ASHRAE 62.1 is the reference US standard for ventilation in commercial, institutional and multifamily common spaces. It gives the outdoor air a zone needs per person and per unit area, plus rules on filtration, exhaust and humidity. Aqueduct's view is on the ASHRAE 62.1 compliance page.

Is CO2 a direct measure of air quality under ASHRAE 62.1?

CO2 mainly indicates how much outdoor air each occupant receives. It says nothing about particles, VOCs or carbon monoxide, which need their own sensors. That is why CO2 monitoring is usually paired with particulate and VOC sensing when a building wants a full indoor air picture.

Is ASHRAE 62.1 mandatory?

Only where a building code, contract or rating system adopts it, and the adopted edition is often older than 2025, so check the local code before designing to the newest text. LEED and WELL both reference it, which brings many voluntary projects into its scope.

How does ASHRAE 62.1 relate to ASHRAE 241?

ASHRAE 62.1 sets everyday ventilation for acceptable air quality. ASHRAE 241 adds a separate target for equivalent clean airflow during periods of elevated infection risk, met by outdoor air, filtration or air cleaning together. A building can meet 62.1 and still fall short of 241.

Glossary

Air quality standards

What is ASHRAE 62.1?

Definition

ASHRAE 62.1 is the ASHRAE standard Ventilation and Acceptable Indoor Air Quality, which sets minimum ventilation rates and related measures to limit health risks for building occupants.

Where it applies

It covers spaces intended for human occupancy, except dwelling units where occupants are nontransient, which ASHRAE 62.2 handles. Mechanical engineers design to it, and building codes and LEED reference it, so the edition a project must meet depends on the code its jurisdiction has adopted. The standard offers three design routes: the Ventilation Rate Procedure, the IAQ Procedure and the Natural Ventilation Procedure.

What the 2025 edition changed

ANSI/ASHRAE 62.1-2025 is the current edition, per ASHRAE. It adds:

Additional humidity control requirements
Mandatory adjustments for air density
Demand control ventilation control sequences
Emergency control requirements for ventilation systems
New calculation methods for exhaust airflow, separation distances and filter efficiency

Checking delivered ventilation zone by zone

Design calculations say what outdoor air a zone should get. aQ AirSafe shows what happened: CO2 per zone overlaid with occupancy, and CO2 exposure in zone-hours, so a zone that is crowded and stale stands out from one that is merely empty. A demand controlled ventilation rule can then adjust outdoor air where control is enabled, with owner approval, and command history records each change.

What is ASHRAE 62.1?

Where it applies

What the 2025 edition changed

Checking delivered ventilation zone by zone

ASHRAE 62.1: common questions

See Aqueduct on your own facility.