Thermal Insulation Performance
This performance metric evaluates a window/door's ability to resist heat transfer between environments with temperature differences when closed. It is quantified by:
K-value (U-value in int'l standards): Heat transfer per hour per square meter (W/(m²·K))
Lower value = better insulation
Jiangsu Province standard: K ≤ 2.4 W/(m²·K)
Key Influencing Factors
1. Frame System
Challenge: Aluminum’s high thermal conductivity (160 W/(m·K) compromises insulation.
Solutions:
Thermal break technology: PA66GF25 polyamide strips (0.3 W/(m·K))
Why PA66GF25?
Matches aluminum’s expansion coefficient
Maintains structural integrity (-30°C to 120°C)
Design essentials:
Vertical isotherm alignment in thermal breaks
Foam-filled cavities to block convective heat transfer
2. Glass Unit (80% of total area)
Heat Transfer Mechanisms:
Solar radiation (infrared/UV transmission)
Conduction through glass and edges
Solutions:
Low-E coatings: Silver layers reflect 90% infrared
Multi-chamber glazing:
Each air gap reduces U-value by ~0.5 W/(m²·K)
Example: Triple glazing (U ≤ 0.6) vs. double (U ≤ 1.1)
Warm edge spacers:
4SG (Uedge ≤ 0.7 W/(m·K))
Super Spacer (stainless steel reinforced)
Gas fills: Argon (U reduction: 0.1-0.2) or krypton (for <12mm gaps)
Performance Benchmarking
Component Standard Solution Enhanced Solution U-value Improvement
Frame 24mm PA66GF25 34mm PA66GF25 + foam 0.8 → 0.6 W/(m²·K)
Glass Double Low-E Triple Low-E + 4SG 1.1 → 0.5 W/(m²·K)
Installation Silicone seal Pre-compressed EPDM tape Reduces Ψ-value 30%
Selection Guidelines
Prioritize test reports over marketing claims (look for K ≤ 1.5 for cold climates).
Verify spacer type – Cheap aluminum spacers increase edge heat loss by 40%.
Request climate-specific configurations:
Northern China: Triple glazing + 30mm+ thermal breaks
Southern China: Double Low-E + spectrally selective coatings
Case Study:
A Nanjing project achieved K=1.3 W/(m²·K) using:
✔ 32mm PA66GF25 thermal breaks
✔ Triple Low-E (SUNERGIZE® 72/39)
✔ 4SG spacers + argon gas
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