Indoor Air Quality in Multi-Family Housing

10 Ways to Keep Tenants Happy by Ensuring Indoor Air Quality

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According to the United States Environmental Protection Agency (US EPA) “Indoor Air Quality (IAQ) refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants."

Indoor air quality has a huge impact on the occupants of a property especially the risk of health issues – both long term and short term. They not only affect homes and residential buildings but also offices, schools and almost every other large commercial property.

Since most people spend over 80% of their time indoors it is important to ensure that high levels of indoor air quality is maintained. It not only affects the health of the occupants but also severely decreases employee engagement, comfort and productivity. Building owners, facility managers, and employers have to ensure that the high standard of indoor air quality is maintained.

A building’s age, design, renovations, density of occupation, maintenance of HVAC, building material and furnishings and ventilation are some of the causes of poor indoor air quality in a building. Other causes can be associated with location of the buildings, outside activity, radon, and internally generated contaminants. Improper temperature and humidity levels can also be found to be the root cause of some of the issues. Pollutants such as biological (fungi, pollen, dust mites etc.), chemical (gases, cleaning products, pesticides etc.) and particle (dust particles from sanding wood or drywall, printing and copying etc.) adversely affect the building air quality since they can rapidly spread throughout the building.

Low maintenance of indoor air quality can cause potential legal problems to the building owners. There have been multiple cases of claims of negligence concerning personal injury due to an indoor air quality problem. ASHRAE Standard 62-2001 establishes the standard of care for the design of commercial, institutional, and residential ventilation systems to “provide indoor air quality that will be acceptable to human occupants and is intended to minimize the potential for adverse health effects.”

6 Reasons Poor IAQ Could Increase Liability

There are multiple steps that facility managers and building owners can take to maintain this standard. Here are some of them:

1. Control of source of contaminants:

Most building managers perform common assessment and identification of indoor air quality throughout the year. Once a contaminant is identified, the immediate step is to find the source and control the spread of the contaminant to mitigate immediate risk.

In order to do that the building owners and managers must maintain the blueprints of the building layout, construction and any renovation documents.

The next steps would be the source control. Removal, substitution and enclosure of the sources are the recommended method. Engineering controls such as a canopy hood or setting up temporary barriers to access the area can be an intermittent solution. Temporarily increasing ventilation can help in situations like carpet cleaning and painting.

Other administrative controls like reducing the time the tenants occupy the building (by adjusting work schedules), educating the tenants about the hazardous situation and housekeeping practices such as removal or storage of food can be implemented.

2.Maintenance of equipment:

It is particularly important to take as many steps as possible in maintenance activities. Strictly adhering to the recommended procedure of the equipment manufacturer, including those that tell you how frequently to change filters. Proper maintenance is also important for new equipment. Other activities that are provide an opportunity for preventing indoor air quality problems are:

  • Cleaning of air filters
  • Checking Air dampeners and actuators
  • Humidifiers
  • Drain pipes
  • Air handling systems
  • Cooling towers

3. Maintain Ventilation:

Another important element of achieving acceptable indoor air quality is proper ventilation. ASHRAE Standard 62-2001 offers two methods for determining the amount of outdoor air required to properly ventilate indoor occupied spaces for acceptable IAQ: the Ventilation Rate Procedure and the IAQ Procedure:

The ventilation rate procedure is a three-step procedure. They are 1. Determine the outdoor air quality 2. If outdoor air quality is unacceptable, it needs to be filtered and 3.Determine the amount of air required in each space.

The ventilation is accepted if it follows this guideline set by ASHRAE Standard 62-2001:

 ASHRAE Standards

4. Check occupancy levels:

A fine balance has to be maintenance between supply of air during times when building is occupied to it’s highest capacity compared to when it is unoccupied or intermittently occupied.

This starts with the construction of the building where an indoor air quality plan has to be implemented and building is cleaned before occupancy.

Once occupied, indoor air testing has to be constantly performed to avoid any emergency situations, incidents and complaints.

