6.3 Windows, Insulation & Customized Materials

6.3 Windows, Insulation & Customized Materials

Exam Focus: Understanding the embodied energy trade-offs in glazing and insulation selection, and mastering the step-by-step EDGE App Customized Materials Workflow—including density, thickness, and EPD input parameters—is essential for passing the EDGE Expert exam and executing advanced project submissions.

While heavy structural elements dominate total material mass, specialized architectural components—such as window framing, glazing units, and thermal insulation materials—exhibit extremely high energy intensity per unit mass ($MJ/kg$). Optimizing these assemblies requires balancing their initial embodied energy against their operational energy performance over the building lifecycle.

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Window Assemblies & Glazing Material Selection

Window performance is evaluated across two tabs in the EDGE App:

1. Energy Tab: Evaluates thermal transmittance ($U\text{-value}$ in $W/m^2K$), Solar Heat Gain Coefficient ($SHGC$), and Visible Light Transmittance ($VLT$).
2. Materials Tab: Evaluates the embodied energy ($MJ/m^2$) of the window framing material and glass pane configuration.

Window Framing Materials & Embodied Impact

Aluminum is widely specified due to its strength, durability, and narrow profile capability. However, primary aluminum smelting is extremely energy-intensive, consuming approximately 190 to 210 MJ of electrical energy per kg of primary metal.

Glazing Configurations: Operational Savings vs. Embodied Energy

Transitioning from single clear glass to double or triple low-E glass increases the initial embodied energy of the glazing component:

• Single Clear Glass ($6\ mm$): Embodied energy $\approx 150 - 180\ MJ/m^2$.
• Double Glazed Unit (DGU, $6\text{mm} - 12\text{mm Air} - 6\text{mm Low-E}$): Embodied energy $\approx 320 - 380\ MJ/m^2$.

Lifecycle Trade-Off Analysis: Although DGU carries approximately double the embodied energy of single glazing, the operational energy savings achieved by reducing HVAC cooling/heating loads outweigh the embodied carbon penalty within 1 to 3 years of building operation in warm or cold climates.

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Thermal Insulation Materials & Energy Intensity

Insulation materials reduce heat transfer through walls and roofs. In EDGE, selecting insulation requires evaluating both thermal resistance ($R\text{-value} = \frac{\text{Thickness}}{k}$) and primary embodied energy per kilogram ($MJ/kg$).

Insulation Material Comparison Table

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The EDGE App Customized Materials Workflow

When a project specifies a novel building material, a locally manufactured low-carbon block, or an assembly not present in the default EDGE dropdown menus, the project team must utilize the Customized Materials Workflow.

Step-by-Step Customization Procedure in the EDGE App

1. Select Component Category: Navigate to the Materials tab and locate the target assembly (e.g., External Walls).
2. Enable Custom Material Option: Select "User Defined / Customized Material" from the dropdown list.
3. Input Physical & Energy Parameters:
   • Material Density ($\rho$, in $kg/m^3$): Extracted from manufacturer technical datasheet or laboratory test report.
   • Component Thickness ($t$, in meters, $m$): Specified from architectural detail drawings.
   • Primary Energy Demand ($PED$, in $MJ/kg$): Extracted from an ISO 14025 / EN 15804 compliant EPD (Cradle-to-Gate Modules A1-A3).
4. Calculated Output Verification: The EDGE App multiplies these parameters to determine the total embodied energy per unit floor/wall area: $$\text{Embodied Energy per Area (MJ/m}^2\text{)} = \text{Thickness (m)} \times \text{Density (kg/m}^3\text{)} \times \text{PED (MJ/kg)}$$
5. Upload Audit Documentation: Attach the verified EPD, product technical specs, and structural quantity takeoffs to the EDGE App project file for Auditor verification.