Thermal bridging is recognised as a signiﬁcant factor in building envelope heat loss. It has been determined that the total heat ﬂow through typical wall assemblies is underestimated by as much as 70% due to thermal bridging, yet simply adding insulation to walls has been proven to not necessarily decrease the energy use of a building. Heat ﬂow paths (thermal bridges) allow heat to by-pass the insulation, negating any beneﬁt of installing more insulation in the wall.
Metal, cement and laminate wall claddings are supported by and attached to continuous girts or clips that penetrate the exterior insulation layer, creating thermal bridges. These fastening systems are normally made of highly conductive steel or aluminium, creating signiﬁcant energy (heat) loss. It has been demonstrated that these thermal bridges in conventional steel stud wall assembly construction reduce insulation effectiveness (R value) by as much as 50%, resulting in wall assemblies and interface details that do not meet current energy code requirements for minimum U value.
When thermal bridging is ignored, the unaccounted for heat ﬂow creates higher heating and cooling costs, oversizing of HVAC equipment, operational inefﬁciencies and higher energy consumption.Read more