Thermal bridging is recognized 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 aluminum, 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.
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:
- The insulation efficiencies of the wall assemblies increase significantly.
Some as high as 98%.
- Higher, effective wall assembly R values are achieved using lower values
of external insulation. For example, to obtain an R value of R-13 minimum
to meet ASHRAE zone 1, steel girts require and external R 20; whereas
Armatherm girts require only R 10.
- Cladding wall assemblies can meet the R value requirements of ALL
geographical zones for both ASHRAE 2013 and NECB 2011 energy codes
using Armatherm Z girts.
- Reduction in thickness and cost of insulation.
- Reduces energy consumption.