Indoor Air Quality and Ventilation

50% of sick building problems are ventilation related

In the ongoing NIOSH, National Institute for Occupational Safety and Health’s investigation of "sick buildings", the percentage of problems attributable to inadequate ventilation continues at 50% - far greater than any other cause.

Current best available information from the broadly accepted Mendell review study relating ventilation rate to problem buildings indicates that rates above 20 cubic feet per minute (cfm) per person are generally successful, while rates below 15 cfm per person are increasingly problematic.

Although rates under 15 cfm per person are less than Ontario Building Code minimums, it is not uncommon for buildings to operate below current code requirements.

Buildings constructed in accordance with ASHRAE 62 ventilation standards prior to the 1989 version were required to meet ventilation rates of only 5 cfm per person, one-third of current standards. In some cases, building use has changed making original design ventilation rates inadequate.

Although higher ventilation rates usually improve indoor air quality, it should be noted that there are some exceptions, mainly in rare cases where outdoor air pollution is very high or the supply air intake is near a source of contaminants.