The Indoor Air Quality Procedure (IAQP) naturally begins with the mechanical engineer. It is a performance-based ventilation design approach within ASHRAE Standard 62.1, and applying it requires project-specific analysis of contaminants, sources, concentration targets, outdoor air and air-cleaning performance. 

Yet the issues the engineer is asked to solve rarely stay solely within the mechanical scope. Outdoor airflow can affect equipment capacity, duct routing, ceiling space, roof loading, electrical demand, energy use, construction timelines and long-term operations. When those pressures begin to shape the project, IAQP may provide another design path. 

Architecture and Structure: When the Design Has to Fit 

Architectural and structural constraints often arrive at the mechanical engineer as a simple problem: the conventional ventilation approach does not fit. Larger ducts may compete for plenum space. Additional outdoor-air pathways may require larger shafts, louvers or equipment rooms. On an existing building, the roof may not be able to support larger or added HVAC equipment without reinforcement. 

When the analysis supports it, IAQP can combine outdoor air with verified air cleaning to meet the required IAQ outcome. That may give the engineer more flexibility around duct routing, equipment placement and capacity, helping the architectural and structural teams work within the building rather than redesigning it around the ventilation system. 

Electrical and Sustainability: When Capacity Is Tight 

Electrical capacity is becoming a more visible constraint as buildings add electrified HVAC equipment, EV charging, technology and other new loads. Outdoor air also has to be heated, cooled and often dehumidified. Depending on the climate and system, that conditioning load can affect both equipment selection and the electrical infrastructure supporting it. 

A project-specific IAQP analysis may reveal an opportunity to reduce the load associated with conditioning outdoor air. Air-cleaning equipment has its own power requirements, so the useful comparison is the whole system: outdoor air, conditioning, air cleaning, controls and operating schedules considered together. 

That same analysis can help sustainability and energy teams evaluate IAQ and decarbonization together. Instead of treating outdoor airflow as the only input, the team can compare how different clean-air strategies affect both IAQ performance and modeled energy use. 

Ownership and Construction: When Scope Starts to Grow 

A ventilation decision can quickly expand into larger equipment, more ductwork, structural reinforcement, electrical upgrades and added construction time. For owners and developers, those changes affect cost and schedule. For contractors, they can introduce difficult routing, new penetrations, shutdowns and phasing challenges. 

IAQP gives the mechanical engineer another scenario to evaluate before those downstream requirements become fixed. If the analysis supports a different balance of outdoor air and air cleaning, the project may be able to reduce disruption or avoid some supporting work. It will not produce the same outcome on every project, but it can make the tradeoffs clearer before the team commits to a more complex path. 

Commissioning and Facilities: When the Design Has to Keep Working 

IAQP is not finished when the calculations are complete. The assumptions behind the design must carry into equipment selection, controls, installation, startup and operation. Air-cleaning performance, sequences, maintenance and changes in occupancy can all affect whether the strategy continues to work as intended. 

Commissioning can verify that the installed systems align with the design intent, while facilities teams can help define practical requirements for monitoring, maintenance and future adjustments. When modern air cleaning is paired with connected monitoring and controls, the strategy can also provide greater visibility into how the building is performing after occupancy. 

Another Path When the Original Design Gets Complicated 

IAQP has the greatest opportunity to influence a project when it is considered early enough to inform mechanical sizing, coordination, energy modeling and budgeting. But the door does not necessarily close after schematic design. It may also be worth evaluating when a project encounters a structural, electrical, spatial, energy or construction constraint. 

Even a project already following the Ventilation Rate Procedure may still have options. The team must confirm the adopted code, authority having jurisdiction (AHJ) expectations, project-specific calculations and documented air-cleaning performance. IAQP will not be the answer in every case. It is another valid design path to evaluate when the original approach begins creating problems elsewhere on the project. 

A Broader Problem-Solving Tool 

The mechanical engineer still owns the analysis and the solution. But IAQP can help solve challenges that originate across the project: limited space, structural constraints, unavailable electrical capacity, energy targets, expanding scope, difficult existing conditions and operational requirements. That is the broader value of IAQP. It gives the engineer another way to deliver the required IAQ outcome when outdoor air alone creates conflicts elsewhere. 

Keep the most common project constraints in view. This quick reference outlines situations where IAQP may be worth evaluating as an alternative design path. 

WHEN TO CONSIDER IAQP 
A Quick Reference 

[Download When to Consider IAQP: A Quick Reference] 

Where could IAQP create options for your project? 

If space, structure, electrical capacity, energy targets or an existing ventilation design are creating constraints, Fellowes Air Quality Management can help your team explore what may be possible with IAQP. Submit your plans for a complimentary IAQP analysis from a Fellowes Sales Application Engineer.