Achieving Energy Efficiency in Buildings through Innovative Design Solutions.
Achieving Energy Efficiency in Buildings through Innovative Design Solutions.
INTRODUCTION
Considering the role and importance of energy as the major driver of economic growth and physical development coupled with limited availability of conventional and non-renewal sources of energy and ever rising demand and spiraling market prices, issues related energy consumption, energy conservation and promoting non-conventional and alternate sources of energy have assumed global concerns.?Considering the fact that existing built up structures account for 40 % of the global primary energy consumption and generator of 24% of CO2 emission, criticality of buildings and their role in minimizing energy consumption and promoting sustainability of human habitat assumes importance. With rapid urbanization and growth of population, more and more buildings would be required to be constructed to meet the increasing demand of shelter, trade & commerce, industries, entertainment, institutions etc. and accordingly level of energy consumption are likely to rise on a compounded pattern.
Making buildings energy efficient have distinct advantages in terms of not only saving money on energy costs but also reduction of adverse impact on the environment through the reduced use of fossil fuels, increased comfort levels achieved through effective use of natural light and ventilation and may be improved resale value of property due to lower power bills.
BUILDING DESIGN
Buildings as they are designed, constructed and used have enormous energy implications. With number of people and institutions rushing towards urban centers, energy requirements of cities due to buildings is going to rise sharply in future. Looking at the high degree of energy consumption by built environment, which has been placed at 300 Kwh for every square metre on annual basis, there appears to be enough options to bring it down to the level of 140 Kwh with proper design..Thus built environment is the sector which would require close scrutiny and monitoring for effecting overall economy in the levels of energy consumption. Experience has shown that buildings can be designed to meet the occupants needs for thermal comfort at reduced level of energy consumption by adopting an integrated approach to building design. The integrated approach could include orientation, shape and size of the building, built form, surface to volume ratio, building efficiency, ratio between length and depth of the building, using simple techniques of building structure, efficient structural design, principles of solar passive techniques in building design, using energy efficient equipment, control and operation strategies for lighting, heating, ventilation etc. using solar energy for meeting the energy needs of buildings,?replacing energy intensive materials with low energy components etc.
Main features of energy efficient buildings would essentially revolve around
1????????????????Site and Building Orientation
2????????????????Internal Layout of Buildings
3????????????????Window placement, sizing and shading
4????????????????Insulation
5????????????????Ventilation
6????????????????Courtyard
7????????????????Landscaping
8????????????????Building Materials
9????????????????Use of energy efficient appliances
SITE AND BUILDING ORIENTATION
Orientation has the greatest impact on the energy consumption by buildings. The issue of energy in context of building, has to be viewed in the dual context of planning of plots/sites and the actual designing of buildings. To ensure that buildings make best use of solar and wind energy, it would be essential that majority of buildings should have the site advantage. Accordingly,?Town Planners have important role cast for themselves while preparing the layout plan, so that maximum number of plots have best orientation. Once this is ensured at the planning level, it would be much easier for the Architects to evolve a design which would be energy efficient. Further, the planners should ensure that ratio of plot width and depth is fixed in a manner that the entire depth of?built up area allowed on a plot should have access to natural light, minimizing the requirement of artificial lighting. This would be particularly important in case of row housing where plots have the option to draw light from front and the rear only.
Orientation needs to be effectively used?in order to evolve energy efficient building design by making use of solar radiation and the wind. However, requirements of building design would vary from region to region, state to state and within regions and states. Accordingly, buildings with regard to sun and wind will have to oriented differently in different regions. Architects can ensure high degree of energy efficiency both in construction and operation by critically studying the macro and micro climate, applying bio-climatic architectural principles and making optimum use of desirable conditions.
Artificial heating and cooling are biggest consumers of energy in buildings, which is placed at 26% of average household energy consumption. Accordingly, it will be critical to minimize the energy load on building due to heating and cooling. A major principle of energy efficient building design would be to orient the building in a manner that maximizes sun heat gain into the building during the winter while excluding it during the long hot?days of summer. This can be made possible due to the fact that angle of sun changes from season to season. In summer, sun rises early in North East and climbs high in the South before setting in North West and heat gain is mainly through roof, east and west windows of buildings. In winter, sun rises later in South of East, stay low in South before setting in South of West. South windows and the walls receive the maximum winter sun and warmth. To achieve the design ?goal of optimal energy ?efficiency, basic rule for a building would be have North and South facing walls 1.5 to 2.00 times the length of East and West facing walls in order to allow reasonable access to morning and late afternoon sun on the East and West whereas maximum sun during winter through the southern walls. However, a small projection on the southern wall will help in cutting the vertical sun and avoiding the heat trickling into the buildings during summers.
INTERNAL LAYOUT OF BUILDINGS
Not only placing of external walls are critical but also rational allocation of internal spaces in the buildings for achieving the desired level of energy efficiency. Spaces can be classified and grouped considering their energy requirements. Space requiring ambience temperatures should be grouped and planned in the best orientation whereas spaces having little relevance to living etc. can be placed in directions considered as adverse from the part of view of orientation. Accordingly, indoor living and entertaining spaces can be placed on the Eastern and Southern sides for having bright and warm areas during winters and cool spaces in the summer. Thus placing bedrooms on the East and South will be more comfortable for sleeping during both summers and winters. Mechanism of grouping rooms with similar uses together for creating different zones and using doors to separate them would help in evolving appropriate design solutions. Closed designs offers distinct advantages in terms of energy efficiency as compared to open designs. However, where ever the specific need of planning requires open plans, then use of glass doors would be appropriate to define different zones. Kitchen, laundry, bathrooms can be grouped ?to minimize the need for long hot water pipes. Garages and stores can be kept on the western side of the house so as to seal the living areas from intense summer heat.
?
WINDOWS PLACEMENT, SIZING AND SHADING
For evolving energy efficient design solutions appropriate placement, sizing and shading of buildings would be critical. Windows have multiple functions to perform including solar collectors trapping heat from sun which is useful in winter but not in summer, acting as ventilators during summer, funneling?cool late afternoon and night time?breeze to reduce heat accumulated during the day and to let in day light to make spaces bright. A balance need to be made between controlling sun access, allowing adequate cross-ventilation and permitting natural light to enter. Accordingly 1/3rd to ? of the southern face of the building can be put under glass for trapping winter sun and shading from summer sun with correctly designed eaves.?An overhang of 0.4 times the distance from ?eaves to bottom of windows will be sufficient to save it from the heat of sun during the summer. Use of solar pergola can also be made to regulate the impact of sun in the building. However, it would be critical that shading devices do not block the sun’s access to the interior of building during winter.?East and Western windows provide warmth in winter from early morning and afternoon sun, but they pose difficulty from the sun in summer. It makes rooms on East and West uncomfortably warm, in particular those on the West. Accordingly it would be critical to keep area of East and Western windows minimum and wherever provided should be have vertical screens, louvers, blinds, shutters to block the sun. North facing windows can be made large to facilitate good ventilation and light without the loss of much heat.
Tinted glass and reflective films absorb and reflect heat leading to reduction of intake of heat and light. They can be used on East and West where glazing is unavoidable due to design/site reasons. Double glazing can be used to reduce winter heat loss. However, during summer, they require full shading?minimize heat gains/transfer.
Internal Windows
The?internal windows are important for reducing winter heat loss. Windows can lose heat five to ten times faster than an equivalent?area of wall. Heat loss can be minimized by keeping warm air inside the room away from cold windows, closed curtain covering entire window up to ground made of heavy fabric are considered effective in minimizing heat loss.
?Sky Light
Sky lights are known for their effectiveness to reduce day time lighting needs. Sky lights can also lead to heat gain during summers and heat loss during winter. To minimize this, sky light can be positioned for shading in summers and provided with, special glazing that minimizes heat transfer during winter by closing non-vented ducted skylights,as the air trapped in duct acts as thermal buffer.
?INSULATION
?Acting as barriers, insulation makes spaces more comfortable by reducing the heat loss in winter and heat gain in summer. Insulation of ceilings, roof, external walls and air gaps would be critical to achieve the desired objectives of energy efficiency. Bulk and reflective are the two major kinds of insulations used. Bulk insulation works by trapping small cells or layers of air within the insulating materials which are effective in retarding heat transfer whereas in case of reflective insulation, reflections of light and?heat are use as mechanism to reduce the heat transfer.
Effective use of thermal insulation, treating ?roof for regulating solar radiation, using cavity walls, locating, sizing and detailing properly windows and shading devices help in evolving design solution which are bio-climatic &ultimately help in reducing energy requirement of the building. However, advanced techniques of passive heating and ventilation ike trombe wall, water wall, roof based air heating system,?wind towers, courtyard, earth-air tunnels, evaporating, cooling etc. can be effectively used for evolving low energy buildings designs.
领英推荐
VENTILATION
Natural ventilation is considered an essential part of energy efficient structures. For achieving cross-ventilation, correct positioning of doors and windows would?be critical. A large opening on the leeward side of building will maximize the air flow through rooms facilitating the removal of heat accumulated during the day. Ventilation is very critical in the hot and?humid zones for creating climate sensitive design solutions for buildings.
COURTYARDS
Courtyards have been considered critical in promoting energy efficiency in buildings. They facilitate not only natural air & light into inner areas but also high degree of cross – ventilation. Courtyards make buildings safe from large heat intake and glare. Acting as large evaporator cooler during summers, courtyards promote enormous cooling without mechanical aids. Landscaped courts are great moderators of micro-climate within buildings. Acting as great heat dump, courtyards minimize heat loss during winters. Courtyards with water column fountains have been considered as great environmental moderators. Looking at the distinct advantages, courtyards should be considered as valued partners in building designs. Building and zoning laws should leverage courtyards for evolving energy efficient building solutions.
