Infosys Software Development Block | Hyderabad, India

Radiant cooling outperforms forced air in side-by-side comparison

Infosys, a global leader in consulting and technology, was rated the eighth greenest company in the world by Newsweek in 2011, the year they opened their new Software Development Block (SDB-1) office building in Hyderabad. SDB-1 is the first radiantly cooled building in India and the world’s largest side-by-side comparison of hydronic radiant versus conventional forced-air HVAC systems.

SDB-1 comprises two symmetrical wings, one of which employs an optimized variable air volume (VAV) system and the other a thermally activated building system (TABS) coupled with a dedicated outdoor air system (DOAS) mainly for providing fresh air. All parameters in the two halves – area, number of occupants, orientation, envelope and lighting – are similar, providing a reliable comparison of the two technologies.

Maximizing energy efficiency in a climate with temperatures reaching 115°F (46°C) and dew points of 77°F (25°C) required optimization of every component from the building envelop to lighting to HVAC systems. Designed by Sundaram Architects, the high-performance structure – comprising insulated walls and roof, argon-filled window glazing and an advanced light-shelf/sun-shade system – limits solar gain to 1 W/ft2.

No Issues With Condensation
"I recommended radiant cooling, knowing that the hot, humid climate would be an important test of the cooling ability and humidity control of a radiant with DOAS system," said Peter Rumsey, PE, one of the lead engineers on Integral Group’s project team. "We haven’t experienced problems with condensation in the radiantly cooled offices."

REHAU radiant cooling specialists supported the project engineers from Integral Group and ARCO Engineering during the design, fabrication and installation of the radiant cooling modules. A total of 230,000 feet (70,000 meters) of REHAU O2 Barrier PEXa pipe was integrated into the massive concrete slabs.

REHAU Trained Workers on Installation
To keep pace with the ambitious construction schedule, REHAU helped to train local workers to pre-fabricate cooling modules on site by tying pipe circuits to metal grids and making secure connections using F2080 compression-sleeve fitting technology. Individual circuits were connected to REHAU manifolds with flow meters designed to circulate fluid at a temperature of 63°F (17°C). Even though the radiant installation required a hybrid of hydronic and air-based systems, its initial cost was slightly lower than the VAV installation.

Radiant Cooling Uses 33% Less Energy Than the Forced-Air System
Data analysis by the Technical University of Braunschweig found that the radiant cooling system used 33% less energy than the forced-air system. The radiant system also scored higher on thermal comfort in a survey of the building’s 2,500 occupants by the University of California at Berkeley’s Center for the Built Environment. Employees working in the radiantly cooled wing felt that the room temperature was cooler than those in the VAV wing, even though the physical air temperature was about 3.6°F (2°C) warmer.

With SDB-1, Infosys proved to themselves and the world that radiant cooling improves comfort, lowers HVAC energy use and saves HVAC construction costs.

SDB-1 has been designated LEED Platinum by the Indian Green Building Council, bringing the total Platinum-certified building area at Infosys to more than 1 million square feet and moving the company closer to its goal of carbon neutrality by 2018.

Project: Infosys Software Development Block, Hyderabad, India
Type of construction:Commercial, office building
Architect:Sundaram Architects
REHAU systems used:Radiant cooling system, RAUPEX®
 Images © Infosys Limited

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