WUFI

from Wikipedia, the free encyclopedia
WUFI
Basic data

developer Fraunhofer Institute for Building Physics
Current  version 6.2
(April 9, 2018)
operating system Microsoft Windows NT
programming language Delphi
category Simulation software
License Commercial and student licenses , free light version
German speaking Yes
http://www.WUFI.de

WUFI ( " W Slee u nd F euchte i nstationär") is a simulation program for the calculation of the simultaneous heat and moisture transport in components.

It is used for the mathematical investigation of the heat and moisture balance of weathered components. The main area of ​​application is the prognosis of possible moisture damage or moisture-related heat loss under natural weather conditions. The lengthy and expensive weathering tests customary up to now can be shortened or replaced in some cases.

functionality

WUFI calculates the unsteady temporal development of the temperature and humidity field in a one-dimensional cross section of a component that can consist of several layers of different materials. The use of simplified transport models tailored to the conditions encountered in building physics facilitates the practical application and the interpretation of the results.

The layer sequence of the component is entered via a graphic editor; the respective material characteristics can be taken from a supplied material database or entered by the user. WUFI uses relatively simple, clear parameters, which make it easier to check the plausibility of the entries and to measure or estimate missing data. In some cases, auxiliary functions are also available to determine missing parameters from other standard parameters.

Weather data can be specified as boundary conditions so that the influence of natural weathering can be taken into account by applying the air temperature and humidity , solar radiation and, if necessary, the driving rain load .

During the calculation, WUFI determines the development of the temperature and moisture profile in the component over time in hourly steps. The transport mechanisms considered are heat conduction , water vapor diffusion and capillary conduction . The storage capacities of the materials for heat and moisture are described by the specific heat capacity or the moisture storage function. Heat and moisture transport are not independent of each other because the thermal parameters depend on the water content and the hygric parameters on the temperature, because latent heat is also transported through water vapor as soon as evaporation or condensation occurs, and because the steam transport is partly driven by the temperature conditions .

Heat and steam transport as a result of air currents, seepage flows driven by gravity or pressure differences, and electrokinetic or osmotic effects are not taken into account .

The time course of the calculated values ​​can be displayed in the form of curves or output in a text file for further processing. The chronological sequence of all calculated temperature and humidity profiles can be animated as a film.

application areas

WUFI is used to evaluate existing buildings, to plan measures that intervene in existing buildings, such as renovation, conversion or subsequent insulation . When developing new components and materials or when transferring existing construction methods to other climatic zones , their suitability can be mathematically investigated in advance.

In the event of damage, WUFI can support the clarification of possible hygrothermal causes; In the context of monument protection, both possible causes of damage and the effects of various countermeasures can be examined.

Concrete questions that are mostly examined in such contexts include:

  • the drying time of building moisture and its effects on thermal insulation , frost damage, etc.
  • the water absorption in driving rain and the drying potential
  • the risk of condensation failure , the amount of condensation and the drying capacity

In addition, the hourly calculated temperature and humidity levels can serve as input data for further evaluation models, which on this basis make statements about the durability and aging of materials or about special damage risks such as mold growth or frost damage. The development of such models is currently still the subject of research.

The use of simulation programs such as WUFI now corresponds to the state of the art and the rules of technology . For example, DIN 4108, which regulates the Glaser method prescribed for testing moisture safety in Germany , in its current version also explicitly allows numerical simulation methods for cases that cannot be assessed using the Glaser method (e.g. drying out of building moisture , Absorption of rainwater, etc.). The requirements that a simulation program must meet are regulated in DIN EN 15026 .

Further programs from the WUFI family

WUFI 2D is a two-dimensional version of WUFI, which also calculates thermal bridges , corner areas, anisotropic materials and the like. similar allowed.

WUFI Plus combines hygrothermal component calculations with a simulation of the entire building (including heating and ventilation) and thus allows the interaction between the temperature and humidity conditions both in the building and in its surrounding areas to be determined.

Publications

  • Künzel, HM: Method for the one- and two-dimensional calculation of the coupled heat and moisture transport in components with simple parameters. Dissertation, University of Stuttgart 1994 ( online , 1.4 MB)
  • Künzel, HM, Kiessl, K .: Calculation of heat and moisture transfer in exposed building components. International Journal of Heat and Mass Transfer, Vol. 40, No. 1, pp. 159-167, 1997
  • Künzel, HM, Holm, A., Zirkelbach, D., Karagiozis AN: Simulation of indoor temperature and humidity conditions including hygrothermal interactions with the building envelope. Solar Energy 78, 554-561, 2005 doi : 10.1016 / j.solener.2004.03.002
  • Künzel, HM, Sedlbauer, K., Holm, A., Krus, M .: Development of hygrothermal simulation in construction using the example of the WUFI software family. WKSB magazine for heat protection, cold protection, sound insulation, fire protection vol. 55, pp. 7-14, 2006 ( online , 639 KB)

See also

  • Delphin , simulation software from TU Dresden for the coupled heat, moisture, air and salt transport in porous materials.