Duct Design
ASHRAE Technical Committee 5.2

Herman and Dorothy Behls Travel and Certification Awards

The ASHRAE Foundation and ASHRAE TC 5.2, Duct Design, are pleased to invite applications for the Herman and Dorothy Behls Travel and Certification Awards. TC 5.2 fully funded the endowment to honor the late Mr. Herman Behls, who was a 50-Year Distinguished Service Award member of ASHRAE. He was a respected engineer in the ASHRAE Illinois Chapter, and a longtime contributor to TC 5.2. He led the effort to write the Duct Design Guide, and was instrumental in developing the Duct Fitting Database. Through this endowment, the TC desires to encourage undergraduate and graduate engineering students, as well as ASHRAE YEA members, to continue the legacy and enhance the profound impact of the Behls family on the engineering profession.

Herman and Dorothy Behls Awards Announcement 

Herman Behls Obituary 

A YEA member can complete an application for the following endowment:

• Herman Dorothy Behls HVAC Designer Certification Award Application - Application Deadline is October 15, Annually 
• Intent of Award: Award is for reimbursement of the CHD Certification application fee after successful completion of the exam.
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• - Applicant must be an ASHRAE YEA Member.
• - Applicant will be an active member of a local ASHRAE Chapter, if available.
• - Applicant will demonstrate potential service to the HVAC&R profession.
• - Applicant will demonstrate leadership ability, strong character and a strong work ethic.  

An engineering undergraduate or graduate ASHRAE Student Member can complete an application for the following endowment: 

• Herman Dorothy Behls Travel Award Application - Application Deadline is October 15, Annually 
• Intent of Award: Provide funding for ASHRAE Winter Conference Travel. Conference attendance is one of the best ways to get involved with the organization, to become familiar with the major players in the HVAC&R industry, to network with experienced professionals in the field, and to learn about the ever-developing HVAC&R Industry.
• Recipient Receives:  Total budget for the trip.  If the cost exceeds $1,100, applicants should identify how the additional funding will be achieved (by applicant, student branch, local chapter, or other funding source).
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• - Applicant shall have a cumulative grade point average (GPA) of at least 3.0 on a scale where 4.0 is the highest.
• - Applicant must be an Engineering undergraduate or graduate ASHRAE Student Member
• - Applicant will be a member of a local student ASHRAE branch, if available 
• - Applicant will demonstrate potential service to the HVAC&R profession.
• - Applicant will demonstrate leadership ability, strong character and a strong work ethic.
• - ASHRAE Student member will shadow a member from TC 5.2 during an ASHRAE Winter Conference and attend technical sessions. The student will be encouraged to provide a short write up on their experience at the corresponding ASHRAE Winter Conference.

Technical Committees are responsible for identifying research topics, proposing research projects, selecting bidders, and monitoring research projects funded by ASHRAE. Information about their specific research program is discussed at each TC meeting and at the TC’s Research Subcommittee meeting. Below are the active research projects (RPs) sponsored by TC 5.2:

1682-RP
STUDY TO IDENTIFY CFD MODELS FOR USE IN DETERMINING HVAC DUCT FITTING LOSS COEFFICIENTS
The objective of this research is to develop CFD techniques that are capable of predicting pressure drop in close-coupled round five-gore elbows accurate to within 15% of the experimental loss coefficients. It should investigate the significance of potential effects due to compressibility, variation in thermal properties, surface roughness and other effects.

A summary of past research projects can be found at this link.

ASHRAE members have free access to research project final reports. Non-ASHRAE members can purchase research reports for $30 per article from the ASHRAE Bookstore.

Duct Systems Design Guide - 2021

Essential Guidance for Designing Duct Systems

Duct Systems Design Guide gives engineers and other design professionals the tools to design properly sized duct systems to minimize fan energy consumption, system-generated noise, and the installed cost of ductwork.

Nearly every facet of duct design is covered in detail in this guide: duct layout, fitting selection, system leakage, acoustics, equipment selection, and more. Chapters dedicated to selection and comparison of duct design methods for commercial and industrial duct systems cover the equal friction method, the static regain method, and the constant velocity method. Online access to spreadsheets in Microsoft® Excel® format that can be used to design commercial and industrial duct systems using these duct design methods is also available with this book. The guide also discusses duct system materials and the impacts they have on design and system efficiency, as well as fan-duct system interaction and using the ASHRAE Duct Fitting Database (DFDB).

Duct Systems Design Guide is a best-practices reference for HVAC engineers and designers seeking to develop more energy-efficient, accurate, user-friendly, and cost-efficient HVAC systems. The information detailed in this guide is useful for entry-level engineers and designers who are first learning about duct design fundamentals and also serves as a tool for more experienced engineers and design professionals wishing to refresh their design knowledge

Get these duct systems essentials together and save!
From now through December 31, when you purchase a subscription to the ASHRAE Duct Fitting Database and the newly published Duct Systems Design Guide, you can save 10% with code DFDS21 at checkout! These tools are the perfect combo for HVAC engineers and designers seeking to develop more energy-efficient, accurate, user-friendly, and cost-efficient HVAC systems. Learn more at the ASHRAE Bookstore! 

Complement these with ASHRAE Standard 215-2018 (Reaffirmed 2021), which you can purchase at the ASHRAE Bookstore - ASHRAE 215-2018 (RA 2021)

ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry. ASHRAE publishes the following three types of voluntary consensus standards: Method of Measurement or Test (MOT), Standard Design, and Standard Practice. ASHRAE does not write rating standards unless a suitable rating standard will not otherwise be available. ASHRAE is accredited by the American National Standards Institute (ANSI) and follows ANSI's requirements for due process and standards development. Standards may be purchased at the ASHRAE Bookstore.

The following standards are supported by TC 5.2:

ANSI/ASHRAE Standard 120: Method of Testing to Determine Flow Resistance of HVAC Ducts and Fittings

ANSI/ASHRAE/SMACNA 126: Method of Testing HVAC Air Ducts

ANSI/ASHRAE Standard 215: Method of Test to Determine Leakage Airflows and Fractional Leakage of Operating Air-Handling Systems

Development of Applications

TC 5.2 is involved with the development of applications, such as the ASHRAE Duct Fitting Database internet application and a Duct Sizing Calculator. More information about program development can be found by attending the TC's meetings and in the TC's meeting minutes.

The ASHRAE Handbook is published in a series of four volumes, one of which is revised each year, ensuring that no volume is older than four years. The Handbook can be purchased at the ASHRAE Bookstore by clicking on this link.

HVAC Systems & Equipment: Duct Construction
This chapter covers construction of HVAC and exhaust duct systems for residential, commercial, and industrial applications. Technological advances in duct construction should be judged relative to the construction requirements described here and to appropriate codes and standards. Although the construction materials and details shown in this chapter may coincide, in part, with industry standards, they are not in an ASHRAE standard.

Fundamentals: Duct Design
In this chapter, system design and calculation of a system’s frictional and dynamic resistance to airflow are considered. Chapter 19 of the 2012 ASHRAE Handbook—HVAC Systems and Equipment examines duct construction and presents construction standards for residential, commercial, and industrial HVAC and exhaust systems.

Comment on the Handbook: ASHRAE welcomes your comments on the Handbook or a specific Handbook chapter.  To submit a comment about any aspect or part of the Handbook series, you can use the Handbook Comment Form.

Review a Handbook Chapter: To provide your feedback about a specific Handbook chapter, you can answer the brief survey questions on the Handbook Chapter Review Form.

Technical committees develop and sponsor technical sessions at the winter and annual conferences. Information about their future technical program is discussed at each TC meeting and at the TC’s Program Subcommittee meeting

ASHRAE publishes papers and transactions from presentations at its conference events. In addition, ASHRAE records most of the seminar sessions from its conferences on DVD. These DVDs are ideal for use at chapter meetings, in university courses, or company lunch and learns. Products available from the most recent conference may be found here.

Upcoming Programs

Seminar - ASHRAE Duct Fitting Database and ASHRAE Duct Design Guide

Presented by: ASHRAE Technical Committee 5.2 Duct Design

Date: Monday, February 6th, 2023

Time: 10:30 AM – 12:00 PM EST

Location: Georgia World Congress Center

Room: Room C102

Speaker(s):

• Jamie Fine, Ph.D, P.Eng., RWDI
• Pat Brooks, P.E., SMACNA
• Stephen Idem, Ph.D., Tennessee Tech University
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Duct Fitting Database

Duct Fitting Database App

Duct System Design Guide

Previous programs sponsored or co-sponsored by this TC are as follows.

Available presentations will have a link associated with their titles.

