205 Indoor Air Quality Iaq Standards1

Indoor Air Quality (IAQ) is an emerging issue of concern to building managers, operators, and designers. Recent research has shown that indoor air is often less clean than outdoor air and federal legislation has been proposed to establish programs to deal with this issue on a national level. This, like the asbestos issue, will have an impact on building design and operations. Americans today spend long hours inside buildings, and building operators, managers and designers must be aware of potential IAQ problems and how they can be avoided.

IAQ problems, sometimes termed "Sick Building Syndrome," have become an acknowledged health and comfort problem. Buildings are characterized as sick when occupants complain of acute symptoms such as headache, eye, nose and throat irritation, dizziness, nausea, sensitivity to odors and difficulty in concentrating. The complaints may become more clinically defined so that an occupant may develop an actual building-related illness that is believed to be related to IAQ problems.

The most effective means to deal with an IAQ problem is to remove or minimize the pollutant source, when feasible. If not, dilution and filtration may be effective.

Dilution (increased ventilation) is to admit more outside air to the building, ASHRAE's 1981 standard recommended 5 CFM/person outside air in an office environment. The new ASHRAE ventilation standard, 62-1989, now requires 20 CFM/person for offices if the prescriptive approach is used. Incidentally, it was the energy cost of treating outside air that led to the 1981 standard. The superseded 1973 standard recommended 15-25 CFM/person.

■^Source: Indoor Air Quality: Problems & Cures, M. Black & W. Robertson, Presented at 13th World Energy Engineering Congress.

Increased ventilation will have an impact on building energy consumption However, this cost need not be severe. If an airside economizer cycle is employed and the HVAC system is controlled to respond to IAQ loads as well as thermal loads, 20 CFM/person need not be adhered to and the economizer hours will help attain air quality goals with energy savings at the same time.

In the fall of 1999 ASHRAE Standard 62-1999 was issued, "Ventilation for Acceptable Indoor Air Quality." The new standard contained the entire 1989 version, which remains unchanged, along with four new addenda. The reference in the 89 standard that the ventilation levels could accommodate a moderate amount of smoking was removed, due to troubles with secondhand tobacco smoke. The new standard also removed reference to thermal comfort, which is covered by other ASHRAE Standards. Attempts were made to clarify the confusion concerning how carbon dioxide can be used to determine air contamination. A statement was also added to assure that designers understand that merely following the prescribed ventilation rates does not ensure acceptable indoor air quality. The Standard was added to the continuous review process, which will mandate firms keep up with the perpetual changes, corrections and clarifications. There are many issues that are still under review as addendums to the standard. The types of buildings that are covered were limited to commercial and institutional, and the methods of calculation of the occupancy levels have been clarified. ASHRAE offers a subscription service that updates all addendum and interpretations. One of the main issues that should be considered during design of HVAC systems is that the outdoor air ventilation is required to be delivered cfm, which may be impacted with new variable volume air handling systems.

Energy savings can be realized by the use of improved filtration in lieu of the prescriptive 20 CFM/ person approach. Improved filtration can occur at the air handler, in the supply and return ductwork, or in the spaces via self-contained units. Improved filtration can include enhancements such as ionization devices to neutralize airborne biological matter and to electrically charge fine particles, causing them to agglomerate and be more easily filtered.

The Occupational Safety and Health Administration (OSHA) announced a proposed rule on March 25, 1994 that would regulate indoor air quality (IAQ) in workplaces across the nation. The proposed rule addresses all indoor contaminants but a significant step would ban all smoking in the workplace or restrict it to specially designed lounges exhausted directly to the outside. The smoking rule would apply to all workplaces while the IAQ provisions would impact "non-industrial" indoor facilities.

There is growing consensus that the most promising way to achieve good indoor air quality is through contaminant source control. Source control is more cost effective than trying to remove a contaminant once it has disseminated into the environment. Source control options include chemical substitution or product reformulating, product substitution, product encapsulation, banning some substances or implementing material emission standards. Source control methods except emission standards are incorporated in the proposed rule.

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