Building Science Practitioners in Hot Humid Climates

FOR IMMEDIATE RELEASE

Contact Information

Wayne Dean

Wayne Dean & Associates

Post Office Box 9078 Naples, FL 34103

Naples, FL 34104

239 272-7375

wayne@portableclassrooms.net

BUILDING SCIENTISTS CAN NOW APPLY FOUR “SECRET” BUILDING SCIENCE PRINCIPLES TO PORTABLE CLASSROOM HEALTH AND DURABILITY ISSUES.

Naples, FL – March 29, 2009  –  School administrators may soon be extolling the advantages of portable classrooms and how portables save scarce taxpayer dollars while providing safe, healthy, comfortable and quick, low-cost classroom space.

Retrofitting both portable and permanent classrooms with a sophisticated, low-cost heating, ventilating and air conditioning system add-on can eliminate teacher and student indoor air quality health and comfort complaints while reducing energy costs by 20-60%. Additional benefits are extension of the useful life of portable classrooms, elimination of most mold-problem remediation and reduction of regular maintenance labor requirements.

A south Florida problem classroom with odor and suspected concealed mold presence was so bad that no teacher would accept an assignment to teach in it. No one knew what to do other than to gut and rebuild. A building scientist offered to demonstrate the correction of all problems by applying new building science principles. Prototype hardware and electronics were assembled for the demonstration and installed. The result? Within 24 hours following completion of the installation, the room presented the most acceptable environment in the entire school building. Afterwards, testing showed that the air conditioner worked less and used nearly $2.00 per day less electricity.

The four secrets?  Pressurize, eliminate unintentional airflows, control humidity and properly ventilate with very clean air.

SECRET 1: Jim Cummings, senior research scientist at the Florida Solar Energy Center, research institute for the University of Central Florida, says that in a hot, humid climate, depressurization of a portable classroom always causes moisture and water vapor to enter the building’s exterior wall cavities.  Once there, moisture causes concealed mold and other microbiological growth.  He further states that simple pressurization of the building most of the time tends to keep the moisture out and to dry the wall cavities.  “Depressurization is very common.  The cause is operation of exhaust fans and air conditioning systems in portable classrooms,” Jim says.  “Because the air pressures that cause serious trouble can be so small, it takes expensive laboratory grade instruments and special training to troubleshoot.  A trained technician with the proper instruments can easily identify potential problems long before the process of decay has developed into serious health and building destruction issues.”

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Wayne Dean of Wayne Dean & Associates, Naples, Florida agrees, and recommends that all portable classrooms be tested immediately upon installation and periodically thereafter. He

advises, “A testing protocol can identify mold-prone portable classrooms in a matter of minutes, long before damage occurs. The defects can then be quickly and permanently corrected.”  Dean strongly recommends that pressurization be done with HEPA filtered outdoor air that is 99.97% free of bacteria, mold spores, pollen, small particulate matter, dust and dirt.

SECRET 2: Almost all portable and permanent classrooms are ventilated at fixed rates, set to bring in a specified amount of hot, humid outdoor air, regardless of the number of students actually in the classroom.  According to Mike Schell, expert on CO₂ controlled ventilation at Air Test Technologies, constantly varying the ventilation rate so as to ventilate only when and to the extent students are present will greatly reduce the moisture load on the air conditioning system to keep the classroom dry and mold-free.  “Use of CO₂ controlled ventilation has proven to reduce the cost of air conditioning and heating of a classroom by as much as 60%,” says Schell.  “Also, CO₂ controlled ventilation can help to keep a portable classroom so dry that mold and bacteria will not grow and insects will leave to look for a better, wetter place to live.” Dean is adamant that classrooms not be over-ventilated which could result in serious high humidity problems. He recommends CO₂ controlled ventilation rather than fixed ventilation in almost all classrooms.

