ASHRAE 62.1 keeps evolving, and state code adoption is pulling more of the industry into the latest expectations. Engineers, designers, and contractors are seeing the same pressure points on project after project. Owners want stronger indoor air quality outcomes, energy costs remain a priority, and permitting teams want documentation that makes compliance easy to verify. Success comes from treating 62.1 as a design process, not a spreadsheet exercise.

This article focuses on three realities shaping the industry right now. The tradeoffs between efficiency, IAQ, and cost are getting sharper. Existing buildings are in a retrofit crunch. Compliance increasingly depends on designing with both energy and health in mind, supported by documentation and operational proof.

What Changed and Why It Matters

ASHRAE 62.1 still supports the Ventilation Rate Procedure VRP that most teams have used for years. Recent revisions and related guidance have also clarified and promoted the Indoor Air Quality Procedure, often called IAQP. This design approach gives teams a code-supported pathway to meet the intent of acceptable indoor air quality by targeting specific contaminants with validated air cleaning, paired with appropriate reduction in outdoor air ventilation.

Verification is the other major theme. Code adoption is increasingly aligned with approaches that are measurable and documentable. Owners and inspectors want to see that systems do what the design says they will do. That expectation affects controls, commissioning, and the quality of the handoff to operations.

A Practical Decision Framework for VRP Versus IAQP

Most teams make better decisions when they choose their compliance path early. These cues help.

Choose the VRP when the building’s outdoor air volumes are required to pressurize the building,  there aren’t excessive conditioning requirements, or occupancy levels stay consistent and you aren’t designing for a maximum occupancy that is only present occasionally in the space. 

Choose IAQP when outdoor air drives unmanageable energy loads, equipment choice is based on an occupancy level that only sporadically reached, retrofit constraints limit equipment changes, contaminant-specific control is needed, or the owner wants measurable outcomes supported by monitoring. IAQP can be a strong fit in hot, humid climates, high-occupancy spaces, and buildings with limited mechanical room capacity.

Both pathways need sound engineering. IAQP typically requires earlier coordination on documentation, controls, and verification, so teams benefit from planning it at schematic design instead of late in CDs.

The Tradeoffs Engineers Are Managing Right Now

The tension between energy and indoor air quality is rarely theoretical. More outdoor air increases heating and cooling loads. Higher-efficiency filtration can increase pressure drop. Fan efficiency limits can tighten the selection window. Controls and sensors add scope, yet they also reduce risk by proving performance.

Practical projects treat these pressures as connected. Filtration upgrades should be evaluated against fan curves and available external static pressure. Outdoor air targets should be evaluated against humidity control,coil capacity, and outdoor pollutants. Air cleaning strategies should include maintenance requirements and how the system proves performance over time.

Cost conversations go better when the team quantifies impacts. Outdoor air reductions translate into predictable load reductions, and therefore lower equipment size requirements. Pressure drop translates into predictable fan energy. Monitoring reduces compliance risk and can shorten disputes during acceptance.

The Retrofit Crunch and Why It Changes Everything

The biggest challenge is not new construction. The hardest work is happening in existing buildings. Many facilities were designed under older assumptions, with systems that already operate near their limits. Ductwork may be undersized. Fan capacity may be constrained. Control sequences may be outdated. Maintenance history may be uneven. These constraints collide with updated standards and owner expectations for better air quality. Retrofits also face practical obstacles, such as tenants, costly downtime and limited space in mechanical rooms. 

In that environment, IAQP can become a valuable tool because it supports design flexibility. Instead of forcing every building into a prescriptive outdoor air approach that may require major equipment replacement, engineers can pursue verified air quality outcomes through a combination of measures. Enhanced filtration, targeted air cleaning, and improved controls can deliver meaningful improvements without incurring the cost of a full system overhaul.

This does not eliminate the need for ventilation. It changes how ventilation is balanced against other strategies and how performance is demonstrated. Verification becomes central. Monitoring confirms whether the system delivers the intended outcome after occupancy and after wear begins to accumulate.

Why Documentation and Validation Matter More Than Ever

Updated standards and code adoptions are increasingly emphasizing documentation, third-party validation, and clarity for inspectors and owners. This trend reduces risk for engineers, provided the design approach is well supported.

IAQP helps by defining contaminants of concern and establishing a methodology for acceptable exposure. It also requires the use of air-cleaning devices with third-party performance ratings. The goal is to move away from claims that are difficult to verify in the field and toward a shared language that engineers, owners, commissioning teams, and code officials can rely on.

Closed-loop control is part of that progression. If the system can monitor indoor conditions and respond in operation, the design becomes more resilient to changes in occupancy, outdoor conditions, and maintenance variability. Building automation integration also supports compliance by producing trend data and reports that demonstrate performance over time.

What to Ask Manufacturers on Any Project

Manufacturers have a role in helping the industry meet updated expectations without increasing burden on facility teams. Several capabilities are becoming table stakes.

Products should be designed with current standards in mind, including long-life filtration options, validated contaminant removal performance, and clear documentation that supports IAQP workflows. Solutions should support closed-loop control so building operators can measure performance against a target rather than relying on periodic spot checks.

Installation and serviceability matter, especially in retrofit contexts. Low-voltage modular wiring, straightforward access, and reliable connectivity to building management systems reduce labor time and commissioning friction. Protocol support for common platforms such as BACnet and Modbus helps ensure interoperability in mixed-vendor environments.

Maintenance requirements should be realistic. Longer-life filters, clear status indicators, and in-operation monitoring reduce the risk that performance declines unnoticed. A system that performs well in a lab but fails under real maintenance conditions creates cost and credibility problems for everyone involved.

Key Takeaways for the Next Project

ASHRAE 62.1 compliance is increasingly outcomes-focused and verification-driven. Projects that succeed treat energy and air quality as co-equal design requirements. Retrofits benefit from sequencing and measurement before major replacement decisions. IAQP can be a practical path when outdoor air drives unsustainable energy loads or when existing systems cannot support prescriptive approaches.

Start with three steps on the next job. Confirm which code edition applies and choose a compliance path early. Model the energy and static impacts of filtration and ventilation decisions. Design the monitoring, controls, and commissioning plan as part of the core scope.

That approach keeps compliance achievable, reduces owner risk, and helps buildings deliver the performance the new standards are designed to support.

By: Audwin Cash, CEO, GPS Air

https://gpsair.com