Optimized Selection and Placement of Sensors using Building Information Models (BIM)

The performance of an advanced lighting system is heavily influenced by the placement and orientation of occupancy sensors and photo-sensors. Incorrect sensor placement can compromise system performance, cause discomfort to occupants and diminish savings. The current process of manually selecting sensors and placing them on a floor plan in a design tool is not only suboptimal but also is tedious and error-prone. To overcome these issues, we have developed a Revit plug-in which automatically deploys sensors on optimal locations in Building Information Models (BIM). Introduction Lighting and HVAC accounted for 60% of the energy used in US commercial buildings in 2010 [1]. Lighting controls and Building Automation Systems are proven methods for improving operational efficiency and occupant comfort [2]. The performance of these systems is heavily influenced by the placement of sensors such as occupancy, photo, temperature, humidity, smoke and CO2 sensors. Incorrect sensor placement can compromise performance, cause discomfort to the occupants and diminish savings. For example, placing PIRbased occupancy sensors close to HVAC exhausts can lead to false positive triggers thereby diminishing savings. If an occupancy sensor’s detection region continues beyond doors (or windows) then it can cause unwanted triggers leading to energy waste. If an occupancy sensor’s line of sight to an occupant is blocked by partitions, then lights may turn-off while occupant is present thereby causing discomfort to the occupant. If the photo-sensor is installed near the window then reflections from outside can cause over-dimming thereby compromising occupant comfort. This research is aimed at developing automatic sensor selection and placement methods based on building geometry and characteristics coming from BIMs. Current State of the Art Typically, an electrical contractor specifies sensor locations on 2D layout drawings. In many cases, the contractor requests a sensor placement service from a lighting controls supplier. A typical sensing device used in lighting applications may have a photo-sensor and a motion-sensor placed inside one physical enclosure. The placement of such a device has to comply with guidelines for placing both types of sensors. Currently, sensor placement on the building layout is done manually as follows: 1. The engineer manually evaluates space characteristics such as size and function (e.g., office, conference room, etc.), and locations of walls, doors, windows, luminaires and HVAC vents. 2. The engineer identifies a suitable sensor for a given space type and manually calculates the coverage area based on ceiling height, walls and partitions in the chosen area. 3. The engineer studies the manufacturer’s guidelines for sensor placement from sensor data sheets (e.g., do not place the PIR sensor within 2 meter radius of HVAC exhausts; do not place the photo-sensors within 0.75 times ceiling height (Fig. 1)). 4. The engineer reviews the code requirements (e.g. CA Title 24) that could impact placement. Figure 1. Sensor placement guideline