Long-term thermal performance of insulations under moisture loads

The performance of thermal building envelope insulation systems may be severely impaired by moisture. The best solution would be to keep insulation materials dry at all times. Alas, building practice has proven time and again that this is wishful thinking. Even if the insulation materials are enclosed by vapor barriers on both sides, there is a fair chance that moisture will get inside eventually through imperfections and small leaks emerging during normal use. Once inside, moisture will be trapped there for a long time. Thus, understanding the long-term performance of insulation materials is vital for sustainable and energy efficient building design. This chapter analyzes and quantifies the impact of moisture on the thermal resistance of insulation systems and explains the interdependece of heat and moisture transfer. This hepls to develop durable envelope solutions and appropriate test methods for insulation materials.