Seismic Certification

The 2009 International Building Code (2009 IBC) incorporates standards for the design of non-structural components subject to seismic events, including HVAC equipment and fans. 

These standards go beyond the need for position retention of components; they include certification of the mechanical equipment itself. The 2009 version of The International Building Code is the latest version to be released; however, regardless of version, the International Building Code (IBC) has been adopted on the state or local level in all 50 states. 

There are three ways in which a component can be seismic certified per the 2009 IBC.

  1. Shake table test
  2. Three-dimensional tests by an analytical method using dynamic characteristics and forces
  3. The use of experience data (historical data demonstrating acceptable seismic performance)


The Office of Statewide Health Planning and Development (OSHPD) is one division within the California Health and Human Services Agency. Their objective is to assure the safety of buildings used in providing healthcare. Though OSHPD enforces building standards for health care facilities per the California Building Code, this code closely reflects the standards presented by the 2009 IBC.

For active parts or energized equipment, OSHPD only accepts seismic certification by way of shake table testing or experience data. OSHPD allows certification of an entire product line by shake table testing the largest and smallest configuration of a product. This certification is known as OSHPD Special Seismic Certification Preapproval (OSP).

Greenheck Testing

Seismic Table Test of Centrifugal Fan Model 73-AFSW

To best encompass the requirements of both the 2009 IBC and OSHPD, seismic certified fans are shake table tested at an independent test facility in accordance with ICC-ES AC 156 and under the responsible charge and review of a California Structural Engineer. Greenheck’s tests incorporated the most severe seismic conditions anywhere in the United States including the most severe spectral response accelerations (SDS = 2.28), an Importance Factor of 1.5, all Site Classes (F being the most severe), all Occupancy Categories (IV- essential facilities), and all Seismic Design Categories (F being the most severe).

Testing equipment for the worst case scenarios allows Greenheck to supply a seismic certified fan to a job anywhere in the United States, regardless of location. For projects presided over by OSHPD, please reference the table below for a listing of Greenheck equipment that meets Special Seismic Certification Preapproval.

The chart below lists the applicable information for each of the certified models. A complete certification report can found on the OSHPD website (


Fan Model OSHPD Number Anchorage SDS (G) z/h
BISW/AFSW* OSP-0113-10 Base mounted, spring isolated < 0.25 in. air gap 2.28 1
LFC OSP-0105-10 Hanging 1.50 1
SQ/BSQ OSP-0113-10 Base mounted or suspended with isolators 2.28 1
SFD/SFB/SWB OSP-0113-10 Base mounted with isolators 2.28 1
RE2 OSP-0113-10









Base mounted on roof curb ≤ 24 in. tall

2.28 1
RS2 OSP-0113-10 2.28 1
RCE3 OSP-0113-10 2.28 1
RCS3 OSP-0113-10 2.28 1
RPDR OSP-0113-10 2.28 1
RBE OSP-0113-10 2.28 1
RBCE OSP-0113-10 2.28 1
RBS OSP-0113-10 2.28 1
RBCS OSP-0113-10 2.28 1
RBF OSP-0113-10 2.28 1
RBCF OSP-0113-10 2.28 1
RPBR OSP-0113-10 2.28 1
RBUMO OSP-0113-10 2.28 1
RSF/RSFP OSP-0113-10 2.28 1
CUE/CUBE OSP-0148-10 2.28 1
CW/CWB OSP-0148-10 2.28 1
G/GB OSP-0148-10 2.28 1
USGF OSP-0148-10 2.28 1
QEI/QEID OSP-0223-10 Base Mounted and Ceiling Hung with Spring Isolators 2.28 1
Vektor-H OSP-0223-10 Rigid Curb Mount 2.28 1


*Note: Models BISW and AFSW are only certified for Arrangements 9 and 10, class I and II.

Below is a Seismic Design Category Reference Map. This map can be used as a general guide to the likely Seismic Design Category present in a region. Note that this map is to be used for reference purposes only and assumes site class of D (Stiff soil per IBC-2009) at all locations. Always consult with the structural engineer of record for site specific conditions of the job and Seismic Design Category.

Seismic Design Category Map

Click here to view larger image

The Seismic Design Category Reference Map, which is based on USGS mapped ground accelerations using a Soil Site Class D, is used with the permission of The VMC Group.

Isolator and Curb Mounted Fans
Greenheck Fan models were tested using a variety of seismic rated isolators or Greenheck curbs throughout the shake table testing process. Even though the units were tested and successfully passed the certification process, the isolators and curbs are external to the equipment and are excluded from the OSHPD Special Seismic Certification Preapproval (OSP). The OSP numbers only certify the fan equipment.

By excluding the isolators and curbs from the certification, any seismically rated isolator or curb with equivalent strength and stiffness to those tested can be used with the fan equipment. This allows the customer to use their seismic isolator vendor for an entire job versus being locked into the exact model used on the fan during the tests. OSHPD pre-approved isolators are certified under a separate OPA number.

While the fans must be mounted in accordance with how they were tested, the responsibility of which isolation type, size, and fastener requirement resides with the structural engineer of record on the job.  



RSS Youtube LinkedIn Facebook