INTRODUCTION

HVAC technicians are not medical doctors or indus-trial hygienists. However, it is estimated that over80% of IAQ-related problems could be remedied byimproving the design or maintenance program ofHVAC systems. The conclusion is obvious—in manycases, a trained HVAC technician can improve theIAQ of a building or facility.

An HVAC system serves as a distribution network forproperly conditioned and filtered air in a building. Thesame system can serve as a path—and sometimes asource—for airborne pollutants. The contaminantscan and do affect the health and productivity of thebuilding’s occupants.

In the past, most of the instruction that a HVAC tech-nician received revolved around the mechanical, pip-ing, and electrical aspects of installing and servicingequipment. Environmental concerns were rarely dis-cussed. Today the environmental aspects of HVACsystems are becoming much more important, andcannot be ignored.

Outbreaks of Legionnaire’s disease have beentraced to air conditioning systems. There are newsreports about buildings that make their tenants sick.Individual homes are linked to increases in allergiesand asthma. Can this happen to your home, or to thebuilding that you service? What can you do to preventit or correct it?

Growing concerns about indoor air quality presentHVAC technicians and contractors with increasedopportunities. Knowledgeable HVAC professionalscan assist building owners and managers in solvingproblems and avoiding the expensive repairs andhigh legal costs associated with poor indoor air qual-ity. (Indoor air quality, or IAQ, is also referred to asindoor environmental quality, or IEQ.)

Indoor air quality in earlier times

Anthropologists and forensic scientists know thatprimitive humans who lived in caves often sufferedfrom poor IAQ. Smoke inhalation, dampness, andgenerally unsanitary conditions, combined with apoor diet, led to respiratory problems and arthritis.Smoke was also a problem in the Native Americantepee. The tepee actually had a ventilation systemthat worked reasonably well. However, the Indianswho lived in tepees had the same problem that wehave today, especially during the winter. When weincrease ventilation, we pay an energy price. Theyalso had to put up with cold drafts. Interestingly, somewinter camping sites were recently studied and com-bustion air tunnels were found that led from outsidethe tepee to its center, where the fire was located.Today, of course, heat wheels or heat tubes serve asheat exchangers and help reduce the energy penal-ties associated with using outside air. Some claim80% efficiency rates.

Indoor air quality in recent times

Before the energy crunch in the early 1970s, indoorair quality wasn’t as much of a problem as it is now.At that time, buildings were not as “tight” as they aretoday, and the cost of bringing in outside air was nota significant factor. In many cases, the quality of theoutside air was also better. In the mid-1970s, how-ever, operating and maintenance costs for commer-cial buildings escalated rapidly, largely because ofrising fuel prices and higher utility rates. Contractorsbegan to construct “tighter” buildings and addedmore insulation. A house built prior to the 1970s mayhave had one or two “natural” air changes per hour. Anew house today may have one-tenth of an airchange per hour.

Most people are aware that outdoor air pollution candamage their health, but may not know that indoor air

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Refrigeration ServiceEngineers Society1666 Rand RoadDes Plaines, Illinois 60016

FUNDAMENTALS OF INDOOR AIR QUALITY

Frank Prah, CMS

© 2002 by the Refrigeration Service Engineers Society, Des Plaines, ILSupplement to the Refrigeration Service Engineers Society.

630-135Section 17A

pollution can also have significant effects. EPA stud-ies of human exposure to air pollutants indicate thatindoor air levels of many pollutants may be 2 to 5times—and in some cases more than 100 times—higher than outdoor levels. High levels of indoor airpollutants are of particular concern in our societytoday because most people spend more time insidethan outside. In fact, it is estimated that many of usspend more than 90% of our time indoors (includingtime spent at home, at work, in the car, shopping,etc.). Despite the fact that most people spend moretime in their homes than at work, the majority of IAQcomplaints originate in the workplace.

Over the past several decades, our exposure toindoor air pollutants is believed to have increaseddue to a variety of factors, among them the construc-tion of more tightly sealed buildings, reduced ventila-tion rates (widely practiced as a means of savingenergy), the use of synthetic building materials andfurnishings, and the prevalence of chemically formu-lated personal care products, pesticides, and house-hold cleaners. In recent years, comparative riskstudies performed by the EPA and its Science Advi-sory Board (SAB) have consistently ranked indoor airpollution among the top five environmental risks topublic health.

