I’m new to the board of a 16-story, 146-unit co-op built in 1961. Over the years we’ve had various complaints about insufficient exhaust and reverse airflow in some of the bathrooms and kitchens, as well as complaints about cigarette smoke and cooking odors (a shareholder likes to cook fish regularly on Fridays!). Our shareholders have tried to cover vents or seal drafts in their units and we’ve attempted several fixes such as fan replacements, but to no effect. Should we call in an engineer and if we do, what should we expect?
Gaps in ductwork change airflow and pressure within the system, and allow odors and smoke to infiltrate common areas and adjacent units
Improper building ventilation not only affects the comfort of all occupants in terms of temperature and smells, but it can also to lead to health issues from poor indoor air quality such as mold allergies and sick building syndrome. It can also impact smoke control systems and fire safety integrity as well as increase operating and energy costs.
Deficiencies and failures can occur at any point along a building’s ventilation system and may be caused by poor design or installation, operation or maintenance failures, occupant behavior, or any combination of these. Relying on local fixes such as applying window and door draft seals and installing bathroom/kitchen fans without proper evaluation may have little to no effect and can often have the adverse effect of exacerbating the issues.
Determining the source or sources of ventilation issues in mid- to high-rise multifamily buildings and resolving them can be tricky and involves a methodical, investigative approach. If something smells fishy at your building, engaging a qualified professional such as an engineer or architect to investigate is a good place to start.
Troubleshooting: The Basics
Most post-war buildings are constructed with a central exhaust-only ventilation system where fans on the roof are connected by vertical shafts, sometimes to branch ducts, and then to exhaust grilles in individual apartment baths and/or kitchens and hallways and common spaces. The rooftop fans exhaust polluted indoor air and fresh, clean outside air is pulled into the building via negative pressure through the small openings around doors and windows.
An evaluation can start at the top, beginning with a check of the rooftop fans. If any of the fans aren’t operating, appear damaged, or are vibrating, or making unusual or loud noises, a simple service call may resolve any 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 for your building.
You can also survey and perform a walk through to check on the exhaust terminals to make sure residents aren’t blocking the grilles purposely, or by accident. You’ll also want to survey adjacent units, other units down the line, and perhaps spot check random units and common space 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, otherwise known as the tissue paper test. At a minimum, the tissue should be drawn to and suctioned to the grille. If it falls, your vent is not exhausting properly. Even if the vent is exhausting, it may not be exhausting enough or up to code. If no to low airflow is detected, you can try cleaning the grille, and removing it to see if there is any debris within the duct that may be blocking airflow. Other signs of insufficient airflow may include visible mold, condensation build up, moisture stains, and peeling paint or wallpaper.
A handheld anemometer may be purchased from a hardware store for around $50 to measure the rate of airflow from the vents, but having a qualified professional measure airflow rates and perform tests along the system will more accurately and better pinpoint the root of the issues when basic troubleshooting is not enough.
Common Culprits: Your Neighbors
Your neighbors’ recent renovations can often contribute to building-wide ventilation issues, if they are not themselves the source of them. Work done during alterations may inadvertently, or deliberately, puncture or collapse part of the shaftway or branchline, leave debris blocking airflow, create gaps in the ducts, or alter the course of ductwork, changing airflow and pressure within the system. Damaged or defected ducts may also pose a fire and smoke hazard and should be checked to ensure they stay fire-rated.
Your neighbors’ recent renovations can often contribute to building-wide ventilation issues, if they are not themselves the source of them.
It’s also common for unit owners to add fans to their kitchens and bathrooms to augment weak ventilation. Central exhaust systems are originally designed to function without the use of in-line or point source fans and rely on the larger rooftop exhaust fans to provide adequate draw from exhaust terminals. The addition of a point source exhaust fans at any point along the system can very likely exacerbate exhaust conditions for adjacent units, creating pressure changes and reversing airflow.
New door and window installations that more tightly seal against air infiltration can also have a negative impact on the exhaust systems due to the decrease in make-up air necessary for proper exhaust in older buildings. Removing draft stoppers and seals or just opening a window may alone improve exhaust performance.
Secondhand Smoke
Cigarette smoke is especially insidious. Even after resolving reverse airflow issues, smoke travels with natural drafts and finds its way through cracks, baseboards, light switches, electrical outlets, vents and then into other apartments.
Infrared cameras or a smoke test can detect air leaks, which can be sealed to ameliorate the situation, but unfortunately the only real 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 an offender's unit that can absorb most smoke and other odors. However, it’s a costly solution and may not be 100% effective.
Expert Solutions
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 and a videoscope probe to clear the shaftway and ducts of debris and build up and check for blockages and major gaps that are impacting 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 and a timeline for any recommended work will be incorporated.
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 range from installing Constant Airflow Regulator damper devices on grilles to balance airflow throughout the building; adjusting fan output or designing modifications or upgrades to improve fan performance; to 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, efficiently, and up to code, and more importantly, keeping your residents comfortable and healthy.
All Systems Are Go
As with any building system, routine maintenance is recommended and proper operational procedures must also be followed. Implementing a preventative maintenance program can go a long way to preserving your system and saving money. 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 cleanings. 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 made through the walls or that involve vents first requires board approval.
Peter Varsalona, PE is principal of RAND Engineering & Architecture, DPC. This column was originally published in the May 2017 issue of Habitat Magazine.
