is a PC-program for three-dimensional transient and steady-state heat conduction.
applications are analyses of thermal bridges, heat transfer through corners of a
window, heat loss from a house to the ground, estimation of surface temperatures
for condensation risk, and fire safety design. The heat equation is solved with explicit forward finite differences. The
successive over-relaxation technique is used in the steady-state case.
HEAT2 and HEAT3 meet the
standard requirements in EN ISO 10211-1 ("Thermal bridges in building
construction - Heat flows and surface temperatures - Part1 General calculation
methods"). This document contains
three calculation cases that have been validated using HEAT2 and HEAT3. Two of
them are covered in the manuals for HEAT2 and HEAT3, see page 138 (HEAT2 5.0)
and page 126 (HEAT3 4.0). HEAT2 and HEAT3 confirm to the standard to be
classified as a high-precision method.
HEAT3 can be used for analyses of thermal bridges, heat transfer through
corners of a window, heat loss from a house to the ground, to mention a few
applications. One important restriction is that the problem has to be described
in a parallelepipedical mesh, i.e. all boundary surfaces are parallel to one of
the Cartesian coordinate planes.
reasonably complicated case, 10-15 minutes work is sufficient for an experienced
user to describe the geometry, the numerical mesh, and the boundary conditions.
A problem often takes less than a few minutes to solve for steady-state.
offers high calculation speed with code optimization for Pentium 2, 3, and 4
processors. The number of numerical nodes is limited by the amount of memory
(RAM). The standard version that allows problems with one million (100·100·100)
nodes requires 64 MB RAM. A PC with 2 GB RAM gives access to more than 50
million nodes using a special version of HEAT3.
input and output can be viewed graphically (geometry, numerical mesh, boundary
conditions, temperature field and heat flows). The three-dimensional figure may
be rotated in space, and details of particular interest can be enlarged. Heat
flows and temperatures can be recorded and used for e.g. thermal response
4.0 uses the same material database as HEAT2 5.0. About 1200 materials are
available. There is also a separate list that contains 200 materials from the
German standard DIN V 4108-4. Material properties may easily be edited and added.
time to generate the complete input for a reasonably complicated case is less
than 10 minutes after a few hours' experience of the program.
following list shows some features:
integrated pre-processor facilitates the input procedure, see below.
properties may easily be edited and added. Several material lists are
available. The default list (Default.mtl) contains about 200 common building
materials. The list General.mtl has over 1200 defined materials. Another
file with over 200 materials (in German) from the German standard DIN (Deutsches
Institut für Normung, DIN V 4108-4) is also available.
graphical capabilities: figures showing geometry, materials, numerical mesh,
boundary conditions, 2D and 3D temperature and heat flow fields may be
displayed. Features: zoom, panning, rotation, color/gray-scale,
high-resolution printing. Heat flows and temperatures can be recorded and
shown during the simulation. Images of heat flows make it simpler to
determine thermal bridges and to improve designs by optimizing the
insulation at areas with large heat flows.
recorder may save at specified intervals (transient or steady-state)
temperatures and heat flows at given points, heat flow through boundaries.
simple numerical mesh generation option is available. The mesh can easily be
structure consisting of adjacent or overlapping parallelepipeds with any
combination of materials may be simulated.
conditions may be a given heat flow, or an air temperature with a surface
resistance. Temperatures and heat flows may vary in time by one of the
following functions: sinusoidal, stepwise constant or linear (data may be
imported/exported from/to programs such as Excel). Several other formats
with climatic data can be imported.
sources/sinks may be specified.
and capacities may be written to file.
field may be written to file and can easily be imported into other programs
such as Matlab.
formats with climatic data may be imported (TRNSYS, METEONORM, HELIOS, DOE,
TMY2 - Typical Meteorological Year, SUNCODE, MATCH) for dynamic calculations
Pre-processor and post-processor
cad-style pre-processor facilitates the input procedure. The following pictures
shows the pre-processor and post-processor.
park bench drawn in the pre-processor. The top figure shows the (x,y)-plane
and the lower one the (x,z)-plane.
post-processor shows a 3D view, here of the materials (top figure) and boundary
conditions (lower figure).
temperature field (top) and heat flows (bottom).
during the three first hours at a point 2 cm under the seat with a boundary
condition temperature of 35 °C. Initial temperature for the bench is 20 °C.
The steady-state temperature for the point is 31.45 °C.
flow through the seat with a boundary condition temperature of 35 °C. Initial
temperature for the bench is 20 °C. The steady-state heat flow is 49.7 W.
following figures shows a steel beam that lies inside a wall/roof connection.
temperature field along the steel (all other wall materials are made invisible