Outside air and good air circulation are always crucial for air quality in the classroom, never more than when it’s hot. Many classroom staff seek to open doors and windows in schools lacking a mechanical ventilation system or air conditioning, only to be told by the administration that doors must remain closed and windows can only be opened a few inches. What are the rules?
Natural ventilation is usually found in older schools, or used in conjunction with other types of ventilation systems. In a natural ventilation system, there is a natural fl ow of outdoor air coming into the classroom through operable windows, doors, leaks, and other openings in the building envelope. Air is exhausted naturally through windows and other openings such as chimney vents, or through a mechanical exhaust fan on the roof which pulls the air out of the building.
Sometimes the heating system is a unit ventilator (Univent), as in the diagram. These take in outside air, mix it with room air, heat the mix in winter, and blow it into the room. Corridor exhaust fans, and louvers in the door or wall greatly improve circulation.
School districts may interfere with natural classroom ventilation
Schools with natural ventilation can get very hot in hot weather or when the sun pours through windows. But districts often install window stops and order classroom doors to be kept closed. Local associations can work with their UniServ representative, using the information below, to have the district reverse these steps when they are not required by codes, or take other steps to improve indoor air quality in classrooms.
Window stops. Districts may install stops that allow windows to open only four to six inches, claiming this will prevent a student from falling out. But the stops drastically reduce the amount of outdoor air entering the classroom through the windows. In reality:
There are no legal requirements for such stops. The district decided to install the stops and the district can decide to remove them.
Children under six are most likely to fall out a window. If falls are a true concern, cages or screens can be installed or windows opened from the top.
Both the current N.J. Uniform Construction Standard (UCC) and the N.J. Educational Facility Standards require the minimum openable area to be 4 percent of the fl oor area being ventilated, if there is no mechanical ventilation. For example, in a 20 foot by 20 foot classroom of 400 square feet, there must be 16 square feet of operable window space.
The Public Employees Occupational Safety and Health (PEOSH) Indoor Air Quality Standard requires that windows are in operable condition in buildings without mechanical ventilation systems.
Operable windows in schools make sense for many reasons even when a good mechanical ventilation system is present. They allow staff to ameliorate excessive heat, problems with mechanical ventilation, and airing of odors. Windows can provide an emergency exit in case hallways are blocked by smoke or fire. Win dows can provide outdoor air in case of nausea, vomiting, asthma attack, urination, defecation, or other health situations.
Open windows are not a solution when occupants have allergies or asthma caused by grass, pollen or other outdoor allergens. In addition, open windows without screens may admit bees.
Closed doors. Districts often order that classroom doors be kept closed, as a means of avoiding the spread of fires. However, the rules that apply are those of the UCC in the year the school was built, back to 1984 (when the UCC first was applied to schools). For older schools, there are no requirements to close the doors, unless the door is fire-rated.
If the school was designed with corridors meant to be fire-protective, the whole corridor is said to be a “fire-rated assembly.” This means the walls and doors are fire-resistant, and the doors are meant to be kept closed, usually with an automatic closing device. To find out if you have such a door, look near the hinges, and see if there is a fire-rating label.
Many staff are concerned about security. The position of the N.J. Department of Community Affairs (NJDCA) is that doors with locks on the inside must be openable without a key, a combination, or other special knowledge or device. This is to ensure quick evacuation in emergencies. Local and district health and safety committees would do well to discuss this balance.
Fix ventilation problems. In many older schools, natural cross-ventilation in old buildings has not been maintained, leading to problems like stuck dampers in ductwork and blocked exhaust ducts. Sometimes ductwork has been taken over for computer wiring. You can work with your UniServ representa- tive to have ventilation problems fixed. Rules that apply include: 1. The PEOSH Indoor Air Quality Standard. 2. The UCC at the time of construction. This may include requirements for natural ventilation.
Use the Univent with heat turned off. In many schools the heat is supplied by a central boiler, which is turned off in warm weather.
Request fans or shades.
Be wary of air conditioners.
Window air conditioners may make you deliciously cool, but they supply only tiny amounts of outside air. If you have them, you may need to alternate periods of their use with periods of open doors and windows.
Finding the rules that apply to your school