Indoor Air Quality for Commercial and Industrial Facilities
Updated: Aug 28
Introduction According to a recent American Industrial Hygiene Association membership survey – the world’s largest association of its kind, representing nearly 12,500 occupational and environmental health and safety professionals — indoor air quality (IAQ) is the most serious issue facing today’s American worker. Considering that IAQ is a constantly changing interaction of biological, chemical, and physical factors, it comes as no surprise that in numerous documented cases over the last several years, “sick building syndrome” has been cited as the primary culprit in the shutting down of workplaces for extensive cleanings and renovations, resulting in production and labor-hour losses well into the tens-of-millions of dollars.
Historically, “sick building syndrome” can be traced back to the rise in heating-oil costs during the 1960s-70s energy crises, and the subsequent boom in construction of “airtight” buildings to keep money from escaping up the chimney. Conventional outdoor air infiltration — through open doors, windows, ventilation and air conditioning systems — which had so effectively diluted “normal” indoor contaminants to heretofore safe levels, was suddenly reduced or eliminated by the “airtight” boom. This is especially evident in regards to the larger commercial facilities and light industrial plants built during that period. Typically, a light manufacturing facility has adjacent office space. Certainly energy efficiency and fuel cost savings are a result of such co-joined buildings, but so too are elevated indoor air contaminant levels and increased worker complaints, illnesses, and sick days.
Assessing Building Air Quality
IAQ, or the indoor environment of any building, is the result of a combination of numerous catalysts, including the site, climate, building system (original design, later modifications, and mechanical systems), construction techniques, outdoor air quality, contaminant sources and their strengths (building materials, furnishings, moisture, processes and activities within, and outdoor sources), building occupants, and the design, operation, and maintenance of heating, ventilating, and air conditioning (HVAC) systems.
The sources of indoor air contaminants are numerous:
Contaminated outdoor air
Special use areas
Mixed use buildings
Redecorating or remodeling
Nearby source emissions
Chemicals released from building
Properly assessing and ensuring optimum IAQ is a complex, though not confounding, process. One superior resource guide for conducting a proper investigation, and the subsequent appropriate steps-to-follow, is “Building Air Quality: A Guide for Building Owners and Facility Managers,” available through the U.S. Government Printing Office.
First and foremost, it is necessary to develop an IAQ Profile — a description of the features of the building’s structure, function, and occupancy that impact air quality — to serve as an owner’s manual or reference specific to the building. By collecting and reviewing existing records, conducting a walkthrough inspection of the building, and by compiling detailed data on the HVAC system, pollutant pathways, pollutant sources, and building occupancy, the four Key IAQ Profile Questions will be answered:
How was the building originally intended to function?
Is the building functioning as designed?
What changes in layout and use have occurred since original design and construction?
What changes may be needed to prevent future IAQ problems from developing?
Once completed, the IAQ Profile will help identify potential problem areas and prioritize budgets for maintenance and future modifications.
With a building’s IAQ Profile in hand, an Air Quality Management Plan can be developed and incorporated into routine procedures. Selection of a single individual as IAQ Manager is recommended, with his/her ongoing responsibilities including:
IAQ Profile development.
Overseeing adoption of new procedures.
Establishing occupant communication system regarding IAQ issues.
Coordinating staff efforts affecting IAQ.
Reviewing major projects for IAQ implications.
Reviewing and negotiating with contractors whose routine activities could create IAQ problems.
Periodic inspections for IAQ problem indicators.
Managing IAQ related records.
Responding to IAQ complaints or observations.
Conducting initial walkthrough investigation of IAQ complaints.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) stands out as an industry leader, by evaluating the impact of its member-activities on the environment. ASHRAE’s Ventilation Standard 62-1999 defines
“… ventilation requirements for spaces intended for human occupancy and specifies minimum and recommended ventilation air quantities for the preservation of the occupants’ health, safety, and well-being.”
Note that these recommended ventilation air quantities no longer – revised since the last published version of the standard, 62-1989 – are intended to accommodate a moderate amount of smoking. The harmful effects of environmental tobacco smoke (ETS) have been widely recognized by cognizant authorities. The standard further provides updated information, procedures, and guidelines on establishing and maintaining optimum indoor air quality in the workplace.
Clearly, periodic inspections and assessments of a facility’s ventilation systems operations, maintenance, and practices & procedures, especially those built in the “airtight” building era, cannot be overly stressed. The basic information required to develop and successfully conduct such periodic survey procedures includes a detailed description of the features, functions, and type of HVAC system; the HVAC system mechanical plans and specifications; current HVAC test and balance reports on air distribution and design vs. performance data; and reports of IAQ complaints, including their nature and location. In the end, two ventilation factors are of paramount importance to proper IAQ — adequate outdoor air quantities for diluting “normal” indoor airborne pollutants, and the ability to effectively furnish supply air to occupied areas. Yet only through regular monitoring and component surveys can a system be properly repaired, rearranged, modified, re-adjusted, or finetuned for optimum IAQ health and improved energy efficiency.
Because of the increasing correlation between the shared-air of commercial office environments and that of their adjoining light industrial/manufacturing plants, the approach to IAQ becomes even more complex and critical. Factors such as the wide variety of prevalent chemicals and the necessity for local exhaust ventilation to remove contaminants are of primary importance.
