The impact of temperature dependency of the building insulation thermal conductivity in the Canadian climate

Constant conductivity values of insulating materials are typically used in building design and assessment. However, the thermal conductivity of insulating materials depends on several factors, including the operative temperature. Linear temperature-dependent laws exist for many inorganic fibrous materials that exhibit a decreased thermal conductivity at lower temperatures. However, some insulating materials, especially the petrochemical-foamed insulations such as the polyisocyanurate, exhibit less regular behavior with poorer performance at cold temperatures. This paper investigates the impact of the thermal conductivity changes due to the temperature when the insulation is used for exterior walls and flat roofs in a cold climate. Experimental results for different materials are used in building simulations focusing on both wall and roof timber frame constructions.