Energy codes, such as the IECC, are requiring occupancy detection for lighting control in nearly any space that is not controlled via a time schedule. Occupancy detectors are required to be vacancy sensors by these codes. In other words, the lighting is required to be turned on via a wall switch, and turned off when occupancy is no longer detected. Another term for this operation is “Manual-On.” Lights that turn on automatically based on occupancy detection are only allowed to turn on automatically to 50% of the full light level. The second 50% is required to be manually turned on. The rationale is, if there is enough light in the space, the occupant won’t turn the lights on and energy is saved.
Occupancy based control in spaces can be accomplished either with stand-alone wall-box occupancy sensors or sensors that are mounted to the ceiling or in corners of the room. All of the wall-box occupancy sensors by Wattstopper or Hubbell Control Solutions can be configured to operate as manual-on. For analog ceiling or corner mount sensors, a power pack and low-voltage switch are required to accomplish manual-on. Line voltage sensors or line voltage switches in series with a power pack will not provide true manual-on operation. If a line voltage switch is left on, the lights in the room will come on automatically as soon as occupancy is detected.
There is no way to accomplish manual-on operation with a ceiling or corner-mounted sensor and a line voltage switch!
If automatic on to 50% is desired, the lighting in the room will either have to be connected as two different switch legs or will have to be dimmed. For separate switch legs, a dual relay wall-box sensor or two power packs connected to a ceiling sensor are required. The first relay or power pack will be set to automatic on, while the second is set to manual-on. For dimming, a wall-box dimming occupancy sensor can be used for 0–10V dimming systems. These devices can generally be configured to automatically turn the lights on to a 50% light level and will have the ability to raise the light level to 100%.
To accomplish automatic on to 50% using ceiling or corner-mount sensors, or for dimming types other then 0–10V, a digital lighting control system such as Wattstopper’s Digital Lighting Management or Hubbell Control Solution’s NX Networked Lighting Controls are recommended. These systems can be configured to operate in a variety of different ways and are the best option for larger rooms requiring ceiling or corner-mount sensors. These systems are also the preferred way to meet this code requirement in conjunction with meeting the automatic daylighting requirement included in IECC 2015.
For more information about this topic, or any lighting controls questions, please reach out to our controls team.