Breathing New Life into Old Buildings: Addressing Indoor Air Quality Challenges in Aging Infrastructure

America’s commercial building stock is overwhelmingly decades old, and many facility managers now grapple with the challenges that accompany their aging infrastructure. With an average age of 53, these structures remain functional and are often valued for their character and location. However, outdated mechanicals, aging building materials that compromise the building envelope and decades-old design approaches—including the once-common practice of constructing “tight” buildings to improve energy efficiency—can reduce fresh air exchange and allow pollutants to accumulate indoors. These conditions increase the risk of Sick Building Syndrome and contribute to buildings that are harder to lease, occupy, and maintain at today’s standards of performance.

One of the most pressing concerns is indoor air quality (IAQ). According to the U.S. Environmental Protection Agency (EPA), indoor air can be two to five times more polluted than outdoor air, and in some cases, more than 100 times. In a comparative study, older buildings had significantly lower ventilation rates, higher temperatures and elevated levels of ultrafine particles than their newer counterparts. As ASHRAE standards and building codes shift to prioritize increased ventilation and particulate filtration, many aging buildings fall short of compliance.

It’s common for these buildings to have HVAC systems that are inconsistent or undersized, filters that are insufficient for capturing ultrafine particulate matter present in densely populated or industrial areas, and sub-par insulation that allows outdoor pollutants and moisture to creep inside. Over-occupancy, which is common in today’s post-COVID tenant configurations, can overwhelm systems originally designed for lower loads. The result is often an accumulation of PM2.5, allergens, mold, volatile organic compounds (VOCs), and carbon dioxide (CO₂). Without the presence of real-time IAQ monitoring, these problems often go unnoticed until they affect tenant health and comfort.

The impacts of poor IAQ are well documented. Even moderate IAQ issues can contribute to noticeable declines in occupant wellbeing and performance. A Harvard study found that workers exposed to CO₂ and VOCs at levels typically found in conventional office buildings scored 61% lower on cognitive performance tests than those who worked in conditions associated with green buildings. Another study found that more than 30% of workers in older buildings experienced symptoms of Sick Building Syndrome, including dizziness or light-headedness, headaches, and tired or strained eyes. Additionally, poor IAQ can contribute to increased asthma and allergy symptoms and greater risk of airborne virus transmission, which can lead to higher rates of illness and absenteeism.

From a commercial real estate standpoint, poor IAQ can negatively affect tenant satisfaction and retention while reducing energy efficiency by increasing the strain on HVAC systems. Tenants are increasingly holding building owners accountable. According to a recent Fellowes survey, 89%  of respondents believe it is the building owner’s responsibility to provide clean indoor air.

Improving IAQ Without a System Overhaul

Thankfully, IAQ improvement is possible with a few simple, cost-effective steps—many of which involve maximizing the performance of the systems already in place. Here’s how to elevate IAQ performance without replacing building infrastructure: 

1. Start with Data

Gathering knowledge about the state of your building’s indoor air is crucial to understanding what needs to be addressed. Survey tenants to identify any comfort or health concerns they may have. Then, install IAQ monitors to establish baseline metrics for the presence of particulate matter (PM10, PM2.5, PM1), VOCs, CO₂, temperature, humidity and more.

2. Inspect and Optimize Existing Systems

Conduct a visual inspection of every part of the HVAC system, including:

• Air handlers: Confirm proper operation and clean coils. Remove any nearby debris.
• Filters: Upgrade to the highest-rated MERV filters the system can accommodate—ideally MERV 13 or above, as these filters are better equipped to capture ultrafine particulate matter, like PM2.5.
• Ductwork: Schedule a professional cleaning and seal any leaks.

3. Inspect the Building Envelope

Evaluate windows, doors, the foundation, and any other areas where air or water may enter. Address leaks and seal openings to prevent infiltration.

4. Optimize Ventilation

Work with an HVAC professional to assess and adjust system settings to improve ventilation rates and humidity control throughout the building.

5. Supplement with Localized Air Purification Units

Stand-alone purification units with H13 True HEPA filtration offer a cost-effective, plug-and-play solution for removing airborne pollutants. Operating independently of the HVAC system, these units deliver immediate and targeted air quality improvements.

Optimizing IAQ with Air Quality Management Systems

Not all IAQ issues can be resolved through HVAC system modifications alone. Environmental events like wildfire smoke, as well as pollutants introduced by tenant activity, including cleaning agents, odors, and more, often require additional interventions.

While portable air purifiers can improve localized conditions, a more robust and strategic solution is the implementation of an air quality management (AQM) system that automates the process of ensuring optimal indoor air quality. Today’s AQM solutions are scalable, efficient and compatible with existing infrastructure without the need for ductwork modifications, making them practical for use in aging buildings of any size. Many can be easily integrated into a property’s building management system (BMS) to work in tandem with the HVAC system, while conserving energy.

Some of the robust benefits of AQM systems include:

• Consistently Optimized Air Quality: Smart sensors continuously monitor critical IAQ factors throughout the building, such as particulate matter, VOCs, CO₂, and humidity, and automatically activate localized purification units when needed, conserving energy when not in use.
• Return On Investment: HVAC strain is reduced thanks to dynamic ventilation management, delivering measurable operational savings and a clear return on investment through lower utility costs and extended equipment life.
• Support for ESG Goals: AQM systems help to meet requirements for building certifications, such as WELL, RESET, LEED, and Fitwel, making them a valuable tool in long-term sustainability strategies.

As tenants become increasingly informed and more wellness-conscious, IAQ has shifted from a “nice to have” to a meaningful differentiator. For older properties, improving air quality isn’t just about protecting occupant health and boosting tenant retention. It also enhances building performance and delivers measurable cost savings. Over time, these improvements translate into stronger tenant relationships and a more resilient, future-proof asset.