NEED OF ENERGY EFFICIENCY IN BUILDINGS Demand for energy is increasing fast day by day and is likely to increase in tune with industrialization/ urbanization. The building sector being one of the largest consumers of energy, has gained prominence over the past few decades. 45% of total global energy is used in heating, cooling and lighting of building. 5% energy is used in building construction. In India energy used for air conditioning of commercial buildings accounts for 32% of the total energy consumption in the commercial sector in 1995. Energy consumption patterns can be substantially reduced by energy conserving measures, particularly during the phase of building design. Space heating load can be reduced by about 50%, when economically-viable insulating measures are applied to the building envelopes, i.e. to ceiling and walls.ENERGY CRISIS IN INDIAAnenergy crisisis any greatbottleneck(or price rise) in the supply ofenergyresources to aneconomy. In popular literature though, it often refers to one of the energy sources used at a certain time and place, particularly those that supply nationalelectricitygrids or serve as fuel for vehiclesThe South Asian subcontinent, which is in fierce competition with other major powers in Asia such as Japan, China and South Korea, faces shortages of coal, oil and natural gas. To make the situation even worse, most of its oil import comes from nearby Iran, a focus point of international political turmoil.

While there are natural deposits of oil on the Indian subcontinent, domestic production is not sufficient for the estimated 1.2 billion people of the country that consists of 28 states. The energy demand of the economy is increasing at a rapid pace, in fact, it is growing exponentially. In 2011, India spent 41% more on fossil fuel imports than in the previous year. Yet, at stake is India's ability to bring electricity to 400 million of its citizens as well as a number of big cities, centers of bustling business life.

Another serious situation was encountered when coal stocks in 32 power plants were so low that for a period of seven days two dozen plants were running at less than 60% capacity. As a result, several high-profile investment projects had to be deferred until some blurred dates in the future. In addition to the partial paralysis of cities and the failure to launch industrial investment projects, rural regions also suffer from the energy crisis. In certain areas, essential medicines that need cooling are not available at all, due to disruptions to power supply. Moreover, irrigation pumps stopped working.

The Indian economy with its earlier dynamic growth projections experiences a dramatic slowdown at the moment. Also, initiated reforms have stopped. And the potential advantage of decreasing world market prices of crude oil has been absorbed by lower rupee exchange rates.EMBODIED ENERGY OF MATERIALSEmbodied energy is the total energy required for the extraction, processing, manufacture and delivery of building materials to the building site. Energy consumption produces CO2, which contributes to greenhouse gas emissions, so embodied energy is considered an indicator of the overall environmental impact of building materials and systems.Unlike the life cycle assessment, which evaluates all of the impacts over the whole life of a material or element, embodied energy only considers the front-end aspect of the impact of a building material. It does not include the operation or disposal of materials.

TROMBE WALL

ATrombe wallis a passive solar building technique where a wall is built on the winter sun side of a building with a glass external layer and a high heat capacity internal layer separated by a layer of air. Heat in close to UV spectrum passes through the glass almost unhindered then is absorbed by the wall that then re-radiates in the far infrared spectrum which does not pass back through the glass easily, hence heating the inside of the building. Trombe walls are commonly used to absorb heat during sunlit hours of winter then slowly release the heat over night. The essential idea was first explored byEdward S. Morseand patented by him in 1881.[1]In the 1960s it was fully developed as an architectural element by French engineerFlix Trombeand architect Jacques Michel.[2][3]Trombe walls work on the basic greenhouse principle that heat from the sun in the form of near-visible shorter-wavelength higher-energy ultraviolet radiation passes through glass largely unimpeded.DAYLIGHT FACTORAdaylight factoris the ratio of internal light level to external light level and is defined as follows:DF = (Ei / Eo) x 100%where,Ei= illuminance due to daylight at a point on the indoors working plane,Eo= simultaneous outdoor illuminance on a horizontal plane from an unobstructed hemisphere of overcast sky.There are three paths along which light can reach a point inside a room through a glazed window, rooflight, or aperture, as follows: Direct light from a patch of sky visible at the point considered, known as the sky component (SC), Light reflected from an exterior surface and then reaching the point considered, known as the externally reflected component (ERC), Light entering through the window but reaching the point only after reflection from an internal surface, known as the internally reflected component (IRC).The sum of the three components gives the illuminance level (lux) at the point considered:Lux = SC + ERC + IRC

TYPES OF SUNSHADING DEVICESSOLAR HEAT GAIN IN BUILDINGSSolar gainisshort wave radiationfrom the sun that heats a building, either directly through an opening such as a window, or indirectly through the fabric of the building. Solar design (orpassive solar design) is an aspect ofpassive building designthat focusses on maximising the use of heat energy fromsolar radiation.Solar gainis a particularly effective form of passiveheatingasradiationfrom the sun is predominately short-wave infraredradiationwhich is able to pass through glazing and heat the internal fabric of the building. The long-wave infraredradiationthat is re-radiated by the heated fabric of the building is not able to pass back out through the glazing. This results in heat accumulating in the interior, sometimes referred to as the greenhouse effect. SeeThermal optical propertiesfor more information.Very broadly,solar gaincan be beneficial in cooler climates when it can be used as a passive way ofheatingbuildings. However, too muchsolar gaincan cause overheating and for this reason,Part Lof theUKbuilding regulationsplaces restrictions on the amount of glazing that can be used in buildings. Overheating as a result ofsolar gainscan be a particular problem in warmer climates. However, the situation is complicated by thevariationin conditions throughout the day and year which can mean thatsolar gaincan be beneficial in the morning and evening, or during the winter, but can be problematic during the middle of the day or in the summer.Relatively straight-forward design solutions such asbrise soleilcan be used to allow low-level winter sun to enter a building, but to shade higher, summer sun. Other solutions, such as planting deciduous trees in front of windows can be effective as leaf cover in the summer will shade glazing fromsolar radiation, whereas in the winter sunlight is able to pass between the bare branches and enter the building.

