Return to Work: Is Your (Entire) Facility Ready to Reopen?Kevin Dugan
The CDC recently updated guidelines for employers reopening their office buildings to prevent the spread of COVID-19. And while the majority of guidelines speak to surface cleaning, social distancing, and PPE, some look at building systems like HVAC.
Aeroseal gathered two industry experts to discuss the HVAC system’s role in building readiness as states reopen and the nation returns to work.
Both experts and their companies offer unique experiences and perspectives including their geographic locations as well as their focus on energy and duct cleaning, respectively.
Plan & Prepare to Prevent
When it comes to HVAC system readiness, it’s key to remember that most systems haven’t been running at full capacity during the shutdown. As a result, they need to be reinspected prior to reopening — particularly the HVAC system.
ASHRAE notes that changes to HVAC systems can reduce airborne exposures. They recommend the following preparation to achieve optimal ventilation and limit the spread of COVID-19.
- Perform maintenance and run equipment prior to re-occupancy
- Flush HVAC system two hours before/after occupancy, operate exhaust fans
- Run garage exhaust two hours before occupancy
- Run the system on minimum outside air when unoccupied.
The CDC offers similar guidance, pointing to the need for outdoor air to dilute the indoor air and exhaust contaminated air.
- Run HVAC longer to enhance air exchange
- Increase outdoor ventilation
- Open dampers to reduce and eliminate the recirculation of contaminated, indoor air.
Leaky Ducts Can Make Preparation Ineffective
As part of preparing the HVAC system, inspecting the ductwork is key to achieving proper ventilation. In a properly operating HVAC system, fresh air dilutes contaminated, indoor air. This air is then exhausted from the building. As shown in this visual.
But with duct leaks, two potential issues arise. And as you’ll see below, they can’t be avoided by increasing ventilation and opening the dampers.
- Inadequate Dilution Rate: Up to 40% of the fresh, outdoor air being supplied to a space is wasted. As a result, contaminated air can’t be properly diluted.
- Fewer Contaminants Exhausted: With leaky ducts on the return side, less of the contaminated air is being exhausted from the building. The amount of air exhausted depends upon the need for pressurization/depressurization in each building.
Rob Hallewick offered some insight into the min/max set points for fresh air. “Be sure your system is designed to handle large amounts of outdoor air. If the system is handling more than specified, it will throw off the building’s relative humidity. Proper air distribution and making sure proper air volumes are reaching all areas of the building is very important to meeting the CDC guidelines.”
“Proper air distribution is critical to meeting CDC guidelines.” — Hallewick
Four-Phase Process to Ensuring Optimal Duct Performance
Larry Pearson stresses the importance of a building’s HVAC system in facility readiness by referring to them as the building’s lungs. “As buildings are prepared for reopening, many facility managers will find problems they didn’t know they had in the first place. Luckily, these problems can be addressed by a comprehensive approach to a building’s ductwork.”
“As buildings are prepared for reopening, many facility managers will find problems they didn’t know they had in the first place.” — Pearson
Phase One: Audit & Evaluation: This visual audit and inspection assess the condition of your entire HVAC system, including ductwork, to identify potential issues. This includes how to minimize disruption during the sealing process.
Phase Two: Test & Plan: To determine the amount of leakage in the ductwork system, Aeroseal’s team blocks off registers including ventilation shafts, heating and cooling shafts, and other ductwork, to pressurize the system. With a thorough understanding of the building’s HVAC system leakage, a project timeline and plan are created. This includes energy modeling to identify energy savings and payback.
Phase Three: Repair, Clean, Sanitize, and Seal Ductwork: Making sure the duct system doesn’t need repairs is critical to ensuring project results, this includes VAV or register box connectors, disconnected ductwork, canvas connectors, diffusers, and registers. Using Aeroseal’s non-invasive technology, we seal the ductwork to ensure the building’s HVAC system can operate at peak efficiency. The video below shows how duct leaks are sealed in commercial buildings.
Phase Four: Project Measurement and Verification: The Aeroseal software used to measure duct leakage monitors leak reduction in realtime, as it’s applied. Once a project’s leakage goals are achieved, the software verifies and records the results. A certificate showing the leakage before and after the process is then issued for the facility’s records.
The end result of a well-prepared building is cleaner, healthier air, and energy savings. And with building occupants more comfortable than before, research shows they are also more productive.