Secondary Author(s)

Shirey III, Don B.; Withers Jr., Charles; Raustad, Richard; Moyer, Neil

Report Number




Air Flow; HVAC; Commercial; Buildings


Twenty commercial and institutional buildings located in central Florida were tested for uncontrolled air flow and cooling system problems. Tested buildings were selected based on three criteria; 1) buildings with large exhaust fans, 2) buildings with leaky ceilings, and 3) education buildings. They ranged in size from a 650 square foot portable classroom to a 50,000 square foot elementary school, with an average floor area of 6518 square feet.

Diagnostic inspection and testing was performed in each building to identify problems related to uncontrolled air flow or HVAC system or control problems. The tests were performed to characterize or identify building airtightness, HVAC flow rates, building ventilation, air flow and pressure imbalances, cooling system performance, and HVAC control strategy. Short-term monitoring (typically for a week or two) of indoor parameters such as temperature, relative humidity, ceiling space temperature, carbon dioxide levels, and indoor pressure was implemented in seven buildings. After testing and inspection (and in some buildings short-term monitoring), a report was written for each building summarizing test results and presenting recommendations for correcting any deficiencies. These reports are found in Appendix B.

Following testing, a variety of retrofits were performed on six buildings. Improvements in cooling energy use and indoor temperature/humidity control resulting from the repairs were monitored. One or more retrofits were implemented in each building. Depending upon the match between cooling load and cooling capacity, some retrofits reduced cooling energy use, others reduced only indoor temperatures (toward greater comfort), and others reduced both cooling energy use and indoor temperature. In one of the six buildings, monitoring was begun and the first retrofit (cooling system tune-up) implemented when the facility changed ownership. As a result of major renovations performed by the new owner which greatly changed the thermal characteristics of both the building and the HVAC systems, this monitoring effort was abandoned because there would be no opportunity to identify the change in energy use resulting only from the retrofits implemented in this project.

A variety of retrofits were implemented, including application of a foam insulation material to both tighten the building and improve the thermal barrier (four buildings), change the color of roof and exterior walls to white (one building), correct unbalanced return air problems (one building), reduce the number of hours of cooling system operation (one building), repair duct leaks (one building), addition of make-up air (one building), service (tune up) the cooling systems to bring refrigerant charge and air flows into design specification (two buildings), and install a dedicated outdoor air preconditioningsystem for improved humidity control (one building).

Date Published



Buildings - Air Flow; Buildings - Commercial; Buildings - HVAC



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