Investigation of the Mould Resistance Design (MRD) model for mould growth in attics

Thor Hansen,Petter Wallentén,J Kurnitski,T Kalamees

doi:10.1051/e3sconf/202017220005

Abstract

Based on measurements of mould in 17 attics in the north of Sweden, 3 were chosen as a tentative validation of the MRD-model (Mould Resistance Design) for long periods of time (1961-2012). Comparing the measurements and the results from the simulations showed great differences regarding the mould growth depending on the simplifications used in the model. How the leakage was simulated and where the moisture from the leakage was placed in the construction were the most important factors. The study could not validate the MRD model as such, but it was clear that the simulations with relatively small adjustments could give realistic data

Highlights

IntroductionThe models are based on different assumptions and sometimes calibrated against in situ measurements or laboratory measurements
There are several models for predicting the mould growth in wood [4]
The conclusions from the mould samples were that no correlation between insulation level on the attic floor and mould growth was found but that there was a tentative correlation between mould growth and leakage areas between living space and attic as well as reduced ambient ventilation by blocking the eaves, see figure 2

Summary

Introduction

The models are based on different assumptions and sometimes calibrated against in situ measurements or laboratory measurements. One of these models is the so called MRD-model (Mould Resistance Design), [3-4]. This model is mainly calibrated against laboratory measurements. Mould samples were taken in 17 cold attics built between 1960-1965 and graded according to a 5 step scale (0-4) from “no mould growth” to “heavy growth over more or less the entire surface”, [2]. The purpose of the study presented here was to investigate how well the MRD-model (Mould Resistance Design) could predict mould growth in roof structures within long periods of time.

Methods

Results

Discussion

Conclusion