Thermal conductivity is a material property describing how readily that material conducts, or transfers, heat, with materials having high thermal conductivity, like metals, transferring heat quickly, while materials with low thermal conductivity, like most insulation products, transfer heat much more slowly.
This property is essentially the inverse of thermal resistance, meaning materials with low thermal conductivity, poor heat conductors, make good insulators, while materials with high thermal conductivity, excellent heat conductors, generally make poor insulators.
Understanding thermal conductivity explains why materials like steel framing create more pronounced thermal bridging than wood, since steel’s significantly higher thermal conductivity allows heat to transfer through it much more readily than through the lower-conductivity wood framing alternative.
What Does Thermal Conductivity Explain?
- Why metals conduct heat rapidly, making poor insulators
- Why materials like fiberglass and foam insulate effectively
- The physical basis for thermal bridging through framing
- Why insulation materials are chosen for low conductivity
Why Is Thermal Conductivity Important?
Understanding thermal conductivity helps explain why certain building materials, like steel or aluminum, create genuine thermal bridging concerns while others, like wood, present a more modest though still real thermal bridging effect, informing decisions about when specific thermal break strategies become particularly important. This foundational understanding supports more sophisticated building envelope design decisions.
Because insulation materials are specifically engineered and selected for their low thermal conductivity, understanding this underlying property helps clarify why simply adding more of a poorly performing material doesn’t achieve the same result as using a genuinely low-conductivity insulation product in the first place. This understanding helps clarify why certain materials are chosen specifically for their insulating properties.
Thermal Conductivity vs. Thermal Resistance
Thermal conductivity describes how readily a material conducts heat, with high conductivity meaning poor insulation. Thermal resistance describes the opposite property, a material’s ability to resist heat flow, the concept R-value specifically quantifies for insulation products.