Thermal Bridging in Details & Impact on Energy Use

 Office Hour Recap – August 8 

During this session, we dug into a very conventional problem: a basement column going through a floor slab. The way this detail was put together reduced the amount of insulation and introduced both metal fasteners and a steel column—creating a clear thermal bridge.

🔍 When we modeled the detail in THERM, the thermal bridge value looked fairly large. But because it only occurs for a very limited length (two columns total), its impact on overall building energy use turned out to be very small—less than a few dollars per year once entered into the energy model.

💡 Key takeaways:

• Not every thermal bridge with a high coefficient has a meaningful energy impact—geometry and scale length matter.

• Adding insulation or expensive thermal break materials in this case would not be cost-effective, since the modeled energy penalty is minimal.

• Surface temperature analysis showed that interior conditions remain warm enough to avoid condensation risk, which is typical for basement details well below grade.

So, while it’s always worth examining junctions for resilience and comfort, this case showed how careful analysis can reveal when a “problem” detail is actually a very low priority in terms of energy performance. It’s all about balancing performance, cost, and constructability.

Thanks to everyone who joined the conversation—lots of thoughtful questions and insights! 🙌

👉 Interested in exploring more thermal bridge cases or joining future office hours? Drop a comment or message us—we’d love to hear your perspective.

#BuildingScience #PassiveHouse #ThermalBridging #EnergyEfficiency #SustainableDesign