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Window

The Window Results focus on calculations related to Heat Loss and Heat Gain. These values depend on the Window’s Material and the temperature difference on both sides. 

The properties can be reviewed and edited in the Floor Plan Mode or specific sections of the Heat Load Settings. 

Below is a detailed breakdown of each result and how to manage it.

Window Area

  • What it is: The total area of the Window is calculated as length multiplied by height.

  • How to review: This value can be reviewed and edited for the window’s properties in Floor Plan Mode.

Window Length

  • What it is: The horizontal dimension (length) of the Window.

  • How to review: Edit the length of the Window’s properties in the Floor Plan Mode.

Window Height

  • What it is: The vertical dimension (height) of the Window.

  • How to review: Adjust the height of the Window’s properties in Floor Plan Mode.

Window U-Value

  • What it is: The thermal transmittance of the Window is determined by its material selection.

  • How to review and edit:

    • This value can be edited in the Window’s properties in the Floor Plan Mode.

    • To change the default material and U-value for all window’s:

      • Go to Heat Load > Materials and select a new material and U-value.

    • To adjust the U-value for a specific window, update it in its individual properties in the Floor Plan Mode.

Heat Loss Through Window 

The heat loss calculation is determined by the Window’s Area, U-value, and the temperature difference between the inside and outside.

Heat Loss Through Window Formula

Heat = Area x U-Value × ΔT

Where:

  • Heat: The heat loss (W in metric, BTU/h in imperial)

  • Area: The window area (m² in metric, ft² in imperial)

  • U-Value: The thermal transmittance of the window (W/m²·K in metric, BTU/h·ft²·°F in imperial)

  • ΔT: The temperature difference across the window (°C in metric, °F in imperial)

Reviewing Heat Loss Through Window

  • The Window Area and U-value can be reviewed in the Window’s properties.

  • The External Winter Temperature is set in Heat Load > General and may be auto-filled based on the project address.

    • This can be overridden in the Room’s properties in the Floor Plan Mode

  • The Room Temperature can be overridden in the Room’s properties in the Floor Plan Mode

Heat Gain Through Window

The heat gain calculation is determined by the Window’s Area, U-Value, Solar Gain, and the temperature difference between the inside and outside.

Heat Gain Through Window Formula

Heat = (Area × U-Value × ΔT) + (Area × Solar Gain Coefficient × Solar Gain)

Where:

  • Heat: The heat gain (W in metric, BTU/h in imperial)

  • Area: The window area (m² in metric, ft² in imperial)

  • U-Value: The thermal transmittance of the window (W/m²·K in metric, BTU/h·ft²·°F in imperial)

  • ΔT: The temperature difference across the window (°C in metric, °F in imperial)

  • Solar Gain Coefficient: A dimensionless factor representing the fraction of solar radiation transmitted through the window (e.g., 0.6 for 60% transmission)

  • Solar Gain: The solar radiation intensity (W/m² in metric, BTU/h·ft² in imperial) based on the orientation and solar gain field in project settings

Reviewing Heat Gain Through Window

  • The Window Area and U-value can be reviewed in the Window’s properties.

  • The External Summer Temperature is set in Heat Load > General and may be auto-filled based on the project address.

    • This can be overridden in the room’s properties in the Floor Plan Mode

  • The Solar Gain and Solar Gain coefficient is set in Heat Load > Solar Gain

  • The Room Temperature can be overridden in the Room’s properties in the Floor Plan Mode

To comprehensively review all window-related heat load results, export the Heat Load Report, which consolidates all calculations in one centralized document

Solar Watt Per Metre Through Window

The Solar Watt Per Metre Through Window represents the solar energy transmitted through a window per square meter. This value accounts for the orientation of the Window and the Solar Gain Coefficient specified in the project settings.

  • What it is: The solar energy (in watts) per square meter passing through the window, influenced by the window’s orientation and solar gain settings.

  • How it is calculated:

    • It is taken directly from the Solar Gain settings in Methods, under the project Settings.

  • How to review:

    • Check the solar gain input in the Methods section.

    • Verify the window's orientation in the properties of the window in Floor Plan Mode.

External Facing Degree

The External Facing Degree represents the direction the window faces relative to the project orientation. This is used for Heat Load calculations to account for solar gains or losses based on exposure to sunlight.

  • What it is: The direction of the external-facing side of the window, measured in degrees.

    • 0° corresponds to the top of the page (north-facing if using standard orientation).

    • 90° corresponds to the right of the page.

    • 180° corresponds to the bottom of the page.

    • 270° corresponds to the left of the page.