Factors that affect occupant’s comfort are over-crowding, odors, temperature control, air velocity, heat or glare from sun, furniture placement, workspace location, noise levels and use of office equipment.

5. Air quality testing:

Indoor air quality testing has to be conducted in a scheduled and frequent manner to ensure that the standards are maintained.  Common test kits are available both for residential and commercial purposes to test the air for a variety of threats.

Common contaminants that can be determined using the testing are Carbon dioxide levels (CO2), Carbon monoxide (CO), nitrogen dioxide (NO2), mold or yeast or fungi, radon, dust mites, pollen, formaldehydes from carpet or wood panels and many more. A complete list can be seen here:

Testing can be a simple or elaborate procedure depending on where you are with regards to tenant’s complaints. It can be a simple test performed in hours or longer depending on the sampling and analysis.

A final formal report of issues, sources and recommendations would help you determine the next steps in the process.

6. Outdoor controls:

The ability to successfully control outdoor/indoor airflow is directly related to indoor air quality. You can control and measure outdoor air using commercial rooftop air-handling units or dampers.

A minimum outdoor air quality of (in units designed to deliver less than 2,000 cfm of supply air) should be measured at least every five years to verify the airflow rates are in compliance with the standard.

HVAC systems use either constant volume (CV) air handling or variable volume (VAV) air handling to provide a constant flow of air ventilation. Maintaining these would depend on the outside temperate and climate of the region and form the crux to establishing a good quality IAQ.

7. Humidity management:

Moisture in buildings causes major deterioration of indoor air quality. This can also damage building structure and furnishings. ASHRAE Standard 62-2001 recommends maintaining indoor humidity levels between 30-60%. Humidity levels less than 30% cause respiratory problems and those that are greater than 60% encourage growth of fungi and mold.

Dehumidification is the process that can be used in humidity control. Most air-conditioning units use a cooling coil to cool the supply air and remove moisture by lowering the air temperature below its dew point.

Reducing the cooling coil’s leaving air temperature below its dew point is

key to the system’s ability to properly dehumidify.

8. Control of Pollutants:

Air pollutants can be controlled through filtration. Filtration systems help to filter both particle and gaseous substances from the air. Most HVAC systems have particulate filtration to remove particles from the air. Other pollutants can be controlled in the following ways:

  • Tobacco smoke: Using the gaseous filtration and increased ventilation
  • Pesticides: Use according to manufacturer’s directions and increase ventilation.
  • Lead: Remove lead from spaces using trained specialists.
  • Asbestos: Do not remove the asbestos if in good condition, since removal causes leakage. If necessary engage trained specialists for removal.

9. Alarm systems:

Indoor air quality monitoring is very important since tenants today have increased awareness of the potential dangers of it.

Today there are multiple notification systems in the marketplace that are either enabled on your computer or on your smart phone. Functions such as a dashboard of environmental information – temperature, humidity, levels of CO2, CO, real-time monitoring and alarm prompts are easily available in these apps.

These would be helpful to prevent damage and reduce the risk of impact to tenants.

10. Manage and design the construction of buildings

Many IAQ problems occur as a result of poor construction or renovation practices. Monitoring all work is critical to good internal air quality. Ensuring that the specifications and designs include IAQ pans is a good starting point.

Some of the ways to address the quality of indoor air are:

  • Monitoring IAQ specification during various phases of construction
  • Proper installation of equipment such as HVAC
  • Monitor contaminant isolation during construction
  • Emissions control during construction
  • Isolation of contaminants if occupants are present



In conclusion, while all building owners and managers are aware of the importance of indoor air quality, maintaining it does not happen automatically. Tenants are happy when efforts are taken to maintain the standard of indoor air quality.

ASHRAE Standard 62-2001 provides a good baseline of standards for indoor air quality that will minimize the potential for adverse health effects on tenants.

There are several ways to ensure that this standard is met. Controlling the source of the issue, frequently testing IAQ, ensuring that early planning is being incorporated, managing humidity are some of the ways that can help you achieve that goal as well as keep your tenants happy.

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