Ventilation Requirements and Infiltration
ASHRAE Technical Committee 4.3

Scope of TC 4.3

TC 4.3 is concerned with ventilation requirements and the analysis of infiltration, airflow around buildings, exhaust, and the re-entry of exhaust, including their integration interactions with indoor air quality and energy calculations for buildings and HVAC system design and operation performance and energy consumption.


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.

Fundamentals: Ventilation & Infiltration
This chapter addresses commercial and institutional buildings, where ventilation concerns usually dominate (though infiltration should not be ignored), and single- and multifamily residences, where infiltration has always been considered important but ventilation issues have received increased attention in recent years. Basic concepts and terminology for both are presented before more advanced analytical and design techniques are given. Ventilation of industrial buildings is covered in Chapter 31 of the 2011 ASHRAE Handbook—HVAC Applications. However, many of the fundamental ideas and terminology covered in this chapter can also be applied to industrial buildings.

Fundamentals: Airflow Around Buildings
This chapter provides basic information for evaluating wind-flow patterns, estimating wind pressures, and identifying problems caused by the effects of wind on intakes, exhausts, and equipment. In most cases, detailed solutions are addressed in other chapters. Related information can be found in Chapters 11, 14, 16, and 36 of this volume; in Chapters 31, 32, 45, 47, and 53 of the 2011 ASHRAE Handbook—HVAC Applications; and in Chapters 30, 35, and 40 of the 2012 ASHRAE Handbook—HVAC Systems and Equipment. This chapter mainly covers equipment and systems that dehumidify air rather than those that dry other gases or liquids. Both liquid and solid desiccants are used; they either adsorb water on the desiccant’s surface (adsorption) or chemically combine with water (absorption).

The ASHRAE HVAC FUNDAMENTALS HANDBOOK may be purchased from the on-line bookstore by clicking on the highlighted text.

HVAC ApplicationsBuilding Air Intake and Exhaust Design
Fresh air enters a building through its air intake. Likewise, building exhausts remove air contaminants from a building so wind can dilute the emissions. If the intake or exhaust system is not well designed, contaminants from nearby outside sources (e.g., vehicle exhaust, emergency generator, laboratory fume hoods on nearby buildings) or from the building itself (e.g., laboratory fume hood exhaust) can enter the building with insufficient dilution. Poorly diluted contaminants may cause odors, health impacts, and reduced indoor air quality. This chapter discusses proper design of exhaust stacks and placement of air intakes to avoid adverse air quality impacts. Chapter 24 of the 2013 ASHRAE Handbook—Fundamentals more fully describes wind and airflow patterns around buildings. Related information can also be found in Chapters 8, 17, 32, 33, and 34 of this volume, Chapters 11 and 12 of the 2013 ASHRAE Handbook—Fundamentals, and Chapters 29, 30, and 35 of the 2012 ASHRAE Handbook—HVAC Systems and Equipment.

The ASHRAE HVAC APPLICATIONS HANDBOOK may be purchased from the on-line bookstore by clicking on the highlighted text.

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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.

ASHRAE Annual Meeting - Montreal, Canada    June 25-29, 2011
Seminar 5: Numerical Methods for Predicting Outdoor Dispersion from Exhaust Stacks 
Sponsor: 4.3 Ventilation Requirements and Infiltration and 9.10 Laboratory Systems
Chair: Michael Ratcliff, Ph.D., P.E., Member, RWDI, Redlands, CA
Exhaust stacks emit pollutants that may be re-entrained into building outside air intakes, thus potentially creating indoor air pollution problems. These issues can be important for central plants, boiler exhausts, kitchen exhausts, and laboratories. Numerical methods, ranging from simple algebraic equations to computational fluid dynamics (CFD) have long been available as an alternative to wind tunnel modeling of exhaust stacks and dispersion of pollutants. This seminar explores recent trends and the current state of the art in numerical methods. CFD and simple equations are covered. Comparisons are made to some wind tunnel modeling as well.
1. Updated Dispersion Model for the ASHRAE Applications and Lab Design Handbooks, Brad Cochran, Member, CPP,
Fort Collins, CO
2. CFD Approaches to Predicting Dilution from Exhaust Stacks in Urban Areas, Ted Stathopoulos, Ph.D., P.E., Member 1, Mauricio Chavez 1 and Ali Bahloul, Ph.D.2, (1)Concordia University, Montreal, QC, Canada, (2) IRSST( Institut de recherche Robert-Sauve en sante et en securite du travail), West Montreal, QC, Canada
3. Evaluation of Several Simple Numerical Methods Against Wind Tunnel Modeling, Michael Ratcliff, Ph.D., P.E., Member, RWDI, Redlands, CA


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.

This TC has the following Research projects in progress:

SSPC 62.2, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings. Co-sponsored by:
TC 4.3, Ventilation Requirements & Infiltration
The results from this project will help ASHRAE members (including HVAC designers, IAQ consultants, researchers and other professionals) to better design low-rise residential buildings to improve occupant comfort, health and safety.  The results will be particularly useful to SSPC62.2 and Guideline 24 consideration of ventilation requirements for attached garages.

The primary objective of this RP is to provide a simple procedure for calculating the minimum distance required between the outlet of an exhaust system and the outdoor air intake to a ventilation system.  The procedure shall be developed from existing and new research.


 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.

ASHRAE Guideline 24: Ventilation and Indoor Air Quality In Low-Rise Residential Buildings
ASHRAE Guideline 28: Air Quality Within Commercial Aircraft
ANSI/ASHRAE Standard 62.1: Ventilation for Acceptable Indoor Air Quality
ANSI/ASHRAE Standard 62.2: Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings

This TC is Cocognizant for the following standards:
ANSI/ASHRAE Standard 161: Air Quality Within Commercial Aircraft
ANSI/ASHRAE Standard 193: Method of Test for Determining the Airtightness of HVAC Equipment

Other Activities

TIP: If MTG involvement add here otherwise leave blank.

MTG.ISPAQE: Indoor Swimming Pool Air Quality and Evaporation
This MTG will coordinate  the research project which will assess/identify the factors affecting air quality problems at indoor swimming pools including: air handling/ air distribution system design and operation; water quality/water chemistry;  pool water treatment operation and maintenance; pool types( flat water, agitated water, hot water); bather load; and evaporation rates of indoor pools to recommend changes to the ASHRAE 62.1 ventilation rate and update the evaporation formula in the HVAC Applications ASHRAE Handbook.


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

What is the current ASHRAE ventilation standard? (1)
How much ventilation is required by code for my application? (8)
How many air changes are recommended for my application? (9)
How much ventilation is required for my industrial ventilation application? (10)
What is the recommended humidity level for occupied spaces? (12)
I don't know which listing to use in Standard 62.1's Minimum Outside Air Ventilation Rate Table for a space in the building that I am designing. Can ASHRAE tell me which listing to use? (27)
How can I tell if my building is a 'sick building'? (29)
What is the allowable level of carbon monoxide in an occupied space? (34)
What is the allowable level of carbon dioxide in an occupied space? (35)
What are the allowable levels of contaminants in the air in an occupied space? (36)
Who enforces the requirements for acceptable levels of contaminants in air in commercial buildings? (37)
What new recommendations regarding indoor air quality is ASHRAE presently developing? (44)
What research is ASHRAE conducting regarding indoor air quality? (45)