Surface Sensor (SU-5i-USB) Design Guidelines

This article provides guidelines for designing and deploying solutions with Enlighted Surface Sensor (SU-5i-USB). The Surface Sensor, available in a minimally-sized package, provides users with real-time occupancy availability. The sensor, optimized for easy deployment, mounts to light fixtures or ceiling tiles and under desks.  The sensor's form factor allows for multiple deployment scenarios that give your building a flexible way to deploy an Enlighted IoT platform quickly. 

Below is a decision matrix showing both the Enlighted Micro Sensor (SU-5E) and Surface Sensor (SU-5i) deployment options based on several factors or criteria. Evaluate and choose the best sensor deployment option based on what elements or criteria you will need to prioritize for your solution. 

Decision Matrix

Power and Cable Requirements

The Enlighted sensors require a 125mW power budget per sensor. This is equivalent to 25mA at 5V from a USB power adapter.

The Surface (SU-5i) sensors must be connected to a low voltage power source. Power the sensor to an uncontrolled receptacle that continuously supplies power. Do not connect it to a controlled receptacle.

Enlighted's recommended cables include:

• USB-A to micro USB-B or micro USB-A connector cable up to 8 m/26 ft. in length
• AC/DC 5V with 10W or 3W external wall mounted power adaptor.

A USB hub can power multiple sensors and consider the cable length for the power requirements.  A standard 1A (5W) 5V USB power adapter can support up to 40 Surface Sensors. However, most Passive USB splitters max out at eight ports.  

Cables are not shipped with the sensor. We recommend purchasing off-the-shelf cables and power adapters that meet any local-specific safety requirements (CE, UL, Plenum) your building may have. Enlighted has tested cables up to 8 m/26 ft. For aesthetics and to reduce accidents, use a cable organizer or cable raceway to keep cables discrete, stay in place, and clutter-free.

Networking Requirements

The Enlighted Surface (SU-5i) sensors require to be connected to an Enlighted Gateway, which is set up with the Energy Manager 3.9.13 or later.

Gateways

The Enlighted Gateway can support up to 100 connected devices per gateway for desk hoteling and conference room management applications. In many scenarios, the design may be well below this number. This is because the desks' locations relative to each other often impact the ability to place one gateway close enough to each cluster of desks.

Refer to the Network and IT Design Guide for the recommended distance between sensors and gateway.

In most cases, gateways need not be directly in-plane with the Surface sensors. When the Surface sensors are mounted to the underside of desks made predominately of wood and plastic, having sensors and gateways up to 15 feet out-of-plane (gateways installed on the ceiling) is acceptable. However, if the desks are made of metal, gateways should be installed in-plane with the sensors or below the desk's metal surface. If a desk has metal obstructions on multiple sides, take additional care when designing the wireless network and placing gateways.

The gateways should be installed at least 4 feet apart and must be configured to use different channels. Increasing the distance between the gateways and their respective wireless channels will reduce the gateways' likelihood of interfering with each other.

Commissioning and Licensing

Real-time desk occupancy solutions require Energy Manager 3.9.13 or later. Desk sensors should be assigned the fixture type' Desk Sensor', a default fixture type preconfigured in Manage. For the sensors to detect occupancy, the sensors in the area need to be enabled and assigned the fixture type "Desk Sensor'. Refer to the article, Enable Desk Sensors. 

The Surface sensor can be deployed either as a

• Desk Occupancy sensor, or
• Area or Conference Room Occupancy sensor

For enabling Desk sensor and access to occupancy APIs, purchase the following software licenses (future Energy Manager 3.10 release or Manage 4.0 onwards) from Enlighted.

1. IoT Sensor License, per sensor on Manage (SU-5i-USB-IOT)
   Note: Occupancy APIs are not available with Enlighted One or Connected Lighting systems
2. Surface Sensor API, per desk sensor on Manage (API-RTO-DSK)
3. Surface Sensor API, per area on Manage (API-RTO-AREA)

1. Deployed as a Desk Occupancy Sensor

Each desk sensor is designed to detect whether or not someone is seated at a standard height desk. The number of sensors should equal the number of desks being monitored. If designing for standing height or adjustable height desks, consider the sensor coverage and desk geometry to achieve the desired functionality; this may require the sensor to be installed in a slightly different position than the recommended guidelines below.

Typically, a Surface sensor installed at 27" H from the front edge of a seated desk can detect occupancy up to 32" outwards the front of the desk. The sensor also detects up to 30 inches circumference from side to side from where it is installed.

When deployed as a desk occupancy sensor, follow the guidelines below:

1. Center and mount the sensor to the underside of the desk 15-26" from the front edge of the desk and at least 5" from the rear edge for a typical 27" height seated desk or a 42-50" height standing desk.
2. Mount the sensor parallel to the front edge of the desk.
3. After installation, the sensor lens must be facing the desk occupant for the sensor to detect occupancy.
4. Ensure that the USB cable is long enough to plug into the nearest USB adaptor.
5. Power the desk sensor to an uncontrolled receptacle that continuously supplies power.
   Do not connect it to a controlled receptacle.
6. Include all the desks that need to be monitored for occupancy.   
7. To avoid false detection of motion, do not remove the pre-installed mask on the lens to restrict the sensor's field of coverage for under-desk coverage.

Desk Overlapping Coverage: In an open office with 5 feet long tables placed adjacent to each other, there is minimal to no overlap of sensor ranges between the adjacent desks. However, for 4 feet long tables, the overlapping coverage is one foot on either side of the table. The one-foot overlapping coverage increases the possibility of occupancy detection by sensors on both desks. To minimize overlapping and occupancy detection, Enlighted recommends placing 4 feet long tables one foot apart.