IAQ problems in schools1

U.S. government studies have shown that one in fiveschools has IAQ problems, but they are problemsthat can be improved through the use of activehumidity control and continuous ventilation. Morethan 8 million students are affected by IAQ problems,according to government research outlined in an arti-cle in IAQ Applications, published by ASHRAE(American Society of Heating, Refrigeration and Air-Conditioning Engineers). Problems can includedrowsiness, lack of concentration, and headaches,all of which affect the student’s comprehension andmotivation.

Dr. Charlene Bayer, of Georgia Tech Research Insti-tute, says that IAQ should be a top priority becausechildren, who are still developing physically, are morelikely to suffer due to indoor pollutants. In addition,the number of children with asthma has increased49% since 1982. It is estimated that one child in fivehas asthma.

IAQ problems may stem from the fact that schooladministration and maintenance personnel do notunderstand how to operate ventilation systems, andfrom the introduction of contaminants, such as plug-in chemical deodorizers and art supplies, into class-rooms.

SICK BUILDING SYNDROME2

The term “sick building syndrome” surfaced in the1970s when, to conserve energy, many naturally ven-tilated homes, schools, and offices were replacedwith tightly sealed, air conditioned buildings. Insula-tion, treated wood, volatile adhesives, and syntheticfabrics, furnishings, and carpets were often incorpo-rated into these buildings. Especially when new,many of these products release low levels of poten-tially harmful chemicals, such as formaldehyde, intothe recycled air. Carpets can add to the problem byabsorbing various cleaners and solvents and thenreleasing them over a long period of time.

A book entitled Chemical Exposures: Low Levelsand High Stakes states that “vapors from various sol-vents are the most prevalent of indoor air contami-nants,” and goes on to point out that “solvents areamong the chemicals most frequently implicated bychemically sensitive patients.” Many people like thesmell known as “new car smell,” produced by thevolatile organic compounds (VOCs) found in newcars. But many of the same materials—upholstery,adhesives, carpeting, and other such outgassingcomponents—are found in so-called “sick” buildings.

While most people seem to be able to cope with theenvironment inside such buildings, some developsymptoms ranging from headaches and lethargy toasthma and other respiratory tract problems. Thesesymptoms generally disappear when the affectedpeople leave the environment. But the British medicaljournal The Lancet notes that in some cases,“patients may develop multiple chemical sensitivi-ties.” Why do some individuals get sick from chemi-cals while others do not? This is an importantquestion, not least because those who seem to beunaffected may find it difficult to be understanding ofthose who become ill.

As noted previously, many building owners and man-agers responded to the increased energy and utility

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costs of the 1970s by reducing outside air, and bymaking their buildings tighter with weatherstripping.To make matters worse, maintenance personnelsometimes were cut to help pay for the additionalenergy costs. Even today, some buildings arewrapped with plastic over the outside walls. Manybuildings have no provision at all for outside air. Insome strip malls, you can see rooftop units withouteconomizers. A building of this type depends onopening and closing the front door for ventilation.

All of these conditions create an indoor environmentin many buildings where fresh air is virtually nonexis-tent. The air is recirculated along with cigarettesmoke and other pollutants. In some cases, bacteria,fungi, and germs grow in the duct system and spreadthroughout the entire building. There have beenextreme instances of “sick” buildings that could notbe cleaned up economically, and had to be torn downcompletely (at great cost, because of the biohazardsinvolved). Both commercial and residential buildingshave been demolished with severe infestations ofblack mold.

Symptoms of poor indoor air quality

So what is sick building syndrome? Sick building syn-drome (SBS), sometimes also known in the U.S. as“tight building syndrome,” refers to those short-termreversible health symptoms that are associated withthe occupancy of a specific building. SBS existswhen a significant percentage (e.g., more than 20%)of the occupants complain during a two-week periodof a set of health-related symptoms. Those symp-toms may include headaches, skin or eye irritation,hay fever-like symptoms, dizziness, nausea, asthma,sinusitis, allergies, and various upper respiratorytract infections.

In addition to health problems (even life-threateningones like Legionnaire’s disease and carbon monox-ide poisoning), indoor air pollution can have otherundesirable effects:

ª reduced productivity due to physical discomfortor employee absenteeism

ª deterioration of furnishings or equipment

ª strained relations between people

ª low occupancy of rental space

ª lawsuits.

If you service a building with SBS, what shouldyou do?

