Marc Rosenbaum, Director of Engineering, South Mountain Company and one of HeatSpring’s expert instructors, taught a free live lecture to more than 200 architects and builders last week. His focus: demonstrate how buildings interact thermally with the ground and teach people how to calculate heat loss to the ground.

Access Full Lecture and Additional Resources Here

During the live lecture, Marc started with a 2D THERM model of a basement, reviewed the U factor that THERM calculates for the foundation assembly, and used that to calculate the design heat loss of the basement. He showed the attendees how to estimate the annual heat loss as well.


He then presented the simplified Los Alamos algorithms for calculating heat loss from basements and slab-on-grade foundations and used those to analyze the model and compare the result with the THERM calculation.


At the conclusion of the lecture, Marc discussed how to apply the algorithms to a walk-out basement condition and how to estimate design heat loss in the case where the insulation is in the frame floor over a basement.

Learning Takeaways

  • Learn about relative conductivity and heat capacity of soils vs. air
  • Learn about variations in soil temperature with time and depth
  • See the results of a 2D THERM model of a basement, including the temperature distribution, direction of heat flow, and heat loss rates
  • Learn about using the U factor calculated by THERM to estimate foundation heat loss
  • Learn how to do simplified heat loss calculations for basements, slab-on-grade, and walkout basement foundations
  • Learn how to estimate design heat loss through an insulated floor to a basement below

Marc Rosenbaum is the Director of Engineering, South Mountain Company. He uses an integrated systems design approach to help people create buildings and communities which connect us to the natural world, and support both personal and planetary health. He brings this vision, experience and commitment to a collaborative design process, with the goal of profoundly understanding the interconnections between people, place, and systems that generate the best solution for each unique project. Marc teaches a 10-week course,Zero Net Energy Homes, where students walk away with a comprehensive understanding of all of the key components of a zero net energy home, do a full design of a Zero Net Energy Home, and earn NESEA’s ‘Zero Net Energy Homes Professional Certificate.’ The next course starts on September 15th.

Read the full course outline of Zero Net Energy Homes and learn more here.
The course is capped at 50 students with 30 discounts.