2. Deployed as Area or Conference Room Occupancy Sensor  

When the Surface Sensor is installed in the ceiling tile, it can be used as an area or conference room occupancy sensor. When used in open areas or conference rooms, the sensors can be mounted on ceilings or walls, depending on the room size, shape, furniture, and spaces with obstacles. Also, in hallways and corridors, consider a combination of both ceiling and wall-mounting options with or without the mask on the lens. For room occupancy applications, remove the mask covering the sensor lens for a wider range of coverage.

The higher the sensor height, the greater is the sensor's FOV (Field of View) for occupancy coverage. Enlighted does not typically recommend ceiling heights of over 15 ft since the Enlighted High Bay and Ruggedized sensors are designed for taller ceilings. Consider the sensor's coverage FOV to achieve the desired functionality.

Ceiling Top and Side View Coverage

Wall or Edge Coverage with Mask on the Lens

Overlapping Coverage: For accurate occupancy detection of an area,  install sensors to cover the area of interest, ensuring that the coverage patterns overlap, as shown below. Use the pre-installed mask on the lens to provide an edge/wall and half-circle coverage for walls with windows, or remove the mask covering the sensor lens to cover as much circular area as possible. Also, make sure that the coverage from each sensor overlaps to avoid blind spots for occupancy detection. The sensor can detect motion from people for up to 20 feet from the installed position. 

Avoid mounting the sensors close to a door frame, exit sign, or furniture that could cause potential FOV interference. 

Ceiling Deployments

Ceiling deployments are suitable for spaces requiring maximum floor space occupancy coverage such as laboratories, large conference rooms, warehouses, shipping/receiving areas. Ceiling deployments need easy access to power outlets.   

Wall or Edge Deployments

Wall-mounted deployments for Surface sensors are the most flexible mounting option available for occupancy sensing. The Wall and Edge deployment can be used in the following scenarios.

1. Video Conference Rooms  

This is an ideal mounting scenario as there are readily available USB ports or power outlets near any video conference setup. To support Safe and Where applications, Enlighted recommends a minimum of two sensors in an enclosed conference room: a Surface sensor mounted under the desk from the farthest side of the TV and an in-wall mounted sensor above the video conference monitor with a direct line of sight for reliable occupancy detection.  

2. Wide-open Areas 

In wide-open areas, use the sensor with the pre-installed mask on the lens to restrict the sensor's FOV to avoid false detection of motion.

3. Corridors or Hallways 

Corridors are an optional but recommended deployment with the tradeoff of not having access to Enlighted Space application or understanding high traffic areas without Enlighted's Tag and Safe deployments.

When designing corridor solutions, consider the length of the corridor and access to power outlets. The sensors can detect occupancy for corridors up to 10 feet wide. For long passages that do not have easy access to power outlets, Enlighted recommends Ceiling-mounted Gen 5 Micro sensors (SU-5E). The sensors can also be enabled for Safe and Where deployments.   

Corridors with Power Outlets

For corridors with power outlets, Enlighted recommends deploying wall-mount sensors on the side of the outlet every 10-15 feet to provide occupancy coverage. For outlets, remove the mask covering the sensor lens before installing the sensors near the outlet so that the sensor's FOV covers the walk-way. When occupants or service staff want to use the outlet, then either install an outlet extender with a USB port (does not require an electrician) or have new outlets with a pre-existing USB port installed. Always power the sensor only to an uncontrolled receptacle that continuously supplies power.

Deployed for Enlighted RTLS Safe and Where Applications

As long as a sensor network is deployed for Desk or Conference room and open-area level occupancy, the sensor density grid should support Safe Work-place Contact Tracing and Where applications. A few additional sensors would need to be deployed to reach certain dead zones or spaces where occupancy detection is not required, but real-time tracking of people or assets would be needed.

The Enlighted Asset and Badge tags can be detected for up to 50ft within each sensor.

Number of Tags

The ideal number of tags per sensor for Safe and Where applications are seven per sensor. If an area of 150 sq. ft has more than seven assets, consider deploying additional sensors to maintain accuracy. For information on design network guidelines, refer to the Enlighted Network and IT Design Guidance for system design guidance. 

Surface Sensor Status

After the Surface sensor is installed, discovered, and commissioned, you can obtain an individual sensor's status by hovering the cursor over the sensor icon in the Energy Manager > Facilities > Floor Plan view.

• Yellow background – The last known status of the device.
• Green background – If the cursor remains over the icon for three seconds, a request is sent to the device to obtain its status. If the device responds, then the popup is updated.  

1. Light Level - Since Desk sensors do not control lighting, the light level is always displayed 'Off,' and wattage is always '0'.
2. Bright - Indicates ambient light level. When the sensor lens is covered, this is displayed as 'Dark.'
3. Occupied - The sensor detected occupancy three seconds ago.
4. Temperature - Measured Temperature in centigrade.
5. Sensor Name, for example, Sensor3ca163;
   Lighting profile name, for example, Desk Sensor;
   Fixture or sensor operation mode set to either Auto or Manual. 

• Pink background – When no response is received from the sensor within five seconds, the popup background changes from green to pale pink. 

Recommended articles:

• SU-5 Sensor Bluetooth Low Energy (BLE) Capabilities 
• Surface Sensor, USB (SU-5i-USB) Spec Sheet