Attempting to correct IAQ problems without under-standing the cause of the problems can be ineffec-tive, expensive, and legally catastrophic. However,there are things that a capable HVAC technician cando when SBS is suspected:

ª First, ensure that there is sufficient ventilation inoccupied spaces. Measure and record air flowrates.

ª Ensure that the HVAC system is clean and freefrom chemical or biological contaminants.

ª Identify potential sources of contaminants, suchas building exhausts, internal combustionexhaust, condensate pans, rodents, etc.

ª If possible, eliminate all potential sources of theproblem, and continue to monitor.

ª Consider installing a UV (ultraviolet) light nearthe outlet of the evaporator coil (or, in somecases, on both sides of the evaporator).

ª Obtain professional help if complaints persist.

HUMIDIFICATION

There are probably more humidifiers in homes thanin commercial office spaces. The benefits to thehomeowner are well known—a reduction in heatingcosts, infections, and illnesses. Humidifiers also pro-tect wooden furniture from drying out and helpreduce static electricity.

ASHRAE has published statistics that support theidea that humidity levels affect health. When humiditydrops below the optimum level of 50%, people aremore susceptible to respiratory infections, viruses,and bacteria. When the relative humidity drops belowthe 40% level, more employees become sick andmiss work. When humidification is installed in winter,complaints are reduced by 95%.

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ASHRAE researchers believe that humidification is “ahealth and safety issue, and a main component ofindoor air quality…An overwhelming amount of med-ical research indicates that humidification is benefi-cial for health as well as comfort reasons.”3 Aprominent U.S. scientist, Dr. Charles S. Sale, con-cluded that humidity control was found to reduce res-piratory illnesses, especially in winter, and assistallergy sufferers. As the result of three studies, Saleconcluded: “The survival of airborne bacteria andviruses increases as the relative humidity falls belowabout 50%.”

AIR FILTERS

Air filters are important IAQ tools, but they are fre-quently overlooked and misunderstood. They are theprimary defense for building occupants and HVACequipment against particular pollutants. Yet moretime is typically spent selecting and specifying wallfinishes than HVAC system air filters.

As a result, the people who specify which filters areto be used in a building often tend to use the samefilter designs and specifications that they have usedin the past, giving little or no consideration to theirimpact on building IAQ. Similarly, many building man-agers select replacement filters based primarily ontheir initial cost, not on the needs of the facility.

This problem has been compounded by the lack of auniform standard for rating filter efficiency. A recentlydeveloped standard, ASHRAE 52.2-1999, Method ofTesting General Ventilation Air Cleaning Devices forRemoval Efficiency by Particle Size, is designed tohelp eliminate confusion and make it easier to matchfilters to facility needs.

Regularly replacing the air filters in a building is animportant part in maintaining indoor air quality. Thesignificance of proper air filtration is easy to overlook,since it is estimated that 99% of all airborne contam-inants are invisible to the human eye (below 10microns). But air filtration can be one of the simplestaspects of a regular preventive maintenance pro-gram. After all, an entry-level custodian is capable ofremoving a dirty filter and replacing it with a new oneevery three or four months. Today, with an ever-increasing emphasis on improving health by reducingexposure to second-hand smoke and other airborne

contaminants, air filtration has taken on a new levelof importance in the overall HVAC maintenance ofcommercial buildings.

Know how your filters are rated. The arrestancemethod, for example, is more concerned with largerparticles, while the dust spot method is used forsmaller particles. (A 70% filtration rate using thearrestance method could be equivalent to just 3%using the dust spot method.) Exercise caution as youretrofit, because as you increase filter media effi-ciency you also increase restriction to air flow. Inaddition, be aware that filters do not filter outgases,although you can install charcoal and other types offilters that will absorb certain gases.

Terminal air filtration

Terminal air filtration is not a new idea. It is a methodof controlling the environment in specific areas of abuilding. In addition to the means of filtration used atthe air-handling unit, extra filters are installed at theterminal units throughout the building. Even whenbeing extremely careful, a technician may jar loosesome dirt or debris, and pollutants can find their waydown the ducts and into the occupied space. Thechances of this happening are reduced by terminalair filtration.

DILUTION VENTILATION

It has been said that “dilution is the solution to pollu-tion.” In most cases, bringing in outside air (“freshair”) will reduce the concentration of contaminants.One problem, however, is that the greater the con-centration of contaminants in the outside air, themore ventilation is required. And when more outsideair is used for ventilation, energy consumptionincreases.

