A Cup of Joe: The Second Law of Thermodynamics


The laws of thermodynamics outline the fundamental rules for understanding heat. If you want to understand building science better, you need to understand thermodynamics. More specifically, the Second Law of Thermodynamics which describes the flow of energy from a hotter body or space to a colder one.

The second law is referenced widely in building science. To design building enclosures that work, we need to know which direction heat, air, and moisture will flow most of the time. In analyzing failures, we can rely on that direction of flow to help us understand what happened.

If you fail to take proper consideration of the specific climate you build in, you risk violating the fundamental laws of physics.


About Dr. Joe Lstiburek 

Dr. Joe Lstiburek is the founding principal of Building Science Corporation, one of the most influential, innovative, and respected building science firms in North America. Dr. Lstiburek’s work ranges widely, from providing expert witness testimony to overseeing research and development projects to writing for the ASHRAE Journal. His commitment to advancing the building industry has had a lasting impact on building codes and practices throughout the world, particularly in the areas of air barriers, vapor barriers, and vented and unvented roof assemblies. His commitment to education earned him the hailing, “the dean of North American building science” by the Wall Street Journal. Dr. Lstiburek holds a Bachelor of Applied Science in Mechanical Engineering, a Master of Engineering in Civil Engineering, and a Doctor of Philosophy (Ph.D.) in Building Science. Get the full scope of Dr. Lstiburek’s work, accolades, and contributions to the industry over at Building Science Corporation.