For Melbourne homeowners, energy-efficient windows should be selected as part of the whole building envelope. Glass, aluminium frame, seals, opening style, orientation, shading and installation all affect performance. JL Windows helps Melbourne homeowners and builders compare practical aluminium window options using whole-window performance data where available.
Call 0481 818 785 or email [email protected] with plans, photographs and project energy requirements.
JL Whole-Window Performance Data
The values below are selected performance results for the specific tested or modelled JL configurations shown. They are provided as a specification reference, not as a blanket rating for every size, glass option or project. Final U-value and SHGC should be confirmed for the exact window or door configuration required.
| Configuration | U-value | Visible Transmittance | SHGC |
|---|---|---|---|
| Essential Series Awning — Configuration A | 4.2 | 0.51 | 0.51 |
| Essential Series Awning — Configuration B | 3.5 | 0.44 | 0.29 |
| Thermal Series Double Hung — Configuration A | 3.2 | 0.60 | 0.56 |
| Thermal Series Double Hung — Configuration B | 2.4 | 0.52 | 0.30 |
| Thermal Series Fixed Window — Configuration A | 2.9 | 0.67 | 0.62 |
| Thermal Series Fixed Window — Configuration B | 2.0 | 0.58 | 0.34 |
| Thermal Series Hinged Door — Configuration A | 3.8 | 0.52 | 0.51 |
| Thermal Series Hinged Door — Configuration B | 3.1 | 0.45 | 0.28 |
| Essential Series Fixed Window — Configuration A | 3.3 | 0.67 | 0.64 |
| Essential Series Fixed Window — Configuration B | 2.4 | 0.58 | 0.35 |
Performance applies to the listed configurations. Window size, frame, glass makeup and other specification changes can alter the result. Project-specific suitability and energy-report requirements must be confirmed before ordering.
Insulated Glass Unit Reference
For the glass units associated with these performance references, the clear double-glazed configuration uses 5 mm clear glass, a 12 mm argon-filled cavity and 5 mm clear glass, with centre-of-glass U-value 2.6, visible transmittance 0.81 and SHGC 0.74. The Low-E configuration uses 5 mm clear glass, a 12 mm argon-filled cavity and 5 mm curved tempered triple-silver Low-E glass, with centre-of-glass U-value 1.3, visible transmittance 0.70 and SHGC 0.40.
Centre-of-glass values are not whole-window values. Frame design, edge conditions, seals, opening style and overall size influence the complete window result. For a dedicated comparison of coatings, argon and glass-only versus whole-window values, see Low-E & Argon Double Glazing Melbourne.
What Makes a Window Energy Efficient?
Thermal performance depends on how the complete window limits heat transfer and unwanted air leakage. The glass and frame both contribute. A higher-performance glass unit in a poorly suited or badly installed frame will not deliver its full potential.
Double Glazing
A double-glazed unit uses two panes separated by a sealed cavity. Pane type, cavity width, spacer and gas fill all influence performance. Compare our double-glazed windows Melbourne options.
Low-E Glass
Low-emissivity glass uses a coating designed to reduce radiant heat transfer. Different coatings have different solar and visible-light characteristics, so “Low-E” alone is not a complete specification.
Thermally Broken Aluminium Frames
Standard aluminium is durable and practical but conducts heat. A thermally broken aluminium frame includes an insulating section between the internal and external aluminium profiles, reducing direct heat transfer through the frame.
Understanding U-Value and SHGC
U-value measures heat transfer through a window system. Lower U-values generally indicate less heat transfer, but comparisons should use like-for-like sizes, frame systems and glass specifications.
Solar Heat Gain Coefficient (SHGC) describes how much solar heat passes through a window. The appropriate balance depends on orientation, shading, climate and the project energy assessment.
Visible transmittance (Tvis) indicates the proportion of visible light transmitted through the glazing/system. Higher and lower values can suit different design priorities.
How to Compare Window Specifications
- Confirm the complete glass makeup.
- Identify the exact frame and opening system.
- Compare whole-window values rather than centre-of-glass values alone.
- Review orientation and shading.
- Check sealing, flashing and installation scope.
- Use project energy requirements where provided.
Technical & Project Support
For standards, glazing and project checks, see Window Quality, Standards & Project Checks and the JL Technical Resource Centre. Builders can send plans and energy reports for project review. Homeowners can also compare window replacement in Melbourne and double glazing cost factors.
Energy Efficient Windows FAQs
Are double-glazed windows always energy efficient?
Double glazing can improve the glass component, but the final result also depends on the frame, seals, window size, orientation, shading and installation quality.
Should I choose Essential or Thermal windows?
The choice depends on the energy report, window configuration, glass specification and project requirements. Thermal frames are worth comparing where stronger thermal performance is required.
What does Low-E glass do?
Low-E glass uses a coating designed to reduce radiant heat transfer. The coating, glass makeup and solar performance should be reviewed as part of the complete specification.
Can JL Windows review my energy report?
Yes. Builders and homeowners can send the energy report, window schedule or project plans so JL can help compare suitable aluminium window and glass configurations.
Request a Project Quote
JL Windows supplies custom aluminium windows and doors for Melbourne homes, renovations and new builds. We operate from 19 Adele Street, Keysborough VIC 3173. Call 0481 818 785 or request a quote.