Ventilation is critical in meeting code requirements forair changes. But how does ventilation affect IAQ? It’strue that adequate ventilation dilutes polluted air bypressurizing the building and forcing the contami-nants outside. However, if the outside air is contami-nated, pollutants also can enter a building throughthe ventilation system.

A case in point: The occupants of a building com-plained that every afternoon around 3:00 p.m., the

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quality of the air in the building became very bad.However, the symptoms went away in the summer.The source of the problem wasn’t difficult to find. Thebuilding was near a school, and every day during theschool year the diesel buses lined up outside to takethe students home around 3:00 p.m. The prevailingwinds pushed the exhaust from the buses toward the“fresh air” intakes of the building.The fresh air intakeshad to be moved to a more favorable location.

When commissioning a new building, some contrac-tors say that “cooking” the building for a few daysbefore occupancy will reduce the VOCs. “Cooking”means to elevate the temperature to around 90°F,and ventilate with maximum outside air.

CARBON DIOXIDE

One way to determine if meaningful ventilation is tak-ing place is to sample carbon dioxide (CO2) levels.Today’s CO2 meters are becoming more accurateand less expensive. New hand-held equipment canquickly and reliably measure the amount of CO2 inany space in a building. High levels of CO2, whichindicate low levels of fresh air, can cause nausea,headaches, and dizziness. Outside air has a normalCO2 level of 350 ppm (parts per million). Adults usu-ally can tolerate CO2 concentrations of 1,000 ppm(parts per million), and children usually can tolerate500 ppm. Outside air dampers should open to allowenough air to enter a building to keep the CO2 levelbelow 1,000 ppm.

The DCV (Demand Control Ventilation) system usesCO2 sensors tied to the outside air damper. Thismeans that the amount of fresh air is controlled bythe amount of CO2 in the building. The result cansave significant energy dollars. Table 1 below showsestimated DCV energy savings.

Proven energy savings with DCV retrofits have beenthe principal driver behind installing CO2-based venti-lation systems. But a critical criterion for the successof any new technology is how easily it can be inte-grated into existing systems.4 Today virtually all majorbuilding control and HVAC equipment manufacturersoffer CO2 sensors to complement their product offer-ings. “Plug-and-play” simplicity is offered for control ofall types of equipment, including economizers, rooftopsystems, and DDC (direct digital control) systems.

As this technology has developed, so have codesand standards. For the last four years, the Interna-tional Mechanical Code (IMC), the mechanical codeof reference for most local building code bodies, hasincluded provisions for CO2-based DCV. In the pastthree years, ASHRAE Standard 62 has clarified theuse of CO2 as a parameter that can be used for con-trolling ventilation based on actual real-time occu-pancy while still maintaining target cfm-per-personventilation rates.

CO2 regulations in Canada

In the Canadian province of British Columbia, aunique partnership between government and com-mercial building owners has established not-to-exceed levels of CO2 as part of a comprehensivehealth and safety standard for office workers(Province of British Columbia, 1998, Regulations forOccupational Health and Safety, Section 4.73–4.81).

FUNGI

Mushrooms are grown underground, and all that’srequired are water, soil, moderate temperatures, air,and seed. All of the same components are present inan air handler. There is a wet coil and a drain pan.There is dirt from dust on the coils, there are sporesarriving in the outside airstream, and there are mod-erate temperatures. No, you won’t find mushrooms inan air handler, but bacteria and fungi can and dogrow in such an environment. It takes only a few daysfor a colony of spores to grow. The more humid theclimate, the worse the condition that you mightencounter.

In the warm, humid environment of southern Texas,for example, mold and mildew have proved to be a

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Air conditioning Heating

Home 10% 28%

Store 17% 93%

Restaurant 16% 92%

School 10% 76%

Table 1. DCV energy savings

HO

NE

YW

ELL

INC

.

persistent problem in school buildings.5 Outbreaks offungus have been reported in many schools in theregion, and have even resulted in closures. In oneschool, a very aggressive maintenance program wasmanaging to keep mold in check. But remedial mea-sures showed no sign of eradicating mold andmildew problems until the air handlers were outfittedwith high-output HVAC-style UVC (ultraviolet light inthe “C” band) lights. These devices helped solve acostly maintenance problem and delivered unantici-pated energy and operational savings. Cooling costswere reduced by 9%.

Evaporator coil cleaning

Although a UV light can reduce fungi growth and helpkeep the evaporator coil clean, contractors occasion-ally have had to replace the evaporator coil com-pletely once a fungi infestation gets started. Attemptsto kill the growth with chemicals have failed in somecases, and even steam cleaning the coils hasn’tworked. Experienced technicians sometimes say thatthe most dangerous part of any duct system is thefirst 10 ft, beginning at the evaporator coil. Why isevaporator coil cleaning so important?

Simply put, keeping coils clean is a major way of pre-venting IAQ problems.6 Restricted air flow preventsproper operation and shortens equipment life. Bacte-ria and fungi growing in coils are blown into theairstream and carried to the conditioned space, trig-gering occupants’ allergies and causing other prob-lems. All air conditioning equipment, refrigerators,dehumidifiers, and cooling towers have the potentialto develop bacteria growth, mold, fungi, and mildew.A comprehensive maintenance program is a must inmodern buildings. The dark, wet, cool recesses of anair conditioner and its condensate drain pan are idealsites for microorganisms to colonize and breed. Anydust that gets through the filter is likely to impinge onthe wet evaporator coil. The coil acts as an air filter ifit is collecting dirt. The water and dust not only plugthe coil, but support biological life.

Robert Tinsley, PE, states: “Dirty coils are primebreeding grounds for just about everything biologicalthat can cause IAQ problems. Once many biologi-cals become established, they produce a biofilm, acoating that helps the growing colonies cling to thesurfaces and protects them from chemical attack. If

the colonies grow big enough, they can release intothe airstream viable organisms that can establishother colonies throughout the duct system and in theconditioned space.”7

Do air filters help?

Yes, but not as much as you might think. Filters areused to remove particulate matter within theairstream. A fiberglass filter may have a 10 to 15%efficiency rating, but that means that 85 to 90% ofparticles aren’t being trapped. Remember, air filterswere invented and designed to protect equipmentfrom dirt and other particulates, not to filter gases,spores, or bacteria.

Filters are also rated according to their ability toremove specific sizes of airborne particles. A filterwith an “arrestance” rating of 80% may indeed stop80% of the bees, flies, and large particles of dirt thatenter the airstream. But the same filter may have anefficiency of only 3 or 4% when evaluated using thedust spot method of testing.

The location of the air filter also must be taken intoconsideration. Usually it is placed before the evapo-rator coil to intercept the dirt coming in. Anythinggrowing on the coil or in the first 10 ft after the coilcan easily enter the airstream.

How do hygienists determine what the problemsare?

An industrial hygienist typically places petri dishesaround the area that is to be tested for bacteria,mold, and fungi. Testing is not limited to the building’soccupied space—tests also can be performed forbacteria and mold spore counts within the air han-dlers. Test results indicate the types of growth thatmight be present, and the hygienist is often able torecommend possible solutions.

What can be done to eliminate or prevent suchproblems?

If mold spores and fungi are allowed to grow in con-densate pans and ducts, the growth eventually willdie. Then it will start to decay, causing foul odors andreleasing micro-sized particles that can seriouslyaffect occupants with allergies.

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Antiseptic soaps spe-cially formulated forthe purpose of reduc-ing bacteria are avail-able for duct cleaning.Chemicals also areavailable for killingbacteria, spores, andfungi. You can placechemical blocks orstrips in the conden-sate pan before biolog-ical growth becomes aproblem.

When you are clean-ing an HVAC system,don’t forget the floors.Shampooing the car-pets is especially im-portant. Use only the approved concentration ofcleaning solution. If you do not clean the carpets—and most HVAC service companies don’t—theninstruct the carpet cleaning company to do so.

GENERAL SERVICE GUIDELINES

Contractors are hired to prevent problems, if possible,and to solve problems when they do occur. In per-forming these tasks, they can provide a useful servicewhile improving their financial bottom line. Here aresome general guidelines for HVAC contractors andtechnicians who deal with IAQ issues.

Keep the building in a positive pressure. The typicalresidential building is usually in a negative pressure.If you maintain a building in a slight positive pressure,you can control where the building gets its outsideair.You also enable exhaust fans, clothes dryers, andmost heating equipment (combustion air) to workbetter.

Today’s weathertight homes trap airborne particlesinside, where everyday household contaminants canbecome increasingly concentrated. The result: the airindoors can be up to 5 times more polluted than theair outdoors.

A whole-house heat recovery ventilator flushes staleair to the outdoors and replaces it with an incoming

stream of fresh air. Plus, it efficiently recovers up to80% of the energy used to heat the outgoing air.