NON CONVENTIONAL SOURCE OF ENERGYEnergy generated by using wind, tides, solar, geothermal heat, and biomass including farm and animal waste as well as human excreta is known as non-conventional energy. All these sources are renewable or inexhaustible and do not cause environmental pollution. More over they do not require heavy expenditure.1. Wind Energy:Wind power is harnessed by setting up a windmill which is used for pumping water, grinding grain and generating electricity. The gross wind power potential of India is estimated to be about 20,000 MW, wind power projects of 970 MW capacities were installed till March. 1998. Areas with constantly high speed preferably above 20 km per hour are well-suited for harnessing wind energy.2. Tidal Energy:Sea water keeps on rising and falling alternatively twice a day under the influence of gravitational pull of moon and sun. This phenomenon is known as tides. It is estimated that India possesses 8000-9000 MW of tidal energy potential. The Gulf of Kuchchh is best suited for tidal energy.3. Solar Energy:Sun is the source of all energy on the earth. It is most abundant, inexhaustible and universal source of energy. AH other sources of energy draw their strength from the sun. India is blessed with plenty of solar energy because most parts of the country receive bright sunshine throughout the year except a brief monsoon period. India has developed technology to use solar energy for cooking, water heating, water dissimilation, space heating, crop drying etc.4. Geo-Thermal Energy:Geo-thermal energy is the heat of the earth's interior. This energy is manifested in the hot springs. India is not very rich in this source,5. Energy from Biomass:Biomass refers to all plant material and animal excreta when considered as an energy source. Some important kinds of biomass are inferior wood, urban waste, bagasse, farm animal and human waste.Importance of non-conventional sources of energy:1. The non-conventional sources of energy are abundant in nature. According to energy experts the non-conventional energy potential of India is estimated at about 95,000 MW.2. These are renewable resources. The non-conventional sources of energy can be renewed with minimum effort and money.3. Non-conventional sources of energy are pollution-free and eco-friendlyBREEAMBREEAM is the world's foremost environmental assessment method and rating system for buildings, with 425,000 buildings with certified BREEAM assessment ratings and two million registered for assessment since it was first launched in 1990.BREEAM sets the standard for best practice in sustainable building design, construction and operationand has become one of the most comprehensive and widely recognised measures of a building's environmental performance. It encourages designers, clients and others to think about low carbon and low impact design, minimising the energy demands created by a building before considering energy efficiency and low carbon technologies.A BREEAM assessment uses recognised measures of performance, which are set against established benchmarks, to evaluate a buildings specification, design, construction and use. The measures used represent a broad range of categories and criteria from energy to ecology. They include aspects related to energy and water use, the internal environment (health and well-being), pollution, transport, materials, waste, ecologyand management processesPASSIVE SOLAR COOLINGPassive coolingis a building design approach that focuses on heat gain control and heat dissipation in a building in order to improve the indoor thermal comfort with low or nil energy consumption.[1][2]This approach works either by preventing heat from entering the interior (heat gain prevention) or by removing heat from the building (natural cooling). Natural cooling utilizes on-site energy, available from the natural environment, combined with the architectural design of building components (e.g.building envelope), rather than mechanical systems to dissipate heat.[3]Therefore, natural cooling depends not only on the architectural design of the building but how it uses the local site natural resources as heat sinks (i.e. everything that absorbs or dissipates heat). Examples of on-site heat sinks are the upper atmosphere (night sky), the outdoor air (wind), and the earth/soil.Passive cooling covers all natural processes and techniques of heat dissipation and modulation without the use of energy.[1]Some authors consider that minor and simple mechanical systems (e.g.pumpsand economizers) can be integrated in passive cooling techniques, as long they are used to enhance the effectiveness of the natural cooling process.[4]Such applications are also called hybrid cooling systems.[1]The techniques for passive cooling can be grouped in two main categories: Preventative techniquesthat aims to provide protection and/or prevention of external and internal heat gains. Modulationandheat dissipation techniquesallow the building to store and dissipate heat gain through the transfer of heat from heat sinks to the climate. This technique can be the result ofthermal massor natural cooling.The efficiency of the building envelope can be maximised in a number of ways to minimise heat gain: shading windows, walls and roofs from direct solar radiation using lighter coloured roofs to reflect heat using insulation and buffer zones to minimise conducted and radiated heat gains making selective or limited use of thermal mass to avoid storing daytime heat gains.To maximise heat loss, use the following natural sources of cooling: air movement cooling breezes evaporation earth coupling reflection of radiation.IGBCThe Indian Green Building Council (IGBC), part of Confederation of Indian Industry (CII) was formed in the year 2001. The vision of the council is to usher in a green building movement in India and facilitate India to become one of the global leaders in green buildings by 2010.A green building is one which uses less energy, water and natural resources, creates less waste and is healthier for the people living inside compared to a standard building. Energy saving to the extent of 30 - 40 % right from day one Enhanced indoor air quality Higher productivity of occupants Potable watersaving to the tune of 20% - 30% Enhanced day light & VentilationUSGBCTheU.S. Green Building Council(USGBC), co-founded by current CEO Rick Fedrizzi, Mike Italiano, and David Gottfried in 1993, is a private 501(c)3, membership-based non-profit organization that promotes sustainability in how buildings are designed, built, and operated. USGBC is best known for its development of theLeadership in Energy and Environmental Design(LEED) green building rating systems and its annual Greenbuild International Conference and Expo, the worlds largest conference and expo dedicated to green building. USGBC was one of eight national councils that helped found theWorld Green Building Council(WorldGBC), of which USGBC CEO Rick Fedrizzi is the current chair, in 1999.[1]Through its partnership with theGreen Building Certification Institute(GBCI), USGBC offers a suite of LEED professional credentials that denote expertise in the field of green building. USGBC incentivizes LEED certification by awarding extra certification points to building projects completed with a LEED-certified professional on staff.[2]EARTHWORMAnearthwormis a tube-shaped, segmentedwormfound in the phylumAnnelida. They are commonly found living in soil, feeding on live and dead organic matter. Its digestive system runs through the length of its body. It conducts respiration through its skin. An earthworm has a double transport system composed ofcoelomic fluidthat moves within the fluid-filledcoelomand a simple, closed blood circulatory system. It has a central and a peripheral nervous system. The central nervous system consists of two ganglia above the mouth, one on either side, connected to a nerve cord running back along its length to motor neurons and sensory cells in each segment. Large numbers of chemoreceptors are concentrated near its mouth. Circumferential and longitudinal muscles on the periphery of each segment enable the worm to move. Similar sets of muscles line the gut, and their actions move the digesting food toward the worm's anus.[2]Earthworms arehermaphroditeseach individual carries both male and female sex organs. They lack either an internalskeletonorexoskeleton, but maintain their structure with fluid-filled coelom chambers that function as ahydrostatic skeleton.

