Looking at the extended forecast, cooler temperatures are certainly on the way. This is the time that is most concerning for those of us concerned with air quality, particularly in the midst of a pandemic. Many school districts are unable to afford central air conditioning systems, and instead relay on room units that may or may not have ventilation air. Up until this point, you may have been able to rely on open windows to meet the ventilation requirement. After all, as long as your operable window area exceeds 4% of the floor area, you meet the letter of the mechanical code.
Unfortunately, if that window is closed, the ventilation rate is, of course, zero. While installation of UVC or Bi-polar ionization may help, it does not replace the need for natural ventilation. Also, if you haven’t placed your order for this equipment by now, you are likely going to be waiting until January for it to be in place.
If you rely on windows for ventilation, have a plan in place now for when the weather gets colder. That plan should include making sure your heating system is fully serviced and capable of operation at 100% load, make sure occupants can tolerate lower space temperatures by dressing to the season, not to a conditioned building. Because your heating system was likely not designed to have the additional load of an open window, it wont be possible to maintain a comfortable 70-72F. Your system may only be capable of mid to low 60s or less during extreme conditions with open windows. Occupants should wear clothing more suited to a fall day outside than a normal conditioned space.
Plans should also include the following items at a minimum:
- A space inspection to make sure plumbing and fire protection piping near openings are insulated. A flood due to a frozen pipe will render a space unoccupiable the same as an outbreak.
- A written plan to be followed when occupying a space with window ventilation.
- Signage on entryways and room doors explaining that the open windows and cooler temperatures are necessary.
- Education of staff and occupants on the strategy.
- Potential schedule modifications to minimize occupancy during the coldest time-periods.
This approach was followed almost a century ago during the Spanish Flu epidemic. It should work the same today, but most likely with more complaints.
Contributor: Stephen Oskin, PE, LEED AP, Director of Mechanical Engineering at Barton Associates.