Installing an air-to-air heat exchanger to allow for theuse of more outside air without paying the usualenergy penalty may be a good solution for somecustomers. More and more of these devices arebeing installed. There are a number of units that aremanufactured for use in single-family residences.

To install a heat exchanger, the technician mustlocate a place where the outside air is of good qual-ity before making the connection for the return air.The heat exchanger not only takes in outside air, butalso provides a relief or exhaust outlet that tempersthe air entering the building.

Take a look around the commercial buildings that youservice. Do you know where the outside air intakesare located? All too often, they are near dumpsters,chimneys, exhaust hoods, or loading docks. A num-ber of banks experienced problems when they mod-ernized and offered drive-through teller service.Why? Because the air intake was right beside thedrive-through lane and the exhaust fumes of the carswaiting in line were drawn directly into the building.Similar problems, as noted in a previous example,have been found in schools (see Figure 1). Moreoften than not, the solution is to move the outside airintake to a better location.

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Figure 1. Engine exhaust can cause IAQ problems when vehicles idle near outdoor air intakes

HPA

CE

NG

INE

ER

ING

Proper maintenance procedures and record-keeping

IAQ in the workplace has become a major concernfor many businesses, building owners, and facilitymanagers. More and more employees who believethat their work environment is not a healthy one arecontacting OSHA or hiring lawyers. Some of the com-plaints are real, and some are hysteria. Most employ-ees spend 23% or less of their time in the building inwhich they work. Most of their time is spent at home.Nevertheless, many complain that their shops oroffices are making them sick. The building may ormay not be the problem, but IAQ is becoming a toppriority in many management meetings.

This is where proper maintenance procedures, regu-lar preventive maintenance inspections, and goodrecord-keeping pay off for the building owner/man-ager. Competent service contractors will provide ser-vice work orders detailing what work was done andwhen. A building owner can take positive steps byasking what can be done to the building to make it ahealthier place to work or live. Mechanical contractorscan offer suggestions on how to upgrade the building.

ASHRAE RECOMMENDATIONS

ASHRAE has developed a written standard(ASHRAE 62, Ventilation for Acceptable Indoor AirQuality) that has been adopted by many code-writingorganizations into model-building codes. It givesdirection to designers, engineers, and building oper-ators, although there are no mandates by law thatrequire a building owner to bring an existing build-ing’s HVAC system up to current ASHRAE stan-dards. ASHRAE has changed and updated thestandard at least three times in the last ten years.ASHRAE 62-2000 states that public buildings need15 to 20 cfm of outside air per person.

PREVENTIVE MAINTENANCE

There are several things that a building owner ormanager can do to help maintain acceptable air qual-ity levels without retrofitting the entire HVAC system.Add the following to your maintenance contract:

ª Regularly sample the CO2 content of the spaceof each air handler.

ª Clean the indoor heat transfer coils to removedust, mold, and other contaminants.

ª Clean the air handler and duct system of dirt,algae, and other contaminants.

ª Consider using a UV light to control bacterial andmicrobial growth in the duct system.

ª Use time-release chemicals to prevent thegrowth of algae and bacteria in the condensatedrain pans.

ª Verify that the outside air ventilation system isworking correctly.

ª Upgrade air filtration if the system can handle theextra static pressure drop.

ª Verify that the path for the return air is free fromdampness, mold, or other contamination.

As you can see, many of the items listed above canbe done while the technician is performing the pre-ventive maintenance part of the contract, so they canbe added to your contract at a reasonable cost. Ofcourse, following the steps listed above will not guar-antee that you will never be party to a lawsuit, butproviding these extra services with documentationwill help you make a good case for your defenseshould the need arise.

In addition, there is a public relations benefit—theperceived value by the tenants or employees inknowing that their landlord or employer is going theextra mile to provide a clean work environment forthem. Consider keeping the occupants informedabout the steps you are taking to ensure the qualityof their indoor environment.

BASIC MANAGEMENT PLAN FOR GOOD IAQ

Building owners and managers should observe thefollowing minimum guidelines, and document eachstep to show that they have made “good faith”attempts to provide a healthy space for their tenantsor employees:

ª Become familiar with your building. What are itsuses?

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ª Discuss the building’s HVAC system with aresponsible contractor.

ª Review the local building codes.

ª Ensure that the building has a program in placefor regularly changing air filters.

ª Ensure that the building is in a positive pressure.

