COND Documentation and User Manual

Starting from a vapor-permeable construction that can consist of several layers, COND considers one-dimensional, stationary heat and moisture transport. A constant climate is assumed on both sides of the construction, described by temperature and relative humidity.

The temperature gradient causes a heat flow through the construction. After a certain period, a stationary heat flow and temperature profile develop. The vapor pressure gradient likewise causes vapor flow. COND calculates the stationary vapor and heat flows and the resulting vapor pressure and temperature profiles.

If the calculated vapor pressure exceeds the saturation vapor pressure at any point in the construction, condensation occurs. The traditional Glaser method estimates the amount of condensate from the vapor flows to and from the condensation plane.

In reality, liquid-water flows also develop away from the condensation zone as soon as condensate forms. This capillary transport is taken into account by the COND method and allows a more realistic description of moisture transport, especially for interior insulation systems.

For the stationary moisture distribution, COND assumes a global equilibrium of the vapor flows and a local equilibrium in which the combined liquid-water and vapor flows equal the stationary global vapor flow. These equilibrium states can be described by equations and solved analytically. The time-dependent adjustment process is then used to calculate the expected moisture distribution after a given period.

Capillary spreading of condensate leads to hygric relaxation of the construction. Calculations with the COND method therefore usually result in lower condensate quantities than the Glaser method. The COND algorithm is particularly suitable for assessing interior insulation systems and constructions that are classified as critical by the traditional Glaser method.

The detailed theoretical foundations are also available as a PDF: Download COND fundamentals →