Which units are commonly used for temperature, pressure, and air flow in BAS?

Which units are commonly used for temperature, pressure, and air flow in BAS?

• A. Temperature: °C or °F; Pressure: Pa or psi; Air flow: m3/s, CFM, or L/s
• B. Temperature: Kelvin; Pressure: Bar; Air flow: L/min
• C. Temperature: °C or °F; Pressure: Pa or psi; Air flow: m3/h
• D. Temperature: °F; Pressure: kPa; Air flow: L/s

Answer: (A)

The idea here is to use units that match what BAS sensors and controllers actually report and display, in a way that works across different regions. Temperature is typically shown in degrees Celsius or degrees Fahrenheit because those are the familiar, human-friendly scales used for comfort and HVAC operation. Kelvin is a scientific unit and isn’t commonly used in day-to-day building automation dashboards. For pressure, pascals (Pa) and pounds per square inch (psi) are the standard choices—Pa covers the SI world and psi covers many US applications. Bar exists, but it’s less common in BAS contexts because it’s a larger unit and can be less convenient for precise control and signaling. Air flow is where you really want flexible, practical options: cubic meters per second (m3/s) for direct SI-based measurement, cubic feet per minute (CFM) for regions and equipment that use imperial units, and liters per second (L/s) for metric contexts that sit between the two. Using these keeps you aligned with real sensors and control strategies, and supports both large and small systems. So, this combination—temperature in °C or °F, pressure in Pa or psi, and airflow in m3/s, CFM, or L/s—matches common BAS practice and provides the most versatile, interoperable set of units. Choices that rely on Kelvin, Bar, or less typical airflow units (like L/min) don’t fit the usual BAS reporting and control conventions as well.

The idea here is to use units that match what BAS sensors and controllers actually report and display, in a way that works across different regions. Temperature is typically shown in degrees Celsius or degrees Fahrenheit because those are the familiar, human-friendly scales used for comfort and HVAC operation. Kelvin is a scientific unit and isn’t commonly used in day-to-day building automation dashboards.

For pressure, pascals (Pa) and pounds per square inch (psi) are the standard choices—Pa covers the SI world and psi covers many US applications. Bar exists, but it’s less common in BAS contexts because it’s a larger unit and can be less convenient for precise control and signaling.

Air flow is where you really want flexible, practical options: cubic meters per second (m3/s) for direct SI-based measurement, cubic feet per minute (CFM) for regions and equipment that use imperial units, and liters per second (L/s) for metric contexts that sit between the two. Using these keeps you aligned with real sensors and control strategies, and supports both large and small systems.

So, this combination—temperature in °C or °F, pressure in Pa or psi, and airflow in m3/s, CFM, or L/s—matches common BAS practice and provides the most versatile, interoperable set of units. Choices that rely on Kelvin, Bar, or less typical airflow units (like L/min) don’t fit the usual BAS reporting and control conventions as well.