Window gas

Window Gas component data is used to define the thermal properties of the cavity fill gas between window Panes in Glazing components.

 

The gas which fills the inter-glazing cavity affects the heat transfer through the assembly but has almost no effect on the solar heat gain or the visible light transmission. Air, of course, is the most common cavity fill gas, but the use of an inert gas (typically argon or krypton) can significantly reduce window heat transfer. Krypton and argon are colourless, odourless and non-toxic. Argon is the most commonly-used fill gas because it offers good thermal performance at low cost. Krypton is more effective at reducing heat loss, but is roughly 200 times more expensive than argon per unit volume. Because krypton works best at smaller pane spacings (8 mm), it is often used in triple and quadruple-glazed windows to minimize the overall thickness of the unit. Other types of gases are used (e.g. sulphur hexafluoride (SF6) and carbon dioxide (CO2)) to reduce sound transmission, but these gases do not offer the improved thermal performance of the inert gases.

Category

This is the gas type. Select from:

 

 

The window gas you are defining does not fit with the available options select Other. Select Air for an air gap.

Thickness

Enter the thickness of the inter-glazing cavity.

Custom material properties

The window gas properties of the gases Air, Argon, Krypton, Xenon are known by EnergyPlus and so no further data is required for these gases.

 

For CO2, Other and SF6 you must enter custom properties.

Custom Gases Only

If you elect to enter custom material properties then you must enter the details. The A and B coefficients are those in the following expression that gives a property value as a function of temperature in degrees K:

 

Property = Coefficient_A + Coefficient_B * Gas_Temperature (K)

Conductivity Coefficient A

The A coefficient for gas conductivity (W/m-K).

Conductivity Coefficient B

The B coefficient for gas conductivity (W/m-K2).

Viscosity Coefficient A

The A coefficient for gas viscosity (kg/m-s).

Viscosity Coefficient B

The B coefficient for gas viscosity (kg/m-s-K).

Specific Heat Coefficient A

The A coefficient for gas specific heat (J/kg-K).

Specific Heat Coefficient B

The B coefficient for gas specific heat (J/kg-K2).

Molecular Weight

The molecular weight (mass) of the gas (Kg/kmol).

 

Window gas component data can be accessed: