The IBC provides a modern, up-to-datebuilding code addressing the design andinstallation of building systems throughrequirements emphasizing performance.Published by the International CodeCouncil (ICC), this comprehensive codeestablishes minimum regulations forbuilding systems using prescriptive andperformance-related provisions thatcombine the scope of existing modelcodes, such as BOCA and ICBO UniformBuilding Code (UBC).
ENGINEERING S Y S T E M S O L U T I O N S Edition No. 23 July 2005 (updated April 2008) IBC Seismic Requirements and HVAC Systems – A Short Course The IBC provides a modern, up-to-date building code addressing the design and installation of building systems through requirements emphasizing performance. Published by the International Code Council (ICC), this comprehensive code establishes minimum regulations for building systems using prescriptive and performance-related provisions that combine the scope of existing model codes, such as BOCA and ICBO Uniform Building Code (UBC). In much the same way as ASHRAE standards, the ICC codes are available for adoption – in whole or in part – by jurisdictions throughout the United States. For example, as of June 9, 2005, 45 states, the District of Columbia and the U.S. Department of Defense have adopted some or all of the provisions of the IBC (Figure 1). The codes can also be adopted internationally. Figure 1. – As of June 9, 2005, 45 states have adopted some or all of the provisions of the International Building Code. 1 1 For map updates, visit http://www.iccsafe.org/government/adoption.html. I n this issue of Engineering System Solutions, we provide a summary of the earthquake (seismic) provisions affecting HVAC systems that are included in the International Building Code (IBC). For designated building functions, the IBC can require that systems critical to life safety and fulfilling the building’s intended purpose remain online immediately after a seismic event. This can affect the HVAC system and require that it be certified compliant for the same seismic design category as the building. Because the IBC is the code for the building structure, it is not typically a document that is used by mechanical engineers. However, the mechanical design professional is responsible for identifying whether HVAC equipment is covered under IBC seismic provisions and specifying products that are certified compliant. HVAC manufacturers are responsible for having equipment certified compliant by an approved, independent agency and providing proof of such compliance from the agency. The designer should require proof of compliance with each manufacturer’s bid to avoid the risk of receiving non-compliant equipment. McQuay has a number of compliant products that are certified to meet these provisions, and the expertise to assist in applying these products. For more information, contact your local McQuay representative or visit www.mcquay.com. Carol Marriott, P.Eng. Applications Manager McQuay International
The data and suggestions in this document are believed current and accurate at the time of publication, but they are not a substitute for trained, experiencedprofessional service. Individual applications and site variations can significantly affect the results and effectiveness of any information, the reader must satisfyhim/herself regarding the applicability of any article and seek professional evaluation of all materials. McQuay disclaims any responsibility for actions basedon this document.
July 2005 (updated April 2008)
IBC Seismic Requirements andHVAC Systems – A Short CourseThe IBC provides a modern, up-to-datebuilding code addressing the design andinstallation of building systems throughrequirements emphasizing performance.Published by the International CodeCouncil (ICC), this comprehensive codeestablishes minimum regulations forbuilding systems using prescriptive andperformance-related provisions thatcombine the scope of existing modelcodes, such as BOCA and ICBO UniformBuilding Code (UBC).
In much the same way as ASHRAEstandards, the ICC codes are available foradoption – in whole or in part – byjurisdictions throughout the United States.For example, as of June 9, 2005, 45 states,the District of Columbia and the U.S.Department of Defense have adoptedsome or all of the provisions of the IBC(Figure 1). The codes can also be adoptedinternationally.
Figure 1. – As of June 9, 2005, 45 states have adopted some or all of the provisionsof the International Building Code.1
In this issue of Engineering SystemSolutions, we provide a summaryof the earthquake (seismic)
provisions affecting HVAC systemsthat are included in theInternational Building Code (IBC).For designated building functions,the IBC can require that systemscritical to life safety and fulfilling thebuilding’s intended purpose remainonline immediately after a seismicevent. This can affect the HVACsystem and require that it be certifiedcompliant for the same seismic designcategory as the building.
Because the IBC is the code for thebuilding structure, it is not typicallya document that is used bymechanical engineers. However, themechanical design professional isresponsible for identifying whetherHVAC equipment is covered underIBC seismic provisions and specifyingproducts that are certified compliant.
HVAC manufacturers are responsiblefor having equipment certifiedcompliant by an approved,independent agency and providingproof of such compliance from theagency. The designer should requireproof of compliance with eachmanufacturer’s bid to avoid the riskof receiving non-compliantequipment.
McQuay has a number of compliantproducts that are certified to meetthese provisions, and the expertise toassist in applying these products. Formore information, contact your localMcQuay representative or visitwww.mcquay.com.
Carol Marriott, P.Eng.Applications ManagerMcQuay International
Step 1 Determine the Seismic Use Group.From Table 1604.5, a hospital with emergency treatment facilities is designated a Seismic use Group III structure.
Step 2 Determine The Component Importance Factor (IP) Of The HVAC EquipmentPer Section 1621.1.6, the Component Importance Factor (IP) = 1.5 because the HVAC system is required toprovide life safety functions and to maintain the continued operation of the facility.
Step 3.1 Determine the Maximum Spectral Response Accelerations (SS and S1) for the area.Per Figure 1615(1) or the software, SS = .271g Per Figure 1615(2) or the software, S1 = .114g
Step 3.2 Determine the Site Class (A to F) and Site Coefficients (Fa and Fv)Because we have no soil analysis, the Code specifies that Site Class D be used for the soil profile. Per Table 1615.1.2(1) or the software, Fa = 1.58 Per Table 1615.1.2(2) or the software, Fv = 2.34
Step 3.3 Calculate the Adjusted Maximum Accelerations (SMS and SM1)SMS = FaSS = 1.58 x .271g = .429gSM1 = FvS1 = 2.34 x .114g = .267g
Step 3.4 Calculate the Design Spectral Response Acceleration Parameters (SDS and SD1)SDS = 2/3 SMS = 2/3 x .429 = .286gSD1 = 2/3 SM1 = 2/3 x .267 = .178g
Step 3.5 Determine the assigned seismic design categoryPer Table 1616.3(1), the Seismic Design Category based on 0.2 second response = C.Per Table 1616.3(2), the Seismic Design Category based on 1.0 second response = D.According to Section 1616.3, the structure shall be assigned the most severe category, which in this case isSeismic Design Category D.
Step 4 a. Determine if the HVAC Equipment is Exempt from Seismic Requirements: The HVAC equipment does not meet any of the criteria for exemption. Therefore, it must meet the same SeismicDesign Category as the structure.b. Calculate the required FP, independent of unit weight, for use in the HVAC equipment specification.To simplify the specification, review and approval process, FP can be calculated independent of equipment weightand specified in terms of a g-force rating. The manufacturer must provide a Certificate of Compliance from anapproved, independent agency that the equipment as a building component, complies with the required FPregardless of size or weight.Determine the associated value of FP. Fp = 0.4apSDSWP x (1 + 2z/h) = 0.4 (2.5)(.286)(1) x (1 + (2)30/30) = 0.515g
(Rp/Ip) (2.5/1.5)Where;• Component amplification factor (ap) = 2.5 from Table 1621.3• Component importance factor (Ip) = 1.5 from Step 2 above• Average roof height (h) = 30 feet • Component response modification factor (Rp) = 2.5 from Table 1621.3.• Design spectral response acceleration at 0.2 seconds (SDS) = .286 from Step 3d above• Component operating weight (Wp) = 1 (reflecting that the calculation is independent of unit weight).• Height in structure at point of attachment of component (z) = 30 because the air handler is located in a
penthouse mechanical room.For this example, the HVAC equipment specification shall reflect that the air handling equipment must becertified compliant to withstand a minimum FP=0.515g
The following illustrates the processfor determining whether a seismic-resistant HVAC system is required tocomply with the IBC and how to statethe requirement in a specificationdocument. For this example, we will
use a 3-story hospital with emergencytreatment facilities located in Atlanta,GA (zip code 30080). To simplify theillustration, we will perform thecalculation for a McQuay air handlerthat is part of a central system. All
other components would require thissame calculation. The figures, tablesand sections referred to below can befound in the printed IBC 2000 or itsaccompanying software (where noted).
Sample Seismic Calculation and Specification
FindingInformation onthe IBCThe following chapters in the IBCdescribe the requirements for seismicdesign and equipment certification:
• Chapter 16 describes the requirementsfor seismic-resistant design. Coderequirements and methodology arebased on data developed in the 1997National Earthquake HazardsReduction Program (NEHRP) whichwas funded by the Federal EmergencyManagement Agency (FEMA). Section1621.3.5 states the requirement toprovide a compliant system.
• Chapter 17 describes the certification,testing and inspection requirements. Italso covers requirements for specialinspections, quality assurance plans,etc. Section 1702 defines Certificate ofCompliance and Section 1703 statesthe requirements and definition ofapprovals, including approved agencyand labeling.
The following resources provideinformation and assistance with the IBCand seismic requirements:
• A printed version of the 2003 IBC andsoftware CD can be ordered online atwww.icbo.org.
• The U.S. Geological Survey providesspectral maps on its website athttp://eqhazmaps.usgs.gov/.
• The Building Seismic Safety Council ofthe National Institute of BuildingSciences (NIBS) provides its NationalEarthquake Hazards ReductionProgram (NEHRP) RecommendedProvisions For Seismic RegulationsFor New Buildings and OtherStructures (FEMA 450) athttp://www.bssconline.org.
• McQuay representatives can helpdetermine a building’s Seismic DesignCategory and define its applicability tocomponents. To locate your localrepresentative, visitwww.mcquay.com.
IBC and Seismic RequirementsThe IBC adds a key new dimension forthe mechanical design professionalbecause its provisions cover buildingsystems and components – not just thebuilding structure. Code provisionsrequire that building life safety systemsremain online immediately after a seismicevent. For critical building designations,systems required for the building to fulfillits intended use are also covered. Inaddition, the Code includes a clause thatthe interrelationship of components beconsidered so that the failure of anycomponent does not cause the failure ofany essential component. HVAC systemsthat are essential for life safety functions,that protect life safety functions or areessential for the building to fulfill itsintended use must be certified compliantto meet the same seismic design categoryas the building (see CertificationRequirements).The remaining portions of this newsletterprovide a summary of the provisions fordetermining whether seismic-resistantHVAC equipment is required to complywith the IBC, and the requirements forcertifying HVAC equipment as IBC-compliant. All information references the2000 version of the IBC. The 2003version and the NFPA 5000 Code usethe same methodology, but somevariations exist in terminology. Thesevariations are noted in this newsletter.
Determining Whether Seismic-Resistant HVAC Equipment IsRequiredFour basic steps are required to determinewhether an HVAC system is required tocomply with the seismic-resistanceprovisions of the IBC:1.Determine the Seismic Use Group of
the structure.2.Determine the Component
Importance Factor (IP) of the HVACequipment.
3.Determine the Seismic DesignCategory of the structure.
4.Determine if the HVAC equipment isexempt from seismic requirements.
The Seismic Sample Calculation sidebarin this newsletter illustrates the procedurefor a specific building and component. 1. Determine The Seismic Use Group
Of The StructureAll structures are assigned to a Seismic UseGroup based on their intended function,as indicated in Table 1604.5 of the Code.This designation is a basic element indetermining the building’s Seismic Design
Category. The Seismic Use Groups thatare applicable to HVAC equipment arelisted below:2
• Seismic Use Group III: Structuresthat have essential facilities requiredfor post earthquake recovery andthose containing substantial quantitiesof hazardous substances, as indicatedby Table 1604.5 or as designated bythe building official. Examples fromTable 1604.5 include:- Hospitals and other health care
facilities having surgery oremergency treatment facilities.
- Fire, rescue and police stations andemergency vehicle garages.
- Designated earthquake, hurricaneor other emergency shelters.
- Designated emergencypreparedness, communication andoperation centers, and otherfacilities required for emergencyresponse.
• Seismic Use Group II: Structureswhose failure would result in asubstantial public hazard due tooccupancy or use as indicated by Table1604.5 or as designated by the buildingofficial. Examples from Table 1604.5include:- Buildings and other structures
where more than 300 peoplecongregate in one area (i.e.theaters, auditoriums, churches).
- Buildings and other structures withelementary school, secondaryschool or day-care facilities withcapacity greater than 250.
- Health care facilities with a capacityof 50 or more resident patients,but not having surgery oremergency treatment facilities (i.e.nursing homes, outpatient clinics).
- Jails and detention centers.• Seismic Use Group I: Structures not
assigned to Seismic Use Group II or III.2The Seismic Use Group numbering used in this newsletter isfrom the IBC version published in 2000. This numbering waschanged in the 2003 version, but definitions remain the same.
2. Determine The ComponentImportance Factor (IP) Of TheHVAC Equipment
A mechanical (HVAC) system becomes aDesignated Seismic System based on itsIP and the building’s determined SeismicDesign Category. The 2000 version ofthe IBC recognizes two values for IP.They are 1.0 and 1.5. Thosearchitectural, electrical and mechanicalsystems and their components thatrequire design in accordance with Section
1621 have a component importancefactor greater than 1.0. The following IPvalues, taken from the Code, have beeninterpreted to relate to HVACequipment:
The Code does not specifically define foreach Seismic Use Group what constitutesa “life safety system” or criticalcomponent for determining IP. However,the following appear to be generallyaccepted:• Seismic Use Group I: Not
applicable.• Seismic Use Group II: Anything
associated with fire and smokecontrol systems.
• Seismic Use Group III: Anythingincluded for Use Group II buildingsplus all HVAC systems.
HVAC components that may have an IP =1.5 include:• HVAC systems that perform as
fire/smoke systems.• Heating and cooling systems required
for maintaining occupant health andsafety (Use Group III structures).
• Heating systems required to preventfailure of life safety systems (firesprinklers).
• Heating and cooling systems requiredto maintain critical life savingequipment (ICU’s, heart/lungmachines, etc. in Use Group IIIstructures)
• Any component covered by theinterrelationship clause.
• Natural gas heating systems. The Codedoes not specifically name natural gassystems as having an IP = 1.5, but theyare clearly identified in the IBCCommentary book that can bepurchased with the code.
3. Determine The Seismic Design CategoryOf The Structure
All structures are assigned to a SeismicDesign Category based on their assignedSeismic Use Group and determined DesignSpectral Response. Use the following steps toarrive at the Seismic Design Category for astructure.Step 1. Determine the MaximumSpectral Response Accelerations (SS andS1) for the area where the structure islocated.The maximum considered spectral responseacceleration at 0.2 seconds (SS) and at 1-second (S1) can be determined using thespectral response maps provided in theprinted version of the IBC or theaccompanying software.• Maps—Locate SS and S1 using the
following maps provided in the Code:- Figure 1615(1): SS , Mapped
Maximum Considered Earthquake 0.2Second Short Periods (5 Hz) SpectralResponse Acceleration
• Software—Locate SS and S1 using thesoftware program, Seismic DesignParameters for Use with the 2000 IBC,provided with the printed Code. Thesoftware accepts either the zip code orlatitude and longitude of the site.3
Note: Sites with SS <0.15g and S1 <0.04g areconsidered Seismic Design Category A.4Buildings on these sites, including SeismicUse Group III buildings, and componentssuch as HVAC system must meet only theminimum structural design criteria unlessspecifically required by local code.3In regions with steep gradients, it is more precise to use latitude andlongitude as program inputs.4The maps and software referenced above provide SS and S1 in %g.To determine g, divide the value for SS and S1 from the maps orsoftware by 100 (i.e. if SS = 5.5 on the map, then SS = .055g).
