Indoor Air Quality - Trane

1 Indoor Air QualityA Guide to UnderstandingASHRAE Standard 62-2001 This guide reviews and explainsthe provisions of ASHRAES tandard 62-2001, Ventilation for Acceptable Indoor AirQuality. It also advocatessystem and equipment solutionsthat meet the explicit andsuggested requirements ofthat standard. We hope theanalysis provided here helpsprofessionals responsible fordesigning, installing,maintaining, and operating of HVAC systems achievecompliance with Standard commentary that follows presentsthe opinion of Trane and not necessarilythat of the American Society of Heating,Refrigerating, and Air-ConditioningEngineers (ASHRAE). It also representsTrane s interpretation of ASHRAES tandard 62-2001 which may or may notbe the interpretation placed on it byothers, including courts, called upon forsuch interpretation. Similarly, the equipment- and system-related conceptsproposed here are offered only assuggestions. Trane does not assumeresponsibility for the interpretation of this standard or for the performance ordesirability of any system resulting fromthese suggestions.

2 Responsibility for finalsystem design like interpretation andcompliance with Standard 62 ultimatelyrests with the 2002 American Standard Inc. All rights reservedTable of Contents2 ISS-APG001-ENAdditional pieces of Traneliterature are referenced atvarious points throughout thisdocument. This supplementalinformation is available on theTrane Bookstore your local Trane ..3 Overview of ASHRAE Standard 62 ..4 Terminology ..4 History of Standard 62 ..4 How ASHRAE 62-2001 Addresses IAQ ..5 Fundamentals of Good Indoor Air Quality ..6 Contaminant Source Control ..6 Indoor Sources ..6 Sloped Drain Pans .. 7 Cleanability .. 8 Accessibility .. 9 Outdoor Sources ..11 Proper Ventilation ..12 Ventilation Rate Procedure ..13 Multi-Space Systems .. 13 The VAV Ventilation Challenge .. 13 Occupied vs. Unoccupied Ventilation .. 14 Ventilation Effectiveness .. 14 Intermittent Occupancy .. 15 Preoccupancy Purge .. 16 Summary of Ventilation Rate Procedure.

3 16 Indoor Air Quality Procedure ..16 Cleaning of Recirculated Air .. 17 Summary of the IAQ Procedure .. 17 Ventilation Control Strategies ..17 Ventilation Reset .. 18 Scheduled Ventilation .. 19CO2-Based Demand-Controlled Ventilation .. 19 Outdoor Airflow Measurement and Control ..21 Building Pressure Control ..23 Humidity Management ..24 Constant Volume, Variable-Temperature Systems ..25 Variable-Air-Volume (VAV) Systems ..28 Humidity Control vs. Heat Recovery ..29 Filtration ..30 Particulate Filtration ..30 Gaseous Filtration ..31 Summary ..32 Addenda Incorporated into ASHRAE Standard 62-2001 ..33 Suggested Mechanical Equipment Specifications ..34approving focused addenda. It isrepublished every two to three years to incorporate all approved addenda. The 2001 version incorporates twelveaddenda that have been approved since1989. The list of approved addenda anda brief description of the changes isincluded on page compliance with applicablecodes and standards within theeconomic context of each projectchallenges building design professionalsto seek innovative HVAC equipment andsystem solutions.

4 This guide attempts to clarify the ventilation, equipment, andsystem-related mandates in ASHRAES tandard 62-2001, and to identifypractical, cost-effective solutions madepossible by current technology. Thematerial presented in this documentreflects onlythe addenda approvedwhen the 2001 version of the standardwas building designers and ownersbelieve the lack of federal regulationrenders Indoor air Quality (IAQ) a soft,highly subjective issue. But the fact isthat poor IAQ reflects on everyoneinvolved with the design, construction,operation, and maintenance of abuilding. Sick buildings hinderoccupant productivity and discouragetenants from renewing their leases. Intoday s litigious society, all parties needto be aware of the legal ramifications ofan unhealthy Indoor Standard 62-2001 establishesthe standard of carefor the design ofcommercial, institutional, and residentialventilation systems to provide indoorair Quality that will be acceptable tohuman occupants and is intended tominimize the potential for adverse healtheffects.

5 Building codes in most statesreference Standard 62, either in part or in its entirety, as part of their definition of minimum ventilation requirements. As a continuous maintenance standard, Standard 62 is modified byIntroductionISS-APG001-EN3 The American Society of Heating, Refrigerating, and Air-Conditioning Engineers(ASHRAE) comprisesrepresentatives from allvantages of the heating,ventilation, refrigeration, and air-conditioning (HVAC)industry. Together, Societymembers draft standards andguidelines that provide counsel on most aspects of HVAC systemselection, design, application,commissioning, safety, andoperational criteria for a broadspectrum of HVAC and local authoritiesfrequently adopt thesestandards and write them into their purchase a copy of ASHRAE Standard 62-2001, call 1-800-5 ASHRAE or visit the online bookstore of ASHRAE Standard 62A building s Indoor air Quality is theresult of the decisions and actions of a wide variety of individuals over anextended period of time.

6 Design of the building s heating, ventilating, andair-conditioning system, contaminantsources, and air-cleaning efficiency all play roles, as do operation andmaintenance of the building and itsmechanical systems. Together, thesevariables make achieving acceptableindoor air Quality a complex,multifaceted problem. ASHRAE Standard 62-2001, Ventilationfor Acceptable Indoor Air Quality , addresses this complexity byestablishing IAQ-related guidance for thedesign, construction, startup, operation,and maintenance of heating, ventilating,and air-conditioning (HVAC) advocates full compliance with thisstandard and considers it the minimumrequisite for ventilation, equipment, andsystems local codes the title of the standard impliesthat it focuses strictly on ventilation, it goes much further by includingprovisions for managing sources of contamination, controlling indoorhumidity, and filtration of the building of the meat related to systemdesign is contained in two sections.

7 Section 5 presents general requirementsthat target microbial contaminationcontrol in HVAC equipment and systems,while Section 6 describes twoprocedures for determining designventilation rates that adequately diluteindoor 7 includes requirements forsystem construction and startup, whileSection 8 contains requirements for theoperation and maintenance of the HVAC system. This document focuses primarilyon system design. Terminology Shall and Should ASHRAE Standard 62 presents bothsuggestions (stated as should and may)and requirements (denoted by shall andmust). Obviously, requirements mustbe met to claim compliance with thestandard. While it might seem suggestions are optional, ignoringthem may not be wise as they reflect the consensus of the HVAC industry and may therefore be viewed as theminimum criteria a prudent designprofessional would exercise whendesigning a ventilation of Standard 62 Like most ASHRAE standards,Standard 62 is based on inputfrom interdisciplinarycommittees of engineers,chemists, physiologists, andmanufacturers.

8 Standard 62-1973, Standard for Naturaland Mechanical Ventilation, was ASHRAE s first ventilationstandard. It provided aprescriptive approach toventilation by specifyingminimum and recommendedoutdoor airflow rates to obtainacceptable Indoor air Ventilation forAcceptable Indoor Air Quality , the 1981 revision of thestandard recommended outdoorairflow rates for smoking andnonsmoking spaces and addedthe Indoor Air QualityProcedure as an alternativemethod for determiningminimum design ventilationrates. The 1989 version of thestandard increased the per-person space ventilation ratesfrom 5 cfm to 15 or 20 cfm perperson based on the type ofoccupancy. The 1999 versionincorporated five addenda thatwere approved since 1989. Thecurrent 2001 version Overview of ASHRAE Standard 62 How ASHRAE Standard62 Addresses IAQASHRAE Standard 62 provides basicequipment and system requirementsand minimum ventilation rates which areexpected to result in Indoor air Quality acceptable to human occupants.

9 Thestandard is based on the meaning andpurpose of the various provisions and its implementation is intended to helpminimize adverse health effects. As a peer-generated and -reviewed standard, it establishes the IAQ-relatedstandard of care for the design,construction, startup, operation, andmaintenance of ventilation systems in commercial buildings. Outdoor Air and Ventilation Air Though the terms outdoor air and ventilation air are often usedinterchangeably, there is an importantdistinction between them. Outdoorair also called intake air or first passair describes air brought into thebuilding from the outdoors, while ventilation air is typically a mixture of first pass andunused recirculatedoutdoor air used to dilute contaminantswithin a building s occupied of Standard62 (continued)incorporates seven moreaddenda that have beenapproved since 1999, includingthe addition of two new sections on construction andstartup, and operation andmaintenance.

10 Abrief descriptionof the changes from each ofthese addenda is included on page 32. What Happened toASHRAE Standard62R ?After years of work, ASHRAES tandard 62R went out for a120-day public review inAugust of 1996. In June of1997, after receiving a largenumber of comments, theASHRAE Board of Directorsdecided to change the ANSI status of the standard from periodic (revised every 5 to 10 years) to continuous maintenance. With this change,revisions will be madecontinuously through focussedaddenda, with the entirestandard being republishedevery 2 to 3 years. At the sametime, the Board divided thestandard into two parts: for commercial andinstitutional buildings and for low-rise residential Acceptable Indoor air Quality (IAQ) istypically not achieved by addressing anyone specific building product, system, orprocedure. Rather, it is the result ofcareful attention to each of the followingfundamental elements: contaminant source control proper ventilation humidity management adequate filtrationCareful attention to each of thesefundamentals during the design andconstruction of the building and HVAC system, followed by proper operationand maintenance throughout the life ofthe building, can significantly reduce therisk of IAQ-related Source ControlControlling the source of contaminants isfundamental to any IAQ strategy.