Indoor Air Quality Starts With The Right Building Pressure: ACI Can Help

The Art of Controlling Air Pressure in Buildings

Controlling air pressure within a building might not be the first thing that comes to mind when thinking about indoor air quality, occupant comfort and energy efficiency, but it plays a pivotal role in both. Proper management of air pressure can significantly impact the building’s heating and cooling load, operational costs of HVAC equipment, and even the health and well-being of its occupants.

 Why Building Pressurization Matters

When we talk about building pressurization, we are essentially referring to the difference in air pressure between the interior and exterior of a building or a room. It might not sound like a critical factor, but it plays a vital role in ensuring a healthy and energy-efficient indoor environment. Here’s why it matters:

Lower Energy Costs

Proper building pressurization can significantly impact your energy bills. By controlling the air pressure, you can lower the heating and cooling load on your HVAC system. This translates to decreased energy consumption and cost savings in the long run.

Improved IAQ

Maintaining the right pressure levels can prevent the cross-contamination of air between different areas within a building. This is particularly crucial in places like hospitals, laboratories, and clean rooms, where the purity of the air is paramount. Pressure sensors help ensure that contaminants stay where they belong.

Enhanced Comfort

Building occupants’ comfort is a top priority. When the pressure is well-regulated, it can lead to a more pleasant indoor environment. Proper pressurization can help prevent drafts, ensuring that people feel comfortable in the space.

abb control system featuresACI’s Pressure Sensors: The Solution

To achieve the ideal pressurization in your building or room, you need reliable pressure sensors. ACI (Automation Components Inc.) offers a range of exceptional pressure sensors, including the MLP2, a cost-effective mini sensor. These sensors are designed to monitor and control pressure effectively.

sub metering benefitsFactors Influencing Building Pressure

Understanding the factors that affect building pressure is essential for maintaining IAQ. These factors include:

  • Wind: External wind patterns can influence the pressure inside a building.
  • Thermal Effects:Temperature variations affect air density, which, in turn, impacts pressure.
  • Building Design: The layout and design of a structure can influence airflow and pressure distribution.
  • HVAC Systems: The operation of heating, cooling, and exhaust systems can also affect building pressure.

Types of Pressure: Positive vs. Negative

Building pressure can be classified into two main types:

 Positive Pressure

Positive pressure occurs when the pressure inside a building is greater than the pressure outside. This is often desirable in clean rooms, where maintaining air purity is essential. Positive pressure keeps contaminants out by ensuring that air flows from the clean room to the surrounding areas.

 Negative Pressure

Conversely, negative pressure occurs when the indoor pressure is lower than the outdoor pressure. This is common in environments like pharmaceutical or chemical labs, where it’s crucial to prevent contaminants from escaping. Negative pressure ensures that potentially harmful substances are contained within the controlled space.

 Seasonal Considerations

Seasonal changes can affect the ideal building pressure. For instance, during cold weather, maintaining a slightly negative or neutral pressure helps prevent moisture buildup inside the building. In contrast, slightly positive pressure in warmer weather can help control humidity levels.

Pressure Control for Specific Environments

Different environments have distinct pressurization requirements:

Clean Rooms: These require positive pressure to keep contaminants out. Pressure sensors can help maintain the necessary air purity.

Pharmaceutical or Chemical Labs: Negative pressure is crucial here to prevent the escape of hazardous materials. Pressure sensors ensure safety.

 Pressure Monitoring Tools

ACI offers a comprehensive range of pressure monitoring tools, including differential pressure transmitters and pickup ports. These tools help you accurately monitor and control building pressure. 

Mounting Options: You can choose from horizontal and vertical pickup ports to suit your installation preferences.

Medical Tubing Kits: ACI provides FDA-approved medical-grade tubing kits for connecting pickup ports and pressure transmitters, ensuring accuracy and reliability.

Active Monitoring and Adjustment

Maintaining the preferred building pressure isn’t a set-it-and-forget-it task. It requires constant monitoring and adjustments, especially in the face of changing conditions. Pressure sensors play a pivotal role in this ongoing process.


Small and cost effective the ACI MLP2 is worth taking a look at:

ACI’s MLP2 Series pressure transmitters are a low-cost, small-footprint option for your panel mount applications.  The standard accuracy is +/- 0.50% with a +/- 0.25% option.  Features include:

  • Ranges from 0.1″ to 40″ w.c.
  • 4-20 mA, 0-5 VDC, & 0-10 VDC output options
  • Uni and Bi-Directional ranges
  • Zero Function
  • External terminal blocks for easy wiring
  • Two DIN rail mounting options (side & back)
  • Durable polycarbonate enclosure
  • NIST certification available
  • Made in the USA / in stock & ready to ship
  • Product Page

 Where to Find ACI Sensors

ACI sensors are readily available through various distributors. Consider reaching out to a CGNA Controls Distributor or Stromquist and Company in Atlanta or Orlando for your pressure sensor needs.

In conclusion, mastering indoor air quality goes beyond temperature and humidity control. Building pressurization is a crucial component that should not be underestimated. With the right pressure sensors and a solid understanding of how pressure influences IAQ, you can create a healthier, more energy-efficient, and comfortable indoor environment for everyone.


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