Step 2. Determine the Site Class (A to F)and Site Coefficients (Fa and Fv)The Site Class depends on the soil profile andproperties, and ranges from A (hard rock) toF (very soft poor soil). Table 1615.1.1 defineseach site class based on the soil propertiespresent on a site. In the absence of a detailedsoil analysis, the IBC allows you to use SiteClass D unless it has been pre-determinedthat Site Class E or F soil is present at thesite.Site Coefficients Fa and Fv are based on theSite Class and the spectral responseacceleration (SS for Fa and S1 for Fv). Fa canbe determined using Table 1615.1.2(1) andFv can be determined using Table
1615.1.2(2) in the printed version of theIBC. The software program accompanyingthe printed IBC can also be used todetermine Site Coefficients. Step 3. Calculate the AdjustedMaximum Accelerations (SMS and SM1)Using Site Coefficients Fa and Fv, calculatethe adjusted Maximum Spectral ResponseAcceleration parameters at 0.2 seconds (SMS)and one second (SM1) as follows:• SMS = FaSS
• SM1 = FvS1
Step 4. Calculate the Design SpectralResponse Acceleration Parameters (SDSand SD1)Use the values calculated for SMS and SM1 inStep 3 to calculate the Design SpectralResponse Acceleration parameters at 0.2seconds (SDS) and one second (SD1) asfollows:• SDS = 2/3 SMS
• SD1 = 2/3 SM1
Step 5. Determine the assigned SeismicDesign CategoryThe Seismic Design Category can bedetermined using Tables 1616.3(1) and1616.3.1(2) in the printed IBC documentand have been reproduced below. The SeismicDesign category is a function of the structure’sdesignated Seismic Use Group and the valuesfor SDS and SD1 calculated in Step 4.
4a. Determine If The HVACEquipment Is Exempt From SeismicRequirements
Mechanical equipment is covered underthe seismic provisions of the Code unlessone of the exceptions listed in Section1621.1.1 apply. These exceptions arebased on the Component ImportanceFactor and the determined SeismicDesign Category. Specifically, mechanicalequipment, including HVAC, is exemptwhen any of the following conditionsapply (Refer to Section 1621.1.1 forcomplete descriptions):• The building is Seismic Design
Category A or B.• The building is Seismic Design
Category C and IP = 1.• The mechanical component is located
within 4 feet of the floor, weighs lessthan 400 pounds and IP = 1.
• The mechanical component weighsless than 20 pounds.
4b. Determining the AssociatedSeismic Design Force (FP) for aCovered Component.
If the component is determined not tobe exempt, calculate the required SeismicForce, FP using the equations given inSection 1621.1.4 of the Code as follows:
Fp = 0.4apSDSWP x (1 + 2z/h)(Rp/Ip)
Where;
ap = Component amplificationfactor that varies from 1 to 2.5(selected from Table 1621.3 ofthe printed IBC 2000).
Fp = Seismic design force centered atthe component’s center ofgravity and distributed relativeto component’s massdistribution.
Ip = Component importance factorthat is either 1 or 1.5.
h = Average roof height of structurerelative to base elevation.
Rp = Component responsemodification factor that variesfrom 1 to 5 (select anappropriate value from Table1621.3 of the printed IBC2000).
SDS = Design spectral responseacceleration at 0.2 seconds.
Wp = Component operating weight.
z = Height in structure at point ofattachment of component. Foritems below the base, z shall betaken as 0. For items at orabove the roof, z is not requiredto be taken as greater than theroof height h.
The component (or equipment) must becertified to meet the calculated value ofFP at a minimum.
What Constitutes a CertifiedSeismic-compliant Product?Seismic-compliant products must havebeen reviewed and certified capable towithstand a given Seismic Force (FP) byan Approved Agency. Section 1702 ofthe Code states that a label must beapplied to the product that indicates thatit has been inspected and evaluated by anapproved agency (see sidebar onMcQuay compliant products). The IBCoutlines the requirements for anapproved agency in Section 1703:• 1703.1 Approved Agency. An
approved agency shall provide allinformation as necessary for thebuilding official to determine that
the agency meets the applicablerequirements.- 1703.1.1 Independent. An
approved agency shall be objectiveand competent. The agency shallalso disclose any possible conflictsof interest so that objectivity canbe confirmed.
- 1703.1.2 Equipment. Anapproved agency shall haveadequate equipment to performrequired tests. The equipmentshall be periodically calibrated.
- 1703.1.3 Personnel. An approvedagency shall employ experiencedpersonnel educated in conducting,supervising and evaluating testsand/or inspections.
As with most Codes, an approved agencyis one that can display proof ofcompetency and that is found acceptableby the local approving authority(building code official). Manufacturersare not allowed to self-certify complianceas they can not pass the objectivityrequirement in 1703.1.1.
Component type IP Value
Life safety components requiredto function after an earthquake 1.5
Components containinghazardous or flammable materialsin quantities that exceed theexempted amounts for an opensystem listed in Chapter 4
1.5
For structures in Seismic UseGroup III, components needed forcontinued operation of the facilityor whose failure could impair thecontinued operation of the facility
1.5
All other components 1
McQuay has several productsthat are certified compliantand available for use inSeismic Use Group II or IIIbuildings as defined in theIBC 2000 (Use Group III & IVin the 2003 edition). Theseproducts are certified tosatisfy the worst case forDesign Categories D (FP =2.88 g) and E/F (FP = 4.42 g)to simplify specification once it has beendetermined that components are coveredunder the seismic provisions of the code.Products currently certified include:• Applied Rooftop Systems (Models RDT,
RPS, RCS, RFS and RPR)• Vision Indoor Air Handler (Models CAH
and CAC)• Skyline Outdoor Air Handler (Models OAH
and OAC) and Rooftop Air Handlers(Models RAH, RDS and RAR)
• AAF®-HermanNelson® Unit Ventilators(Models AV, AH, AZ, AE, and AE/ER)
As specified in IBC 2000 and 2003, allMcQuay products that are designated ascompliant have been analyzed, tested andcertified by an independent agency, VMC
Seismic Consulting Group, that is competentin seismic analysis and design. Each productincludes: • An appropriate Certificate of Compliance
to be used at the time of specification andsubmittal for each compliant product, asspecified in IBC 2000 and 2003.
• A label of compliance from the certifyingagent is displayed on the product for theinspecting authority to review, as specifiedin IBC 2000 and 2003.
• Installation instructions for installing theproduct in a manner that supportscompliance.
For more information on IBC seismicprovisions and certified McQuay products,contact your McQuay representative or visitwww.mcquay.com.
McQuay Provides Seismic-CertifiedProducts
Value of SDSSeismic Design Category
Use Group I Use Group II Use Group III
SDS < 0.167g A A A
0.167g ≤ SDS <0.33g B B C
0.33g ≤ SDS < 0.50g C C D
0.50g ≤ SDS D* D* D*
Table 1616.3(2): Seismic design categorybased on 1-second period responseaccelerations.
Value of SD1Seismic Design Category
Use Group I Use Group II Use Group III
SD1 < 0.067g A A A
0.067g ≤ SD1 < 0.133g B B C
0.133g ≤ SD1 < 0.20g C C D
0.20g ≤ SD1 D* D* D*
*Seismic Use Group I and II structures located on sites with mappedmaximum considered earthquake spectral response acceleration at 1-second period, S1, equal to or greater than 0.75g, shall be assignedto Seismic Design Category E, and Seismic Use Group III structureslocated on such sites shall be assigned to Seismic Design Category F.
Table 1616.3(1): Seismic design categorybased on 0.2 second period responseaccelerations.
FindingInformation onthe IBCThe following chapters in the IBCdescribe the requirements for seismicdesign and equipment certification:
• Chapter 16 describes the requirementsfor seismic-resistant design. Coderequirements and methodology arebased on data developed in the 1997National Earthquake HazardsReduction Program (NEHRP) whichwas funded by the Federal EmergencyManagement Agency (FEMA). Section1621.3.5 states the requirement toprovide a compliant system.
• Chapter 17 describes the certification,testing and inspection requirements. Italso covers requirements for specialinspections, quality assurance plans,etc. Section 1702 defines Certificate ofCompliance and Section 1703 statesthe requirements and definition ofapprovals, including approved agencyand labeling.
The following resources provideinformation and assistance with the IBCand seismic requirements:
• A printed version of the 2003 IBC andsoftware CD can be ordered online atwww.icbo.org.
• The U.S. Geological Survey providesspectral maps on its website athttp://eqhazmaps.usgs.gov/.
• The Building Seismic Safety Council ofthe National Institute of BuildingSciences (NIBS) provides its NationalEarthquake Hazards ReductionProgram (NEHRP) RecommendedProvisions For Seismic RegulationsFor New Buildings and OtherStructures (FEMA 450) athttp://www.bssconline.org.
• McQuay representatives can helpdetermine a building’s Seismic DesignCategory and define its applicability tocomponents. To locate your localrepresentative, visitwww.mcquay.com.
IBC and Seismic RequirementsThe IBC adds a key new dimension forthe mechanical design professionalbecause its provisions cover buildingsystems and components – not just thebuilding structure. Code provisionsrequire that building life safety systemsremain online immediately after a seismicevent. For critical building designations,systems required for the building to fulfillits intended use are also covered. Inaddition, the Code includes a clause thatthe interrelationship of components beconsidered so that the failure of anycomponent does not cause the failure ofany essential component. HVAC systemsthat are essential for life safety functions,that protect life safety functions or areessential for the building to fulfill itsintended use must be certified compliantto meet the same seismic design categoryas the building (see CertificationRequirements).The remaining portions of this newsletterprovide a summary of the provisions fordetermining whether seismic-resistantHVAC equipment is required to complywith the IBC, and the requirements forcertifying HVAC equipment as IBC-compliant. All information references the2000 version of the IBC. The 2003version and the NFPA 5000 Code usethe same methodology, but somevariations exist in terminology. Thesevariations are noted in this newsletter.
Determining Whether Seismic-Resistant HVAC Equipment IsRequiredFour basic steps are required to determinewhether an HVAC system is required tocomply with the seismic-resistanceprovisions of the IBC:1.Determine the Seismic Use Group of
the structure.2.Determine the Component
Importance Factor (IP) of the HVACequipment.
3.Determine the Seismic DesignCategory of the structure.
4.Determine if the HVAC equipment isexempt from seismic requirements.
The Seismic Sample Calculation sidebarin this newsletter illustrates the procedurefor a specific building and component. 1. Determine The Seismic Use Group
Of The StructureAll structures are assigned to a Seismic UseGroup based on their intended function,as indicated in Table 1604.5 of the Code.This designation is a basic element indetermining the building’s Seismic Design
Category. The Seismic Use Groups thatare applicable to HVAC equipment arelisted below:2
• Seismic Use Group III: Structuresthat have essential facilities requiredfor post earthquake recovery andthose containing substantial quantitiesof hazardous substances, as indicatedby Table 1604.5 or as designated bythe building official. Examples fromTable 1604.5 include:- Hospitals and other health care
facilities having surgery oremergency treatment facilities.
- Fire, rescue and police stations andemergency vehicle garages.
- Designated earthquake, hurricaneor other emergency shelters.
- Designated emergencypreparedness, communication andoperation centers, and otherfacilities required for emergencyresponse.
• Seismic Use Group II: Structureswhose failure would result in asubstantial public hazard due tooccupancy or use as indicated by Table1604.5 or as designated by the buildingofficial. Examples from Table 1604.5include:- Buildings and other structures
where more than 300 peoplecongregate in one area (i.e.theaters, auditoriums, churches).
- Buildings and other structures withelementary school, secondaryschool or day-care facilities withcapacity greater than 250.
- Health care facilities with a capacityof 50 or more resident patients,but not having surgery oremergency treatment facilities (i.e.nursing homes, outpatient clinics).
- Jails and detention centers.• Seismic Use Group I: Structures not
assigned to Seismic Use Group II or III.2The Seismic Use Group numbering used in this newsletter isfrom the IBC version published in 2000. This numbering waschanged in the 2003 version, but definitions remain the same.
2. Determine The ComponentImportance Factor (IP) Of TheHVAC Equipment
A mechanical (HVAC) system becomes aDesignated Seismic System based on itsIP and the building’s determined SeismicDesign Category. The 2000 version ofthe IBC recognizes two values for IP.They are 1.0 and 1.5. Thosearchitectural, electrical and mechanicalsystems and their components thatrequire design in accordance with Section
1621 have a component importancefactor greater than 1.0. The following IPvalues, taken from the Code, have beeninterpreted to relate to HVACequipment:
The Code does not specifically define foreach Seismic Use Group what constitutesa “life safety system” or criticalcomponent for determining IP. However,the following appear to be generallyaccepted:• Seismic Use Group I: Not
applicable.• Seismic Use Group II: Anything
associated with fire and smokecontrol systems.
• Seismic Use Group III: Anythingincluded for Use Group II buildingsplus all HVAC systems.
HVAC components that may have an IP =1.5 include:• HVAC systems that perform as
fire/smoke systems.• Heating and cooling systems required
for maintaining occupant health andsafety (Use Group III structures).
• Heating systems required to preventfailure of life safety systems (firesprinklers).
• Heating and cooling systems requiredto maintain critical life savingequipment (ICU’s, heart/lungmachines, etc. in Use Group IIIstructures)
• Any component covered by theinterrelationship clause.
• Natural gas heating systems. The Codedoes not specifically name natural gassystems as having an IP = 1.5, but theyare clearly identified in the IBCCommentary book that can bepurchased with the code.
3. Determine The Seismic Design CategoryOf The Structure
All structures are assigned to a SeismicDesign Category based on their assignedSeismic Use Group and determined DesignSpectral Response. Use the following steps toarrive at the Seismic Design Category for astructure.Step 1. Determine the MaximumSpectral Response Accelerations (SS andS1) for the area where the structure islocated.The maximum considered spectral responseacceleration at 0.2 seconds (SS) and at 1-second (S1) can be determined using thespectral response maps provided in theprinted version of the IBC or theaccompanying software.• Maps—Locate SS and S1 using the
following maps provided in the Code:- Figure 1615(1): SS , Mapped
Maximum Considered Earthquake 0.2Second Short Periods (5 Hz) SpectralResponse Acceleration
• Software—Locate SS and S1 using thesoftware program, Seismic DesignParameters for Use with the 2000 IBC,provided with the printed Code. Thesoftware accepts either the zip code orlatitude and longitude of the site.3
Note: Sites with SS <0.15g and S1 <0.04g areconsidered Seismic Design Category A.4Buildings on these sites, including SeismicUse Group III buildings, and componentssuch as HVAC system must meet only theminimum structural design criteria unlessspecifically required by local code.3In regions with steep gradients, it is more precise to use latitude andlongitude as program inputs.4The maps and software referenced above provide SS and S1 in %g.To determine g, divide the value for SS and S1 from the maps orsoftware by 100 (i.e. if SS = 5.5 on the map, then SS = .055g).
Step 2. Determine the Site Class (A to F)and Site Coefficients (Fa and Fv)The Site Class depends on the soil profile andproperties, and ranges from A (hard rock) toF (very soft poor soil). Table 1615.1.1 defineseach site class based on the soil propertiespresent on a site. In the absence of a detailedsoil analysis, the IBC allows you to use SiteClass D unless it has been pre-determinedthat Site Class E or F soil is present at thesite.Site Coefficients Fa and Fv are based on theSite Class and the spectral responseacceleration (SS for Fa and S1 for Fv). Fa canbe determined using Table 1615.1.2(1) andFv can be determined using Table
1615.1.2(2) in the printed version of theIBC. The software program accompanyingthe printed IBC can also be used todetermine Site Coefficients. Step 3. Calculate the AdjustedMaximum Accelerations (SMS and SM1)Using Site Coefficients Fa and Fv, calculatethe adjusted Maximum Spectral ResponseAcceleration parameters at 0.2 seconds (SMS)and one second (SM1) as follows:• SMS = FaSS
• SM1 = FvS1
Step 4. Calculate the Design SpectralResponse Acceleration Parameters (SDSand SD1)Use the values calculated for SMS and SM1 inStep 3 to calculate the Design SpectralResponse Acceleration parameters at 0.2seconds (SDS) and one second (SD1) asfollows:• SDS = 2/3 SMS
• SD1 = 2/3 SM1
Step 5. Determine the assigned SeismicDesign CategoryThe Seismic Design Category can bedetermined using Tables 1616.3(1) and1616.3.1(2) in the printed IBC documentand have been reproduced below. The SeismicDesign category is a function of the structure’sdesignated Seismic Use Group and the valuesfor SDS and SD1 calculated in Step 4.
4a. Determine If The HVACEquipment Is Exempt From SeismicRequirements
Mechanical equipment is covered underthe seismic provisions of the Code unlessone of the exceptions listed in Section1621.1.1 apply. These exceptions arebased on the Component ImportanceFactor and the determined SeismicDesign Category. Specifically, mechanicalequipment, including HVAC, is exemptwhen any of the following conditionsapply (Refer to Section 1621.1.1 forcomplete descriptions):• The building is Seismic Design
Category A or B.• The building is Seismic Design
Category C and IP = 1.• The mechanical component is located
within 4 feet of the floor, weighs lessthan 400 pounds and IP = 1.
• The mechanical component weighsless than 20 pounds.
4b. Determining the AssociatedSeismic Design Force (FP) for aCovered Component.
If the component is determined not tobe exempt, calculate the required SeismicForce, FP using the equations given inSection 1621.1.4 of the Code as follows:
Fp = 0.4apSDSWP x (1 + 2z/h)(Rp/Ip)
Where;
ap = Component amplificationfactor that varies from 1 to 2.5(selected from Table 1621.3 ofthe printed IBC 2000).
Fp = Seismic design force centered atthe component’s center ofgravity and distributed relativeto component’s massdistribution.
Ip = Component importance factorthat is either 1 or 1.5.
h = Average roof height of structurerelative to base elevation.
Rp = Component responsemodification factor that variesfrom 1 to 5 (select anappropriate value from Table1621.3 of the printed IBC2000).
SDS = Design spectral responseacceleration at 0.2 seconds.
Wp = Component operating weight.
z = Height in structure at point ofattachment of component. Foritems below the base, z shall betaken as 0. For items at orabove the roof, z is not requiredto be taken as greater than theroof height h.
The component (or equipment) must becertified to meet the calculated value ofFP at a minimum.
What Constitutes a CertifiedSeismic-compliant Product?Seismic-compliant products must havebeen reviewed and certified capable towithstand a given Seismic Force (FP) byan Approved Agency. Section 1702 ofthe Code states that a label must beapplied to the product that indicates thatit has been inspected and evaluated by anapproved agency (see sidebar onMcQuay compliant products). The IBCoutlines the requirements for anapproved agency in Section 1703:• 1703.1 Approved Agency. An
approved agency shall provide allinformation as necessary for thebuilding official to determine that
the agency meets the applicablerequirements.- 1703.1.1 Independent. An
approved agency shall be objectiveand competent. The agency shallalso disclose any possible conflictsof interest so that objectivity canbe confirmed.
- 1703.1.2 Equipment. Anapproved agency shall haveadequate equipment to performrequired tests. The equipmentshall be periodically calibrated.
- 1703.1.3 Personnel. An approvedagency shall employ experiencedpersonnel educated in conducting,supervising and evaluating testsand/or inspections.
As with most Codes, an approved agencyis one that can display proof ofcompetency and that is found acceptableby the local approving authority(building code official). Manufacturersare not allowed to self-certify complianceas they can not pass the objectivityrequirement in 1703.1.1.
Component type IP Value
Life safety components requiredto function after an earthquake 1.5
Components containinghazardous or flammable materialsin quantities that exceed theexempted amounts for an opensystem listed in Chapter 4
1.5
For structures in Seismic UseGroup III, components needed forcontinued operation of the facilityor whose failure could impair thecontinued operation of the facility
1.5
All other components 1
McQuay has several productsthat are certified compliantand available for use inSeismic Use Group II or IIIbuildings as defined in theIBC 2000 (Use Group III & IVin the 2003 edition). Theseproducts are certified tosatisfy the worst case forDesign Categories D (FP =2.88 g) and E/F (FP = 4.42 g)to simplify specification once it has beendetermined that components are coveredunder the seismic provisions of the code.Products currently certified include:• Applied Rooftop Systems (Models RDT,
RPS, RCS, RFS and RPR)• Vision Indoor Air Handler (Models CAH
and CAC)• Skyline Outdoor Air Handler (Models OAH
and OAC) and Rooftop Air Handlers(Models RAH, RDS and RAR)
• AAF®-HermanNelson® Unit Ventilators(Models AV, AH, AZ, AE, and AE/ER)
As specified in IBC 2000 and 2003, allMcQuay products that are designated ascompliant have been analyzed, tested andcertified by an independent agency, VMC
Seismic Consulting Group, that is competentin seismic analysis and design. Each productincludes: • An appropriate Certificate of Compliance
to be used at the time of specification andsubmittal for each compliant product, asspecified in IBC 2000 and 2003.
• A label of compliance from the certifyingagent is displayed on the product for theinspecting authority to review, as specifiedin IBC 2000 and 2003.
• Installation instructions for installing theproduct in a manner that supportscompliance.
For more information on IBC seismicprovisions and certified McQuay products,contact your McQuay representative or visitwww.mcquay.com.
McQuay Provides Seismic-CertifiedProducts
Value of SDSSeismic Design Category
Use Group I Use Group II Use Group III
SDS < 0.167g A A A
0.167g ≤ SDS <0.33g B B C
0.33g ≤ SDS < 0.50g C C D
0.50g ≤ SDS D* D* D*
Table 1616.3(2): Seismic design categorybased on 1-second period responseaccelerations.
Value of SD1Seismic Design Category
Use Group I Use Group II Use Group III
SD1 < 0.067g A A A
0.067g ≤ SD1 < 0.133g B B C
0.133g ≤ SD1 < 0.20g C C D
0.20g ≤ SD1 D* D* D*
*Seismic Use Group I and II structures located on sites with mappedmaximum considered earthquake spectral response acceleration at 1-second period, S1, equal to or greater than 0.75g, shall be assignedto Seismic Design Category E, and Seismic Use Group III structureslocated on such sites shall be assigned to Seismic Design Category F.
Table 1616.3(1): Seismic design categorybased on 0.2 second period responseaccelerations.
FindingInformation onthe IBCThe following chapters in the IBCdescribe the requirements for seismicdesign and equipment certification:
• Chapter 16 describes the requirementsfor seismic-resistant design. Coderequirements and methodology arebased on data developed in the 1997National Earthquake HazardsReduction Program (NEHRP) whichwas funded by the Federal EmergencyManagement Agency (FEMA). Section1621.3.5 states the requirement toprovide a compliant system.
• Chapter 17 describes the certification,testing and inspection requirements. Italso covers requirements for specialinspections, quality assurance plans,etc. Section 1702 defines Certificate ofCompliance and Section 1703 statesthe requirements and definition ofapprovals, including approved agencyand labeling.
The following resources provideinformation and assistance with the IBCand seismic requirements:
• A printed version of the 2003 IBC andsoftware CD can be ordered online atwww.icbo.org.
• The U.S. Geological Survey providesspectral maps on its website athttp://eqhazmaps.usgs.gov/.
• The Building Seismic Safety Council ofthe National Institute of BuildingSciences (NIBS) provides its NationalEarthquake Hazards ReductionProgram (NEHRP) RecommendedProvisions For Seismic RegulationsFor New Buildings and OtherStructures (FEMA 450) athttp://www.bssconline.org.
• McQuay representatives can helpdetermine a building’s Seismic DesignCategory and define its applicability tocomponents. To locate your localrepresentative, visitwww.mcquay.com.
IBC and Seismic RequirementsThe IBC adds a key new dimension forthe mechanical design professionalbecause its provisions cover buildingsystems and components – not just thebuilding structure. Code provisionsrequire that building life safety systemsremain online immediately after a seismicevent. For critical building designations,systems required for the building to fulfillits intended use are also covered. Inaddition, the Code includes a clause thatthe interrelationship of components beconsidered so that the failure of anycomponent does not cause the failure ofany essential component. HVAC systemsthat are essential for life safety functions,that protect life safety functions or areessential for the building to fulfill itsintended use must be certified compliantto meet the same seismic design categoryas the building (see CertificationRequirements).The remaining portions of this newsletterprovide a summary of the provisions fordetermining whether seismic-resistantHVAC equipment is required to complywith the IBC, and the requirements forcertifying HVAC equipment as IBC-compliant. All information references the2000 version of the IBC. The 2003version and the NFPA 5000 Code usethe same methodology, but somevariations exist in terminology. Thesevariations are noted in this newsletter.
Determining Whether Seismic-Resistant HVAC Equipment IsRequiredFour basic steps are required to determinewhether an HVAC system is required tocomply with the seismic-resistanceprovisions of the IBC:1.Determine the Seismic Use Group of
the structure.2.Determine the Component
Importance Factor (IP) of the HVACequipment.
3.Determine the Seismic DesignCategory of the structure.
4.Determine if the HVAC equipment isexempt from seismic requirements.
The Seismic Sample Calculation sidebarin this newsletter illustrates the procedurefor a specific building and component. 1. Determine The Seismic Use Group
Of The StructureAll structures are assigned to a Seismic UseGroup based on their intended function,as indicated in Table 1604.5 of the Code.This designation is a basic element indetermining the building’s Seismic Design
Category. The Seismic Use Groups thatare applicable to HVAC equipment arelisted below:2
• Seismic Use Group III: Structuresthat have essential facilities requiredfor post earthquake recovery andthose containing substantial quantitiesof hazardous substances, as indicatedby Table 1604.5 or as designated bythe building official. Examples fromTable 1604.5 include:- Hospitals and other health care
facilities having surgery oremergency treatment facilities.
- Fire, rescue and police stations andemergency vehicle garages.
- Designated earthquake, hurricaneor other emergency shelters.
- Designated emergencypreparedness, communication andoperation centers, and otherfacilities required for emergencyresponse.
• Seismic Use Group II: Structureswhose failure would result in asubstantial public hazard due tooccupancy or use as indicated by Table1604.5 or as designated by the buildingofficial. Examples from Table 1604.5include:- Buildings and other structures
where more than 300 peoplecongregate in one area (i.e.theaters, auditoriums, churches).
- Buildings and other structures withelementary school, secondaryschool or day-care facilities withcapacity greater than 250.
- Health care facilities with a capacityof 50 or more resident patients,but not having surgery oremergency treatment facilities (i.e.nursing homes, outpatient clinics).
- Jails and detention centers.• Seismic Use Group I: Structures not
assigned to Seismic Use Group II or III.2The Seismic Use Group numbering used in this newsletter isfrom the IBC version published in 2000. This numbering waschanged in the 2003 version, but definitions remain the same.
2. Determine The ComponentImportance Factor (IP) Of TheHVAC Equipment
A mechanical (HVAC) system becomes aDesignated Seismic System based on itsIP and the building’s determined SeismicDesign Category. The 2000 version ofthe IBC recognizes two values for IP.They are 1.0 and 1.5. Thosearchitectural, electrical and mechanicalsystems and their components thatrequire design in accordance with Section
1621 have a component importancefactor greater than 1.0. The following IPvalues, taken from the Code, have beeninterpreted to relate to HVACequipment:
The Code does not specifically define foreach Seismic Use Group what constitutesa “life safety system” or criticalcomponent for determining IP. However,the following appear to be generallyaccepted:• Seismic Use Group I: Not
applicable.• Seismic Use Group II: Anything
associated with fire and smokecontrol systems.
• Seismic Use Group III: Anythingincluded for Use Group II buildingsplus all HVAC systems.
HVAC components that may have an IP =1.5 include:• HVAC systems that perform as
fire/smoke systems.• Heating and cooling systems required
for maintaining occupant health andsafety (Use Group III structures).
• Heating systems required to preventfailure of life safety systems (firesprinklers).
• Heating and cooling systems requiredto maintain critical life savingequipment (ICU’s, heart/lungmachines, etc. in Use Group IIIstructures)
• Any component covered by theinterrelationship clause.
• Natural gas heating systems. The Codedoes not specifically name natural gassystems as having an IP = 1.5, but theyare clearly identified in the IBCCommentary book that can bepurchased with the code.
3. Determine The Seismic Design CategoryOf The Structure
All structures are assigned to a SeismicDesign Category based on their assignedSeismic Use Group and determined DesignSpectral Response. Use the following steps toarrive at the Seismic Design Category for astructure.Step 1. Determine the MaximumSpectral Response Accelerations (SS andS1) for the area where the structure islocated.The maximum considered spectral responseacceleration at 0.2 seconds (SS) and at 1-second (S1) can be determined using thespectral response maps provided in theprinted version of the IBC or theaccompanying software.• Maps—Locate SS and S1 using the
following maps provided in the Code:- Figure 1615(1): SS , Mapped
Maximum Considered Earthquake 0.2Second Short Periods (5 Hz) SpectralResponse Acceleration
• Software—Locate SS and S1 using thesoftware program, Seismic DesignParameters for Use with the 2000 IBC,provided with the printed Code. Thesoftware accepts either the zip code orlatitude and longitude of the site.3
Note: Sites with SS <0.15g and S1 <0.04g areconsidered Seismic Design Category A.4Buildings on these sites, including SeismicUse Group III buildings, and componentssuch as HVAC system must meet only theminimum structural design criteria unlessspecifically required by local code.3In regions with steep gradients, it is more precise to use latitude andlongitude as program inputs.4The maps and software referenced above provide SS and S1 in %g.To determine g, divide the value for SS and S1 from the maps orsoftware by 100 (i.e. if SS = 5.5 on the map, then SS = .055g).
Step 2. Determine the Site Class (A to F)and Site Coefficients (Fa and Fv)The Site Class depends on the soil profile andproperties, and ranges from A (hard rock) toF (very soft poor soil). Table 1615.1.1 defineseach site class based on the soil propertiespresent on a site. In the absence of a detailedsoil analysis, the IBC allows you to use SiteClass D unless it has been pre-determinedthat Site Class E or F soil is present at thesite.Site Coefficients Fa and Fv are based on theSite Class and the spectral responseacceleration (SS for Fa and S1 for Fv). Fa canbe determined using Table 1615.1.2(1) andFv can be determined using Table
1615.1.2(2) in the printed version of theIBC. The software program accompanyingthe printed IBC can also be used todetermine Site Coefficients. Step 3. Calculate the AdjustedMaximum Accelerations (SMS and SM1)Using Site Coefficients Fa and Fv, calculatethe adjusted Maximum Spectral ResponseAcceleration parameters at 0.2 seconds (SMS)and one second (SM1) as follows:• SMS = FaSS
• SM1 = FvS1
Step 4. Calculate the Design SpectralResponse Acceleration Parameters (SDSand SD1)Use the values calculated for SMS and SM1 inStep 3 to calculate the Design SpectralResponse Acceleration parameters at 0.2seconds (SDS) and one second (SD1) asfollows:• SDS = 2/3 SMS
• SD1 = 2/3 SM1
Step 5. Determine the assigned SeismicDesign CategoryThe Seismic Design Category can bedetermined using Tables 1616.3(1) and1616.3.1(2) in the printed IBC documentand have been reproduced below. The SeismicDesign category is a function of the structure’sdesignated Seismic Use Group and the valuesfor SDS and SD1 calculated in Step 4.
4a. Determine If The HVACEquipment Is Exempt From SeismicRequirements
Mechanical equipment is covered underthe seismic provisions of the Code unlessone of the exceptions listed in Section1621.1.1 apply. These exceptions arebased on the Component ImportanceFactor and the determined SeismicDesign Category. Specifically, mechanicalequipment, including HVAC, is exemptwhen any of the following conditionsapply (Refer to Section 1621.1.1 forcomplete descriptions):• The building is Seismic Design
Category A or B.• The building is Seismic Design
Category C and IP = 1.• The mechanical component is located
within 4 feet of the floor, weighs lessthan 400 pounds and IP = 1.
• The mechanical component weighsless than 20 pounds.
4b. Determining the AssociatedSeismic Design Force (FP) for aCovered Component.
If the component is determined not tobe exempt, calculate the required SeismicForce, FP using the equations given inSection 1621.1.4 of the Code as follows:
Fp = 0.4apSDSWP x (1 + 2z/h)(Rp/Ip)
Where;
ap = Component amplificationfactor that varies from 1 to 2.5(selected from Table 1621.3 ofthe printed IBC 2000).
Fp = Seismic design force centered atthe component’s center ofgravity and distributed relativeto component’s massdistribution.
