Increased human activities are causing irreversible damage to the global environment causing threat to the quality of life for the coming generations. With the tremendous growth in economic activity across the globe placing pressure on natural and environmental resources, experts and thinkers are seeking sustainable solutions in all aspects of our lives.

Real estate development is a significant contributor to global warming as it uses about 40% of the energy and it is one of the prime contributors to extensive emission of greenhouse gases. Therefore there is an extreme need to develop green buildings. Though Green Building concept is not new in India and the principles have been successfully utilized for centuries, it has become an essential instrument towards sustainability in the recent years. Sustainability in buildings is not only limited to energy conservation, but also includes efficient use of water & natural resources, impact on the neighboring environment and working conditions for occupants.

Green building design is based on ‘Form follows function’ kind of designing which is associated with modernist architecture and design in the 20th century. This principle rests on the concept that the shape of a building or object should be primarily based upon its intended function or purpose. This however should not be mistaken as a compromise in the aesthetic appeal of the design. In fact, buildings all around the world are being built with its functionality and sustainability in mind without losing out on its visual appeal.

Green buildings integrate several sustainable features, such as efficient use of water, energy-efficiency, eco-friendly environment, use of renewable energy, use of recycled/recyclable materials, preserving natural topography, soil erosion and sedimentation control, effective control and building management systems and improved indoor quality for health and comfort. There are a few challenges with respect to such constructions in India. Primarily it is due to the perception that building such projects incurs higher costs and a lot of maintenance. A certified or silver rated green building would have incremental costs in the range of 3-5% over conventional ones, whereas the cost can go up further for Gold or Platinum rated projects. However, we found out that certain developers were already considering green building initiatives in their projects such as building materials with good thermal insulating properties, high efficiency HVAC and Lighting equipments, solar water heating, water recycling plants, rain water harvesting systems, etc. For such developers the incremental costs would be restricted to the fees for certification and consulting only. In a Commercial Green Building, even these incremental costs could be easily recovered within a few years through energy savings, provided best Operation and Maintenance practices are followed.

Different technologies in each component of a building have contributed to bringing down the incremental costs for going green. Some of them have been mentioned below:

• Building Envelope: Building envelope consists of roof, fenestration, glazing and the exterior walls.  A thermally insulated building envelope involves using materials that reduce heat transfer by conduction, radiation and convection. It helps cut down the heat load in the building, downsizing the air conditioning equipment required to cool the spaces and hence, results in lowering of the capital costs for the project. Thermal performance of fenestration, wall and roof assembly depends on Solar Heat Gain Coefficient (SHGC) & that of glazing depends on the solar energy transmittance through the glazing (measured by U-value). Lower the SHGC and U values, better are the thermal insulating properties of the wall, roof, fenestration and glass.

Using insulation materials like extruded expanded polystyrene (XPS), molded expanded polystyrene (EPS), etc. decreases the SHGC value of the wall and roof assembly, thereby offering good thermal insulation. But due to incremental cost, developers restrict the usage of insulation materials to roof. As a cheaper alternative to insulation materials for exterior walls, one may opt for Fly Ash bricks or Autoclaved Aerated Concrete (AAC) blocks instead of clay or normal concrete bricks, as they have excellent thermal insulation properties. Fly ash acts as a good insulating material and is used in both Fly ash bricks as well as AAC blocks. The autoclaved aerated concrete is a versatile lightweight construction material which has low density and excellent insulation properties. The low density is achieved by the formation of air voids to produce a cellular structure.

External shading devices such as awnings, overhangs, and trellises are part of the building envelope. These are installed over windows and prevent unwanted solar heat from entering a conditioned space.

• Lighting Systems:

Lighting is an essential requirement for any facility and it touches the day-to-day lives of people in more ways than one. It accounts for 15% of the total energy consumed in a developing country as against 7 to 10% in developed countries.

Energy efficiency has often been viewed as a ‘resource option’ just like coal, oil or natural gas. For India it is provides additional value by preserving the resource base and mitigating the global climate change.

