By Leslie Larocque
As administrators develop plans for students to return to school, the safe operation of a building is at the center of this discussion. Decision makers face tough questions around steps they can take to accommodate social distancing requirements and reduce the spread of airborne illnesses such as COVID-19. How will school facilities continue to promote educational success and contribute to overall student, teacher and staff wellness, while recognizing that classroom instruction may never be the same? Moreover, with many school districts facing steep declines in revenue, administrators want to understand how new sanitation and social distancing requirements will impact budgets.
These are all great questions, especially since many buildings have been shut down or operating in a limited capacity for several months now. Staff will need to inspect mechanical, temperature and water systems before occupants are cleared to safely return. Systems not placed back in a mode that meets initial design intent may be at risk of equipment failure, false system reporting, indoor air quality (IAQ) issues or increased maintenance costs.
The Importance of IAQ In Schools
IAQ standards typically involve systems that impact indoor air temperature and humidity, filtration, and building pressure. IAQ will remain a hot topic – and for good reason. If a school is perceived as unhealthy or unsafe, fear will creep in and confidence in the decisions made to protect students, teachers and staff can deteriorate quickly.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recently reported that “ventilation and filtration provided by heating, ventilation and air-conditioning systems can reduce the airborne concentration of SARS-CoV-2 and thus the risk of transmission through the air.” School districts should prioritize the regular cleaning and replacement of media filters. While clogged filters will not promote the spread of viruses, they will compromise IAQ, shorten the life of the ventilation system over time, and decrease system performance.
School facility teams should get in the habit of documenting filter changes, both in writing and with pictures. Filters with a minimum MERV 8 rating should be used; however, those with MERV 17 ratings or higher will remove at least 99.97% of all particles less than .03 mm in diameter (which can include airborne viruses).
Mechanical systems consist of condenser coils, evaporators, pumps, fan motors, and outdoor air and return dampers, to name just a few. Prior to turning on mechanical systems, a visual inspection is necessary to identify equipment that requires cleaning or repair. An assessment can also help to surface any blocked vents, troubling noises, vibrations or odors that require further diagnosis; however, some equipment may require a more focused eye. For example, look for leakage and cross contamination on heat recovery wheels. In addition, drain pans and condensate drains should be clear from obstruction and standing water, while cooling towers and loops should receive chemical treatment as required.
We recommend implementing strategies that limit moisture accumulation and the potential for mold growth that can result from any water filtration of condensation within buildings. Balance is needed to limit the growth of pathogens and maintain relative humidity levels conducive to occupant health and well-being.
After assessing mechanical systems, the evaluation of temperature controls and control strategies can drive efficiencies, reduce maintenance requirements, and decrease operating costs. Repair or replacement of old or non-functioning temperature controls, whether pneumatic, electric or digital, is often one of the most impactful changes a facility can make.
In preparation for the first day back at school, teams should evaluate temporary temperature and humidity setpoints against future application needs. Schools with air handling units should ensure controls are programmed to have a 100% outside air flush strategy prior to occupancy. Operable windows can complement this effort and increase the outdoor air flow. It will be important to incorporate this variable without sacrificing occupant comfort but still addressing concerns about airborne illnesses. Schools with unit ventilators and simple controls can manually flush the system over time.
Other control schedules should also be considered, such as disabling demand control strategies and keeping outside air dampers open 24/7 at minimum speed. In addition, economizers can be used to control the regular change of air in the building.
Finally, one area that is often overlooked – but just as critical to safely reopening a school – is the building’s water system (potable, non-potable, cooling towers, evaporative HVAC equipment). Most building operators aren’t accustomed to dealing with health risks from these systems. However, in school buildings that have had low or no use for extended periods of time, there is significant risk of bacteria such as legionella building up. This build-up puts students, teachers and staff at risk of exposure to Pontiac Fever, an acute nonfatal respiratory disease, or Legionnaires Disease, a type of pneumonia caused by inhaling bacteria from water – and the deadliest waterborne disease in the United States.
The Centers for Disease Control and Prevention (CDC) has issued guidance advising building operators to test water before occupants return – and to have a plan in place to test and maintain water quality. Time and temperature are natural enemies to chlorine levels in water that keep bacteria from blooming. In an overabundance of caution, the CDC also recommends that building operators take the step of flushing the system to ensure the bacteria, biofilm build-up and stagnant water is removed, and chlorine levels are appropriate to keep blooms from developing.
The Time is Now
While schools sit vacant and administrators weigh decisions for the next school year, the time is right to ensure buildings and systems are ready for safe, sustainable operation and focused on the well-being of students, teachers and staff. Providing a safe and healthy learning environment is paramount, and reopening schools will require focus, adherence to specific procedures, and expertise to establish the right strategy for each system and piece of equipment.
Leslie Larocque is Vice President, Energy & Technical Services – Mountain Regions for McKinstry, where her responsibilities include managing the strategic direction, market growth and delivery of McKinstry’s offerings in Arizona, Colorado, Nevada and Utah. She has been providing energy and environmental solutions to both public and private sector customers throughout the U.S. and internationally since 1991.