How to Improve Indoor Air Quality in Commercial Buildings

Improving indoor air quality in a commercial building starts with finding out what is causing the problem. The right solution may involve removing a pollution source, improving outdoor-air ventilation, upgrading filtration, correcting moisture problems, or adjusting how the HVAC system operates.

For building owners and facility managers, the most effective approach is to make changes in a clear order:

1. Identify the indoor air quality problem and establish a baseline.
2. Reduce or eliminate sources of pollutants whenever possible.
3. Check whether the building is receiving and distributing enough outdoor air.
4. Improve HVAC filtration without restricting airflow.
5. Correct humidity, condensation, and other moisture problems.
6. Use building controls and monitoring to maintain performance over time.

The goal is not to install every available IAQ technology. It is to identify what is actually wrong with the building and correct those specific problems without creating unnecessary energy use or replacing HVAC equipment that is still capable of doing its job.

Start by Identifying the Indoor Air Quality Problem

Before investing in HVAC upgrades, determine what is happening in the building and when it happens.

Indoor air quality problems can show up as repeated occupant complaints, odors, stuffy rooms, visible condensation, excessive dust, uneven temperatures, or conditions that consistently worsen during certain hours or seasons.

Start by comparing those observations with available building information, such as:

• occupancy schedules;
• HVAC operating schedules;
• maintenance and filter records;
• temperature and humidity trends;
• outdoor-air damper operation;
• previous service issues;
• data available through the building management system.

Depending on the problem, targeted measurements or continuous data logging can then help show whether conditions change with occupancy, weather, or HVAC operation.

The purpose of monitoring is not simply to collect more data. It is to connect an indoor condition with a possible cause.

What IAQ Measurements Can Tell You

Different measurements answer different questions.

These measurements need context.

For example, a rise in CO₂ when a conference room fills with people may suggest that ventilation is not keeping up with occupancy. However, a low CO₂ reading does not prove that overall indoor air quality is good because other pollutants may still be present.

When possible, compare IAQ measurements with occupancy and HVAC operating data through the building management system. That makes it easier to determine whether the problem involves ventilation, equipment operation, controls, or something unrelated to the HVAC system.

Control Pollution Sources Before Adding More HVAC Capacity

The most efficient way to solve many indoor air quality problems is to address the source first.

Adding more ventilation or filtration may reduce the concentration of a pollutant, but it does not always fix what is creating it.

Common sources of commercial-building IAQ problems can include:

• cleaning products and chemicals;
• new furniture, flooring, paint, or construction materials;
• dust from renovation work;
• moisture intrusion or water leaks;
• dirty or wet HVAC components;
• vehicle exhaust entering outdoor-air intakes;
• poorly exhausted restrooms, kitchens, storage areas, or process spaces;
• pollutants generated by activities taking place inside the building.

EPA considers source control one of the primary strategies for improving indoor air quality and, where practical, often the most effective approach.

For a facility manager, this means asking a simple question before changing the HVAC system:

Can the source of the problem be removed, reduced, isolated, or exhausted directly?

If it can, solving the source may be more effective and less expensive than increasing the amount of air the entire building has to condition.

Check Outdoor-Air Ventilation and Airflow

Once obvious pollution sources have been addressed, check whether the HVAC system is bringing in and distributing the appropriate amount of outdoor air.

The required ventilation rate is not the same for every commercial space. It depends on factors such as the number of occupants, how the space is used, its size, the HVAC configuration, and applicable building requirements.

ASHRAE Standard 62.1 is the primary industry standard for ventilation and acceptable indoor air quality in commercial and institutional buildings. It establishes minimum ventilation requirements and includes provisions covering filtration, controls, air cleaning, and system operation and maintenance.

A building can develop ventilation problems even when the original system was properly designed.

For example:

• a space may now hold more people than it was originally designed for;
• an office may have been converted into a conference room;
• dampers may no longer open correctly;
• airflow may be poorly balanced between zones;
• supply or return-air paths may be restricted;
• operating schedules may no longer match actual building use.

A professional system balancing assessment can show whether the required airflow is actually reaching the areas where it is needed.

Improve Ventilation Without Creating Excessive Energy Costs

Bringing more outdoor air into a building can improve ventilation, but that air usually has to be heated, cooled, or dehumidified.

Simply increasing outdoor air without evaluating the HVAC system can therefore solve one problem while increasing utility costs or creating comfort issues.

Energy recovery can help in buildings with high ventilation loads.

An energy recovery ventilator, or ERV, transfers some of the heating or cooling energy from exhaust air to the incoming outdoor air. This reduces the amount of work required from the main HVAC equipment.

Some buildings may also benefit from a dedicated system that handles outdoor ventilation air separately from the equipment responsible for most of the space heating and cooling.

Whether these upgrades make sense depends on the existing HVAC system, climate, operating hours, occupancy, and amount of outdoor air the building requires. They should be evaluated as part of the building’s broader HVAC energy-efficiency strategy.

Improve HVAC Filtration Without Restricting Airflow

Better filtration can remove more airborne particles, but a more efficient filter is not automatically better for every HVAC system.

Filters are commonly rated using MERV, or Minimum Efficiency Reporting Value. A higher MERV rating generally means the filter captures smaller particles more effectively.

The trade-off is that some higher-efficiency filters also make it harder for air to pass through them.

If an existing HVAC fan cannot overcome that additional resistance, airflow can fall. That can affect comfort, equipment performance, and energy use.

