Mold in schools is getting a lot of attention at local, state, and federal levels - and it's getting expensive. For example, in 2002, the Austin (TX) School District estimated it would spend a minimum of $12 million on mold cleanup in eight schools over three years.

Indeed, the problems are widespread and expensive. A solution that controls humidity without increasing energy costs is ideal.

School Problem

Wide variations in temperatures and humidity levels in South Texas make it difficult to maintain internal atmospheric conditions to minimize the formation of mold or mildew.

At Pharr-San Juan-Alamo School District's Memorial High School, mold grew on ceilings, walls, equipment, and books. Students and staff complained of allergic reactions, respiratory infections and, in some cases, neurological responses to the poor air quality. On two separate occasions, students staged a walkout to protest the conditions.

As with many schools, the IAQ at the three-year-old school was poor due to high ventilation and people loads in classrooms, high intermittent ventilation loads, carryover from showers in gyms and locker rooms, and long periods where the building was unoccupied. Small roof and window leaks were a minor issue in the scheme of things. Most importantly, unconditioned and uncontrolled hot, humid outside air from ventilation and infiltration had brought in so much moisture, the building had reached a saturation point, and mold proliferated.

Desks and floors were wet; humidity inside the building ranged between 80% and 90%.

"We had a lot of complaints from teachers and from staff and from students - some staff and students were becoming ill," said Arturo Guajardo, superintendent of PSJA School District.

The school district filed a lawsuit with the builder, which was settled for more than $22 million.


The district contracted Assured Indoor Air Quality (AIAQ) to identify the problem, cut off the source of moisture, and clean up the mold.

The main source of humidity was outside air drawn into the building. AIAQ brought in Munters to begin supplying dry air to the building via temporary dessicant dryers. While the mold was removed and some materials replaced, the company designed a permanent system using Munters dessicant dehumidifiers.

The permanent drying equipment conditions outside air efficiently and pressurizes the building to keep humid air from being drawn inside.


Over a three-month period, the dessicant dehumidification system dried the building. Today, the school is kept at 45% rh and 75°F. Hourly operating costs have decreased 50%.

"Two previous studies offered solutions that didn't address the source of the problem," said Bill Holder, senior vice president of AIAQ. "The most effective way to control a high-humidity environment is to employ dessicant dehumidifiers."AMCA