Ventilation and IAQ Standards
ASHRAE 62.1 is titled “The Standards for Ventilation and Indoor Air Quality.” As the name suggests, this standard establishes minimum ventilation and indoor air quality (IAQ) requirements to reduce occupant exposure to air pollutants that lead to adverse health effects. This standard applies to all commercial and institutional buildings, but does not cover industrial processes with special exhaust requirements or low-rise residential buildings (see ASHRAE 62.2 for that). Some of the requirements this standard addresses include:
- Outdoor air ventilation design and rates
- System controls (Direct-Controlled Ventilation (DCV))
- Air distribution and acceptable IAQ
- Exhaust and filtration requirements
- Contaminant control
- Operations and maintenance
ASHRAE 62.1 Compliance Methods
All commercial facilities that fall within the umbrella of this standard are required to comply with the requirements. Poor compliance can lead to impacted occupant comfort, increased health complaints, failed inspections, and excessive energy consumption. Adherence to ASHRAE 62.1 is important for facility managers and service providers alike so they understand the accurate settings and operations necessary to keep occupants healthy and buildings in compliance.
To be compliant with ASHRAE 62.1, you must be able to show specific proof. Things typically required for inspections include:
- Compliance pathway declaration
- Ventilation calculations
- Mechanical design drawings
- TAB (Testing, Adjusting, and Balancing) and commissioning reports
- Control sequences
- Filtration documentation
- O&M and maintenance records
The specifics of each item listed above depend on the compliance pathway you are using. ASHRAE 62.1 lays out 3 different paths that facilities can take for compliance. We’ll explore them more below.
Ventilation Rate Procedure (VRP)
This is also referred to as the ventilation method and is the most common approach, adopted for its simplicity, consistency, and code acceptance. This is a prescriptive method that calculates the minimum outside air required based on the number of people, the use of the space, and the facility type. To prove compliance with this method, you must show calculations for occupancy category, people outdoor air rate (cfm/person), area outdoor air rate (cfm/ft2), and zone and system ventilation effectiveness. This is the default method used for commercial offices, schools, retail and mixed-use buildings, and non-critical healthcare facilities.
VRP influences a few key things: minimum outdoor air (OA) damper positions, equipment sizing, and energy use, particularly in hot and cold climates. VRP does not measure actual IAQ or adapt to real-time conditions, unless paired with controls. VRP is not ideal for facilities that have large floor areas but low occupancy, like data centers or self-storage facilities. There’s a large discrepancy between the area-based rate and the area-based rate that can skew the calculation and lead to excessive ventilation.
IAQ Procedure (IAQP)
This method is performance-based and allows you to reduce the amount of outside air used by implementing systems that reduce contaminants. To be compliant with IAQP, you must show proof that contaminant levels remain acceptable through design contaminant identification, air cleaning effectiveness, monitoring or analytical modeling, and occupant satisfaction criteria. IAQP is typically used with VRP ventilation rates are energy-prohibited, unusual contaminants are present, the space employes advanced filtration or air cleaning, or you need to justify reducing outdoor air. Facilities that use IAQP are often laboratories, healthcare spaces, industrial or process-driven buildings, or high-performance or net-zero buildings. Another good use case for IAQP is gymnasiums. Gyms experience fluctuating occupancy and high contaminant loads during peak use. IAQP can help reduce minimum ventilation during low-use periods while still working alongside DCV strategies during high-use periods.
There are a variety of benefits that could lead to choosing IAQP over VRP. One is enhanced energy efficiency. By reducing the amount of outside air required, you’re also reducing the amount of energy needed to treat it. This makes IAQP an ideal method for facilities in cold climates, as less heat is required for the outdoor air. Another benefit is improved health outcomes and occupant satisfaction, as you’re targeting and mitigating specific contaminants of concern. Finally, this method has greater design flexibility. Buildings with large ventilation rates may need large centralized systems, but the building’s size or layout could make it difficult to fit equipment and ductwork in the space, so IAQP can be a good alternative. While this method is more flexible than VRP, it does require heavy monitoring, validation, documentation, and analysis.
Natural Ventilation Procedure (NVP)
This method allows for natural ventilation, such as using gaps in the building, windows, and/or doors to provide outside air, but only if a building meets certain criteria. Specific requirements are set to ensure compliance and that the proper amount of ventilation can occur. These include a certain number and size of operable openings, their locations and distributions, and occupants that can control them. As this method assume windows or vents will be used during occupied hours, climate suitability is another requirement. Buildings in areas with commonly low temperatures, humidity extremes, air quality impacts from ozone, wildfire smoke or traffic pollution, or noise and security constraints would not qualify. In essence, if windows must be closed the majority of the time, NVP cannot be used. Common facilities that can comply with NVP are offices, classrooms, and residential or senior living facilities.
HVAC Parts Required for ASHRAE 62.1 Compliance
To remain compliant with ASHRAE 62.1, your HVAC systems need to continue to operate efficiently, so regular maintenance is crucial. Sometimes, that involves replacing parts that have failed or wear over time. Here are some common parts needed to keep in compliance: