Adopting Low-cost Alternative for Energy Saving
Case Study

General Information:

City: Hyderabad
Climate: Hot & Dry
Operational schedule – 10 hours, 5 working days in a week
Area of the building: 21778m² (2 towers each of 5 floors including ground floor)

Function of the building: Office Space

Existing Building Design Features

Building Envelope


230mm brick wall with 30mm plaster on
exterior side and 20mm on interior side


The U-value is higher than that of ECBC recommended (0.409 W/m2K).
This results in high external solar heat gains and increased cooling loads


  • Double glazing windows with aluminium frames
  • WWR – 60%
  • The glazing of the building has been designed to maximize the effect of natural light, largely eliminating the need for artificial light during day time
  • WWR which is higher than ECBC recommended (40%) increases external solar heat gain and cooling loads

Building Lighting

Lighting system

  • 19 % of the total connected load (150 kW during daytime)
  • 32W & 18W OSRAM CFL with electronic chokes
  • The LPD 12.7 W/m2 is higher than that of ECBC recommended (11.8 W/m2) for office space which has high energy consumption potential.
  • Lighting energy consumption: 19.3%
Lighting controls
  • Manual lighting controls used
    in the building
  • No occupancy sensors
HVAC system Design
  • Central AC plant with 4 air cooled screw chillers of 270TR each
  • The COP of the chillers is 3.05 (rated) / ECBC recommended is 3.05
  • Rated Sqft/TR – 166
Energy Performance of the Building

Lighting Energy Performance of the Building

  • Annual Consumption (lighting) – 30%
  • Lighting Performance Index – 47 KWh/Sqmt/annum

Space Conditioning Energy Performance of the Building

  • Annual Consumption (A/C) – 70% of the total
  • HVAC Performance Index – 137 KWh/Sqmt/annum

Annual energy consumption due to lighting & air conditioning (kWh): 3323335

Energy Performance Index of the building (KWh/Sq.mts of built up area/annum): 199

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