Libraries - Material/Glazing Layer Sets

Location = Libraries/Materials and Assemblies/Material-Glazing Layer Sets

 

Type and Sub Type Mapping

The Type and Sub Type options that can be selected from the drop down lists in that area of the workspace, which filter the Source Library to display the variables the user can select to include, along with a value, in a Library Entry.

Note: The links within the table are to the EnergyPlus Input Output Reference providing additional detailed explanation of the EnergyPlus objects.

 

Type Options Sub Type Options EnergyPlus Objects (IO Reference links)

Opaque Layer Set

Default
CfactorUndergroundWall
FfactorGroundFloor
Internal Source

Construction

Construction:CfactorUndergroundWall

Construction:FfactorGroundFloor

Construction:InternalSource

Glazing Layer Set

Default

WindowDataFile

WindowEquivLayer

Construction

Construction:WindowDataFile

 

 

Opaque Layer Set (Type)

Default (Sub Type)

Outside Layer

Each construction must have at least one layer. This field defines the material name associated with the layer on the outside of this construction—outside referring to the side that is not exposed to the zone but rather the opposite side environment, whether this is the outdoor environment or another zone. Material layers are defined based on their thermal properties elsewhere in the input file (ref: Material and Material Properties and Materials for Glass Windows and Doors). As noted above, the outside layer should NOT be a film coefficient since EnergyPlus will calculate convection and radiation heat transfer more precisely.

Layers

The next fields are optional and the number of them showing up in a particular Construction definition depends solely on the number of material layers present in that particular construction. The data expected is identical to the outside layer field (see previous field description). The order of the remaining layers is important and should be listed in order of occurrence from the one just inside the outside layer until the inside layer is reached. As noted above, the inside layer should NOT be a film coefficient since EnergyPlus will calculate convection and radiation heat transfer more precisely.

 

Algorithm

The algorithm for calculating heat transfer through the construction.

 

C factor Underground Wall (Sub Type)

This input differs from the usual wall construction in that it describes an entire construction rather than individual layers. This object is used when only the wall height (depth to the ground) and the C-factor are available. 

Note: This object accesses a model that creates an equivalent layer-by-layer construction for the underground wall to approximate the heat transfer through the wall considering the thermal mass of the earth soil.

This object is referenced by underground wall surfaces with their fields ‘Outside Boundary Condition’ set to GroundFCfactorMethod.

C-Factor

C-Factor is the time rate of steady-state heat flow through unit area of the construction, induced by a unit temperature difference between the body surfaces. The C-Factor unit is W/m2·K. The C-factor does not include soil or air films. ASHRAE Standard 90.1 and California Title 24 specify maximum C-factors for underground walls depending on space types and climate zones.

 

 

F factor Ground Floor (Sub Type)

This input object differs from the usual ground floor construction object in that it describes an entire construction rather than individual layers. This object is used when only the floor area, exposed perimeter, and the F-factor are available.  This object accesses a model that creates an equivalent layer-by-layer construction for the slab-on-grade or underground floor to approximate the heat transfer through the floor considering the thermal mass of the earth soil.

 

This object is referenced by slab-on-grade or underground floor surfaces with their fields ‘Outside Boundary Condition’ set to GroundFCfactorMethod.

F-Factor

F-Factor represents the heat transfer through the floor, induced by a unit temperature difference between the outside and inside air temperature, on the per linear length of the exposed perimeter of the floor. The unit for this input is W/m·K. ASHRAE Standard 90.1 and California Title 24 specify maximum F-factors for slab-on-grade or underground floors depending on space types and climate zones.

 

 

Internal Source (Sub Type)

In some cases such as radiant systems, a construction will actually have resistance wires or hydronic tubing embedded within the construction. Heat is then either added or removed from this building element to provide heating or cooling to the zone in question. In the case of building-integrated photovoltaics, the energy removed in the form of electricity will form a sink.

Source Present After Layer Number

This field is an integer that relates the location of the heat source or sink. The integer refers to the list of material layers that follow later in the syntax and determines the layer after which the source is present. If a source is embedded within a single homogenous layer (such as concrete), that layer should be split into two layers and the source added between them. For example, a value of “2” in this field tells EnergyPlus that the source is located between the second and third material layers listed later in the construction description (see layer fields below).

