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Energy Efficient Glass Façade for building envelope Sri Ram.N – IGBC AP; GRIHA Trainer Saint Gobain Glass India 15 th J

Energy Efficient Glass Façade for building envelope Sri Ram.N – IGBC AP; GRIHA Trainer Saint Gobain Glass India 15 th June 2011. Glass for building envelope. Indispensible construction material Freedom from conventional building shapes, with unmatched aesthetics .

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Energy Efficient Glass Façade for building envelope Sri Ram.N – IGBC AP; GRIHA Trainer Saint Gobain Glass India 15 th J

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  1. Energy Efficient Glass Façade for building envelope Sri Ram.N – IGBC AP; GRIHA Trainer Saint Gobain Glass India 15th June 2011

  2. Glass for building envelope Indispensible construction material Freedom from conventional building shapes, with unmatched aesthetics. Transparent to visible light – daylighting of interiors Blending of interiors with exteriors Helps to maintain hygienic environment with easy maintenance Glass is 100% recyclable – Sustainable building envelope

  3. RESIDENTIAL 80 % of Building Energy Consumption COMMERCIAL Consumption Pattern Source: Res :UNEP SBCI & TERI Study, Comm: IGDB Study

  4. Key Performance Factors Lighting Energy • Light Transmission Cooling Energy • Total Heat Gain / Heat Transmission • SHGC or SF : Solar Heat Gain Coefficient or Solar Factor • U Value

  5. Performance Parameter Light Factors

  6. Visual Light Transmission (VLT) • Percentage of incident light transmitted • Percentage transmission depends Tint & Coating out Light Transmitted

  7. Factors affecting Visual Light Transmission (VLT) Single Glazed Unit Clear VLT = 89% Single Glazed Unit Green tint VLT = 73% Single Glazed Unit Clear - Solar control VLT = 67% – 7% Single Glazed Unit Blue Tint VLT = 57% Single Glazed Unit Green - Solar control VLT = 54% – 6%

  8. Energy Performance Factors Total Heat Gain / Heat Transferred SHGC U Value

  9. Total Heat Gain Near Infra Red Far Infra Red UV Visible .25 .38 .78 2.50 50 µ Electromagnetic Spectrum at Terrestrial Level TOTAL HEAT GAIN Amount of heat Transferred due to temperature difference Heat Gain due to direct solar radiation Wave Length

  10. directly + re-emitted energy = S F / SHGC Heat gain due to Direct solar radiation 1# 2# incident solar radiation directly transmitted energy reflected energy re-emitted energy re-emitted energy

  11. Factors affecting SOLAR FACTOR (SF) or Solar Heat Gain Coefficient (SHGC) Single Glazed Unit Clear SHGC = 0.84 Single Glazed Unit Green SHGC = 0.56 Single Glazed Unit Blue SHGC = 0.56 Single Glazed Unit Green–solar control SHGC = 0.16– 0.47 Single Glazed Unit Clear –solar control SHGC = 0.15 – 0.68

  12. Shading Coefficient Shading Coefficient (SC) = Solar factor of Glass Solar factor of 3.0mm Clear Glass (0.87) • SC should be used if the solar value are through 3mm clear glass • SF or SHGC should be used if it is direct solar value from sun Eg: Weather Files

  13. Amount of heat Transferred due to temperature difference U Value Area = 1 m2 U = 5.7 W/sqm K T1 = 1oC T2 = 0oC

  14. Factors affecting U value Inert Gas Double Glazed Unit Low-e + inert gas U value = 1.0 to 1.3 W/SqmK Double Glazed Unit Low-e U value = 1.4 to 2 W/SqmK Single Glazed Unit U value = 5.8W/SqmK Double Glazed Unit U value = 2.9W/SqmK

  15. ECBC – [Energy Conservation Building Code] Glazing Requirements for building envelope

  16. ECBC Compliance Approach • Prescriptive: component based approach (specs given for each) • Low Flexibility • Easy Approach • Trade Off: system based approach (trade off between performance of envelope) • Moderate Flexibility • Comparatively Tedious Approach • Performance Method: Whole Building Design Analysis Approach (overall building energy efficiency) • High Flexibility • Tedious Approach – High Detailing

  17. Prescriptive Compliance Approach

  18. Climatic zone map of India

  19. WWR: Window to wall ratio • WWR = Net Glazing area / Gross wall area • Net glazing area (window area minus mullions and framing) divided by • Gross exterior wall area (e.g., multiply width of the bay by floor-to-floor height) • Spandrel Glass & Glassin front of dead wall are not considered as glass area Z Z Case 1 : WWR = X / Y Case 2 : WWR = (X+Z) / Y

  20. Prescriptive Requirements Light Transmission SHGC / U value ECBC Prescriptive requirements

  21. Glass Performance Coated Glass with Solar / Thermal Insulation

  22. Coating Technology - Glass Conforming to ECBC Compliance

  23. Online Coating C O A T I N G T E C N O L O G Y CVD Coating Manufactured during manufacturing of glass it self. Process of manufacturing known as pyrolysis Offline Coating Manufactured in a separate process (offline) by Magnetron sputtering on to raw glass

  24. Choosing “Correct” Glass Energy Efficiency Daylighting

  25. Daylighting

  26. Daylight Integration Sunlight aids in, • Reduction of Artificial lighting • Increasing Vitamin D level • Alleviate depression &anxiety • Eliminates Claustrophobic effect Glass, • Allows abundant natural sunlight • When compared to conventional brick-mortar building, daylight integration saves about 40 to 60% of the energy used for lighting • For a fixed lumen requirement, sunlight generates lesser heat in comparison to artificial lighting – reduce the A/C bill Light Heat ratio Heat Built up

  27. Clear Glass Solar Control Coated Glass Light Transmission 89% Light Transmission 30% Average Lux Level 430 lux Peak Lux level 1680 lux Average Lux Level 220 lux Peak Lux level 670 lux Outdoor Lux level : 9000Lux Room Size : 4m X 5m Window Size: 1.0mX 2.4m (WWR:20%)

  28. Energy Efficiency

  29. Air conditioned Spaces

  30. Energy Analysis of air conditioned space Glass Performance on cooling & Lighting load • Lower Solar Heat Gain coefficient significantly reduces the cooling • Optimized light transmission of glass reduces lighting energy during daytime operation Location: Mumbai Floor area : 12000 Sqft WWR – 20%

  31. Non - Air conditioned Spaces

  32. Case 1: Double Glazed Unit – Clear Glass Solar Factor : 0.71 U value : 2.8W/SqmK Case 2: Double Glazed Unit – Single silver Low-e Glass Solar Factor : 0.54 U value : 1.8W/SqmK Case 3: Double Glazed Unit –Double silver Low-e Glass Solar Factor : 0.32 U value : 1.6W/SqmK Location : Mumbai Room Size : 4m X 5m Glass Direction : South Glass Size : 1.9m X 4.6m Over hang : 1.0m Simulation : Ecotect Simulation hours : 8760 Hrs Temperature Distribution

  33. Temperature Distribution Comfort Temperature Range Discomfort Temperature Range

  34. Go Green • Do your little bit to the planet ! • Every reduction in Unit of electricity (KwHr) means 1.4 kg(CO2e) per kWh* • Every reduction in a single KWH, 1.4 Kg of CO2 emission is prevented • Conversion factor includes GHG emission for handling, generation & transportation loss *Source: DEFRA – Dept of energy & climatic change

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