Thermal Considerations According to Steel Structures

Published on August 27, 2015 by Structural Innovations in Structural Engineering

Building design requires more thought than just enough substance to support its own weight. Thermal considerations are important to the structural engineer to provide energy efficiency to a building. Heating and cooling averages 25% of energy costs in a commercial building and 40% in residential. Due to rising costs of power and environmental concerns this becomes a major factor in modern building design.

Thermal Bridging

Thermal bridging is the effect of heat transfer through building materials. Although the term is typically used to refer to materials that conduct more thermal energy than the surrounding structure, from the perspective of a structural engineer all materials inherently have some level of thermal bridging. It is responsible for energy loss by allowing heat to disperse during winter or enter the building in summer. It can cause further problems through condensation inside the walls. Fortunately, proper building design by a trained structural engineer in North Carolina can minimize the problem with appropriate layers of insulation and structural materials.

Heat transfer occurs in one of three ways. The most common for building purposes is conduction, or the direct transfer of heat through building materials. Convection is the loss of heat through airflow such as leaks in the building’s air barrier. Radiation does not play a significant role in heat loss, although structural engineers should be aware that it can play a role in introducing heat during the summer, increasing the cost of cooling.

Thermal Capacity

Thermal capacity is defined in terms of R-values and U-factors. They are opposite in that the R-value is equal to one divided by the U-factor, and is explained by defining R-value as a material’s resistance to heat flow while U-factor is the material’s ability to conduct heat. Since heat travels the path of least resistance, it is important to consider the orientation of building layers to add up different layers of varying parallel R-values rather than provide a single U-factor of perpendicular structural materials.

Solutions

Structural engineer in North Carolina should be aware that not only are the placement and thickness of materials important factors toward thermal capacity, but it is also largely affected by the building’s climate zone. North Carolina’s mild winters and the southern heat of summer can affect a building’s design comparative to one built in a northern climate. However, some design elements remain consistent across the board to prevent thermal transfer. Continuous bridging can be divided into intermittent bridging with barriers between the components and minimal thickness of bridging elements provide for less space the heat energy to transfer through. Stainless steel provides a more efficient barrier than carbon steel and can be strategically placed as needed to provide a better overall R-value.

Thermal considerations are more important in today’s world of building design than ever before. It needs to be addressed with the initial design rather than as an afterthought. Whether designing buildings or building materials, structural engineers have to be aware of heat transfer and building efficiency.

You may have questions after reading this information. If so, please feel free to reach out to our team of structural engineer experts at 704-910-8397.