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School Ventilation during COVID

Ventilation (Fresh Air Intake) at each school has been adjusted to 100% as closely as can be achieved.  Roughly 50%-60% of the schools HVAC systems are controlled by computer, Direct Digital Control  (DDC), so were done remotely. The balance had to have staff physically on site to disconnect linkages  and manually open the fresh air intake dampers.  

Let’s remind teaching staff they can open their windows if desired. Upper floor windows are restricted  to 3 to 4 inches of opening. That is enough based on conversations with one of our Mechanical  Engineering firms we deal with. If an upper level window opens greater than 3 to 4 inches, please let us  know. Schools Protection Program will not authorize upper openings greater than the 3 to 4 inches. 

The ventilation system will bring in 100% fresh air and the return air ducting will circulate that air back  to the point where it is met with more fresh air, thereby providing a dilution of sorts to any droplets that  may have made it that far. The air then moves through filtration and then distributed back through the  facility. 

Buildings are designed to maintain a slightly pressurized atmosphere within itself. Volume of intake air  and air relief are designed together based on building designs. High ceiling areas of most facilities use a  gravity relief damper high up to allow release of built up warm air, allowing cooler air to enter the  building (free cooling). All district HVAC filters are changed every 3 months. We have a staff member  who starts at one school and by the time he is finished he starts over again. 

Air handling units are checked to ensure drain pans are kept clean, any P-trap on the drain pan is  functioning as designed, fan systems are lubed and belts checked to ensure they are not broken or  cracked while the filters are being replaced.  

During cold weather in the winter, outside air will be reduced down from 100% to allow the system to  be able to heat the facility. The percent amount will vary from site to site depending on the systems in  place for each facility. Where the balancing act is more difficult to maintain, we will do what we can to  help. Typically outside air is reduced significantly during unoccupied hours, but the system will start up  again around 6 am on school days with maximum possible fresh air. 

The content above is reflective of ASHRE Standard 55, 62 Standard and 62.1