ABSTRACT
Office building envelopes are generally successful in meeting a range of structural, aesthetic and
thermal requirements. However, poor thermal envelope performance does occur due to the
existence of defects in the envelope insulation, air barrier and vapor retarder systems. These
defects result from designs that do not adequately account for heat, air and moisture transmission,
with many being associated with inappropriate or inadequate detailing of the connections of
envelope components. Other defects result from designs that appear adequate but can not be
constructed in the field or will not maintain adequate performance over time. Despite the existence
of these thermal envelope performance problems, information is available to design and construct
envelopes that do perform well. In order to bridge the gap between available knowledge and
current practice, NIST has developed thermal envelope design guidelines for federal office buildings
for the General Services Administration. The goal of this project is to transfer the knowledge on
thermal envelope design and performance from the building research, design and construction
communities into a form that will be used by building design professionals. These guidelines are
organized by envelope construction system and contain practical information on the avoidance of
thermal performance problems such as thermal bridging, insulation system defects, moisture
migration, and envelope air leakage.
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