Manufacturing (process) equipment requires well designed and enclosed local exhaust ventilation to properly capture contaminants using the least air flow. The local exhaust air flow should be matched with an equal amount of tempered make-up air to ensure ventilation system operational efficiency. The exhaust and make-up air systems should be operated to maintain a slight negative pressure in the manufacturing plant relative to the office environment. This balance will help avoid air being drawn into and contaminating the office environment through doors, ceiling plenums, cracks, and other leakage points.
Another key factor to consider is the proximity of the exhaust stacks to outside air intakes. These should be positioned to minimize the chances of contaminated exhaust air being drawn into the outside air intakes of the office HVAC systems. Any modifications to either the office or manufacturing facilities, no matter how slight, must carefully consider subsequent ventilation system modifications, so as to guard against negative consequences to the air balances.
In addition to the air contaminants and IAQ indicators for commercial office spaces (temperature, humidity, airflow, asbestos, carbon dioxide, carbon monoxide, formaldehyde, lead, nitrogen dioxide, ozone, particulates, radon, and sulphur dioxide), the indoor air in an industrial facility will be affected by the chemicals and processes unique to that environment. The ventilation guidelines provided in ASHRAE Standard 62-1999 are for commercial, institutional and residential facilities. Ventilation in industrial facilities requires many additional considerations related to the chemicals in use in the industrial processes. The Industrial Ventilation Manual published by the American Conference of Governmental Industrial Hygienists (ACGIH) provides ventilation design procedures specific to numerous industrial operations.
Minimizing worker exposure to the chemicals that are present in industrial facilities is regulated by the Occupational Safety and Health Administration (OSHA). Maintaining exposures below the regulated levels (Threshold Limit Values, as published by the ACGIH and Permissible Exposure Limits, as established by OSHA) may not eliminate all unpleasant smells and mild irritation. In cases where air from the manufacturing area is allowed to enter the office area, IAQ problems may arise, even if the manufacturing area is in full compliance with the OSHA worker exposure levels.
Innovations in IAQ
Providing the 15-20 cubic feet per minute (cfm) of outside air per occupant as recommended in ASHRAE 62-1999 is not always straightforward, particularly with variable air volume (VAV) HVAC systems. Occupancy variability, such as in conference rooms, causes additional difficulty in meeting the ASHRAE outside air standard.
Dedicated outdoor air systems are a recent innovation which may prove to be an efficient means for providing the recommended outdoor air quantities at comfortable temperatures and humidities for building occupants. In a recent article in Engineered Systems, it was estimated that from 20% to 70% more outdoor air is required for a VAV system than for a dedicated outdoor air system to meet the ASHRAE 62-1999 recommended quantities.
Along with providing sufficient outdoor air for building occupants, another effective means for improving IAQ is to provide effective filtration of the supply air. There are a wide variety of air filters for particulate removal on the market, and several factors are important to consider in the choice of filters when retrofitting an existing HVAC system or constructing a new system, including:
Pressure drop across the filter
Removal efficiency of the filter for various ranges of particle size
Maintenance interval and expected filter life
Ease of access for filter cleaning and changing
Alternatives to paper or cloth filters, such as electrostatic precipitators and electronic filters
Is filtration of gases through carbon adsorption desired?
In 1999, ASHRAE published a major revision to its standard for testing air-cleaning devices. ANSI/ASHRAE Standard 52.2-1999 – “Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size” provides an accurate method for rating filters for their ability to remove particles of various size ranges from an air stream. Filters can now be rated by their Minimum Efficiency Reporting Value (MERV), which is a single numerical value from 1 through 20. The MERV is a way of summarizing the removal efficiency vs. particle size tests of an air cleaner as it is loaded with dust. The following table, adapted from Table E-1 in Standard 52.2-1999, provides some application guidelines for filters of various MERV values.
Whether outdoor or recirculated air, it is vital that all ventilation supply air be passed through a filter. The proper selection of filtration products and the implementation of a routine maintenance program — the cleaning of reusables or the replacement of damaged filters, both pre- and final — is a necessary prerequisite for optimum IAQ.
Achieving and maintaining adequately healthy Indoor Air Quality is an ongoing process of complex issues, considerations, and challenges, including:
sources of contaminants
HVAC system design and operation
building occupancy factors
IAQ Profiling, Diagnosis, and Management Planning
hiring professional assistance as needed
When renovating or building new facilities, always consider IAQ — and the newest ventilation and filtration technologies and guidelines — in the design. And remember, Indoor Air Quality is a progressive process that can only yield optimum health, fiscal, and production benefits with the establishment of a comprehensive and continuing Preventative Maintenance Program.
References 1. Building Air Quality: A Guide for Building Owners and Facility Managers. U.S. Environmental Protection Agency. 1991.
2. ASHRAE 62-1999, Ventilation for Acceptable Indoor Air Quality. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA. 1999.
3. ANSI/ASHRAE 52.2-1999, Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size. American Society of Heating, Refrigerating and Air- Conditioning Engineers, Inc., Atlanta, GA. 1999.
4. Mumma, S.A. Fresh Thinking: Dedicated Outdoor Air Systems. Engineered Systems, Troy, MI. Vol. 18 No. 5, May 2001.
5. Industrial Ventilation: A Manual of Recommended Practice, 23rd Edition. American Conference of Governmental Industrial Hygienists, Cincinnati, OH. 1998.
Tom Petersen of EES at (215) 704-1506 or email@example.com