76 real ISO 15099 simulations across aluminium curtain wall, thermally broken aluminium, uPVC, timber, steel and skylights — the only published cross-material Uf reference for Australian window practice.
76
Simulations
9
Frame types
1.57
Best Uf (W/m²K)
<3%
Mean Uf δ vs THERM
By Frame Material
Window frame Uf — material comparison
Mean frame thermal transmittance (W/m²K) from THERM finite-element model. Lower is better. All values to ISO 15099 / NFRC 100.
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Frame section reference · WinISO profiles · ISO 15099
Individual section Uf — 320 profiles, 24 systems
Component-level frame thermal transmittance (W/m²K) from WinISO section modelling across 24 Australian aluminium systems. Section Uf ≠ window Uf — this is the raw frame member value before area-weighting with the glass fraction. Data genericised; no supplier attribution.
Steel
Sections8
Uf range (W/m²K)3.98 – 7.17
Mean Uf4.59
Thermally broken aluminium
Sections178
Uf range (W/m²K)3.84 – 19.23
Mean Uf6.26
Aluminium (inline reveal)
Sections30
Uf range (W/m²K)5.49 – 18.60
Mean Uf9.45
Aluminium curtain wall
Sections104
Uf range (W/m²K)6.54 – 35.79
Mean Uf10.05
What is a section Uf? Each frame member (head, sill, jamb, mullion, transom, interlock) has its own thermal transmittance modelled to ISO 15099 from its cross-section geometry. The window Uf is then area-weighted across all frame members and the glass area — typically 10–30% lower than the worst-performing section alone. High-end section values reflect specialised types: spandrel panels, recessed sill geometries, and inline curtain wall transoms. All 320 profiles modelled with WinISO to ISO 15099 / NFRC 100.
Raw simulation register
Every run — sortable & searchable
All 76 Uf simulations. CFL solver vs THERM finite-element. Add a run: every BTW project AFRC completes is added here.
Description
Material
Section
Uf THERM
Uf CFL
δ%
Basis
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Methodology: All Uf values modelled to ISO 15099 / NFRC 100 using THERM finite-element analysis and independently verified against the CFL solver. Results are frame-only thermal transmittance and reflect the specific system configurations listed — not generic product ratings. Project-specific simulation to your actual window is available via BTW — Build The Window.
Model your actual window — not a generic rating
BTW runs ISO 15099 on your project's exact configuration: real size, system, glazing, sub-frames. What you get isn't a WERS label — it's the number your installed window will actually perform to.