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.
How can we improve cladding attachment details and design wall
assemblies that maximize insulation values so they reduce heat
loss, reduce cost and meet energy codes?
Armatherm cladding attachments significantly improve wall
assembly thermal performance. Armatherm FRR Z Girt, clip and
thermal break shims provide a combination of low thermal
conductivity and high compressive strength transferring load and
reducing heat loss. The material is made of a reinforced, thermoset
resin that is fire resistant and exhibits very limited creep under
load, making it the ideal material for use in structural and façade
thermal break connections.
Armatherm thermally broken cladding support connection solutions
prevent excessive heat flow and potential condensation problems
otherwise associated with thermal bridging. Moreover, wall assemblies
using Armatherm attachments will meet the continuous insulation
requirement of ASHRAE 90.1 and the effective R value requirements of the
Canadian NECB energy code.
Modeling results show that using Armatherm Z girts results in several
improvements in the thermal efficiency of wall designs, reducing heat flow: