Adopting Low-cost Alternative for Energy Saving
Case Study

General Information:

City: Noida
Climate: Composite
Operational schedule –  8 hours, 5 working days in a week
Area of the building: 10300m² (out of which 9122 m² - conditioned area, 1178 m² - Non- conditioned area)

Function of the building: Office space

Existing Building Design Features:

Building Envelope


The U-value which is much higher than the ECBC standard (0.44W/m2K) increases the solar heat gain and the energy consumption


    1/8” clear single glazed window in thermally unbroken aluminium frames

    (SC – 0.91
    U- Value of Glass – 6.97W/m2K)
    WWR – 48%

    Clear single glazed window and WWR which is more than that of ECBC recommended (40%) increases the external solar heat gains and thereby increasing the cooling loads


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

Building Lighting

Lighting system
  • 14.3% of the (253kW of indoor lighting, 14kW of outdoor lighting) total connected load
  • Fluorescent lamps and 12V miniature halogens in working spaces. CFLs in corridors and lift lobbies. Metal halide lamps and High pressure sodium lamps used for external lighting
  • LPD – 24W/m2
  • The LPD (24W/m2) is double than the max allowed LPD of ECBC recommended (10.8W/m2) for office space which has high energy consuming potential
  • Fluorescent lamps generate heat, further increasing the cooling loads
  • Lighting energy consumption: 30%
HVAC System Design

  • Central AC plant with five 200TR water cooled reciprocating chillers
  • The COP of the chillers is 4.01 (rated) / ECBC recommended is 4.20
  • Rated Sqft/TR – 98
Energy performance of the building

Lighting Energy Performance of the Building

  • Annual Consumption (lighting) – 30% of the total
  • Lighting Performance Index – 70 KWh/Sqmt/annum

Space Conditioning Energy Performance of the Building

  • Annual Consumption (A/C) – 70% of the total
  • HVAC Performance Index – 183 KWh/Sqmt/annum

Annual energy consumption due to lighting & air conditioning (kWh):2382112

Energy Performance Index of the building (KWh/Sq.mts of built up area/annum):231
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