LANDSCAPING
Effective use of landscaping as part of building design can help considerably in lowering energy consumption in the buildings. Gardens can act as significant climate moderators. Use of deciduous trees/vines in West can help in providing required shade during summers and permitting?winter sun to filter through when the leaves are dropped, as a simple option to manage the ill/good effects of sun. Plantation of trees can also be used to shield the buildings from adverse impact of some trees. Shrubs or creepers grown an open pergola on the southern face of a building can provide windows with required level of shading in the summers. Use of evergreen creepers and trees along Western walls can help in considerable reduction of heat intake in the summer. Use of unshaded?pavings on the south and Western sides should be avoided ?to minimize the intake of heat reflected into the windows during ?the summer. Wherever provided they need to the properly designed and shaded.
BUILDING MATERIALS
Choice of building materials have important bearing on the energy consumption level of the building. Using low energy materials, efficient structural design and reduction of energy used for transportation can help in achieving high degree of energy efficiency. Choice of locally available materials and innovative construction techniques has clearly demonstrated their usefulness in reduction of energy consumed by the buildings during construction and operations. In addition, using dense materials such as brick, stone, concrete and rammed earth, which heat up and cool down slowly (having high thermal mass) are critical for adequately storing winter day light warmth and gradually releasing at night. In summer thermal mass can also help in keeping buildings cooler during the day when provided with proper ventilation, allowing the night air to cool down the inside mass resulting in more comfortable conditions next day.
For evolving energy efficient buildings, role of building industry would be critical. Government should encourage the industry which produces energy efficient materials. Industry must evaluate and monitor every material in terms of energy. Industry should be encouraged to promote R & D with support from?BMPTC to ensure that energy requirement of each material is thoroughly studied before the material is allowed to be marketed. Specification should also include the energy component in order to make Architects/ builders understand the energy implication of material being used.??
Colours of External Building finishes
External finishes of buildings need a?careful choice in order to regulate the heat gain/loss by walls/roof. As a general rule, light colours have a tendency to reflect the sun’s heat, while darker colours absorb it. This fact can be made use of for identifying colours for roof and walls. During summer’s, choice of light colour would be critical to minimize heat gain and to keep the inside spaces cooler by reflecting heat from the sun and?for heat gain, during the winter, the?colours will have to be darker. This would call for repeatedly changing the colours of walls and roof. Better option will be to keep the building properly insulated which is an effective mechanism of controlling and regulating heat transfer.
USE OF ENERGY EFFICENT APPLIANCES
80% of the energy consumed by any building over its entire life cycle is during the operational phase of the building whereas 20% energy is consumed during the construction. Accordingly, ?it would be critical that energy consumed after the buildings are made operational should be minimized. Substantial portion of energy is consumed by the electric gadgets which are used for lighting, heating and cooling which can be reduced considerably provided energy efficient appliances are used. CFL lights, evaporative coolers, rated kitchen gadgets etc. would be critical to minimize the energy consumption. With careful design and planning only low energy light fittings should be used along with dimmers placed strategically to achieve the maximum impact.
Roof areas can be used for installing series of photo voltaic solar panels which can generate enough ?electricity to cater to the entire electricity needs of the building making it a zero energy building. Excess power, if available, can be returned to the main power grid. Buildings having large facades can be used for installing solar panels to generate electricity to meet its energy requirements.
CONCLUSION???????????????????????????????
Looking at the existing scenario, accelerated urbanization in the Indian context imposes immense pressure on the dwindling energy resources. However, the resource crunch confronting the energy sector can be effectively alleviated if we plan, design and develop human settlements and buildings by using appropriate strategies and incorporating sound concepts of energy efficiency and sustainability.
Appropriate knowledge and technology is available for creating energy efficient buildings but behavioral, organizational and financial barriers would require immediate demolition for achieving the desired results. Adopting holistic and integrated approach, shared accountability and responsibility towards improved energy performance, making energy more valued by educating and motivating professionals involved in building industry would be critical to promote energy efficient buildings. Efficiency gains in buildings are likely to provide the greatest energy reduction globally. It is estimated that demand reduction measures could almost halve expected growth in global electricity demand and CO2 emissions from building energy use can be reduced by 29% at no net cost by 2020. However, creating energy efficient buildings would involve design community producing energy efficient building designs, financial community supporting investment in energy efficiency, building industry offering product and services for supporting designs economically, building owners and operators supporting designs financially and ?utilities supporting intelligent distribution and sustainable content of energy to and from building. Making all stakeholders work together would require effective policies and programme to be put in place on priority.
Reference
·??????Energy Efficient Designs of Human Settlements – Ar. J.K. Gupta
·??????Energy Efficiency in Buildings-Business realization and opportunities – Summary Report – World Business Council for Sustainable Development.
·??????Representative Design of Energy-Efficient buildings in India – Tata Energy Research Institute.
·??????Energy Efficiency Fact sheet – Washington State University.
·??????Energy Efficient Design Principles- Government of Western Australia.
Authors:
* Ar. Jit Kumar Gupta????????????????????????????????????** Ar. Navdeep Virdi???????????????????????????
??Director??????????????????????????????????????????????????????????????????Lecturer
????????College of Architecture, I.E.T, Bhaddal????College of Architecture, I.E.T, Bhaddal
#344, Sector 40-A?????????????????????????????????????????#3222, Sector 47-D
Chandigarh- 160036?????????????????????????????????????Chandigarh- 160047
????Email i.d. [email protected][email protected]????
?