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.jpg "Landscaping in front of the PEDA building buffers sound and pollution (Photographs: Tushar Kumar)")
Designing sustainable buildings in a composite climate is a challenge. The techniques that are effective during summers do not work in winters. But a building in Chandigarh has achieved this. More than 10 years ago, the Punjab Energy Development Agency (PEDA) decided to construct an office building that utilises the movement of the sun for lighting, cooling and heating.
The Rs 5.5 crore building, a pilot, was ready in 2004. Six years later, the Bureau of Energy Efficiency (BEE) awarded it a five-star rating, the highest grade of energy efficiency. With a built-up area of 6,146 sq m, the building incorporates the techniques of passive solar architecture that is based on seasonal and diurnal variations in the sun’s movement (see ‘Know the building’). Monuments like the Red Fort in Delhi were designed using these techniques. The PEDA office has an energy performance index (EPI) of 14 kWh/m2/year (the lowest in the country) in the category of non-air-conditioned buildings.
EPI is the ratio of the total energy used to the total built-up area. The EPI of commercial buildings is above 180 kWh/m2/year and the benchmark set by BEE for buildings compliant with the Union power ministry’s Energy Conservation Building Code (2007) is 140 kWh/m2/year. By following passive solar techniques, the PEDA office has become one of the most energy-efficient buildings without adhering to the code, which came later, says Harsimran Singh, an architect in Chandigarh. According to the PEDA building’s architect, Arvind Krishan, unlike conventional buildings, the office’s design is in accordance with the external envelope, which he calls solar envelope.
This envelope refers to the features and materials used in the building’s skin that makes it responsive to varying weather conditions. The internal structure has floating slabs which help in air circulation. The building is oriented in the north-south direction, minimising solar exposure on the western and eastern facades. Although a building’s southern facade can be shaded, the western façade remains exposed to the setting sun and cannot be shaded, he explains.
A simulation-based study by the University of Nottingham in the UK says the PEDA building functions successfully as a passive solar complex.
.jpg "The PEDA building, designed for 500 people, is currently occupied by 100 individuals")
A portion of the roof of the atrium (open space in the centre of the building) is covered by a lightweight shell roofing. The roofing consists of 10 cm of high-density EPS (extruded polystyrene) sandwiched between high-grade FRP (fibre-reinforced plastic) sheets reinforced with steel. 
There is an integrated 25 kWp solar photovoltaic plant in the building. More than half of the building’s electricity requirement is provided by the panels. The panels are placed on the roof of the atrium, in between two sheets of toughened glass. This helps filter daylight.