THERM Components

THERM has three basic components:

Graphic User Interface: a graphic user interface that allows you to draw a cross section of the product or component for which you are performing thermal calculations.

Heat Transfer Analysis:
a heat-transfer analysis component that includes: an automatic mesh generator to create the elements for the finite-element analysis, a finite-element solver, an optional error estimator and adaptive mesh generator, and an optional view-factor radiation model.

a results displayer.

Graphic User Interface

THERM has standard graphic capabilities associated with the Microsoft Windows™ operating system. For example, THERM allows you to use:

Both mouse and cursor operations;

Standard editing features, such as Cut, Copy, Paste, Select All, and Delete;

A toolbar to access frequently used commands and short-cut keys;

Multiple windows so several projects can be open concurrently.

THERM has powerful drawing capabilities that make it easy to model the geometry of the cross section of a building component.

You can use two methods to draw a cross section:

Trace an imported DXF or bitmap file.

Draw the geometry based on a dimensioned drawing.

The following thermal properties must be defined for the cross section geometry:

Material properties (broken into two classes: solids and cavities) of each component of the cross section,

Boundary conditions at the external edges of the cross section.

Heat-Transfer Analysis

THERM uses two-dimensional (2D) conduction and radiation heat-transfer analysis based on the finite-element method, which can model the complicated geometries of fenestration products and other building elements. This method requires that the cross section be divided into a mesh made up of nonoverlapping elements. This process is performed automatically by THERM using the Finite Quadtree method. Once you have defined the cross section’s geometry, material properties, and boundary conditions, THERM meshes the cross section, performs the heat-transfer analysis, runs an error estimation, refines the mesh if necessary, and returns the converged solution.


The results from THERM’s finite-element analysis of a fenestration product or building component can be viewed as:



color-flooded isotherms,

heat-flux vector plots,

color-flooded lines of constant flux,

temperatures (local and average, maximum and minimum).

Updated: 04/10/03