Surprisingly, recent news from the Harvard School of Public Health discloses the existence of another health threat that is estimated to cause about 75,000 deaths in the US annually.  http://www.hsph.harvard.edu/press/releases/press03152006.html . Very small particulate matter, including much from as far away as Africa and the industrial smokestacks of China, are present in the air all over the United States.  Research has shown that these very small particles, which may number 2-20 million particles per cubic foot of air, are inhaled, pass deeply into the lungs, cross over into the blood stream and are transported to the brain and heart, where they can cause serious injury, possibly resulting in death.  “According to the Harvard researchers, the death rate due to very small particulate matter is nearly four times higher than the death rate resulting from exposure to radon gas,” says Dean. “HEPA filtration of ventilation air is a very good idea.”

SECRET 3: Research at the Florida Solar Energy Center has revealed methods of improving an air conditioner’s ability to wring more moisture from air conditioned air.  “It is commonly believed that if indoor relative humidity can be maintained at 50% or less, dust mite, mold, and insect growth may be nearly eliminated, absent unintentional airflows and water leaks,” says Subrato Chandra, PhD, Director, Building America Industrialized Housing Partnership at the Florida Solar Energy Center. http://www.fsec.ucf.edu/bldg/baihp/pubs/mites/index.htm http://www.fsec.ucf.edu/  http://www.fsec.ucf.edu/bldg/baihp/casestud/index.htm  New and simple retrofits to most classroom air conditioners can help them to dehumidify much more powerfully when necessary and to do it automatically says Dean

SECRET 4: According to Joe Lstiburuk, PhD, PE, internationally renowned mold and moisture guru at the Building Science Corporation, Westford, MA, a major factor in portable classroom decay in hot, humid climates is “unintentional airflows.”  These airflows deliver hot, humid outdoor air into wall cavities where the moist air encounters chilled surfaces. Moisture then condenses, and mold and other microbiological growths occur where they cannot be seen.  Lstiburuk says, “Elimination of unintentional airflows is not always easy, but it is very effective in preventing mold growth and decay within wall cavities.”

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According to Wayne Dean, building scientist at Wayne Dean & Associates, Naples, FL, in portable classrooms, the installation of air conditioning systems, especially including wall-mounted units, often results in unintentional airflows within exterior wall cavities.  “A trained technician can map and correct these unintentional airflows quickly and inexpensively with remarkably good results,” says Dean.

According to Dean, new hardware and electronics have been developed and integrated into a system to solve all indoor air quality and moisture problems in portable classrooms.  “Cutting edge systems can correctly pressurize a portable classroom with HEPA filtered ventilation air that will remove 99.97% of even the very small particles.  These systems will also ventilate to respected standards using CO₂ controlled ventilation with little effect on indoor relative humidity,” Dean states, “New electronic controllers can be added to existing air conditioners to increase their ability to dehumidify more powerfully when necessary and do so automatically.”

“Even portable classrooms that have already developed mold and odor problems respond quickly, effectively and permanently to the “Four Secrets,” and they do so at remarkably reasonable costs,” says Dean

Thanks to Building Scientists, portable classrooms can now have a much longer, useful life and deliver healthier environments for students and teachers, while saving taxpayer dollars and preventing mold and other health-related litigation.

Wayne Dean & Associates is a Florida consulting firm which strives to meet the needs of schools by applying building science skills and technology to solve portable and permanent  classroom indoor environment issues quickly, effectively, and economically.

Wayne Dean, Naples, FL, ( 239) 435-0774, w.p.dean@att.net

Jim Cummings, Member ASHRAE, Florida Solar Energy Center, Cocoa, FL  (321) 452-8248 jcummings@cfl.rr.com

Mike Schell, Member ASHRAE, Air Test Technologies, Santa Barbara, CA (805) 687-3175 mike.schell@airtesttechnologies.com

Joe Lstiburek, PhD, P.Eng, Building Science Corporation, Westford, MA, (978) 852-9220,  joe@buildingscience.com

Subrato Chandra, PhD., Project Director Building America Industrialized Housing Partnership, Florida Solar Energy Center of the University of Central Florida, 1679 Clearlake Road Cocoa, FL

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03/16/2010

The USEPA makes recommendations regarding portable classrooms at http://www.epa.gov/iaq/schooldesign/portables.html

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