Dedicated Outdoor Air System Good for Buildings, Employees

September 12, 2020

By Richard Boothman

We’ve all heard of Sick Building Syndrome: Employees with irritated eyes; managers taking a day to visit the doctor; and an assortment of sniffles and sneezes throughout the day from those at the water cooler or at their desks. It all adds up to lost productivity and increased medical costs. Multiplied across the nation’s commercial sector, the economic impact of poor indoor air quality can amount to billions in losses over the years.

Richard Boothman, Modine
Richard Boothman

Keep in mind that most people spend the vast majority of all their time indoors, including their working hours. This means that IAQ is an important part of all of our lives, and even more so as the United States, and the world, tries to recover economically from the COVID-19 pandemic.

DOAS in Addition to HVAC

An increasingly popular technology that is increasingly being used to improve ventilation and IAQ is the Dedicated Outdoor Air System. Known as DOAS, the units process high quantities of outside air often 100%, working separately from but supplementing traditional HVAC systems. They are capable of dehumidifying and cooling warm moist summer air and warming cold winter air. Above all, they increase ventilation, and when it comes to the dilution of pollutants inside a building, ventilation is key.

But before extolling the virtues of DOAS, it’s important to take a good look at indoor air quality and the contaminants and activities that diminish it. Building managers, tenants and employees need to know that pollutants can actually be in greater concentrations inside a building than outside.

When this is the case, the risk of illness increases. And there are plenty of things that can make an employee ill. Pollutants can come from the inside or the outside, and they can emanate from maintenance, pest control, renovations, furniture finishes, biological contaminants, chemical pollutants, particles, moisture and mold.

For Old and New

IAQ can always change. In an HVAC system that might not be functioning at its optimum level, whether it’s through an error at the maintenance or at the design level, there can be good days and bad days, and oftentimes the bad days manifest themselves in the form of moisture and humidity. Tell-tale signs of poor IAQ could be odors, hot spots and cold spots.

As buildings become more and more energy efficient and air tight, HVAC systems don’t have to work as hard. This is good for cost savings and the environment, of course, but it causes a greater need for outdoor air to improve ventilation because contaminants can get trapped in these modern buildings. For new construction, DOAS should be considered in the initial design.

In many instances, however, people work and play in established buildings. In these instances, it’s important that the occupants designate an IAQ-point person, someone who can communicate directly with facility managers. That way, problems with air quality can be identified and solved. For older buildings in need of an enhancement, DOAS could be the ideal add-on.

Keeping Buildings Healthy

In the age of COVID-19, a lot of people are asking about IAQ and the effectiveness of filters. While filters are important, alone they will not be enough to keep a virus out of a building. Low-efficiency filters, those less than MERV-8, are unlikely to make a difference. A MERV 13 filter is needed in order to effectively trap particles. Properly designed UV lamps can also be effective, but if they are not properly integrated with the surrounding HVAC unit, they will not perform at their optimum level. For building owners looking for more than filters and UV lamps to improve their commercial properties, DOAS could be the answer. They also help with efficiency, and are good at putting the appropriate amount of ventilated air quantities into every space, thus meeting ASHRAE guidance.

The reason DOAS was created is to provide straight ventilation, not just ventilation as a byproduct pursuant to heating and cooling