The hygrothermal conditions in a building or within a building envelope assembly can be crucial for the overall performance of the construction and its mechanical system.
— ASHRAE Handbook, Fundamentals

The movement of heat and moisture through both prospective and existing building enclosure assemblies can be assessed mathematically with hygrothermal models.  Bell & Spina utilizes both traditional, steady-state calculation methods and computer software to evaluate the risk of condensation within a given assembly.  These methods further assist in the determination of U-Values for proposed enclosure assemblies.     

- Neil W Garry, PE, RRC, REWC, BECxP, CxA+BE