This is the twelfth post in a series by J. David Odom (ASHRAE), Richard Scott (AIA/NCARB/LEED AP), and George H. DuBose (CGC). It was first published as a mini-monograph for NCARB (National Council of Architectural Registration Boards).

Florida Solar Energy Center (FSEC) of Cocoa, Florida called this condition the “Smart Air Syndrome” concept – that air is supposed to be smart enough to get from one place to another in spite of barriers. Additional ventilation air should always be designed in conjunction with considering the impact of the distribution of the ventilation air. This requires identifying parts of the building that could become depressurized with respect to outside conditions, thus potentially drawing humid outside air into the envelope cavity or occupied spaces. (Note: Even in less humid climates, an unbalanced HVAC system can inadvertently transfer odors and airborne pollutants in unintended ways through a building.) This increased risk of moisture problems caused by greater air volumes (and thus unbalanced areas of the building) is depicted in the FSEC graph below (Figure 3.6).

FSEC’s research has demonstrated the relationship between building complexity (architectural and structural complexity), the intensity of the HVAC drivers (air volumes and pressures), and the risk of building failures. The solution is not to build simpler, less ventilated buildings but it is to insure that the ventilation air is effectively delivered to the space. This means that ventilation must be distributed so that it not only reaches the desired breathing zone but does so in a manner that does not adversely affect the building.

smart air syndrome

Figure 3.6: FSEC graphic on risk of building failures related to building complexity and intensity of HVAC drivers (air volumes and pressures). Source: 1996 Florida Solar Energy Center (FSEC) Study

To be continued…

J. David Odom is a Vice President and Senior Building Forensics Consultant with Liberty Building Forensics Group. He has managed some of the largest and most complex mold and moisture problems in the country, including the $60M construction defect claim at the Hilton Hawaiian Village in Honolulu and the $20M claim at the Martin County courthouse. He has also managed over 500 projects for the Walt Disney Corporation dating back to 1982 that have included technical issues related to corrosion, moisture, and design & construction defect-related problems. He has published numerous manuals and technical articles, including a monograph on moisture and mold for the National Council of Architectural Registration Boards (NCARB). For more information, contact J. David Odom at

With over 35 years of experience, Richard S. Scott is an expert in the areas of architecture, interior design, and building forensics, with a focus on moisture-related building problems. He is certified by both the American Institute of Architects/AIA Florida and the National Council of Architectural Registration Boards (NCARB). He has published over 30 articles, and has lectured or presented at nearly 40 seminars or events. Mr. Scott has developed various training courses, including a 16-hour IAQ training course for NASA and an 8-hour water intrusion prevention training course for the Naval Facilities Engineering Command (NAVFAC). He can be reached at

George H. DuBose, CGC is a certified Florida General Contractor and Vice President with Liberty Building Forensics Group, a firm specializing in moisture intrusion, mold problems, litigation support/buildings forensics, problem-avoidance peer reviews, commissioning, and implementation of green buildings. He has authored numerous articles and co-authored three manuals on moisture-related indoor air quality (IAQ) problems and building commissioning. He has diagnosed and solved hundreds of moisture and mold related building problems worldwide. DuBose can be contacted at