Indoor Air Quality in Schools

A 1995 report by the US General Accounting Office (GAO) to members of Congress on the condition of public schools provides data on "the overall physical condition and prevalence of schools that need major repairs."  The report is based on estimates given by school officials in a national sample from over 5,000 school districts. It notes that half of all schools surveyed reported at least one unsatisfactory environmental condition involving ventilation, heating, lighting or physical security, most of these schools having multiple problems. This GAO study and a number of others have identified classroom ventilation and indoor air quality as major concerns

The U.S. Environmental Protection Agency (EPA) studies of human exposure to air pollutants indicate that indoor levels of pollutants may be two to five times -- and occasionally more than 100 times -- higher than outdoor levels. These levels of indoor air pollutants are of great concern in school buildings where our children, their teachers and administrators spend about 90 percent of their time indoors. Good indoor air quality (IAQ) management includes:

  • Control of airborne pollutants;
  • Introduction and distribution of adequate outdoor air; and
  • Maintenance of acceptable temperature and relative humidity.
  • Outdoor sources should also be considered since outdoor air enters school buildings through windows, doors, and ventilation systems. Thus, transportation and grounds maintenance activities become factors that affect indoor pollutant levels as well as outdoor air quality on school grounds.

Project Description

Large Scale Study of Indoor Air Quality Problems in Schools and Classrooms and Retrofit Benefits -- The Florida Solar Energy Center (FSEC) conducted a three-part project to investigate indoor air quality problems in eight schools located in Florida, Minnesota, New York, Oregon, Texas and Washington. The project consisted of

  1. a nationwide, web-based survey designed to determine the levels of occupant satisfaction or dissatisfaction with the IAQ, thermal, lighting and acoustical conditions in schools and classrooms;
  2. characterization of actual operating conditions of schools and classrooms through field audits and diagnostic tests and measurements; and
  3. conduct of retrofits in problem schools and classrooms to alleviate problems.

Survey Results

Based on 239 total respondents, temperature was indicated by far as the greatest comfort complaint in regular classrooms, with 50.5% of respondents indicating many or chronic problems. Indoor air quality (IAQ) and then humidity were the next greatest areas of complaints in regular classrooms, with 20.4% and 13.1% of respondents indicating many or chronic complaints in these categories respectively.


Percent of respondents indicating chronic problems by category


Based on the results of the web-based survey, eight schools were identified for comfort conditions audits.

Comfort Conditions Audits

Conditions audits were conducted in a total of eight schools located in Florida, Minnesota, New York, Oregon, Texas, and Washington. The audits typically included zone pressure mapping, ventilation tests, sampling and monitoring of indoor temperatures, CO2 levels and relative humidity (RH), and in some cases, a blower door building air tightness test.

Significant ventilation problems were present in each of the eight audited schools. These problems occurred due to a combination of factors including lack of maintenance, lack of knowledge of the systems and in some cases poor system design. It also appears that since ventilation air problems are not easily identified unless comfort or other conditions issues arise, they typically go unresolved. In cases where a problem has been detected, a solution may be provided that does not resolve the root problem(s). Bathroom and other exhaust fan problems were also a common find in the audits where the fans were either non-functional or inadequate.

The audits also found high RH levels (60-70%) and several instances of low classroom temperatures (70oF and lower) in the hot-humid climate schools. Portable dehumidifier "band aids" were commonly in use in these classrooms to help control RH levels.

Retrofit Results

A total of four retrofit projects were completed at audited elementary schools: two in Florida, one in Oregon, and one in Washington State.

Lessons Learned

  • School conditions improvements are possible. The limited results from project retrofits indicate that conditions problems can be successfully diagnosed and solved.
  • Schools must have real incentive(s) to participate.
  • Schools must employ on-site experienced maintenance personnel knowledgeable in the buildings' diverse and unique systems.
  • A qualified energy analyst must be paid to supervise all work. From initial testing to verification of retrofit effectiveness, a knowledgeable professional needs to initiate, closely follow and verify all project steps.
  • Schools in humid climates need to be designed with separate means of treating outside air.
  • Relatively minor changes/improvements can offer big improvements in indoor air quality.