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Building Envelope & Materials11 min read•July 24, 2026
Window Fenestration Design: UPVC vs Aluminium Frames, Glass Types & Energy Performance
Spoken by: AGNAA Building Envelope Team
Primary Reference: CIBSE Window Design Guide & ECBC Energy Conservation Building Code
Direct Answer (AGNAA Engineering Standard)
UPVC casement windows with double glazing (5mm glass + 12mm argon + 5mm glass) provide 35% better thermal insulation than aluminium single-glazed frames. AGNAA Design Studio specifies Low-E double-glazed UPVC windows for all West, South, and East facade openings, and aluminium curtain wall glazing for contemporary commercial facades with a U-value target of 2.0 W/m²K.
Executive Key Takeaways
- Low-E double-glazed UPVC windows achieve a U-value of 1.4–1.8 W/m²K.
- Argon gas filling in double-glazed units reduces heat conduction by 34% over air filling.
- Aluminium curtain wall systems with thermal break prevent condensation on interior sills.
- Window-to-wall ratio should not exceed 40% on West/South facades to limit solar heat gain.
- ECBC 2017 mandates a maximum SHGC (Solar Heat Gain Coefficient) of 0.25 for Hyderabad.
Frequently Asked Questions
Should I choose UPVC or aluminium windows for my Hyderabad home?
UPVC offers better thermal insulation and noise reduction for residential homes. Aluminium is preferred for large commercial curtain wall facades, high-rise structural glazing, and contemporary aesthetic statements.
What is Low-E glass and is it worth the extra cost?
Low-E (Low-Emissivity) glass has a thin metallic coating that reflects infrared heat, reducing solar heat gain by 40% while maintaining visible light clarity—definitely worth the 15–20% cost premium in Hyderabad's climate.
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