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design includes daylight pane, vision pane, light shelves, and other shading devices which let in a good amount of natural light, removing the requirement to switch on lights during the day. These interventions enable maximum daylight penetration into the building with no glare, providing a natural and healthy work environment to the employees. Today, the company has 14 buildings with LEED Platinum and 4 buildings with GRIHA 5-star rating. This covers a total of about 5.25 million sq.ft. of built up area with highest level of green certification. We have also achieved an Energy Performance Index (EPI) of 75 kWh/ sq.m. / Year, among the lowest in the industry. Deep green retrofits While making the new buildings superefficient, Infosys realized the great potential in the existing buildings. Thus, to make old buildings as efficient as the new ones, they undertook massive HVAC, lighting, and UPS system retrofits. These deep green retrofits have significantly reduced the connected load in four years. The short payback period of these projects clearly demonstrates the viability of retrofits in improving efficiency by huge numbers. Chiller Plant Room retrofit: • Complete re-engineering of chiller plants minimized piping, eliminated use of balancing valves, thereby reducing pressure drop and right sizing the pumps • Primary secondary systems in chiller plants replaced with variable primary inline pumps, resulting into about 30% reduction in energy and about 45% reduction in equipment • In the air handling units, conventional fan system replaced with EC (Electronically Commutated) fans leading to nearly 50% reduction in energy • Variable speed drives installed in each and every equipment • Chiller plants are designed with series counter flow arrangement for optimum energy use • Reduction in the number of chiller plants from 54 to 41. • Older air-cooled Variable Refrigerant Volume (VRV) units replaced with chilled-water-based units which are free from harmful refrigerants and require lower maintenance as compared to the previous system ENERGY EFFICIENCY These interventions have freed up almost a third of the space that was previously occupied in the plant room. Deep green retrofits in the air conditioning systems have helped achieve 15 MW connected load reduction in the last four years. These retrofits have a short payback period of less than three years with the life of equipment being more than ten years, thus making them financially viable for implementation. UPS retrofit: In addition, conventional UPS systems have been replaced with energy efficient modular UPS systems to reduce installed capacity and energy consumption. Modular UPS systems offer highest level of efficiency and flexibility through a unique system design with cutting-edge architecture, consisting of independent hot swappable modules- about 5 to 10 in number. These modules allow online interchangeability TABLE 3 Description Old System New System Impact Number of UPS systems 350 230 Elimination of 120 UPS systems UPS Capacity 30200 KVA 20000 KVA 34% reduction Efficiency 79% 93% 18% improvement Number of batteries 19500 10000 49% reduction TABLE 4 Particulars Conventional UPS Modular UPS Design Load–80 KVA 80 KVA x 2 20 KVA x 5 Total installed KVA 160 KVA 100 KVA Operating daytime load -70 KVA 70 KVA 70 KVA Actual load on each UPS 44% 70% Day time efficiency of UPS 84% 93% Operating night time load–35 KVA 35 KVA 35 KVA Actual load on each UPS 22% 35% Night time efficiency of UPS 73% 92% Figure 1: Façade of Infosys SDB-1 building, Hyderabad. 49 energetica INDIA · JAN | FEB16


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