Glazing calculated data

Calculated tab on Glazing Dialog.

The Calculated data on the Glazing tab has been calculated by EnergyPlus using the Layer data on the previous tab. You can refresh the Calculated data by clicking on the Update link in the Info panel on the right of the dialog.

The data can be useful for setting up glazing model descriptions in cases where global glazing system data is known rather than data on individual panes and window gases.

Two different U-values are provided, one using standard ISO 10292 / EN 673 and the other using the ASHRAE method.

For the ASHRAE calculation, the U-value is determined by EnergyPlus through a heat balance calculation on the glazing layers for the following standard ASHRAE winter conditions which are based on the values used in the WINDOW program:

• Inside air temperature = 21°C (69.8°F)
• Outside air temperature = -18°C (-0.4°F)
• Wind speed = 5.5 m/s (12.3 mph)
• Outside convective air film conductance = 26 W/m2-K (4.58 Btu/h-ft2-F)
• Inside convective air film conductance: calculated by EnergyPlus
• No solar radiation

The 'Total solar transmission (SHGC)' (Solar Heat Gain Coefficient) is the fraction of incident beam solar radiation that enters the zone. This includes the transmitted solar radiation and the inward flowing heat from the solar radiation that is absorbed by the glazing. SHGC applies only to the centre of the glazed part of a window construction; it does not include the effect of beam solar radiation absorbed by a window frame or divider. SHGC is calculated for the following standard summer condition:

• Inside air temperature = 24°C (75.2°F)
• Outside air temperature = 32°C (89.6°F)
• Wind speed = 2.8 m/s (6.2 mph)
• Incident beam solar radiation normal to glazing = 783 W/m2 (248 Btu/h-ft2)