Glazed Construction - Thermo-Optical properties grid

 

These properties, with the exception of the last three, are also displayed on the ‘Glazing material (pane)’ dialog.

Thickness: the thickness of the layer.

Conductivity: the thermal conductivity of the material. Values for commonly used building materials are listed in Table 6 in the Apache Tables document and in CIBSE Guide A.

Outside emissivity: the emissivity of the outside surface of the pane. This is used to calculate the thermal resistance of the adjacent surface or cavity (unless this resistance has been specified explicitly).

Inside emissivity: the emissivity of the inside surface of the pane. This is used to calculate the thermal resistance of the adjacent surface or cavity (unless this resistance has been specified explicitly).

Angular dependence: pane angular dependence behaviour. The default value is set to ‘Fresnel’, the other options are: ’Explicit’, ‘Constant’ and ‘LBNL’.

Refractive index: The refractive index of the material composing the pane. Editable only if the angular dependence is set to ‘Fresnel’.

Transmittance: The transmittance of the pane for solar radiation at normal incidence.

Outside reflectance: the reflectance of the outside surface of the pane for solar radiation at normal incidence.

Inside reflectance: the reflectance of the inside surface of the pane for solar radiation at normal incidence.

Visible Transmittance (not currently used): The transmittance of the pane for visible solar radiation at normal incidence.

Outside visible reflectance (not currently used): the reflectance of the outside surface of the pane for visible solar radiation at normal incidence.

Inside visible reflectance (not currently used): the reflectance of the inside surface of the pane for visible solar radiation at normal incidence.

 

Optical properties – angular dependence grid

 

When ‘Angular dependence’ is set to ‘Explicit’ this grid allows the specification of explicit values for solar transmittance (tau), outside reflectance (rho_o) and inside reflectance (rho_i) for a range of incidence angles (0°-90°). For other settings of ‘Angular dependence’ only the normal incidence value can be edited (these being duplicates of the values appearing in the ‘Thermo-optical properties’ grid). The values must be between 0 to 1.0 and the sum of transmittance and inside reflectance or transmittance or outside reflectance cannot exceed 1.0.

 

When ‘Angular dependence’ is set to ‘Explicit’ this grid allows the specification of explicit values for visible light transmittance (tau), outside reflectance (rho_o) and inside reflectance (rho_i) for a range of incidence angles (0°-90°). For other settings of ‘Angular dependence’ only the normal incidence value can be edited (these being duplicates of the values appearing in the ‘Thermo-optical properties’ grid). All the values must be between 0 to 1.0 and the sum of transmittance and inside reflectance or transmittance or outside reflectance cannot exceed 1.0.

 

For more information see: ‘Radiance’ manual.

Surface type: ‘plastic’, ‘metal’, ‘glass’ or ‘trans’.

Roughness: the roughness of the pane surface. Roughness range value 0.0-1.0.

Overall transmissivity: the ratio of the directly transmitted light after passing through the pane to the amount of light that would have passed the same distance through a vacuum.

Transmitted specularity: is the ratio between the reflected light by specular mechanisms and the diffuse light.

Specularity: the amount of light reflected by specular mechanisms (basically how shiny a surface is).

Red transmittance: pane transmittance in the Red spectrum.

Green transmittance: pane transmittance in the Green spectrum.

Blue transmittance: pane transmittance in the Blue spectrum.

Red reflectance: pane reflectance in the Red spectrum.

Green reflectance: pane reflectance in the Green spectrum.

Blue reflectance: pane reflectance in the Blue spectrum.

Red transmissivity: pane transmissivity in the Red spectrum.

Green transmissivity: pane transmissivity in the Green spectrum.

Blue transmissivity: pane transmissivity in the Blue spectrum.

 

For more information see: ‘Life Cycle Analysis’ (LCA) manual.

Service life (years): expected pane service life.

Site wastage %: How much wastage is produced when installing.

Adjust factor: to account for instances where adjustment is required e.g. overlapping roof slates.

BRE material #: read only – unique BRE id used when calculating the LCA.

BRE category 1 ID: read only – used when constructing composite constructions.

BRE category 2 ID: read only – used when constructing composite constructions.

Last edited: date when this material was last edited.

Info/Notes: user notes on the pane.

Quantity method: default value ‘Area’.

Overall mass: gives the kg/m value of the material.

Generic/Certified: Generic or certified – generic is a BRE generic construction, certified is generally a specific construction (see description of construction for more details).