Ip = Component importance factorthat is either 1 or 1.5.
h = Average roof height of structurerelative to base elevation.
Rp = Component responsemodification factor that variesfrom 1 to 5 (select anappropriate value from Table1621.3 of the printed IBC2000).
SDS = Design spectral responseacceleration at 0.2 seconds.
Wp = Component operating weight.
z = Height in structure at point ofattachment of component. Foritems below the base, z shall betaken as 0. For items at orabove the roof, z is not requiredto be taken as greater than theroof height h.
The component (or equipment) must becertified to meet the calculated value ofFP at a minimum.
What Constitutes a CertifiedSeismic-compliant Product?Seismic-compliant products must havebeen reviewed and certified capable towithstand a given Seismic Force (FP) byan Approved Agency. Section 1702 ofthe Code states that a label must beapplied to the product that indicates thatit has been inspected and evaluated by anapproved agency (see sidebar onMcQuay compliant products). The IBCoutlines the requirements for anapproved agency in Section 1703:• 1703.1 Approved Agency. An
approved agency shall provide allinformation as necessary for thebuilding official to determine that
the agency meets the applicablerequirements.- 1703.1.1 Independent. An
approved agency shall be objectiveand competent. The agency shallalso disclose any possible conflictsof interest so that objectivity canbe confirmed.
- 1703.1.2 Equipment. Anapproved agency shall haveadequate equipment to performrequired tests. The equipmentshall be periodically calibrated.
- 1703.1.3 Personnel. An approvedagency shall employ experiencedpersonnel educated in conducting,supervising and evaluating testsand/or inspections.
As with most Codes, an approved agencyis one that can display proof ofcompetency and that is found acceptableby the local approving authority(building code official). Manufacturersare not allowed to self-certify complianceas they can not pass the objectivityrequirement in 1703.1.1.
Component type IP Value
Life safety components requiredto function after an earthquake 1.5
Components containinghazardous or flammable materialsin quantities that exceed theexempted amounts for an opensystem listed in Chapter 4
1.5
For structures in Seismic UseGroup III, components needed forcontinued operation of the facilityor whose failure could impair thecontinued operation of the facility
1.5
All other components 1
McQuay has several productsthat are certified compliantand available for use inSeismic Use Group II or IIIbuildings as defined in theIBC 2000 (Use Group III & IVin the 2003 edition). Theseproducts are certified tosatisfy the worst case forDesign Categories D (FP =2.88 g) and E/F (FP = 4.42 g)to simplify specification once it has beendetermined that components are coveredunder the seismic provisions of the code.Products currently certified include:• Applied Rooftop Systems (Models RDT,
RPS, RCS, RFS and RPR)• Vision Indoor Air Handler (Models CAH
and CAC)• Skyline Outdoor Air Handler (Models OAH
and OAC) and Rooftop Air Handlers(Models RAH, RDS and RAR)
• AAF®-HermanNelson® Unit Ventilators(Models AV, AH, AZ, AE, and AE/ER)
As specified in IBC 2000 and 2003, allMcQuay products that are designated ascompliant have been analyzed, tested andcertified by an independent agency, VMC
Seismic Consulting Group, that is competentin seismic analysis and design. Each productincludes: • An appropriate Certificate of Compliance
to be used at the time of specification andsubmittal for each compliant product, asspecified in IBC 2000 and 2003.
• A label of compliance from the certifyingagent is displayed on the product for theinspecting authority to review, as specifiedin IBC 2000 and 2003.
• Installation instructions for installing theproduct in a manner that supportscompliance.
For more information on IBC seismicprovisions and certified McQuay products,contact your McQuay representative or visitwww.mcquay.com.
McQuay Provides Seismic-CertifiedProducts
Value of SDSSeismic Design Category
Use Group I Use Group II Use Group III
SDS < 0.167g A A A
0.167g ≤ SDS <0.33g B B C
0.33g ≤ SDS < 0.50g C C D
0.50g ≤ SDS D* D* D*
Table 1616.3(2): Seismic design categorybased on 1-second period responseaccelerations.
Value of SD1Seismic Design Category
Use Group I Use Group II Use Group III
SD1 < 0.067g A A A
0.067g ≤ SD1 < 0.133g B B C
0.133g ≤ SD1 < 0.20g C C D
0.20g ≤ SD1 D* D* D*
*Seismic Use Group I and II structures located on sites with mappedmaximum considered earthquake spectral response acceleration at 1-second period, S1, equal to or greater than 0.75g, shall be assignedto Seismic Design Category E, and Seismic Use Group III structureslocated on such sites shall be assigned to Seismic Design Category F.
Table 1616.3(1): Seismic design categorybased on 0.2 second period responseaccelerations.
The data and suggestions in this document are believed current and accurate at the time of publication, but they are not a substitute for trained, experiencedprofessional service. Individual applications and site variations can significantly affect the results and effectiveness of any information, the reader must satisfyhim/herself regarding the applicability of any article and seek professional evaluation of all materials. McQuay disclaims any responsibility for actions basedon this document.
July 2005 (updated April 2008)
IBC Seismic Requirements andHVAC Systems – A Short CourseThe IBC provides a modern, up-to-datebuilding code addressing the design andinstallation of building systems throughrequirements emphasizing performance.Published by the International CodeCouncil (ICC), this comprehensive codeestablishes minimum regulations forbuilding systems using prescriptive andperformance-related provisions thatcombine the scope of existing modelcodes, such as BOCA and ICBO UniformBuilding Code (UBC).
In much the same way as ASHRAEstandards, the ICC codes are available foradoption – in whole or in part – byjurisdictions throughout the United States.For example, as of June 9, 2005, 45 states,the District of Columbia and the U.S.Department of Defense have adoptedsome or all of the provisions of the IBC(Figure 1). The codes can also be adoptedinternationally.
Figure 1. – As of June 9, 2005, 45 states have adopted some or all of the provisionsof the International Building Code.1
In this issue of Engineering SystemSolutions, we provide a summaryof the earthquake (seismic)
provisions affecting HVAC systemsthat are included in theInternational Building Code (IBC).For designated building functions,the IBC can require that systemscritical to life safety and fulfilling thebuilding’s intended purpose remainonline immediately after a seismicevent. This can affect the HVACsystem and require that it be certifiedcompliant for the same seismic designcategory as the building.
Because the IBC is the code for thebuilding structure, it is not typicallya document that is used bymechanical engineers. However, themechanical design professional isresponsible for identifying whetherHVAC equipment is covered underIBC seismic provisions and specifyingproducts that are certified compliant.
HVAC manufacturers are responsiblefor having equipment certifiedcompliant by an approved,independent agency and providingproof of such compliance from theagency. The designer should requireproof of compliance with eachmanufacturer’s bid to avoid the riskof receiving non-compliantequipment.
McQuay has a number of compliantproducts that are certified to meetthese provisions, and the expertise toassist in applying these products. Formore information, contact your localMcQuay representative or visitwww.mcquay.com.
Carol Marriott, P.Eng.Applications ManagerMcQuay International
Step 1 Determine the Seismic Use Group.From Table 1604.5, a hospital with emergency treatment facilities is designated a Seismic use Group III structure.
Step 2 Determine The Component Importance Factor (IP) Of The HVAC EquipmentPer Section 1621.1.6, the Component Importance Factor (IP) = 1.5 because the HVAC system is required toprovide life safety functions and to maintain the continued operation of the facility.
Step 3.1 Determine the Maximum Spectral Response Accelerations (SS and S1) for the area.Per Figure 1615(1) or the software, SS = .271g Per Figure 1615(2) or the software, S1 = .114g
Step 3.2 Determine the Site Class (A to F) and Site Coefficients (Fa and Fv)Because we have no soil analysis, the Code specifies that Site Class D be used for the soil profile. Per Table 1615.1.2(1) or the software, Fa = 1.58 Per Table 1615.1.2(2) or the software, Fv = 2.34
Step 3.3 Calculate the Adjusted Maximum Accelerations (SMS and SM1)SMS = FaSS = 1.58 x .271g = .429gSM1 = FvS1 = 2.34 x .114g = .267g
Step 3.4 Calculate the Design Spectral Response Acceleration Parameters (SDS and SD1)SDS = 2/3 SMS = 2/3 x .429 = .286gSD1 = 2/3 SM1 = 2/3 x .267 = .178g
Step 3.5 Determine the assigned seismic design categoryPer Table 1616.3(1), the Seismic Design Category based on 0.2 second response = C.Per Table 1616.3(2), the Seismic Design Category based on 1.0 second response = D.According to Section 1616.3, the structure shall be assigned the most severe category, which in this case isSeismic Design Category D.
Step 4 a. Determine if the HVAC Equipment is Exempt from Seismic Requirements: The HVAC equipment does not meet any of the criteria for exemption. Therefore, it must meet the same SeismicDesign Category as the structure.b. Calculate the required FP, independent of unit weight, for use in the HVAC equipment specification.To simplify the specification, review and approval process, FP can be calculated independent of equipment weightand specified in terms of a g-force rating. The manufacturer must provide a Certificate of Compliance from anapproved, independent agency that the equipment as a building component, complies with the required FPregardless of size or weight.Determine the associated value of FP. Fp = 0.4apSDSWP x (1 + 2z/h) = 0.4 (2.5)(.286)(1) x (1 + (2)30/30) = 0.515g
(Rp/Ip) (2.5/1.5)Where;• Component amplification factor (ap) = 2.5 from Table 1621.3• Component importance factor (Ip) = 1.5 from Step 2 above• Average roof height (h) = 30 feet • Component response modification factor (Rp) = 2.5 from Table 1621.3.• Design spectral response acceleration at 0.2 seconds (SDS) = .286 from Step 3d above• Component operating weight (Wp) = 1 (reflecting that the calculation is independent of unit weight).• Height in structure at point of attachment of component (z) = 30 because the air handler is located in a
penthouse mechanical room.For this example, the HVAC equipment specification shall reflect that the air handling equipment must becertified compliant to withstand a minimum FP=0.515g
The following illustrates the processfor determining whether a seismic-resistant HVAC system is required tocomply with the IBC and how to statethe requirement in a specificationdocument. For this example, we will
use a 3-story hospital with emergencytreatment facilities located in Atlanta,GA (zip code 30080). To simplify theillustration, we will perform thecalculation for a McQuay air handlerthat is part of a central system. All
other components would require thissame calculation. The figures, tablesand sections referred to below can befound in the printed IBC 2000 or itsaccompanying software (where noted).
The data and suggestions in this document are believed current and accurate at the time of publication, but they are not a substitute for trained, experiencedprofessional service. Individual applications and site variations can significantly affect the results and effectiveness of any information, the reader must satisfyhim/herself regarding the applicability of any article and seek professional evaluation of all materials. McQuay disclaims any responsibility for actions basedon this document.
July 2005 (updated April 2008)
IBC Seismic Requirements andHVAC Systems – A Short CourseThe IBC provides a modern, up-to-datebuilding code addressing the design andinstallation of building systems throughrequirements emphasizing performance.Published by the International CodeCouncil (ICC), this comprehensive codeestablishes minimum regulations forbuilding systems using prescriptive andperformance-related provisions thatcombine the scope of existing modelcodes, such as BOCA and ICBO UniformBuilding Code (UBC).
In much the same way as ASHRAEstandards, the ICC codes are available foradoption – in whole or in part – byjurisdictions throughout the United States.For example, as of June 9, 2005, 45 states,the District of Columbia and the U.S.Department of Defense have adoptedsome or all of the provisions of the IBC(Figure 1). The codes can also be adoptedinternationally.
Figure 1. – As of June 9, 2005, 45 states have adopted some or all of the provisionsof the International Building Code.1
In this issue of Engineering SystemSolutions, we provide a summaryof the earthquake (seismic)
provisions affecting HVAC systemsthat are included in theInternational Building Code (IBC).For designated building functions,the IBC can require that systemscritical to life safety and fulfilling thebuilding’s intended purpose remainonline immediately after a seismicevent. This can affect the HVACsystem and require that it be certifiedcompliant for the same seismic designcategory as the building.
Because the IBC is the code for thebuilding structure, it is not typicallya document that is used bymechanical engineers. However, themechanical design professional isresponsible for identifying whetherHVAC equipment is covered underIBC seismic provisions and specifyingproducts that are certified compliant.
HVAC manufacturers are responsiblefor having equipment certifiedcompliant by an approved,independent agency and providingproof of such compliance from theagency. The designer should requireproof of compliance with eachmanufacturer’s bid to avoid the riskof receiving non-compliantequipment.
McQuay has a number of compliantproducts that are certified to meetthese provisions, and the expertise toassist in applying these products. Formore information, contact your localMcQuay representative or visitwww.mcquay.com.
Carol Marriott, P.Eng.Applications ManagerMcQuay International
Step 1 Determine the Seismic Use Group.From Table 1604.5, a hospital with emergency treatment facilities is designated a Seismic use Group III structure.
Step 2 Determine The Component Importance Factor (IP) Of The HVAC EquipmentPer Section 1621.1.6, the Component Importance Factor (IP) = 1.5 because the HVAC system is required toprovide life safety functions and to maintain the continued operation of the facility.
Step 3.1 Determine the Maximum Spectral Response Accelerations (SS and S1) for the area.Per Figure 1615(1) or the software, SS = .271g Per Figure 1615(2) or the software, S1 = .114g
Step 3.2 Determine the Site Class (A to F) and Site Coefficients (Fa and Fv)Because we have no soil analysis, the Code specifies that Site Class D be used for the soil profile. Per Table 1615.1.2(1) or the software, Fa = 1.58 Per Table 1615.1.2(2) or the software, Fv = 2.34
Step 3.3 Calculate the Adjusted Maximum Accelerations (SMS and SM1)SMS = FaSS = 1.58 x .271g = .429gSM1 = FvS1 = 2.34 x .114g = .267g
Step 3.4 Calculate the Design Spectral Response Acceleration Parameters (SDS and SD1)SDS = 2/3 SMS = 2/3 x .429 = .286gSD1 = 2/3 SM1 = 2/3 x .267 = .178g
Step 3.5 Determine the assigned seismic design categoryPer Table 1616.3(1), the Seismic Design Category based on 0.2 second response = C.Per Table 1616.3(2), the Seismic Design Category based on 1.0 second response = D.According to Section 1616.3, the structure shall be assigned the most severe category, which in this case isSeismic Design Category D.
Step 4 a. Determine if the HVAC Equipment is Exempt from Seismic Requirements: The HVAC equipment does not meet any of the criteria for exemption. Therefore, it must meet the same SeismicDesign Category as the structure.b. Calculate the required FP, independent of unit weight, for use in the HVAC equipment specification.To simplify the specification, review and approval process, FP can be calculated independent of equipment weightand specified in terms of a g-force rating. The manufacturer must provide a Certificate of Compliance from anapproved, independent agency that the equipment as a building component, complies with the required FPregardless of size or weight.Determine the associated value of FP. Fp = 0.4apSDSWP x (1 + 2z/h) = 0.4 (2.5)(.286)(1) x (1 + (2)30/30) = 0.515g
(Rp/Ip) (2.5/1.5)Where;• Component amplification factor (ap) = 2.5 from Table 1621.3• Component importance factor (Ip) = 1.5 from Step 2 above• Average roof height (h) = 30 feet • Component response modification factor (Rp) = 2.5 from Table 1621.3.• Design spectral response acceleration at 0.2 seconds (SDS) = .286 from Step 3d above• Component operating weight (Wp) = 1 (reflecting that the calculation is independent of unit weight).• Height in structure at point of attachment of component (z) = 30 because the air handler is located in a
penthouse mechanical room.For this example, the HVAC equipment specification shall reflect that the air handling equipment must becertified compliant to withstand a minimum FP=0.515g
The following illustrates the processfor determining whether a seismic-resistant HVAC system is required tocomply with the IBC and how to statethe requirement in a specificationdocument. For this example, we will
use a 3-story hospital with emergencytreatment facilities located in Atlanta,GA (zip code 30080). To simplify theillustration, we will perform thecalculation for a McQuay air handlerthat is part of a central system. All
other components would require thissame calculation. The figures, tablesand sections referred to below can befound in the printed IBC 2000 or itsaccompanying software (where noted).
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