January 2021 ASHRAE Virtual Winter Conference
Seminar on ASHRAE Standard 215
This seminar provided a brief overview of ASHRAE Standard 215, followed by more detailed rationale and background for the standard's procedures and calculations.
1. Why is There a Standard 215?
Larry A. Smith, Member, Linx Industries, Portsmouth, VA
2. ASHRAE Standard 215-2018: Rationale and Background
Craig Wray, P.Eng., Winnipeg, MB, Canada

June 2020 ASHRAE Virtual Annual Conference
YEA Seminar on Duct Design Fundamentals
This seminar addressed the basics of duct design and provided a comprehensive look of the Duct Design Guide.
1. A Comprehensive Look of the Duct Systems Design Guide
Larry A. Smith, Member, Linx Industries, Portsmouth, VA
2. Duct Design Fundamentals
Stephen A. Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN

January 2016 ASHRAE Winter Conference, Orlando
Study to Identify CFD Models for Use in Determining HVAC Duct Fitting Loss Coefficients
Chairs: Stephen A. Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN, & Ahmad K. Sleiti, Ph.D., P.E., Member, Qatar University, Doha, Qatar
The seminar gave a report of the finals results from RP-1682.
1. Experimental Results
Stephen A. Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN
2. CFD Model Results
Ahmad K. Sleiti, Ph.D., P.E., Member, Qatar University, Doha, Qatar

June 2014 ASHRAE Annual Conference, Seattle
Performance of Metal and Fabric Air Dispersion Systems
Chair: Stephen A. Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN
The seminar compared traditional metal duct system performance with metal and textile air dispersion systems. Metal duct systems discharge air to specific zones, resulting in less efficient mixing of air in the occupied space. Air dispersion systems continuously convey discharge air within the space being conditioned, thus providing consistent and uniform air dispersion in the occupied space and resulting in less energy usage. Air dispersion systems are typically made of woven textile material, but they can also be constructed from sheet metal or plastic film. Porous and non-porous options are available. Advantages and disadvantages of air dispersion systems are discussed.
1. Textile Air Dispersion Systems
Kevin Gebke, Member, DuctSox Corporation, Peosta, IA
2. Metal Air Dispersion Systems – An Overview
Scott Hobbs, Member, McGill Airflow, LLC, Renion, WA
3. Design and Construction of Metal Air Dispersion Systems
Bob Reid, Member, Tangible Products, The Woodlands, TX

June 2013 ASHRAE Annual Conference, Denver
Innovative Solutions for Improving Thermal Performance and Efficiency in HVAC&R Applications

Paper 5: CFD Analysis of Pressure Losses in Flat-Oval Duct Fittings
Emir Sirbubalo, Haris Lulic & Milovan Gutovic; Sarajeva, Bosnio

June 2012 ASHRAE Annual Conference, San Antonio
Improvements in HVAC System Energy Efficiency

Paper 3: Laboratory Testing of a Fabric Air Dispersion System
D. Kulkarni, Student Member, A.N. Nalla, S. Idem, Ph.D., Member, & K. Gebke, Member

January 2012 ASHRAE Winter Conference, Chicago
Air-Handling System Leakage: Benefits and Costs of Field Tests
Sponsor: TC 5.2 Duct Design and TC 4.3 Ventilation Requirements and Infiltration
Chair: Stephen A. Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN
SMACNA together with ASHRAE is developing a new standard that will contain test procedures and requirements for total HVAC system air leakage in commercial buildings.  This activity is needed because as much as one third of a system’s airflow can leak through the air distribution system, which in turn causes a loss of comfort and heating and cooling capacity.  System air leakage also significantly increases air conditioning and heating bills, and can contribute to indoor air quality problems.  This seminar focus on the benefits and costs of performing system leakage tests from the perspective of a TAB contractor, an association of sheet metal contractors, and researchers.  Steps needed to achieve widespread reductions in leakage and improved air-handling system efficiency are also presented.
1. Testing for Duct Leakage
Gaylon Richardson, Engineered Air Balance, Spring, TX
2. Energy Impacts of Air-Handling System Leakage in Large Commercial Buildings: Measurements and Simulation
Craig Wray, P.Eng., Oakland, CA
3. The Need for Field Ductwork Leakage Tests
Mark Terzigni, SMACNA, Chantilly, VA
4. Duct Leakage: Measured Magnitudes and Calculated Impacts
Mark Modera, Ph. D., P.E., Fellow ASHRAE, University of California Davis, Davis, CA.

Technical Paper Session 9
Pressure Loss Measurements in Air Duct Junctions
Chair: Herman Behls, Behls & Associates, Arlington Heights, IL
The first paper of this session reports results from RP-1488.  The purpose of that study was to obtain experimental loss coefficient data for various diverging flow flat oval tees and laterals.  The results for branch loss coefficient data for tee and lateral fittings were shown to fit a power law correlation developed previously.  The main loss coefficient data could not be correlated by power law.  The average value for the main loss coefficient for straight body tees was found to be -0.167.  Likewise the main loss coefficient for straight body laterals was found to be -0.216.  This session also presents a method of correlating main and branch loss coefficients for saddle tap tees operated in the converging and diverging flow modes.  The goal of that test program was to determine if the saddle tap tee is as efficient air moving junction and if so to include the resulting loss coefficient data in the ASHRAE Duct Fitting Database (DFDB).
1. Measurements of Flat Oval Diverging Flow Fitting Loss Coefficients
Daniel Gibbs, Associate Member & Stephen A. Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN
2. Laboratory Testing of Saddle Tap Tees to Determine Loss Coefficients
Ananth Nalle & Stephen A. Idem, Member, Tennessee Technological University, Cookville, TN

June 2010 ASHRAE Annual Conference, Albuquerque
Technical Paper Session 1: Leakage and Pressure Loss Measurements in Duct Systems
Chair: Stephen A. Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN
The influence of test section entrance conditions on straight flat oval duct apparent relative roughness was studied. The apparent relative roughness obtained using a test setup in compliance with Standard 120 was considerably lower than the value of relative roughness obtained with a test setup that did not conform to the standard. Experiments were performed to determine the absolute roughness of three corrugated circular spiral ducts. Pressure loss predictions for corrugated and standard spiral ducts are compared. Measurements to determine the leakage class for three cross sections of sealed and unsealed flat oval ducts under positive and negative internal pressures were conducted. The leakage data were found to be a power law function of static pressure difference between the interior and the exterior of the duct.
1. Influence of Test Section Entrance Conditions On Straight Flat Oval Duct Apparent Relative Roughness
Swapnil Khaire & Stephen A. Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN
2. Measured and Predicted Pressure Loss in Corrugated Spiral Duct
Daniel Gribbs, Associate Member & Stephen A. Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN
3. Flat Oval Duct Leakage Class Measurement
Daniel Gribbs, Associate Member & Stephen A. Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN

January 2009 ASHRAE Winter Conference, Chicago
Transactions Session 2:  Laboratory Testing of Duct Fittings to Determine Loss Coefficients
Chair: Stephen A. Idem. Ph.D., Member, Tennessee Technological University, Cookville, TN
ASHRAE RP-1319, an experimental program was initiated to determine the friction factor in circular corrugated galvanized spiral ducts.  This session presented the results of the project, which performed an analysis to calculate the required diameter of corrugated ducts required to convey the same volumetric flow rate of air at the same pressure loss per unit length as non-corrugated spiral ducts.  Likewise pressure loss coefficients were determined for the following types of flat oval elbows having various aspect ratios: 5-gore 90° easy bend with and without vanes, and mitered 90°hard bend with and without vanes.
1. Pressure Loss of Corrugated Spiral Duct
Devendra Kulkarni, Student Member; Swapnil Khaire, Student Member; & Stephen Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN
2. Measurement of of Flat Oval Elbow Loss Coefficients
Devendra Kulkarni, Student Member; Swapnil Khaire, Student Member; & Stephen Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN
3. Influence of Aspect Ratio and Hydraulic Diameter on Flat Oval Elbow Loss Coefficients
Devendra Kulkarni, Student Member; Swapnil Khaire, Student Member; & Stephen Idem, Ph.D., Member, Tennessee Technological University, Cookville, TN

ASHRAE Technical FAQs are provided as a service to ASHRAE members, users of ASHRAE publications, and the general public. While every effort has been made to ensure their accuracy and reliability, they are advisory and provided for informational purposes only, and in many cases represent only one person’s view. They are not intended and should not be relied on as an official statement of ASHRAE. Technical questions not addressed may be submitted to the ASHRAE Technical Services department at tse@ashrae.net.

What is ASHRAE's recommendation regarding duct cleaning? (19)

What is ASHRAE's position on the use of internal duct lining? (20)

Does ASHRAE have recommendations for return air plenum design? (55)

What is ASHRAE's position on the use of fiberglass internal insulation in ducts or fiberglass duct board? (64)