EARTH AIR TUNNELSAlthough, this technique is essentially used for cooling the air in Hot and dry climates, it can also be used for winter heating. Earth- air tunnels may be considered as special types of wind towers connected to an underground tunnel. The cooling process is based on the fact that the temperature a few meters below the ground is almost constant throughout the year. A wind tower is connected to the underground tunnel, which runs from the bottom of the wind tower to the basement of the building. The wind tower catches the wind which is forced down the tower into the tunnel. The temperature of the tunnel, being lower than that of the ambient temperature, cools the air before it is circulated into the living space. In winter, the temperature of the air tunnel is higher than the ambient temperature and hence warms the air passing through it.Sensible cooling can b aided by evaporative cooling. To reduce the underground temperature, the ground can be shaded using vegetation and can be wetted by sprinkling water. This water seeps through and dampens the tunnel walls. Consequently, air from the tunnel is evaporatively cooled as it passes through the tunnel. Another variation possible is to use buried pipes instead in place of tunnel. WIND TOWERA windcatcher is an architectural device used for many centuries to create natural ventilation in buildings. The function of this tower is to catch cooler breeze that prevail at a higher level above the ground and to direct it into the interior of the buildings. It is not known who first invented the windcatcher, although some claim it originated in Iran and it can be seen in. Windcatchers come in various designs, such as the uni-directional, bi-directional, and multi-directional. Examples of windcatchers can be found in traditional Persian influenced architecture throughout the Middle East , Pakistan and Afghanistan. Central Iran has a very large day-night temperature difference, ranging from cool to extremely hot, and the air tends to be very dry all day long. Most buildings are constructed of very thick ceramics with extremely high insulation values. Furthermore, towns centered on desert oases tend to be packed very closely together with high walls and ceilings relative to Western architecture, maximizing shade at ground level. The heat of direct sunlight is minimized with small windows that do not face the sun.

EXTERNAL &INTERNAL HEAT GAIN/LOSS IN BUILDINGS

Just as the human body has heat exchange processes with the environment, the building can be similarly considered as a defined unit and its heat exchange processes with the outdoor environment can be examined. Heat energy tends to distribute itself evenly until a perfectly diffused uniform thermal field is achieved. Heat tends to flow from higher temperatures to lower temperature zones by conduction, convection and radiation. The rate of heat flow by any of these three forms is determined by the temperature difference between the two zones or areas considered. The greater the temperature difference, the faster the rate of heat flow.The equations and the calculations methods given below are valid only when both the out-door and indoor temperature are constant. Such static conditions do not occur in the nature, and hence the assumption of the steady state conditions is a simplification. Calculations based on steady state assumptions are useful to determine the maximum rate of heat loss or gain and also for establishing the cooling or heating load for mechanical installations.Figure illustrates the following: Qi + Qs +- Qc +- Qv +- Qm -Qe = 0

Thermal balance i.e. the existing thermal condition is maintained if the sum of the above equation is zero. If the sum of this equation is less than zero (negative), the building will be cooling and if more than zero, the temperature in the building will increase.ENERGY SHADING DEVICESExterior shading devices such as overhangs and vertical fins have a number of advantages that contrib - ute to a more sustainable building. First, exterior shading devices result in energy savings by reducing direct solar gain through windows. By using exterior shading devices with less expensive glazings, it is sometimes possible to obtain per - formance equivalent to unshaded higher performance glazings. A sec - ond benefit is that peak electricity demand is also reduced by exterior shading devices resulting in lower peak demand charges from utilities and reduced mechanical equip - ment costs.ApplicationThe most successful applications of external shading devices are medium to large office buildings where economies of scale provide more cost effective solutions. In temperate climates external shades are more likely to be already well integrated into the design, but with increasing energy costs these solutions are being used in more northerly locations. Designers who may be predisposed to the architectural merits of external shades may be able to promote these shades on the basis of their benefits to building mechanical system design.

External shading devices should be designed to be durable and, if possible, to be of recyclable components.

Care should be taken to integrate the design with the glazing and/or curtain wall design. It is recommended to include the sunshade design responsibility with the curtain wall or glazing specification in order to preserve the integrity of the respective warranties. Consideration should also be given to ensure that the window washing process is not adversely affected by the sunshades. Other design considerations should include seismic and snow loading.