Peter Häupl

Coupled heat air and moisture transfer in building structures

Abstract Based on the energy, mass and linear momentum conservation laws as well as the entropy law, a coupled, partial, non-linear, differential equation system for the heat, air and moisture transfer in porous materials follows, and for the more-dimensional solution of it, a suitable algorithm including the simulation software has been developed. Its efficiency is demonstrated by a recent building structure—chuted concrete between fibre board with polystyrol-foam outside insulation-under the boundary conditions of the TRY Essen: hourly values of outdoor climate. As a result of the high built-in moisture, moisture damages (mould growing) in the base level (exterior wall/concrete plate over the basement garage) and inadmissible high heat losses caused by the moisture depending thermal conductivity and the additional enthalpy flows coupled to the moisture movement and phase changing are observed in the first years.

Towards an Engineering Model of Material Characteristics for Input to Ham Transport Simulations - Part 1: An Approach

Heat, Air and Moisture (HAM) modelling of building performance is a quite young research subject but the experimental determination of material properties is often based on classical methods. One should review the manner in which we define characteristic material parameters and there is a need to develop an approximation used to generate the required material functions for input to HAM-transport simulations. The paper presents such an approach, called an engineering model for hygrothermal material characterisation. The paper poses the question, how to arrive at input data that can be used for a model based on thermodynamically defined potentials (Only such a model allows introduction of new potential components (freezing depression, osmotic pressure, air pressure, overburden envelope pressure)) (e.g., Grunewald, J. (1997) and Grunewald, J. (1999)) and yet the respective functions used to describe changes in the material response as a function of the variables of state. Such functions should have a reasonable precision and goodness of fit while the number of measured points must be reduced to a minimum. Those measurements should be relatively easy to perform (i.e., they would not require determination of temporal and spatial profiles of moisture). This discussion paper highlights steps already taken (Part 1), and lists issues that need to be resolved before reaching this goal (Part 2).

Model and program for the prediction of the indoor air temperature and indoor air relative humidity

The solution of the simplified thermal and hygric room balance equations and adjacent walls is compared in selected application cases. In this article, the moisture part of the model is first reviewed and then applied to scenarios designed to illustrate the experimental and calculation results. For the common professional use, the user-friendly program CLIMT (Climate–Indoor–Moisture–Temperature) has been developed.

The Thermohygric Performance of Insulated Building Structures Under Conditions of Use

Based on the energy, mass and momentum conservation laws, a system of coupled non-linear transport equations including a suitable computer code has been developed to determine the temperature, moisture, ice, vapour pressure, air pressure fields and the heat, enthalpy, vapour, water and air flows in porous building materials and in building structures under conditions of use. The contribution demonstrates the thermohygric behaviour of a typical heavy concrete flat roof with a mineral wool insulation layer, the drying out process of an insulated light-weight wooden roof caused by a capillary-active vapour barrier, the moisture and temperature field in an air permeable building component, and the impact of a capillary-active inside insulation of a framework-house (exposed timber) being thermally renovated right now.

Komponenten des Außenklimas

Das warme- und feuchtetechnische Verhalten des Gebaudes und der einzelnen Bauwerksteile wird ganzjahrig (in Mitteleuropa wahrend der Heizperiode und in der Jahreszeit mit zweit gehend freier Klimatisierung) vom Ausenklima masgeblich beeinflusst.

Charakterisierung des Raumklimas

Fur die hygrothermische Bemessung der Bauteile und Gebaude sind auch die die raumseitigen Klimakomponenten zu quantifizieren. Neben der Eigensicherung des Gebaude dient das Raumklima auch der Gewahrleistung der Funktionssicherung, z. B. der Behaglichkeit in Wohn- und Burobauten oder der Sonderklimate in Produktionshallen, Museen usw. [2], [15], [18], [21], [23], [62], [64]. Auf Schadstoffe und Verunreinigungen in der Raumluft wird hier nicht eingegangen.