• Cladding reflectivity affects moisture and energy across climates. • Higher reflectivity lowers cooling but slightly raises heating demand. • Mould risk rises with reflectivity in Montreal and Toronto. • In Vancouver, higher reflectivity improves moisture behavior. • Optimal reflectivity: 0.2–0.4 cold climates, 0.6–0.8 marine climate. This study investigates the long-term impact of cladding reflectivity on the hygrothermal and energy performance of residential wall assemblies in three Canadian cities: Montreal, Toronto, and Vancouver, under the coldest and hottest historical climate year conditions. A parametric simulation approach was used to evaluate four wall cladding reflectivity levels (0.2, 0.4, 0.6, and 0.8). The analysis focused on cumulative heating and cooling energy loads and moisture content. Results indicate that increasing reflectivity consistently reduces cooling demand across all cities. Results indicated that cooling loads decreased by 61.5% and 42.5% in Montreal, 63.8% and 42.4% in Toronto, and 98.2% and 87.4% in Vancouver from reflectivity 0.2 to 0.8 during the coldest and hottest years, respectively. However, this reduction was accompanied by increased heating demand, with rises of 19.9% and 22.4% in Montreal, 16.4% and 22.3% in Toronto, and 20.8% and 9.4% in Vancouver. Moisture analysis showed increased long-term moisture buildup in wall components at higher reflectivity levels. In buildings, considering both energy performance and moisture safety, the optimal reflectivity is 0.2 in Montreal and Toronto for both the coldest and hottest runs. In Vancouver, the optimum reflectivity is 0.6 during the coldest year and shifts to 0.8 under the hottest year conditions. These results emphasize the need for climate-adapted cladding reflectivity specifications to ensure durable, moisture-resilient, and energy-efficient envelope design.
Arasteh et al. (Sun,) studied this question.
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