Air Movement (17 min) One common misconception is that improved energy efficiency in commercial buildings has led to an increasing number of problems with mold, moisture and compromised indoor air quality. Learn how more energy efficient buildings actually reduce the potential for these types of building problems. Building envelope performance is determined by controlling unwanted air flow, moisture and pressure differences. By controlling air movement within a building, many problems resulting from condensation and moisture intrusion can be controlled. And, by understanding how materials should be assembled in a commercial construction project, many less common but costly problems can be avoided.

Moisture Management (6 min) Several factors affect moisture movement within a commercial building - temperature, pressure differences and vapor pressure. Steve Easley discusses the relationship between all three in this segment, as he explains some basic building science principles. By understanding basic concepts such as dew point, buildings are less likely to experience condensation within the envelope.

Bulk Water Intrusion (5 min) The most common way in which wall assemblies get wet is through bulk water intrusion. Building architects must design structures so that they deflect and drain wind-driven rain. In addition, since all building cladding systems leak, the envelope must also be designed so that it can dry out when moisture does enter. In this video, Steve Easley covers the 4D's of moisture management - deflection, drainage, drying and durable components.

Air Current (12 min) Complicated commercial structures are challenging to insulate, particularly in Illinois where the region experiences both cold, dry winters and warm, humid summers. Most buildings offer little resistance to the passage of moisture vapor. If this moisture vapor comes into contact with a cool surface (where the temperature is at or below the dew point of the air), it will condense, creating an environment where mold can grow. Air driven moisture can also corrode or damage nearly any type of building component. Insulation can mold, fasteners can corrode or rust; other types of components can also decay over time if exposed to moisture-laden air. In this segment, Steve Easley cites a number of project examples where incorrect detailing caused corrosion or mold problems.

Diffusion (11 min) Vapor migration by diffusion has more to do with how buildings can dry out than with how they get wet initially. Air flow directly affects the potential for condensation, so reduced air flow through a building reduces the potential for mold growth. However, when the building envelope does get wet, it must be designed so that it can dry out. Here, Steve Easley explains the concepts of water vapor diffusion and vapor transport through air currents. He also describes and shows several types of air barrier systems.