This paper evaluates the reliability of the currently used climate-based indices in selecting a moisture reference year (MRY) for the freeze-thaw (FT) damage risk assessment of internally insulated solid brick walls. The evaluation methodology compares the ranking of the years determined by the climate-based indices and response-based indices from simulations, regarded as actual performance. The hygrothermal response of an old brick masonry wall assembly, before and after retrofit, was investigated in two Canadian cities under historical and projected future climates. Results indicated that climate-based indices failed to represent the actual performance. However, among the response-based indices, the freeze-thaw damage risk index (FTDR) showed a better correlation with the climate-based indices. Additionally, results indicated a better correlation between the climatic index (CI), the moisture index (MI), and FTDR in Ottawa; however, in Vancouver, a better fit was found between MI and FTDR. Moreover, the risk of freeze-thaw increased considerably after interior insulation was added under both historical and projected future climates. The risk of FT damage would increase for Ottawa but decrease for Vancouver under a warming climate projected in the future, based on the climate scenario used in this study. Further research is needed to develop a more reliable method for the ranking and the selection of MRYs on the basis of climate-based indices that is suitable for freeze-thaw damage risk assessment.

Today, it is globally known that climate change needs to be addressed to mitigate its harmful effects on our environment. It is also common knowledge that the contribution of historical buildings to the energy consumption of the existing Canadian building stock is severe. Buildings of historical identity are often poorly thermally insulated. Thus, to increase energy efficiency and occupant comfort in cold climates, the application of thermal insulation on the interior side of solid masonry walls offers a possibility to improve the historic buildings' energy performance, without compromising their identity and cultural heritage values. As a result, the historical masonry will be subjected to lower temperature during the heating season, which can increase the potential for condensation and frost within the wall. A balance must therefore be reached between durability measures and thermal performance objectives. This paper intends to achieve this balance through determining the impact of the interior insulation thickness on the durability of a typical historical masonry wall under the effect of climate change. A stochastic approach is used in hygrothermal simulations to account for the uncertainty in material properties. Results in Ottawa indicate a higher risk to frost damage after interior insulation is added to a brick wall having a moisture critical degree of saturation (Scrit) of 0.25 and 0.35. Moreover, both deterministic and the stochastic results were in good agreement. Also, both methods showed an increase risk to frost damage under a changing climate.

Hygrothermal simulations are necessary to permit analyzing moisture performance when designing building envelopes. Owing to the high computing time and cost of the long term simulations, a common approach is to select representative year(s), the Moisture Reference Year(s), from a longterm series of climate data. It is assumed that the use of Moisture Reference Year(s) (MRYs) provides equivalent results as those provided using long-term series. The selection of MRY(s) is by itself based on the one of the methods available in the literature. In the present study, three methods of selecting the MRYs were evaluated i.e. the moisture index (MI), severity index (Isev) and climatic index (CI). Simulations were performed using individual years of historical climate data extending from 1986 to 2016 and projected future climate data representing the scenario with a 3.5°C increase in average temperature which is expected to occur from 2062 to 2092. Brick cladding installed on a wood frame wall assembly subjected to the climate of three different Canadian cities was selected for analysis. The cities selected were Vancouver (BC), Calgary (AB) and Ottawa (ON). These cities have differing levels of moisture loads. The year having the mould index value more than 3 for highest number of hours among the individual years was compared with the MRY given by three selected methods. A method was considered to be accurate in terms of the prediction if the year selected by that method gives the number of hours with mould index more than 3 which lies in the same class as that of year having maximum corresponding value. In general, it was observed that none of the methods provides the worst year with 100% accuracy, however for most of the cases, Isev method performs better than other two methods in terms of MRY selection.

To mitigate the effects of climate change, higher insulation levels in buildings are mandated by the National Energy Code for Buildings. However, increased insulation levels within building envelopes may lead to a greater risk of moisture problems. With a changing climate, higher rainfall intensity, stronger winds and more storms are expected, which may increase wind-driven rain loads on façade and risks for rain penetration damages of building envelopes. This paper aims to present results of the effects of climate change on the freeze-thaw damage risk of internally insulated brick masonry walls of buildings in different Canadian cities, using different freeze-thaw models. Freeze-thaw damage was evaluated using different freeze-thaw models. Simulations were performed using DELPHIN 5.9.4. Results showed potential risk to freeze-thaw in Montreal and Vancouver after retrofit. Under climate change, Winnipeg has the lowest risk to frost damage, though damage functions showed an increase in the level of severity. Comparing the results of different models under a changing climate, the damage functions seemed in a good agreement for most of the cases, except for the Indicative Freeze-Thaw Cycles (IFTC) evaluated in St-Johns. This model counts the number of freeze-thaw cycles based on short duration of freezing and thawing and therefore does not consider longer freeze-thaw period.