The effect of the temperature dependency of building insulation conductivity in continental and humid temperate climate

Constant conductivity values of insulating materials are typically used in building design and assessment. However, the thermal conductivity of insulating materials changes with temperature. Linear temperature-dependent law exist for many inorganic fibrous materials such as fiberglass or rockwool, that exhibit a decreased thermal conductivity (better performance) at low temperatures, and a higher thermal conductivity (weaker performance) at high temperatures. However some insulating materials, especially the petrochemical-foamed insulation such as the polyisocyanurate (PIR), exhibit less regular behavior with poorer performance at cold temperatures. In this scenario, using constant thermal resistance values results in actual building are different from the design predictions, with increasing building energy consumptions, greater risks of condensation issues, and decreased occupant comfort. This thesis aims to understand the impact of the thermal conductivity change due to temperature when the insulation is used for exterior walls and flat roofs. Experimental results were used in detailed building energy simulations in the continental and humid temperate climates of Toronto and Milan respectively. Common rigid insulating materials boards were taken into account, such as fiberglass, rock- wool, polyisocyanurate, extruded polystyrene, and a hybrid insulation system, that is constituted by two different materials, polyisocyanurate and rockwool.