings. Lesser the extraction, processing and refining, lower is the EE, and greener the product. People hassle more over reducing operational energy, or energy used to operate equipment, because it affects their day-to-day lives. EE is intangible and, therefore, largely neglected. EE of any building can be less than or greater than its operational energy. If a building is highly conditioned through artificial means, its operational energy can be more than EE. But assessing EE accurately is difficult, says B V V Reddy, professor at the Indian Institute of Science, Bengaluru. This is because energy consumed in the making of a building material is documented only till the factory gate. From there, the material can traverse several areas and keeping track is not easy. Researcher G Ding of University of Technology, Sydney, found that EE of a residential building is in 3,600-8,760 megajoules per square metre (MJ/m2) range and that of a commercial building is 3,400-19,000 MJ/m2. Major EE contributors Cement, steel and bricks, the basic construction materials, are the major EE contributors. Their use can be reduced only to an extent. Materials like ceramic and vitrified tiles, which are highly energy intensive, can be easily replaced with energy-benign materials like stone. Transportation also has a sizable contribution to EE. Delhi-based architect Deepandra Prashad says fly ash brick has less EE compared to stabilised earth block. But it loses its green edge if it
  25. 25. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 25 travels more than 50 km. It’s the same with green building materials like bamboo and mud. About 25 per cent of India’s total primary energy demand is attributed to manufacture of building materials, says Reddy. Another 15 per cent is to operate them. Buildings account for the largest energy and ecological footprint. Globally, buildings consume one-third of the world’s resources. In India, the construction sector adds 30 per cent of the greenhouse gas emissions, states a 2007 report by the Indian Network for Climate Change Assessment. Companies claim they offset carbon emissions by taking steps such as planting trees and installing energy-saving bulbs in villages. While such steps are commendable, most companies do this to claim green credentials for products that are harmful to people and environment. To make our surroundings environment-friendly, Indian regulators are pushing for energy-efficient buildings with tools like energy conservation building code (ECBC). But it does not take into account EE of the building materials, says Anurag Bajpai, director of Green Tree Building Energy Consultant, Delhi. In the UK and Australia, building regulations include grading of materials based on their environment impact. In India, there is acute shortage of research on EE of building materials, says Reddy. The unstructured nature of the little research complicates the issue of incorporating EE in ECBC. “It is important to consider the durability and recyclability of a product as well,” says Prashad. Using recycled or reclaimed material lowers EE. It is also good to invest in products that can be recycled or reused. At times, it makes sense to invest in high EE products that will last the duration of the building than in low EE products that will need to be replaced frequently, or require considerable maintenance. While India is taking time to wake up to the importance of reducing EE, the West is a step ahead trying to lower embodied carbon of materials. Embodied carbon takes into account the source of energy and then evaluates its impact on environment. So while the same product made in different factories—such as one using coal energy and the other hydro power—may have the same EE, they will have vastly different embodied carbon values. Government bans on mining of stone, sand and earth, among others, indicate a deepening crisis of resource overexploitation. Low market prices of products made of these materials, which have high EE value, complicate the problem. High EE products should be more expensive to dissuade its use,” says Prashad.
  26. 26. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 26 BIODEGRADABILITY The biodegradability of a material refers to its potential to naturally decompose when discarded. Organic materials can return to the earth rapidly, while others, like steel, take a long time. An important consideration is whether the material in question will produce hazardous materials as it decomposes, either alone or in combination with other substances. Biodegradable materials are those which break down organically and may be returned to the earth with none of the damage associated with the generation of typical waste materials. • Earthen materials • Wood • Straw bales • Wool carpet • Linoleum flooring Biodegradable Materials in Concrete Concrete is a material which has tremendous compression strength, but needs another material to help in tension. In the past, steel has been the material used in strengthening concrete under tensile loading. In addition, other materials have also been used i.e. fiber reinforcement. In today’s ‘green’ construction, we look to limit the embodied energy of the physical structure. We need to find materials which can be high- performing, fast-renewing, and serve as reinforcing. At the same time, these materials will need to function properly in extreme conditions. In 1966, the U.S. Naval Civil Engineering Laboratory released a document entitled ‘Bamboo Reinforced Concrete Construction’ and noted design properties for bamboo used as structural elements and ultimately as reinforcing in concrete. The differing varieties of bamboo in the world will offer a range of mechanical properties for this use. Bamboo might replace steel in light construction as the tensile source in concrete design if coated with a decay-resistant cover. As with steel, bamboo can be bent and formed when heat is applied during forming pressure. This procedure can be used in forming the splints into C-shaped stirrups used as anchorage reinforcing. This can take place with either wet or dry bamboo. To protect the bamboo from moisture rotting, the bamboo must have waterproof coatings added to the exterior. These waterproof coatings are added to reduce the swelling of the bamboo when in contact with the moisture of young concrete. Without such protection, the bamboo will swell before the concrete has developed sufficient strength to prevent cracking, and the member may be damaged. The same techniques for the design of reinforced concrete are used for bamboo reinforced concrete with only the properties and techniques changing. Due to the low modulus of elasticity of bamboo, flexural members will nearly always develop some cracking under normal service loads. With this, above grade reinforcing of concrete structures with bamboo treated by today’s standards will not handle the loading expected from extreme conditions. However, buildings using concrete foundation structures only, the massing of concrete might generate acceptable conditions for normal use, and during a natural disaster event.
