Enhanced mechanical design to help fight the spread of illness

air conditioning systems on the roof of modern building

How a building is designed not only reflects a vision for the exterior and the function of the interior, but also has a major impact on the health of the people working inside.

The International WELL Building Institute’s WELL program has recommendations on design technology that can be applied to minimizing the transmission of viruses in the workplace. These recommendations positively impact overall employee health, as well. One focus of these suggestions is a building’s mechanical design.

Focusing on the cleanliness and comfortability of the internal air, a building’s mechanical design can have a profound impact on the healthfulness of its occupants. Especially in today’s climate of greater concern over controlling the spread of illness, mechanical design is more important than ever.

There are four main aspects of mechanical design which directly relate to a healthier environment: ventilation, filtration, sanitization, and humidity management. Let’s explore each one and learn how using enhanced techniques, processes, and standards can improve the health of your building and its people. We will also examine the interconnectedness of the aspects for total air health.


How the air gets into a room is important. As part of their COVID-19 guidelines, the CDC recommends increasing the percentage of outside air entering a building. This involves having openable windows—one of the easiest methods to get outside air into a building.

Increasing outside air ventilation rates by 100% (from about 15% to 30%) is possible at many times within most office structures without an excessive disruption to the building’s temperature and humidity control. The balance of humidity and outside air is just one way these aspects of mechanical design are interconnected.

Another method of moving air through a building is displacement ventilation. This process involves cooler air brought into a room near the floor. As it warms (normally helped through the heat sources in the room: people, machinery, electronics, etc.), it rises and is removed from the room though exhaust vents in or near the ceiling. This constant replenishment can improve air quality and the health of those working in it.


Air moving through a building’s ventilation system passes through filtration. Filtration, of course, is the process of removing all the things in the air you don’t want in your lungs: bacteria, viruses, microorganisms, and other harmful particulates.

Air filters are measured with a Minimum Efficiency Reporting Value (MERV), which is an ASHRAE scale to rate the smallest particles the filter can remove from the air. MERV 8 filters are one of most commonly used filter in commercial building applications and can remove pollen, dust mites, mold spores, and animal dander.

LEED and WELL, however, recommend MERV 13 filters. These filters remove everything a MERV 8 can, plus some bacteria, most smoke, and four times the amount of virus droplet nuclei.


Adding in an air sanitizing system helps destroy viruses and microbes too small to be stopped by the building’s air filtration. There are several methods of sanitization— however,  ultraviolet germicidal irradiation (UVGI) is the most widely accepted technology.

UVGI can be integrated into the HVAC system or as upper room lighting bathing the room in UV light at predetermined intervals. Both have space and compatibility requirements which must be considered when evaluating and developing an air sanitization plan. As UVGI needs time to destroy microbes, the duration of the light’s exposure to air currents or surfaces must also be examined.

Humidity control

Both excessive humidity and lack of moisture can be detrimental to health. Bacteria, viruses, mites, mold, respiratory infections, and already existent breathing conditions can all be affected by the amount of humidity inside a building. Electrical equipment, flooring, woodwork, and other office features can also be damaged by ineffective humidity control.

With an optimal level of between 40-60% humidity, often both humidifiers and dehumidification cycles are required to regulate the most healthful amount of moisture in the air. This constant tag-team approach ensures that the air is comfortable for workers and their equipment, but not for microscopic things in the air negatively impacting health.


Each of the aspects of mechanical design can work together to improve indoor air quality. But it’s a delicate balancing act between building form and function, and mechanical design budget. Engineers and architects should review these aspects of mechanical design when considering new projects, renovations, and the preparation work to bring employees back after the current stay at home orders have expired.

Though these enhanced mechanical designs are above industry standards and can have a substantial cost impact on the construction and operational costs of a facility, the end benefits can be worth the investment. Not only will they limit the spread of viruses and disease, but they will also improve the health and productivity of those working inside the building.

Allen & Shariff is currently providing a webinar deep dive into this and other topics for healthier buildings.

Contact us today to schedule your webinar.

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