Adopting Low-cost Alternative for Energy Saving
Energy Saving Potential

This section showcases the energy conservation measures in a building with ECBC envelope case. The Energy Conservation Measures considered here are ECBC compliant envelope and efficient lighting with Daylight integration and optimum Window Wall Ratio (WWR). Although there is energy saving potential from individual ECBC wall and roof and window, the overall energy saving potential from the ECBC envelope as a whole strategies are mentioned here under.

  • ECBC wall
  • ECBC roof
  • ECBC window
  • Efficient lighting
  • Daylight integration and optimum WWR

For more information on the ECBC envelope, refer Technical Information Section.


Lighting Power Density*

Daylight integration

Window Wall Ratio

U-value : 0.391 W/m2°C

U-value : 2.22 W/m2°C

U-value : 0.385 W/m2°C

L.P.D = 6 W/m2

Daylight integration

(20- 30)%


Impact of Energy Conservation Measures-3 design Strategies:

Energy Performance Index of an ECBC envelope + efficient lighting with daylight integration & optimum WWR in a day use and 24 hour use building with above mentioned energy conservation measures is in the following range:

Dayuse Building

24 Hour use Building

Lighting: 18.01 (kWh/m2/annum)
HVAC: 76.67 (kWh/m2/annum)
EPI of the building (including lighting & HVAC
consumption only): 94.7 (kWh/m2/annum)

Lighting: (kWh/m2/annum)
HVAC: (kWh/m2/annum)
EPI of the building (including lighting & HVAC
consumption only): (kWh/m2/annum)


It is observed in air-conditioned buildings for both day use and 24 hour-use, ECBC compliant envelope + efficient lighting with daylight integration & optimum WWR has high energy saving potential. The below graphs shows the reduction in energy consumption in a day time and 24 hour-use buildings by adopting low energy strategies;

Fig 1: Energy saving potential due to ECBC compliant envelope (ECBC envelope + Daylight integration and optimum WWR) in a day use building

**Note: The energy saving potential of Energy Conservation Measures (ECM2), is calculated with Building Envelope against Base case (conventional building). Low energy design strategies, lighting and HVAC systems in ECM2 are same as in Base case/Conventional Building

From the graph below it is also observed that by just using efficient lighting (lower LPD) there is 38.2% reduction in the total EPI for day use buildings.
Fig 3: Impact of using efficient lighting on EPI

Life Cycle Cost Analysis:

The Life Cycle Cost Analysis (LCC) of this ECBC Compliant+ Efficient lighting case with daylight integration with optimum WWR of 0.30) was carried out under this project. The LCC of this case in day use buildings considering 25 yrs is 672 Million Rs. The Pay back period is found out to be as 2 yrs.

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