Solving Issues Caused by Negative Pressure in a Building

Have you ever opened a window and then went to close a door in the same room, and the door slammed shut? The force behind this jarring phenomenon is called negative pressure. Not only does this cause doors to close so abruptly, but it also makes them more difficult and, in some cases, impossible or dangerous to open. Negative pressure in buildings, more specifically industrial buildings, can amplify the severity of this force and affect other HVAC-related issues. Overcoming this pressure force is vital to maintaining a safe industrial environment and is achievable with the proper equipment.

What are the Side Effects of Negative Pressure in Industrial Buildings?

Both wind and temperature affect air pressure, so ventilation systems need to be able to overcome these fluctuating forces. The ideal pressure situation for a building would be positively pressurized, inverse to negative pressure. This creates an environment where the air quality is more ideal and negates issues such as: difficulty opening and closing doors, high humidity, high energy costs, more mess, insect infiltration, & hot and cold spots.

Difficulty Opening and Closing Doors

Doors in industrial buildings tend to be very heavy and connected to electronic controls, which can be damaged if closed improperly. Since negative pressure forces doors to shut and makes them more challenging to open, this can weaken the door’s controls, shorten its lifespan, and cause it to become completely inoperable.

High Humidity

Negative pressure in a building creates a stagnant and moist environment, which is uncomfortable for people to work in and is also conducive to mold growth, rust accumulation, and more significant debris buildup. This creates an unhealthy and uncomfortable environment that can lead to even more significant issues down the line, such as machine failure.

High Energy Costs

Correcting negative building pressure can save companies money on HVAC energy costs. A properly pressurized room is less stressful on HVAC systems, as the pressure gradient to overcome negative pressure and properly filter a room is less demanding, consuming less energy.

More Mess

Negative air pressure in buildings can force outside debris and dirt inside when doors are open and shut, creating a dirty working environment that is not only unsanitary but also dangerous since debris can create safety hazards. Properly pressurized buildings don’t have this problem and can save time and money by cutting cleaning costs and labor.

Insect Infiltration

Negative pressure at personnel entry and loading dock doors can invite unwanted visitors into your facility, like small or large insects that are easily pulled in by the pressure differential and are a huge sanitary issue for manufacturers of food or food-grade packaging.

Hot and Cold Spots

Two previously mentioned side effects—high humidity and high energy costs—are both exacerbated by negative pressure due to the creation of hot and cold spots caused by this phenomenon. This is not only inefficient for HVAC purposes but could cause damage to machinery or products located in these hot or cold spots, potentially causing a lot of expensive energy loss.

How to Improve Negative Pressure Ventilation in Buildings?

Examples of fine, airborne media commonly found in industrial settings are dust, moisture, or a combination of both. The finer and more frequent these particles are, the more likely they are to diminish ventilation and create negative pressure. The ways you can improve negative pressure ventilation in buildings is to: evaluate airflow dynamics, enhance filtration, upgrade exhaust systems, implement advanced control systems, ensure regular maintenance, integrate ventilation with building design, and address specific building use cases.

Evaluate Airflow Dynamics

Optimizing airflow dynamics is the foundation of effective negative pressure ventilation. It begins with ensuring the system achieves optimal air exchange rates, often specified as air changes per hour (ACH). For example, healthcare facilities might require 12 ACH or more in isolation rooms to promptly remove contaminants. Additionally, gaps and leaks in windows, doors, and other structural areas can compromise negative pressure. These should be sealed with weather stripping, caulking, or gaskets. Strategic design of airflow pathways, guided by tools like Computational Fluid Dynamics (CFD) modeling, ensures air moves smoothly from clean areas toward exhaust points without turbulence or stagnation.

Enhance Air Filtration and Air Quality

Enhancing air filtration and quality is another critical step. High-efficiency particulate air (HEPA) filters, capable of capturing at least 99.97% of particles ≥0.3 microns, are essential in applications like healthcare and clean rooms. To extend the lifespan of these filters, pre-filters can be installed to capture larger particles, reducing clogging and maintenance costs. Real-time air quality monitoring using sensors for particulate matter, volatile organic compounds (VOCs), and CO2 levels helps maintain optimal conditions and provides actionable data to adjust the system as needed.

Upgrade Exhaust Systems

Upgrading exhaust systems is key to maintaining consistent negative pressure. High-capacity exhaust fans with variable speed capabilities ensure the system can meet demand without straining. Multiple exhaust points distributed across a room or building improve pressure uniformity and prevent stagnant air pockets. For critical operations, backup power systems such as generators or uninterrupted power supplies (UPS) ensure continuous functionality, even during power outages.

Implement Advanced Control Systems

Advanced control systems can significantly enhance the efficiency and responsiveness of ventilation systems. Automated pressure monitoring with strategically placed sensors provides real-time feedback on pressure differentials and alerts operators those differences. Dynamic controls adjust fan speeds, damper positions, and airflow rates based on occupancy or air quality data, optimizing performance and energy use. Zoning systems further refine this approach by dividing buildings into independent zones, each with tailored ventilation settings to meet specific needs.

Ensure Regular Maintenance

Regular maintenance is crucial to sustain performance over time. Routine inspections should identify leaks, wear, or contamination in ducts, fans, and other components. Cleaning and disinfection of these elements prevent microbial growth and ensure optimal airflow. Pressure, airflow, and air quality sensors must also be recalibrated periodically to maintain accuracy and prevent system inefficiencies.

Integrate Ventilation with Building Design

Integrating ventilation design into the architectural planning phase yields long-term benefits. Early planning allows for optimal placement of ducts, vents, and equipment, reducing the need for costly retrofitting. High-quality insulation materials can further minimize air leakage and thermal transfer, contributing to stable pressure differentials. Proper design ensures that negative pressure rooms are located near exterior walls, simplifying the installation of exhaust systems.

Address Specific Building Use Cases

Specific use cases may require tailored solutions. For example, healthcare facilities should adhere to guidelines such as the CDC’s standards for airborne infection isolation rooms (AIIRs) or ASHRAE Standard 170, which specify requirements for pressure levels, filtration, and air exchange rates. Laboratories often need additional containment measures like airlocks, fume hoods, or biosafety cabinets to safely manage hazardous substances. Industrial applications benefit from localized extraction points near pollutant sources to contain contaminants at their origin.

Advanced Equipment Sales offers effective solutions for controlling negative pressure conditions in buildings. These systems can be either incorporated into existing HVAC infrastructure or function as standalone pieces of equipment installed to suit their environment appropriately.

Negative Air Pressure Solutions from AES

Fresh Air intake System

Traditional scrap conveyance system designers don’t consider the cost impact of replacing, filtering, or returning make-up air to the facility.

To effectively eliminate negative pressure due to scrap conveyance system exhaust, utilize an AES Fresh Air Intake System to use outside air to convey the scrap. The AES Fresh Air Intake System eliminates the need for any make-up air via the HVAC system or return air via a dust collector system by avoiding the loss of conditioned air in the first place.

The result is a balanced atmosphere that creates a more comfortable and safe working environment while also cutting costs from heating and cooling unconditioned air. These economic machines can remove the need for a dust collector entirely and are effective combatants against negative pressure in manufacturing facilities.

Choose AES

Negative pressure can cause a laundry list of compounding issues for buildings that aren’t properly ventilated. At AES, we’re dedicated to finding the perfect solution for your ventilation needs to ensure you don’t have to worry about this issue interrupting your operations.