| A comparison is made between the predictions of a numerical model of structural moisture behavior and the experimental results from afield study in which the moisture performance of roofs of several newly constructed houses was monitored over one year of occupation in different New Zealand climate zones. There was good agreement between the model and the experimental results, with a maximum standard deviation of difference of 1.3% moisture content. Most of the difference is due to limitations in measurements rather than to deficiencies in the model. Both the field study and the model confirmed that air infiltration was a dominating influence in the moisture transfer.
Modelling of moisture transfer in structures¡ªI. A description of a finite-difference nodal model
M. J. Cunningham
Building and Environment, Volume 25, Issue 1 , 1990, Pages 55-61
The physical, numerical and computational basis of a 1- 2- or 3-D time-dependent finite-difference nodal model for heat and moisture transfer in buildings is described. The model is designed to be very flexible so as to be able to analyse a wide variety of geometries and circumstances. The solution procedure is fully implicit with non-linear processes such as condensation, radiation and convection being described in terms of an effective conductance at each time step. The model is iterated at each time step to arrive at a good estimate of the updated value of these effective conductances. The performance of this model is analysed in a later paper.
Modelling of moisture transfer in structures¡ªII. A comparison of a numerical model, an analytical model and some experimental results
M. J. Cunninghama
Building and Environment, Volume 25, Issue 2 , 1990, Pages 85-94
The results of comparing the predictions of an analytical and a numerical model against experimental data on the moisture performance of four flat roofs is presented. The experimental data was obtained by placing one metre square roof specimens between two controlled climate chambers and subjected them to steady-state driving conditions. The agreement with the experimental data shown by both models is good, the numerical model showing the ability to follow fine detail in the moisture behaviour. The results suggest that the concepts rising from the analytical model are useful ones, and that the numerical model should perform well under field conditions. |