High Performance Commercial Buildings in India: Adopting Low-cost Alternative Passive Strategies for Energy Saving

Case Study

General Information:

City: Bangalore
Climate: Temperate
Operational schedule – Day use, 5 working days in a week
Area of the building: 13635 m² (out of which 13010 m² - conditioned area, 625 m² - non-conditioned area)

Function: Office space

Existing Building Design Features

Building Envelope

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

Window 6mm clear single glazed window in the thermally unbroken aluminium frames (SC – 0.69, U- Value of Glass – 5.7W/m2K) WWR – 60% Clear single glazed window and WWR which is more than that of ECBC recommended (40%) increases the external solar heat gain and the cooling loads

Building Lighting
Lighting system 14 % of the total connected load (150 kW during daytime) 36W OSRAM high lumen slim tube lights in the office space, 150W HPSV lamps Copper chokes are used The LPD for different towers of the building: Tower I – 15.06W/m2 Tower II – 17.21W/m2 Tower III – 21.41W/m2 Tower IV – 10.76W/m2 Most of the LPD values are higher than the ECBC recommended (11.8W/m2) for office space which has high energy consuming potential Lighting energy consumption – 19.9%	HVAC system Design Central AC plant with 3 air cooled screw chillers, 2 of 300TR and 1 of 240TR The COP of the chillers is 3.07 (rated) / ECBC recommended is 3.05 Rated Sqft/TR – 167
Energy Performance of the Building Lighting Energy Performance of the Building Annual Consumption (lighting) – 20% Lighting Performance Index – 61 KWh/Sqmt/annum Space Conditioning Energy Performance of the Building Annual Consumption (A/C) – 80% of the total HVAC Performance Index – 259 KWh/Sqmt/annum
Annual energy consumption due to lighting & air conditioning (kWh): 4208963 Energy Performance Index of the building (KWh/sq.mts of built up area/annum): 309

Conventional Building, Bangalore

Existing Building Design Features

Building Envelope

Walls

Roof

Window

Building Lighting

Lighting system

HVAC system Design

Energy Performance of the Building

Lighting Energy Performance of the Building

Space Conditioning Energy Performance of the Building