The importance of considering the total window/glass combination

2. Selecting windows when rating The importance of considering the total window/glass combination

3. Glass Terminology SOLAR CONTROL • SHGC Solar Heat Gain Coefficient • How well a product blocks heat caused by the sun. • Expressed as a % of solar heat gain transmitted. • SC Shading coefficient Similar to SHGC, not commonly used.

4. THERMAL INSULATION • U value • The rate of heat loss • Smaller the number the better VISIBLE LIGHT • VT • Expressed as a % of visible light transmitted. DOUBLE GLAZING • IGU • Insulating glass unit. • The hermetically sealed glazing unit, normally comprising of 2 sheets of glass and a spacer bar.

5. 3mm Clear Glass • Standard 3mm glass • Basis of all other glass calculations and comparisons. U value = 4.53 SHGC = 0.87 87% of solar heat gain transmitted SC = 1

7. 3mm Bronze Glass (Toned) • Traditional toned glass U value = 4.81 SHGC = 0.73 73% of solar heat gain transmitted VT = 0.63 63% of visible light transmitted

9. 5mm Spectrally Selective Glass (SST) • Spectrally selective toned glass • Lower solar heat gain • High light transmission U value = 4.8 SHGC = 0.66 66% of solar heat gain transmitted SC = .57 VT = 0.63 63% of visible light transmitted

11. 3/12/3 Clear Double Glazing (D3123) • Cuts heat loss in ½ due to the insulating air space between the glass layers. • Allows transmission of high % of visible light and high solar heat gain. U value 2.43 SHGC = .77 77% of solar heat gain transmitted SC = .891 VT = 0.81 81% of visible light transmitted

13. Low E Low Transmittance (DGET) • Best used on position 2 of a IGU • Spectrally selective • Use to reject heat • Not generally available, additional cost involved. U value 2.2 SHGC = 0.39 39% of solar heat gain transmitted SC = .45 VT = 0.70 70% of visible light transmitted

15. Low E Argon Filled (DLEA) • Best used with Low e on position 2 of a IGU • Spectrally selective • Use to reject heat • Not generally available, additional cost involved. U value 1.5 SHGC = 0.39 39% of solar heat gain transmitted SC = .45 VT = 0.80 80% of visible light transmitted

17. Low E ( High Transmittance) • Used on position 3 of a IGU • Enhances the insulating value of a IGU • Ideal for a heating environment to retain internal heat. U value 1.92 SHGC = 0.71 71% of solar heat gain transmitted SC = .82 VT = 0.75 75% of visible light transmitted

20. Window Terminology • Window frame Generic Aluminium (ALSTD) Aluminium Improved (ALIMP) Thermally Broken (ALBRK) Timber (TIM) PVC Steel

21. Generic aluminium windows • Readily conducts heat. • Increases the overall U factor of the window. • In cold climates condensation can form on the inside surfaces.

25. Thermally Broken • Thermally broken by splitting the frame into interior and exterior pieces. • Frame U value = 3.8 compared to Generic Aluminium window of U = 12.7

28. Aluminium Improved Frame • Slender frame, reducing the overall frame area. • Built into a timber reveal breaking the heat loss path from inside to outside

31. Timber Windows • Energy efficient frame • Requires good sealing system to minimise air leakage • Maintenance

35. AGGA would like to thank the following: • A&L Windows • Canterbury Windows • Efficient Windows Collaborative • Pilkington • SEAV For further information on energy efficient glass contact AGGA on 03 9853 3464 agga@bigpond.com.au

36. 03 9853 3464 agga@bigpond.com.au