  27. 27. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 27 RECYCLING AND REUSE OF STEEL AND ALUMINIUM Producing aluminium and steel products is energy intensive, using finite natural resources and resulting in emission of greenhouse gases. Sending steel and aluminium to landfill is a wasted opportunity because less energy is required to rework recycled steel and aluminium than to produce original material. Global Warming : How does production of steel and aluminium contribute to climate change? Alumina is found in bauxite and used in the production of aluminium. Production of alumina from bauxite requires direct consumption of energy for heat and steam, as well as indirect consumption of energy as electricity. Steel is an alloy of iron and carbon and much energy is required to produce heat during the production process. Most electricity is generated by burning fossil fuels, which releases greenhouse gases into the atmosphere, contributing to global warming. Transport of steel and aluminium materials is also energy intensive: fossil fuels are required for energy to transport materials at every stage of the product life cycle. This includes from mine-site to manufacturing facility to retail outlet to waste management facility. Benefits of Recycling Aluminium : Aluminium is particularly well suited to recycling. Production of aluminium products from recycled scrap material requires 90 – 95% less energy than the production of primary aluminium. Steel : Every tonne of recycled steel saves 1131kg of iron ore, 633kg of coal and 54 kg of limestone Sustainability Benefits of Recycling Aluminium and Steel  Conserve valuable natural resources and raw materials  Avoid air and water pollution: using recycled materials generally creates less pollution  Save landfill space by closing the loop: steel can be recycled indefinitely keeping it out of the waste stream. Recycling also ensures materials don’t become litter!  Reducing the need to dig for virgin materials conserves soil integrity and wildlife habitats  Save energy: recycled products require less energy to manufacture thus conserving oil and reducing greenhouse gas emissions Steel is an excellent reusable material. Independent agencies (and some steel producers) around the world have performed life-cycle analyses on the environmental impacts of using steel. Based on the results, informed designers can confi dently specify steel products in their various forms for projects of all sizes, from single storey, low rise to high rise buildings. Steel can be recycled repeatedly without any degradation in terms of properties or performance in quality. Steel construction has excellent low waste credentials during all phases of the building life cycle. It generates very little waste, with the byproducts of steel production widely reused by the construction industry. Any waste generated during manufacture is recycled. There is virtually no waste from steel products on the construction site. Construction using sustainable materials offers many benefi ts throughout the various stages of a building’s life cycle, as elaborated in the following pages.
  28. 28. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 28 RECYCLING AND REUSE OF GLASS A simple analogy; medicines are vital to all life to maintain health and cure disease. Drug abuse is when we use these in an inappropriate way and actually cause harm to ourselves. Similarly, glass is a vital element in our buildings bringing in daylight and a connection to the outdoors. Just like drug abuse, when architects and clients use glass with no respect to the climate and site, it becomes a deterrent to the operating cost of the building and health of its occupants. Energy and lighting simulations can help you to optimize the glass quantity, orientation, shading and thermal properties as well as guides like ECBC and ASHRAE can assist in the building design. If used intelligently “Glass can be Green”. GREEN BUILDING MATERIAL & SYSTEM : BASIC CONCEPTS Environmental impact of building materials • Through consumption of resources • Through production of resources (by-products, wastes, pollution, recyclables) Objectives • Make informed environmental choices about building materials and systems • Careful design & understanding about materials
  29. 29. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 29 PRE-BUILDING PHASE  Materials acquisition & preparation o Land degradation & depletion of resources  Manufacturing & fabrication o Energy & water use o Fugitive emissions o Water pollution  Distribution & transport i. Fuel use & air pollution BUILDING PHASE  Construction & installation on site o Noise, waste & pollutants from construction site  Maintenance & repair o Energy & water use o Maintenance & operation requirements  Use & operation of the building o Effects on indoor air quality & occupants’ health POST-BUILDING PHASE  Demolition o Noise, air & water pollution during demolition  Disposal o Need for transportation, landfil, etc. for the waste  Reuse or recycling o Energy & water use “De-construction”  Building disassembly & materials salvage
  30. 30. Notes on ARC 306 GREEN BUILDINGS : Unit 4 Compiled by CT.Lakshmanan B.Arch., M.C.P. Page 30 CRITERIA IN MATERIAL SELECTION: • Resource quantity (use less & more efficiently) • Reused materials (salvaged & reused) • Recycled content (post- & pre-consumer waste) • Renewable materials (e.g. sustainable forestry) • Local content and reduced transportation • Life-cycle cost & maintenance requirements • Resource recovery & recycling • Effects on health & indoor air quality • EVALUATE BUILDING MATERIALS • Collect as much information as possible • Make judgements & assumptions if needed • Basic questions • What is in them? • How they are made? • Where they come from? • How they perform in the building? • What happens to them afterwards? LIFE-CYCLE COSTING (LCC) • Analyses the design of building or building systems including initial costs, maintenance costs, repair costs, energy & water costs, and other significant costs over the assumed life of the facility or system • Combines all costs into net annual amounts, discounts them to present value, and sums them to arrive at total LCC LIFE-CYCLE ASSESSMENT (LCA) • Analyses the potential environmental impacts that are associated with the entire life cycle of a product, from the raw materials to final disposal • Also called “cradle-to-grave” analysis • LCA expresses the results in energy units, mass units of pollutants, potential impacts, and other units