The outdoor sensor unit(s) for automatic home or building HVAC systems provide outdoor data from one or multiple bearings (North, East, West, South) to a master actuator. This can be one or all of the following data:​

• Outdoor air quality (OAQ according to the Environmental Protection Agency)​
• Temperature and relative humidity (degrees, percentage)​​
• Light/Sun (lux)​​
• Barometric pressure (mbar)​​