An Overview of Structural Thermal Breaks

Brief 

Alyson Hallander, a product engineer for Schöck North America, offers an overview of structural thermal breaks, including the ways they curtail heat transmission, their challenges they present and the solutions available. Hallander also provides insight into how they are installed in concrete applications.

Insight

Structural thermal breaks prevent condensation and mold, reduce heat loss through envelope penetrations, lower energy costs and carbon emissions, and reduce owner liability – while meeting increasingly stringent building energy codes.

Reducing energy usage in buildings has become a focal point of the architectural, engineering, and construction (AEC) industry to meet national energy goals and reduce costs to building owners. Heating, ventilation, and air conditioning (HVAC) contribute significantly to total building energy use, leading designers to pursue strategies for achieving better thermal performance.

The industry has responded with improved efficiency of HVAC systems and strengthened building envelopes via increased wall insulation and high-performance windows and doors. However, significant heat energy transmission through steel and concrete thermal bridges penetrating the envelope of otherwise well-insulated buildings is often overlooked.

That is changing as revised building energy codes directly address thermal bridging. An addendum to the American Society of Heating, Refrigeration, and Air Conditioning Engineers’ ASHRAE 90.1-2019, Energy Standards for Buildings Except Low-Rise Residential Buildings, specifically addressing thermal bridging and structural thermal breaks, is currently under review – a prelude to possible inclusion in future editions.

In 2020, New York City and Seattle became the first cities in the United States to mandate the mitigation of thermal bridging at concrete penetrations through the building envelope. In addition, major utilities offer financial incentives for builders and developers to improve energy efficiency by various means, including incorporating structural thermal breaks to strengthen the building envelope.

Mitigating Heat Transmission

The thermal conductivity of structural steel at beams, canopies, rooftop connections, and concrete that comprises a conventional pour-through balcony, for example, allows the rapid dissipation of interior heat into the exterior.