Adopting Low-cost Alternative for Energy Saving
Case Study

Wipro Limited





General Information:

Client: Wipro Limited
City: Kolkata
Climate: Warm & Humid
Operational schedule –24 hours, 6 working days in a week
Area of the building : 11079.2m² (out of which 7621.0 m² - conditioned area, 3458.2 m² - Non- conditioned area)

Green Building Design Features:

Building Design

Orientation

  • Tower 1 & 2: Longer axis N-S
  • Tower 3 & Cafeteria: E-W
  • Learning Center – N-E

The orientation of Towers 1 & 2 helps in reducing solar heat gains.

Orientation of window openings of Tower 1 & 2 on N-S helps in reducing cooling loads and reducing the overall air-conditioning requirement and hence saves energy.

The proper building orientation plays an important role with regard to solar radiation and wind.

Landscape

The three towers are planned around courtyards which are green spaces around the building blocks.

Maintains comfortable micro-climate and contribute towards energy conservation. Trees reduce direct solar heat, provide shade and prevent heating up of building surfaces and heat island effect.

Also helps in maintaining a lower ambient temperature around the buildings and hence better microclimate.






Building Envelope

Walls

Walls of air-conditioned zones in all blocks - 230 mm brick with 12.5 mm plaster

Roof

Roof Towers 1,2,3, learning centre, and guest house





Window

6 mm brown single windows




  • (SC – 0.52, U-value of Glass – 5.7 W/m2K) WWR – 11.1%

Tinted single glazed window helps in reducing solar heat gain. Optimum WWR which is less than ECBC standard (40%) helps in reducing external solar heat gain.


Building Lighting

Day light integration


Due to less window wall ratio, daylight integration has not been the focus in this building.



Small windows at the seating areas can reduce thermal discomfort.
The reduced percentage of window area to wall area helps in reducing the external heat gain into the building.

Lighting system

  • 6% of the total connected load for the building (273 kW of indoor lighting, 30 kW of outdoor lighting)
  • Luminaires used mostly – one efficient recessed type luminaires with twin 36 W CFLs
  • LPD – 6.9 W/m2
  • The LPD (6.9 W/m2) is less than the maximum allowed LPD of ECBC (10.8 W/m2) which is very good.
  • According to Energy Star, CFLs provide the same amount of light as ordinary bulb using 75% less energy.
  • It also generates 75% less heat, reducing cooling costs.
HVAC system Design

Central plant with 4 chillers of 2 types with 1610 TR cooling capacity
  • Screw type chillers
  • Centrifugal chillers

Energy Performance of the Building

Lighting Energy Performance of the Building

  • Annual consumption (lighting) – 917501 kWh
  • Lighting Performance Index – 23 kWh/sq.mt/annum

Space Conditioning Energy Performance of the Building

  • Annual consumption (A/C) – 7798385 kWh
  • Operating cooling demand – 196 sq.ft/TR


Annual energy consumption due to lighting & air conditioning (kWh): 445335

Energy Performance Index of the building (KWh/sq.mts of built up area/annum): 219

Energy Saving Potential

Impact of Low energy strategies:


Parameter comparison Conventional case Existing case (Low energy strategies)
Electrical load Base case 6% less than the conventional case
Cooling Load Base case 17% less than the conventional case
EPI Base case 5% less than the conventional case

Impact of ECBC envelope:

 

Parameter comparison Conventional case Existing case (ECBC envelope)
Electrical load Base case 5% less than the conventional case
Cooling Load Base case 13% less than the conventional case
EPI Base case 5% less than the conventional case

 

Impact of ECBC recommended LPD:

 

Parameter comparison Conventional case Existing case (ECBC envelope)
Electrical load Base case 12% less than the conventional case
Cooling Load Base case 9% less than the conventional case
EPI Base case 13% less than the conventional case

 

Impact of ECBC recommended chiller efficiency:

 

Parameter comparison Conventional case Existing case (ECBC envelope)
Electrical load Base case 9% less than the conventional case
Cooling Load Base case No change
EPI Base case 7% less than the conventional case

 

Impact of HVAC controls:

 

Parameter comparison Conventional case Existing case (ECBC envelope)
Electrical load Base case 16% less than the conventional case
Cooling Load Base case No change
EPI Base case 16% less than the conventional case

 

Impact of ECBC recommended energy conservation measures:

 

Parameter comparison Conventional case Existing case (ECBC envelope)
Electrical load Base case 23% less than the conventional case
Cooling Load Base case 23% less than the conventional case
EPI Base case 21% less than the conventional case

Impact of ECBC recommended energy conservation measures:

 

Parameter comparison Conventional case Existing case (ECBC envelope)
Electrical load Base case 38% less than the conventional case
Cooling Load Base case 30% less than the conventional case
EPI Base case 35% less than the conventional case

Comparison of various parameters for solar passive building (Wipro) with conventional case:

 

Parameters Solar passive Case Conventional Case
Building design Building longer facades are 45 degree inclined to North

No roof and wall shading
Building orientation was changed to longer facades facing East-West

No roof and wall shading
Building Envelope No insulation on wall and roof.
U value for Wall -1.92 W/m2/K
U Value for Roof-2.74 W/m2/K

Single Glazed windows( U value of glass -5.7 W/m2/K and Shading coefficient-0.52)
No insulation on wall and roof.
U value for Wall -1.92 W/m2/K
U Value for Roof-3.35 W/m2/K

Single Glazed windows( U value of glass -6.14 W/m2/K and Shading coefficient-0.815)
Building Lighting Power density Lighting power density is 6.9 W/m2 Lighting power density changed to 20 W/m2

Building Chiller 2 water cooled screw type chillers having a COP 2.6-2.9
2 water cooled Centrifugal water cooled chiller having a COP 4.0-4.3
Air cooled screw chillers with COP of 3.2
Energy performance Index (KWh/m2/yr) 219 335
Copyright 2012. All rights reserved by HPCB Privacy Policy