1D:Wufi 1D What is

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What is WUFI?

WUFI is the acronym for "Wärme- und Feuchtetransport instationär" ("Transient Heat and Moisture Transport").

WUFI is designed to calculate the simultaneous heat and moisture transport in one-dimensional multi-layered building components.

A comfortable Windows® user interface allows quick set-up of a calculation project, easy change of parameters for numerical experiments and comfortable viewing of the results as graphics or a 'film'.

The physical and numerical ideas underlying WUFI are developed and discussed in the doctoral thesis:

Künzel, H.M.:
Verfahren zur ein- und zweidimensionalen Berechnung des gekoppelten Wärme- und Feuchtetransports in Bauteilen mit einfachen Kennwerten.
Dissertation Universität Stuttgart 1994
(may be ordered from IBP: [| http://www.hoki.ibp.fhg.de/index.html])
Künzel, H.M.:
Simultaneous Heat and Moisture Transport in Building Components.
One- and two-dimensional calculation using simple parameters.
IRB Verlag 1995
(may be ordered from IRB Verlag, Stuttgart: [[http://www.irb.fhg.de | http://www.irb.fhg.de]]).

In the calculation of heat transport, WUFI takes into account:

  • thermal conduction
  • enthalpy flows through moisture movement with phase change
  • short-wave solar radiation
  • nighttime long-wave radiation cooling (with TRY, DAT, WAC and WBC weather data only).

Convective heat transport by air flows has been disregarded, since it is usually difficult to quantify and rarely one-dimensional.

The vapor transport mechanisms included in WUFI are:

  • vapor diffusion
  • solution diffusion.

Again, convective vapor transport by air flows has been ignored.

The liquid transport mechanisms taken into account are:

  • capillary conduction
  • surface diffusion.

Seepage flow through gravitation, hydraulic flow through pressure differentials, as well as electrokinetic and osmotic effects have not been included.

The choice of temperature and relative humidity as driving potentials allows the use of simple, easily comprehensible storage and transport coefficients. These can also readily be derived from standard material data if no measured data are available and utmost precision of the results is not required.

The boundary conditions for each time step are expressed in terms of meteorological data (temperature, relative humidity, driving rain, radiation), since in building physics these are the relevant parameters specifying the conditions at surfaces exposed to natural weather.
However, conditions for laboratory experiments (e.g. imbibition measurements) can also be expressed as 'meteorological' data.
Heat, moisture and air change sources may be specified within the component.