Temperature Calculation Requested After Layer Number

The nature of this field is similar to the source interface parameter (see previous field) in that it is an integer, refers to the list of material layers that follow, and defines a location after the layer number identified by the user-defined number. In this case, the user is specifying the location for a separate temperature calculation rather than the location of the heat source/sink. This feature is intended to allow users to calculate a temperature within the construction. This might be important in a radiant cooling system where condensation could be a problem. This temperature calculation can assist users in making that determination in absence of a full heat and mass balance calculation.

Dimensions for the CTF Calculation

This field is also an integer and refers to the detail level of the calculation. A value of “1” states that the user is only interested in a one-dimensional calculation. This is appropriate for electric resistance heating and for hydronic heating (when boiler/hot water heater performance is not affected by return and supply water temperatures). A value of “2” will trigger a two-dimensional solution for this surface only. This may be necessary for hydronic radiant cooling situations since chiller performance is affected by the water temperatures provided.

A few things should be noted about requesting two-dimensional solutions. First, the calculation of the conduction transfer functions (CTF) is fairly intensive and will require a significant amount of computing time. Second, the solution regime is two-dimensional internally but it has a one-dimensional boundary condition imposed at the inside and outside surface (i.e., surface temperatures are still isothermal is if the surface was one-dimensional).

Tube Spacing

This field defines how far apart in meters the hydronic tubing or electrical resistance wires are spaced in the direction perpendicular to the main direction of heat transfer. Note that this parameter is only used for two-dimensional solutions (see previous field).

Outside Layer

Each construction must have at least one layer. This field defines the material name associated with the layer on the outside of this construction—outside referring to the side that is not exposed to the zone but rather the opposite side environment, whether this is the outdoor environment or another zone. Material layers are defined based on their thermal properties elsewhere in the input file (ref: Material and Material Properties and Materials for Glass Windows and Doors). As noted above, the outside layer should NOT be a film coefficient since EnergyPlus will calculate convection and radiation heat transfer more precisely.

IS Layers [2-10]

The next fields are optional and the number of them showing up in a particular Construction definition depends solely on the number of material layers present in that particular construction. The data expected is identical to the outside layer field (see previous field description). The order of the remaining layers is important and should be listed in order of occurrence from the one just inside the outside layer until the inside layer is reached. As noted above, the inside layer should NOT be a film coefficient since EnergyPlus will calculate convection and radiation heat transfer more precisely.

 

 

 

Glazing Material Layer (Type)

Default (Sub Type)

Outside Layer

Each construction must have at least one layer. This field defines the material name associated with the layer on the outside of this construction—outside referring to the side that is not exposed to the zone but rather the opposite side environment, whether this is the outdoor environment or another zone. Material layers are defined based on their thermal properties elsewhere in the input file (ref: Material and Material Properties and Materials for Glass Windows and Doors). As noted above, the outside layer should NOT be a film coefficient since EnergyPlus will calculate convection and radiation heat transfer more precisely.

Layers [2-10]

The next fields are optional and the number of them showing up in a particular Construction definition depends solely on the number of material layers present in that particular construction. The data expected is identical to the outside layer field (see previous field description). The order of the remaining layers is important and should be listed in order of occurrence from the one just inside the outside layer until the inside layer is reached. As noted above, the inside layer should NOT be a film coefficient since EnergyPlus will calculate convection and radiation heat transfer more precisely.

 

Window Data File (Sub Type)

The WINDOW 5 program, which does a thermal and optical analysis of a window under different design conditions, writes a data file (“Window5 data file”) containing a description of the window that was analyzed. The Construction:WindowDataFile object allows a window to be read in from the Window5 data file.

File Name

This is the file name of the Window5 data file that contains the Window referenced in the previous field. You must specify this file name completely, including path, but it must be 60 characters or less.

 

Window Equivalent Layer (Sub Type)

 

Outside Layer

Each construction must have at least one layer. This field defines the material name associated with the layer on the outside of this construction—outside referring to the side that is not exposed to the zone but rather the opposite side environment, whether this is the outdoor environment or another zone. Material layers are defined based on their thermal properties elsewhere in the input file (ref: Material and Material Properties and Materials for Glass Windows and Doors). As noted above, the outside layer should NOT be a film coefficient since EnergyPlus will calculate convection and radiation heat transfer more precisely.

 

WE Layer [2-11]

 

 

______________________________________________________________________________________

© Copyright 2013 Simergy, Sustainable IQ, Inc.