The Role of HVAC in Indoor Air Quality and Health

Heating, ventilation, and air conditioning (HVAC) systems are central to providing good indoor air quality and healthy environments for the occupants of buildings. They provide thermal comfort, filter pollutants from the ventilation air, and maintain appropriate moisture levels for optimum comfort.

Currently, 14 buildings on campus are scheduled for HVAC renovations. The minimum investment cost is nearly $45 million, an average of $3.2 million per building.


HVAC is often used to describe heating, ventilation, and air conditioning systems. These systems include heating and cooling units, ductwork to move the heated or cooled air around, and filters that remove dust and other pollutants.

Temperature can play an important role in indoor air quality and health by impacting occupants’ comfort levels and ability to perform tasks. For example, heat increases systemic and pulmonary inflammation, possibly leading to cardiovascular disorders.

It can also promote the growth and spread of microorganisms like mold, allergens, animal dander, and bacteria. The temperature, humidity, and ventilation of indoor spaces can all influence the microbial load and make it easier for these organisms to spread.

Increasing the temperature of indoor spaces is an easy way to help maintain good IAQ and reduce exposure to pollutants. It also allows people be more comfortable and concentrate on their work. It can also be a more cost-effective approach than controlling pollutants, which typically requires an expensive overhaul of the existing HVAC system or installing a more powerful filter.


Humidity plays a big role in air quality, making it vital for keeping the indoor environment clean and healthy. Low humidity can create problems for a variety of health issues, including dry skin and chapped lips, asthma and allergies, and even odors.

Similarly, high humidity increases the birth rate of disease-causing microorganisms. This also affects the building materials, such as windows and doors.

Relative humidity is the amount of water vapor in the air that can be held at certain temperatures. It is typically expressed as a percentage of the total moisture in the air, called absolute humidity.

In addition, air humidity also influences some other aspects of air quality, such as the survival rates of viruses and bacteria and the ability of humans to breathe easily and comfortably. For example, the virus COVID-19 is known to survive well in cold climates, but it can be spread more effectively and efficiently with high relative humidity.


Ventilation is a vital part of heating, cooling, and air handling systems that provide a range of indoor environmental conditions. Whether residential or commercial, ventilation helps control odors, moisture, and pollutants affecting the health and well-being of occupants, visitors, or employees.

Mechanical ventilation (forced ventilation) controls indoor air quality by bringing in outside air and exhausting room air. This can dilute indoor pollutants and odors and remove excess humidity.

One crucial benefit of mechanical ventilation is that it can be designed to control where intakes and exhausts occur. This can help prevent odors and pollutants from migrating into the building from adjacent buildings.

Another significant advantage is that it can be designed to exhaust contaminated air into areas that don’t need it. This can be especially helpful if a building is next to a restaurant, gas station or industrial facility where the pollutants are likely to migrate into the home or business and contaminate the occupants.


There’s an increasingly active coalition building across the country for improving indoor air quality and health. Improving air quality inside homes and other buildings can help reduce the risk of infection with COVID-19, as well as many other viruses, bacteria, and fungi.

A key part of improving indoor air quality is ventilation, which brings in fresh air from outdoors and helps release pollutants already present in the home. Contaminants that can build up inside a house come from various sources, including cigarette smoke, cooking oil, cleaning products, and certain types of insulation.

Filtration separates solid particles from liquids or gases using a filter medium that allows the fluid to pass through but not the solid. Often the fluid filtrate is recovered as a separate product, or the solid filter cake may be recycled.