ASHRAE Standard 62.1
ASHRAE Standard 62.1-2022 titled "Ventilation and Acceptable Indoor Air Quality" provides information about the outdoor air ventilation rates that are needed in buildings based on the type of spaces. It includes several different methods. With buildings being built to more stringent energy codes, the supply and conditioning of outdoor air becomes a very important contributor to the overall energy consumption of many buildings. Given the importance of outdoor air, a modeler of commercial buildings should become familiar with the requirements of 62.1 and the various paths available.
Two important energy efficiency measures to consider for high-performance buildings are both enabled by alternative paths through Standard 62.1:
- Monitoring air quality is often combined with air cleaning devices to reduce the amount of outdoor air required.
- Natural ventilation is used to supply the needed outdoor air.
Previous versions of Standard 62.1 were titled "Ventilation for Acceptable Indoor Air Quality," a subtle change of a "for" into an "and" but one that changes the focus of the standard.
Purpose and Scope
The official purpose and scope are shown below:
1. PURPOSE
1.1 The purpose of this standard is to specify minimum ventilation rates and other measures intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects.
1.2 This standard is intended for regulatory application to new buildings, additions to existing buildings, and those changes to existing buildings that are identified in the body of the standard.
1.3 This standard is intended to be used to guide the improvement of indoor air quality in existing buildings.
2. SCOPE
2.1 This standard applies to spaces intended for human occupancy within buildings except those within dwelling units in residential occupancies in which occupants are nontransient.
2.2 This standard defines requirements for ventilation and air-cleaning-system design, installation, commissioning, and operation and maintenance.
2.3 In addition to ventilation, this standard contains requirements related to certain contaminants and contaminant sources, including outdoor air, construction processes, moisture, and biological growth.
2.4 This standard does not prescribe specific ventilation rate requirements for:
Spaces that contain smoking or that do not meet the requirements in the standard for separation from spaces that contain smoking
Patient care areas not listed in this standard
Laboratories with hazardous materials
Procedures
Section 6 of the standard establishes the three different procedures that can be used:
- Ventilation Rate Procedure
- Indoor Air Quality Procedure
- Natural Ventilation Procedure
The most common procedure used for determining outdoor air requirements is the Ventilation Rate Procedure described in Section 6.2. and is based mainly on a large table of people's outdoor air rates expressed in cfm/person and in area outdoor air rates expressed in cfm/sqft for a long list of occupancy categories. This establishes the breathing zone requirement, but translating that into the amount of outdoor air needed at the intake can be complicated, especially for multiple-zone recirculation systems. The standard has established terminology that is used throughout the industry to understand different airflows and effectiveness. Most modern BEM software have inputs related to ventilation that are directly or related to this terminology and also often have output reports that report using this same terminology. Based on this, studying the various equations in the ventilation rate procedure and coming to an understanding of the different equations and terms is important to any modeler for commercial buildings.
High-performance buildings may use either the Indoor Air Quality or Natural Ventilation procedure in Section 6 of Standard 62.1 as a method of achieving acceptable air quality while still reducing energy use.
Other portions of the Standard 62.1 include
- Outdoor Air Quality – providing an understanding of what to do in areas with poor outdoor air quality
- Systems and Equipment – describing the configuration and engineering requirements of portions of buildings, systems, and equipment related to providing outdoor air
- Construction and System Start-Up – requirements related to these initial stages, including testing
- Operation and Maintenance – describes the regular procedures needed to keep an outdoor air system operating as expected over the building's lifetime, including inspection and maintenance.
In addition, Standard 62.1 includes many appendices, several of which are referenced as requirements for specific portions of the procedures and some that are informative and provide extra information beyond the requirements.
Additional Resources
Main ASHRAE page on 62.1 and 62.2 (residential)
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