European Standards on Thermal Heat Bridges
The European standards
"Thermal Bridges in building construction Heat flows and surface
temperatures - Part 1: General calculation methods" (EN ISO 10211-1) pertaining to aspects of thermal performance of
building constructions are already available since 1996.
EN ISO 10211:2007 "Thermal bridges in building construction — Heat flows and
surface temperatures — Detailed calculations" shows further development
of the standardisation. The standard EN ISO
6946 "Building Components or Building Elements - Calculation of Thermal
Transmittance" is also available.
The EN ISO 10077-2:2003 "Thermal performance of windows, doors
and shutters - Calculation of thermal transmittance - Part 2:
Numerical method for frames" shall be also considered.
The ramifications of the adoption
of these European Standards became apparent: they describe the substance of
tasks for designers, manufacturers, and builders, as well as their significance
for quality control in the field of energy conservation.
The purpose of the standard EN ISO 10211 "Thermal Bridges - Calculation of Surface
Temperatures and Heat flows" is explicitly stated as:
- the calculation of minimum (lowest) surface temperatures in order to assess
the risk of surface condensation
- the calculation of heat flows in order
to predict overall heat loss from a building (for the constant, steady state
i.e. time independent temperature distribution)
- determination of linear and point thermal transmittance and surface
temperature coefficients (of thermal bridges).
precision methods" of calculation are demanded, whereby precision criteria
which must be satisfied by the method chosen are defined in the standard.
According to EN ISO 6946 "Building Components or Building Elements -
Calculation of Thermal Transmittance", calculation of heat transfer coefficients
of parallel plane surface building components shall be performed based, of
course, on one-dimensional models. For such components, composed of surface
parallel layers of thermally homogeneous or non-homogeneous materials, a
well-known method of estimation (ISO-method) can be implemented in order to
obtain a design thermal resistance - assuming the maximum relative error remains
For all other heat flow patterns, i.e. for all cases of more than one
dimension, in particular in the presence of thermal bridges, the standard EN ISO
"Thermal Heat Bridges" requires the implementation of numerical methods of
Further standards to be considered (exemplary):
- ISO 7345 "Thermal insulation - Physical quantities and
- ISO 10456 "Building materials and products - Hygrothermal
properties - Tabulated design values and procedures for
determining declared and design thermal values"
- ISO 13370 "Thermal performance of buildings - Heat transfer
via the ground - Calculation methods"
- ISO 13786 "Thermal performance of building components -
Dynamic thermal characteristics - Calculation methods"
- ISO 13788 "Hygrothermal performance of building components
and building elements - Internal surface temperature to avoid
critical surface humidity interstitial condensation -
- ISO 13789 "Thermal performance of buildings - Transmission
and ventilation heat transfer coefficient - Calculation method"
- ISO 14683 "Thermal bridges in building construction - Linear
thermal transmittance - Simplified methods and default values"
A calculation program as instrument
In order to perform tasks imposed by European regulations in practice, the
qualified planner, designer, or expert needs a calculation program which:
meets the demands of the European
Standards with respect to input data and more importantly output data
requirements (evaluation results),
is capable of executing calculation with
and is sufficiently convenient to the user in application (providing ease and
clarity of operation, as well as speed).
AnTherm® possesses these instrumental characteristics
- AnTherm facilitates the generation of geometrical models by supporting a
graphic input display of building structures, as well as by providing an
entirely independent, fully automatic method of fine subdivision (which can
also be influenced by the user through manual manipulation of parameters).
- It delivers complete input model documentation (geometry of material
elements, thermal design values of materials, spaces, heat sources...) upon
- It allows the precision of numerical solutions to be influenced and
controlled by the user (definition of calculation parameters).
- AnTherm provides results conformant to European standards:
- generally applicable results in the form of g-values and conductance
matrices. These conform to the temperature weighting factors and "thermal
coupling coefficients" defined in the European Standards, including the
required information on calculation precision,
- specific results, applicable to particular air temperature
conditions in spaces thermally coupled by the building components analyzed, in
the form of surface temperature minima and maxima as well as respective
- It creates graphic plots and prints of isotherms, surface temperatures or
temperatures along an edge (2- or 3-dim. models), as well as heat flow
diagrams (not limited to 2-dim. models only, but also in 3D).
- AnTherm meets
all demands of the European Standards with respect to input data and -
more importantly - output data requirements (evaluation results) - validated
according to EN ISO 10211: AnTherm has been qualified as a "Class A"
tool – as for two- and three-dimensional, stationary precision method.
See also: Validation
according to EN ISO 10211:2007,
Validation according to EN
Structure of the application