Ventilation affects the comfort of all occupants in terms of odor and humidity control, and it can lead to health issues from poor indoor air quality, such as mold allergies and sick building syndrome. It can also affect smoke-control systems and fire-safety integrity, and it can increase operating and energy costs.
Deficiencies and failures can occur at any point along a building’s ventilation system. They can be caused by design, installation, operation, or maintenance failures, or by occupant behavior. Relying on local fixes such as window and door draft seals and bathroom/kitchen fans without proper evaluation might do little good and can actually exacerbate the problems.
Determining the odor’s source involves a methodical evaluation. Most postwar buildings are constructed with a central exhaust-only ventilation system where fans on the roof are connected to vertical shafts, and then to exhaust grilles in apartment bathrooms and kitchens, and in hallways and other common spaces. The rooftop fans send indoor air pollutants out and draw fresh air into the building, via negative pressure, through the small openings around doors and windows.
An evaluation can start on the roof, beginning with the fans. If any of these aren’t operating, appear damaged, are vibrating, or making unusual or loud noises, a simple service call may resolve the issues. Keep in mind, your rooftop fans may be running properly and even up to code, but an engineer or architect can determine if they are performing at the proper capacity. Your superintendent or maintenance staff can also inspect apartments to make sure residents aren’t blocking the grilles. You’ll also want to survey adjacent units, other units down the line, and common-area grilles to determine if the issues are localized or systemic.
The easy way to test if a vent is working is to hold up a tissue paper or sheet of toilet paper in front of it. At a minimum, the tissue should be drawn to the grille. If it falls, your vent is not exhausting properly. If there is a low airflow or none is detected, you can try cleaning the grille and removing it to see if there is any debris blocking airflow. Other signs of insufficient airflow include mold, condensation build-up, moisture stains, and peeling paint or wallpaper.
A hand-held anemometer (purchased from a hardware store for around $50) can measure the rate of airflow from the vents, but having a qualified professional do this will more accurately pinpoint the root of the problem when basic troubleshooting is not enough.
The Trouble with Alterations
Apartment renovations can contribute to or be the source of building-wide ventilation issues. Workers may inadvertently puncture or collapse part of the shaftway or branch line, leave debris blocking airflow, create gaps in the ducts, or alter the course of ductwork. That could change airflow and pressure within the system.
It’s also common for unit-owners to add fans to their kitchens and bathrooms to augment weak ventilation. Central exhaust systems were originally designed to function without the use of in-line fans, relying instead on the larger rooftop exhaust fans to provide adequate draw. The addition of exhaust fans within the system can hamper exhaust conditions for adjacent units, creating pressure changes and reversing airflow.
New door and window installations that are tightly sealed against air infiltration can also have a negative effect on the exhaust systems because of the decrease in make-up air necessary for proper exhaust in older buildings. Removing draft-stoppers and seals may improve exhaust performance.
Cigarette smoke is especially insidious. Even after airflow issues are resolved, smoke travels with natural drafts and finds its way into neighboring apartments through cracks, baseboards, light switches, electrical outlets and vents.
Infrared cameras or a smoke test can detect air leaks, which can be sealed to ameliorate the situation. Unfortunately, the only effective way to combat smoke infiltration is at its source. If you can’t stop a smoker from lighting up, a commercial-grade “smoke-eater” air filtration system can be installed within a smoker’s unit that can absorb most smoke and other odors. However, it’s a costly solution and may not be 100 percent effective.
When no conclusive answers can be derived from visual observations and airflow testing alone, the engineer or architect may recommend a cleaning of the shaftway and ducts. Also, a videoscope probe may be needed to clear the shaftway and ducts of debris and build-up and to check for blockages and major gaps that are affecting airflow. After conducting a full survey and evaluation, the engineer or architect will issue a report with findings and recommendations, generally starting with the most cost-effective and least intrusive solutions possible. Budget considerations are also addressed as is a timeline for implementation of any recommended corrective work.
Problems with the shaftway or ducts stemming from construction defects, alteration damage, or aging may require more intrusive types of repairs, such as opening up walls or ceilings to remove blockages and seal gaps and openings. Solutions for systemic ventilation issues can include installing constant airflow regulators at exhaust ducts to balance airflow throughout the building; adjusting fan output or designing modifications to improve fan performance; and redesigning the entire ventilation system.
When experiencing ventilation issues, a good engineer or architect will work with you to determine and design the best solution, whether it’s a simple fix or a major capital improvement program to ensure your building’s ventilation system is performing optimally and up to code.
A preventive maintenance program can go a long way toward preserving your system. Exhaust fans should be balanced and inspected periodically. Shaftways and ducts should be checked and cleaned every couple of years, while exhaust grilles and laundry dryer ducts require more frequent cleaning. Keeping dryer ducts clean can improve dryer efficiency and save your building money in energy costs. Additionally, residents need to be reminded that any alterations that involve vents require board approval.