EPA recommends using the highest-efficiency filter that is compatible with the building’s HVAC system rather than simply installing the highest-rated filter available.

Before changing filtration, check:

• the filter currently installed;
• whether air is bypassing the filter;
• the condition and size of the filter rack;
• airflow through the system;
• how much resistance the filter adds;
• whether the fan has enough capacity to maintain proper airflow.

A professional HVAC filter analysis can determine whether filtration can be improved with the existing equipment or whether other system changes are needed.

Why Airflow Testing Matters When Upgrading Filters

A filter upgrade should be evaluated as part of the whole air-delivery system.

For example, poor airflow may not actually be caused by the filter. It can also result from dirty coils, restrictive ductwork, closed dampers, inadequate return-air paths, or fan problems.

A total system analysis can identify where the restriction is occurring before money is spent on the wrong correction.

In some buildings, improving filtration may require a larger filter rack, fan changes, or duct modifications. In others, the existing equipment may already be capable of supporting the upgrade.

The important point for the building owner is simple:

verify airflow before assuming that a higher-rated filter can be installed without affecting the rest of the system.

Correct Moisture and Humidity Problems

Moisture is another major part of commercial indoor air quality.

Persistent high humidity, condensation, wet materials, or drainage problems can damage building components and create conditions that support mold growth. Air that is excessively dry can also contribute to occupant discomfort.

The correct humidity conditions depend on the building type, climate, equipment, and how the space is used. For that reason, humidity problems should be diagnosed by looking for the cause rather than relying on one universal target for every commercial building.

Common HVAC-related causes include:

• excessive humid outdoor air entering the building;
• water entering through the building envelope;
• cooling equipment that is not removing enough moisture;
• equipment cycling on and off too quickly;
• condensate that is not draining correctly;
• incorrect control settings;
• spaces that have changed use without corresponding HVAC changes.

One common mistake is lowering the thermostat simply to make the cooling system remove more moisture. If a building has to be overcooled to control humidity, the underlying HVAC or control strategy should be investigated.

Depending on the cause, the solution may involve ventilation changes, dedicated dehumidification, control adjustments, equipment modifications, drainage repairs, or correction of a building-envelope problem.

Use Building Controls to Maintain Indoor Air Quality

Indoor air quality changes as the building changes.

Occupancy varies throughout the day. Outdoor temperature and humidity change. Filters load with dirt. Tenant schedules change. Equipment performance can gradually deteriorate.

A building management system can help facility teams respond to those changes instead of operating the building according to fixed assumptions.

Useful IAQ-related controls can include:

• ventilation schedules based on occupied hours;
• ventilation adjustments based on occupancy;
• humidity alarms;
• filter pressure alerts;
• fan-speed control;
• monitoring of outdoor-air dampers;
• temperature and humidity trending;
• CO₂ trending in high-occupancy areas.

For example, a conference room may need significantly more ventilation while it is occupied than it does when it is empty. Controls can help the HVAC system respond to that difference rather than operating at the same level all day.

The goal is to provide the building with the ventilation and conditioning it needs when it needs it.

Prioritize IAQ Improvements Based on the Building’s Actual Problems

Not every commercial building needs an ERV, new controls, higher-efficiency filtration, or a new HVAC system.

Once the problem has been identified, compare potential improvements based on:

This is more useful than applying a generic industry payback period to every project.

For an energy-saving upgrade with measurable savings, a simple payback calculation can be useful:

Simple Payback = Installed Cost ÷ Annual Net Savings

However, not every indoor air quality improvement should be expected to pay for itself through lower utility bills.

For example, adding necessary outdoor ventilation may increase heating and cooling energy use. The business case may instead be based on meeting ventilation requirements, protecting the building from moisture damage, reducing repeated complaints, improving reliability, or avoiding a larger future repair.

That distinction is important when presenting an IAQ project to ownership.

When Should a Commercial HVAC Contractor Evaluate Indoor Air Quality Problems?

Facility teams can resolve some indoor air quality problems through routine maintenance, source control, and operating changes.

A commercial HVAC contractor becomes especially useful when the problem appears to involve the mechanical system itself.

Consider a professional HVAC evaluation when:

• some areas consistently feel stuffy or receive poor airflow;
• ventilation cannot be verified in occupied spaces;
• humidity or condensation problems continue despite normal HVAC operation;
• a filtration upgrade may affect airflow;
• outdoor-air changes are increasing heating or cooling loads;
• the building has changed use or occupancy;
• controls and equipment are not operating together correctly;
• several IAQ symptoms appear to have the same mechanical cause.

The purpose of the evaluation is not automatically to recommend new equipment.

It is to determine whether the issue comes from airflow, ventilation, filtration, controls, maintenance, equipment capacity, or another building condition before choosing the solution.

That fits particularly well with Lightning Mechanical’s actual positioning: the company provides commercial HVAC service, maintenance, installation, diagnostics, design and building-management-system work rather than being simply an indoor-air-quality product seller.

Improving Commercial Indoor Air Quality Is an Ongoing Process

Improving indoor air quality in a commercial building means controlling pollution sources, providing appropriate ventilation, filtering airborne particles, managing moisture, and keeping the HVAC system operating as intended.

The most effective strategy is not to add as many IAQ technologies as possible. It is to understand how the building is actually performing, identify the cause of the problem, and make the smallest effective correction first.

For facility managers and building owners, that approach makes indoor air quality easier to manage and also helps avoid unnecessary equipment replacement, excessive energy use, and capital spending that does not solve the original problem.