Real R-Value of Exterior Insulated Wall Assemblies

By Morrison Hershfield|Dec 1, 2014 1:00:00 AM

The recent drive towards sustainable building construction has placed new emphasis on the provision of durable wall assemblies that provide a high effective resistance to heat flow (R-Value).

The authors’ practice focuses on large multiresidential, commercial and institutional buildings constructed of concrete, steel, masonry and glazing systems. In these types of buildings thermal performance has not historically been treated as a high priority item. Now, however, the requirements of sustainability programs such as LEED are requiring architects to design wall systems that provide high levels of thermal resistance. Architects are often shocked at the difference between effective R-value of a proposed opaque wall assembly and the nominal R-value of installed insulation materials. The difference is a result of the thermal bridges associated with structural elements and connections that pass through the building thermal envelope.

The Concept of Linear and Point Transmittance and its Value in Dealing with Thermal Bridges in Building Enclosures

By Morrison Hershfield|Dec 1, 2014 1:00:00 AM

Thermal bridging through insulating layers can greatly reduce the thermal performance of building assemblies. As such, determining the effects of thermal bridging is often of immense importance to building engineers, energy modelers and architects in accurately designing a building. This can be very difficult to accomplish, and as a result many building codes and standards do not comprehensively address this problem.

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