There has been continuous development in lighting technologies over the past 60 years to produce the best lighting products and controls for creating higher lighting quality with reduced energy consumption. However, the speed at which these technological developments have taken place has not been complemented by a corresponding pace in generating awareness about them and their availability to the end-users. Also, the emergence of new secondary players has generated a lot of competition in the lighting market. Thesemarket barriers should be addressed through aggressive customer-oriented awareness programmes and demonstration Projects

Since last decade technology has leap frogged given various cost effective options to the end users. There are various strategies which can be adapted to realize Energy Efficiency in lighting system.

1. Design : Selection of appropriate Luminaries to render desired Illumination level. For normal Office application 250 -300 Lux is the design standard. To achieve
2. Efficient Design Lighting Power density (LPD) works out to 0.8 watts/sft to achieve the above mentioned illumination levels.
3. LED / T-5 with Electronic Ballasts, Reflective Luminaries etc. has resulted in improving the Lighting Efficacy.
4. ‘Lighting Management System’ play a major role in Hospitality, Hospitals, Offices, IT/ Data Centres and even in Residential Common Area to control unwanted usage of light. (Occupancy Sensors, Natural Daylight Sensing, Astronomical Timer for Outdoor lighting controls etc are proven technologies)
5. Daylight Harvesting by way of appropriate façade design, Light Pipes are some of the techniques which can be incorporated during the design of the Strucure.
6. In Industry North lighting, and Transparent Polycarbonate Sheets has found acceptance and it has become a norm in design consideration.

• Heating, Ventilation and Air Conditioning (HVAC) systems:

HVAC by and large consists of Centralized Air Conditioning System, Basement Ventilation system, Staircase Pressurization system etc. In Indian context there is not much requirement of Heating.

HVAC system is one of the costliest form of Energy End use in a building or even in Industry.

CommercialBuildings are categorized as per their End use.

1. 1. IT Space
   2. Office Space
2. Malls
3. Hotels
4. Hospitals
5. Residential

Energy profile of the above mentioned buildings vary significantly from each other.

Some of the Factors impacting the Energy consumption are as follows

1. Occupancy
2. Hours of Operations
3. Heat load Profile
4. Seasonal ambient conditions. 

Basically there are Three aspects which contribute to Energy Efficiency in Air Conditioning System.

1. DESIGN
2. INSTALLATION, TESTING AND COMMISSIONING OF SYSTEMS
3. OPERATIONS AND MAINTENANCE

• ENERGY EFFICIENT DESIGN

Who is responsible for Energy Efficiency in the Building?

1. Owner / Developer..?
2. Architect…?
3. MEP consultant…?
4. PMC..?
5. Facility Management..?

 All the above mentioned Professionals contribute significantly towards Energy Efficiency right at the   conceptual Design of the building.

One of an architect’s primary functions as part of the design team is to create an environment. This environment has both a psychological and a physiological effect on the occupants, which in turn, impacts human productivity, building operational efficiency, and effectiveness of natural resource use.

Building is a complex entity and by the day aspirations of the occupant are ever increasing. The activity commences from selection of Site, construction of the Core and Shell of the building, carrying out Interior Fit outs, Operation and Maintenance are some of the critical phases in lifetime of a building.

Institutionalizing a process for proper Operations and Maintenance of the building is as much crucial for sustaining the efforts put in for design of the Building.

Energy Efficient design in a Building can be achieved by efficient design of

1. Building Envelope

FaçadeOrientation

1. Glazing
2. Shading Devices
3. Roof
4. Landscape

Designing a good building envelope helps in reduction of Heat Load which will have repercussions on the Capex and Opex. Following get downsized.

1. Sizing of the Chillers, Pumps
2. Sizing of Transformers, DG sets, Cables
3. Contract Demand
4. Lower Energy consumption during Operations

2. Systems : The systems are highly interactive in nature.
   1. Heating Ventilation & Air Conditioning System (HVAC)
   2. Electrical
   3. Integrated Building Management System (IBMS)
   4. Fire Protection System
   5. Fire Fighting system
   6. Plumbing
   7. Control Access

 Hard fact is most of the times Project Team spends lots of time and Money in Energy Efficient Design but not even part of the resource is spent on Best Operations and Maintenance practice.