ª Ensure that the building is taking in adequatefresh air.

ª Ensure that the duct system is free of mold andother micro-contaminants.

ª Review and have available all MSDSs (MaterialSafety Data Sheets) of products and furnishings.

ª Seek professional help if symptoms persist.

CONCLUSION

The effects of poor indoor air quality on humans canbe dramatic. Consequently, IAQ is an importanthealth concern, and will continue to be one for theforeseeable future. In a building with poor IAQ, majorsources of contaminants include:

ª the occupants themselves (bioeffluents)

ª building materials and furnishings (especiallyVOCs such as formaldehyde)

ª cigarette smoke

ª paper processing from copy rooms

ª pesticides

ª cleaning products.

But not all of the contaminants originate inside thebuilding. Some originate outside, and can be drawninto the building through its intake vents. Outdoorsources of poor IAQ include:

ª industrial pollution

ª internal combustion engines

ª pesticides

ª radon.

Service technicians and contractors can minimizethe health risks to a building’s occupants—and thelegal risks to the building’s owner or manager. How?By maintaining the HVAC system with a well-planned, regularly scheduled approach.

If the tenants or employees are experiencing anyproblems, complaints should be documented andaddressed immediately. An evaluation of the buildingshould be initiated, with an IAQ audit to identify thesource of the problem and implement correctiveaction. Urge owners and managers to take a pro-active approach to your buildings by starting a com-prehensive maintenance program to reduce IAQrisks and liabilities.

Note: Communication with occupants can take a vari-ety of forms, including the placement of articles in abuilding’s newsletter or the distribution of pamphletson IAQ (an example is the EPA’s An Office BuildingOccupant’s Guide to Indoor Air Quality).

SUPPLEMENTAL INFORMATION

1RSES Journal, September 2000.

2Awake Magazine, August 8, 2000, “EverydayChemicals: Are They Making You Sick?”

3Air Conditioning/Heating/Refrigeration NEWS,January 8, 2001.

4HPAC Engineering, February 2001.

5HPAC Engineering, May 2001.

6 Air Conditioning/Heating/Refrigeration NEWS,February 23, 1998.

7HPAC Engineering, December 2000.

Links to the Web

For up-to-the-minute information, use your searchengine. Type in the words “Indoor Air Quality” andpress search. Some useful links include:

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ª ASHRAE:http://www.ashrae.org

ª EPA:http://www.epa.gov/iaq

ª Maintenance Solutions:http://www.facilitiesnet.com/ms

ª RSES:http://www.rses.org

ª Canada:http://www.healthyindoors.comhttp://www.ceeformt.org/resid/resid-main.php3

APPENDIX: MATHEMATICAL CALCULATIONS

Determining the percentage of outside air

By knowing the temperature of the outside air andthe temperature of the return air, you can determinethe temperature of the mixed air that enters the inletside of the supply blower. Use the following equation:

TMA = (TOA × %OA) + (TRA × %RA)

where

TMA = mixed air temperatureTOA = outside air temperature

%OA = % of outside air volumeTRA = return air temperature%RA = % of return air volume.

Let’s say that the temperature of the return air is70°F, and that the temperature of the outside air is40°F. Assume that you’re working on a building that

requires a mixture of 10% outside air and 90% returnair. Then:

TMA = (40°F × 0.1) + (70°F × 0.9)= 4°F + 63°F= 67°F

Now you know that the temperature of the mixed airshould be 67°F. If you’re servicing a 10-ton unit thatmoves 4,000 cfm of air, you also know that you wantabout 400 cfm of outside air (10% of 4,000). Measurethe temperature of the air at the blower inlet. If themixed air temperature is above 67°F, then theamount of outside air is less than 10%, or 400 cfm. Ifthe mixed air temperature is below 67°F, then theamount of outside air is more than 10%, or 400 cfm.In either case, you can adjust the dampers accord-ingly. Within a short period of time, you can takeanother temperature reading to determine whetherthe dampers have been adjusted properly.

Air changes

To calculate the number of air changes per hour in abuilding, use the following equation:

where

NO = number of outdoor air changescfmO = cubic feet per minute of outside air (this

figure must be multiplied by 60 becauseyou are solving for number of air changesper hour, and there are 60 minutes in anhour)

V = total volume of the structure in cubic feet.

N =cfm 60

VO

O ×

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Refrigeration Service Engineers Society1666 Rand Road Des Plaines, IL 60016 847-297-6464