I'm looking for information about what may, or may not be, traditional Vietnamese architecture.

There is a book called, "The Tapestries" by Kien Nguyen. In it he writes,

"The sturdy walls were made of cement mixed with peppercorns. As the temperature outside dropped, the heat from the peppercorns would help keep this room's temperature at a comfortable level.Ven knew that this system of construction was a luxury only the rich could afford."

Does anyone know if this is an actual method of construction and if so, are the peppercorns themselves giving off heat or do they just have properties of thermal mass (like cement)?

Any help is greatly appreciated.

David Cooper Salamon