Reasons are plenty many.

1. Management’s conviction and commitment toward Best Sustainable Practices
2. Allocation of funds towards Operation and Maintenance
3. Trained Manpower and retention of the same
4. Understanding & analysis of Energy performance of   Systems in a building

o   Radiant Cooling – A radiant cooling system is an efficient cooling system that typically involves running cool water through a building’s floors, walls, or ceilings. It works on the basic idea that thermal comfort is determined not only by the temperature of the air around us but a combination of the ambient air and heat being radiated to or from objects nearby. What is required is that a fairly large surface which is exposed to the occupants must be cooler than the ambient air to provide radiant cooling. Occupants then radiate heat to the object, causing a sense of cooling. In practice, cooling is accomplished by chilled water circulating in an intricate network of pipes in panels or building components which can be walls, ceilings or floors.

Radiant systems can save large amounts of energy while also providing better comfort, depending on the building and the climate. They can be built into floors or ceilings, preferably in spaces with large air volumes and large amounts of unavoidable infiltration.

o   Geo-thermal cooling: The ground absorbs nearly half of the solar energy our planet receives. As a result, the earth remains at a constant, moderate temperature just below its surface all year round. Geo-thermal cooling is a type of renewable energy system that utilizes this stored energy by moving heat from above the ground to a cooler environment several feet under the earth’s surface. Water circulated through a geo-thermal loop then carries heat below the earth’s surface, where it is absorbed into the ground; and the cooled water is then carried back up to regulate the higher ambient temperature. The main advantage is that due to the mass of the earth below, geo-thermal systems can cool even intense sources of heat.

o   Chilled Beam:A chilled beam is a type of convection HVAC system designed to heat or cool large buildings. Chilled beam systems use chilled water pipes mounted to the ceiling to cool air in a space. Chilled beams use water as a medium instead of air to cool a room. Chilled beams have the potential to save existing buildings large amounts of energy due to smaller air movement requirements as only ventilation needs to be delivered to the occupied space, and also chilled beams can use warmer water than conventional fan-coil units. Also, chilled beams increase thermal comfort, air quality, and have lower than conventional installation costs.

o   Under Floor Air Distribution (UFAD): This is an air distribution system for providing ventilation and space conditioning in Data centers and Server Rooms as UFAD systems use an under floor supply plenum chamber located between the structural concrete slab and a raised floor system to supply conditioned air through floor diffusers directly into the occupied zone of the building. It effectively cools the equipments, significantly reduces energy use and costs by way of: increased air-side or water-side economizer potential due to higher supply air temperatures, increased cooling COP due to higher supply air or chilled water temperatures, reduced fan energy via reduced fan static due to reduced ductwork, reduced fan energy via reduced design flow requirements due to reduced heat gain to the lower occupied region, reduced outside air requirements due to improved ventilation efficiency.

• Building Automation/ Building Management System (BMS) – BMS includes centralized monitoring and control of systems such as Lighting, HVAC (heating, ventilation and air conditioning) and Fire Detection system.

As citizens of the world grow more aware of the impact that green building and sustainable development can have in saving our earth from climate change, we can hope that more of such innovations will be created to help experts make that a reality. In the midst of a global ecological crisis, green building consultants and architects are relentlessly pursuing design strategies that manage to mitigate the toxic byproducts of our consumption habits, while maximizing our use of sustainable energy sources. Meeting these challenges means more deeply integrating green technologies like wind and solar power, natural climate controls and space-age materials in to the building processes, it is about realizing that it not just a way to conserve energy but also our responsibility towards our future generations. In the spirit of eco-optimism, we hope that more and more designs with a right balance of both sustainability and aesthetic innovation will be developed to assist us with the same.