Adopting Low-cost Alternative for Energy Saving
Case Study

General Information:
Client: Hindustan Unilever Limited
City: Bangalore
Climate: Moderate
Operational schedule – 8.30 hours, 5 working days in a week
Area of the building: 10,714m² (out of which 5665 m² - conditioned area, 5049 m² - non-conditioned area)

Green Building Design Features:

Building Design

Orientation

  • Longer facades: N-S
  • Large window openings: N-S
  • Blank walls on E-W (separate layer of outer walls on East)
  • West shaded by existing buildings
  • Building orientation has been a significant design consideration
  • Large window openings on N-S for daylight integration
  • Separate layer of outer wall on east shades the building on east facades and reduces the solar heat gain

Landscape

  • Buildings designed around the existing mature trees
  • Circulation areas designed around these trees
  • Prevent heating up of building surface and reduces direct solar heat and heat island effect
  • Circulation areas designed around these trees make these areas naturally daylit and ventilated
  • Shade the semi-open circulation and meeting areas
  •  

Water Bodies

  • Reception areas as well as research building blocks surrounded by water bodies
  • Water bodies – major modifiers of micro-climate around the building
  • Evaporative cooling through water bodies lower the temperature of micro-climate by evaporating water
  • Helps in maintaining thermally comfortable circulation areas and semi-open spaces


  •  

 
 Walls

  • Separate layers of wall of E-W orientation to shade from high intensity of solar radiation
  • Walls on west adjacent to existing buildings to prevent solar heat gain and to shade the building
Roof

 Windows
  • Blue-Grey glass 6mm single glaze window with shading provided
  • Tinted glass with shading on all windows helps in reducing solar heat gain and also the problem of glare

Building Lighting

Day light integration
  • Sky lights extensively used in common areas, circulation areas with no artificial lights
  • Labs are also well day lit
  • Natural day light integration through skylights and atrium spaces helps in reducing annual electricity consumption due to artificial lights
Occupancy sensors

  • Occupancy sensors in the laboratories
  • Reduce energy by turning the lights on when someone enters the room and switches when the room is empty
Lighting System
  • 11.65% of the total connected load for the building (connected load of lamps 49.4kW)
  • Luminaires used – mostly FTLs, CFLs, and Sodium Vapour Lamps
  • Translucent glass for roof in between I, II, III & IV blocks
  • LPD – 6.3W/m2
  • The LPD (6.3W/m2) is less than the max allowed LPD of ECBC (10.8W/m2) which is very good
  • According to Energy Star, CFLs provides the same amount of light as ordinary bulbs using 75% less energy
  • Translucent glass to make use of natural lighting and reduce the electricity consumption due to artificial day light during day time
HVAC system design



3 water cooled screw type chillers
Total cooling capacity is 360TR
Chiller COP (rated) – 4.23
Operating Sqmt/TR – 24
Energy performance of the building

Lighting Energy Performance of the Building

  • Annual Consumption (lighting) – 220103.3 KWh
  • Lighting Performance Index – 21 KWh/Sqmt/annum

Space Conditioning Energy Performance of the Building

  • Annual Consumption (A/C) – 593985.9 KWh
  • HVAC Performance Index – 105 KWh/Sqmt/annum
Annual energy consumption due to lighting & air conditioning (kWh): 814089.2

Overall Energy Performance Index due to lighting & air conditioning (kWh/m2): 76

Energy Saving Potential

Comparison of various parameters for solar passive building (HUL, Bangalore) with conventional case

Parameters Solar passive Case (Existing Building) features Conventional Case (Building features)
Building design Building longer facades are facing North-South. Building orientation was changed to longer facades facing East-West
Windows are shaded while roof is not shaded No roof and wall shading
Building Envelope No insulation on wall and roof. U value for Wall - 1.32 W/m2/K U Value for Roof - 0.97W/m2/K

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 - 5.7 W/m2/K and Shading coefficient - 0.47) WWR - 50% Single Glazed windows (U value of glass - 5.79 W/m2/K and Shading coefficient - 0.69)
WWR – 60%
Building Lighting Power density Lighting power density is 6.3 W/m2 Lighting power density is 10.76-21.41 W/m2
Controls Occupancy sensors in the laboratories No controls or sensors
Building Chiller 3 water cooled screw chillers with COP of 4.23 (rated) Air cooled screw chillers with COP of 3.08 (rated)
Energy performance Index (KWh/m2/yr) 76 309

 

Impact of Low energy strategies

 

The conventional case was run by incorporating low energy solar passive design strategies on the annual electricity consumption (kWh), electric load (kW) and cooling demand (TR) of the building.

 

Parameter comparison Conventional case Existing case (Low energy strategies)
Electrical load Base case 27% less than the conventional case
Cooling Load Base case 30% less than the conventional case
EPI Base case 18% less than the conventional case

 

Impact of ECBC envelope

 

The conventional case was run by incorporating ECBC envelope on the annual electricity consumption (kWh), electric load (kW) and cooling demand (TR) of the building.

 

Parameter comparison Conventional case Existing case ECBC envelope
Electrical load Base case 12% less than the conventional case
Cooling Load Base case 10% less than the conventional case
EPI Base case 9% less than the conventional case

 

Overall Impact of Low energy solar passive design strategies, ECBC measures and HVAC controls

The conventional case was run by incorporating both the low energy solar passive design strategies, ECBC measures and HVAC controls on the annual electricity consumption (kWh), electric load (kW) and cooling demand (TR) of the building.

Parameter comparison Conventional case Existing case Low energy strategies + ECBC recommended strategies + HVAC controls
Electrical load Base case 49% less than the conventional case
Cooling Load Base case 34% less than the conventional case
EPI Base case 34% less than the conventional case

 

 

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