C077 -- Review and Evaluation of 20 Methods to Select Moisture Reference Years for Damage Risks in Solid Masonry Walls

A Moisture Reference Year (MRY) is used as boundary conditions in hygrothermal simulations to assess the durability of building envelopes. An MRY is typically a time series of one year of climate data, including variables as temperature, relative humidity, precipitation, etc. The data are selected from 30-year datasets based on climate indices, e.g., wind-driven rain load, moisture index, …, or based on the results of HAM simulations for preselected years. The main reason for using MRYs is reducing computational time, i.e., to avoid a full 30-year climate dataset in the simulations. However, methods to select MRYs are usually developed for estimating the risk of interstitial condensation and mould growth in building envelopes. It is uncertain whether these methods are valid for assessment of other damage mechanisms in specific wall assemblies, such as solid masonry walls. We evaluated 20 existing MRY selection methods to estimate freeze-thaw damage in solid masonry walls in Brussels, Belgium, as well as wood decay of beam-heads embedded in the masonry. Brick type and rain exposure are varied for masonry walls with and without interior insulation. This paper presents the simulation results of long-term 30-year simulations and simulations using MRYs. The 30-year simulations are represented quite well for several MRY methods. However, when considering multiple damages simultaneously, the performance of most MRY methods decreases. Moreover, it is recommended to select an MRY based on climate variables with a physical relation to the studied damage mechanism(s). In this paper, the optimal MRY method is based on wind-driven rain load for the critical orientation, i.e., the south-west in Brussels. Nonetheless, when sufficient computational resources are available, using the complete 30-year period in HAM simulations, at least for a reference case, is preferred over an MRY.