93 Low-cost sensor network in cognitive buildings for maintenance optimisation Juan Diego Blanco Cadena, Nicola Moretti * , Tiziana Poli, Fulvio Re Cecconi Highlights Abstract Facility Management services can be optimised in cognitive buildings through ultrasonic sensors-based occupancy monitoring. A low-cost ultrasonic sensor network can be employed for occupancy monitoring with suffcient accuracy and reliability. The proposed method allows to effectively monitor users’ occupancy in a space of a building without jeopardizing occupants’ privacy. Sensor-based occupancy monitoring can be encompassed in a smart contract for maintenance management fostering disintermediation. Sensor network confguration, set-up and latency are key factors for boosting reliability and accuracy. Buildings cannot perform without a proper planning, execution and monitoring of Facility Management services. Moreover, occupancy monitor procedures for cognitive buildings are gaining momentum in performance optimization through dynamic adaption of indoor conditions (e.g. temperature, humidity, shadings). In this article, the application of a similar approach for automated execution of maintenance contracts (e.g. cleaning services) is presented. This approach is allowed by monitoring occupancy, through an ultrasonic sensor network. The methodology has been validated on a case study, concerning an offce building in Milan, Italy. Keywords Ultrasonic sensors, Arduino, Occupancy monitor, Cognitive buildings, Facility Management 1. INTRODUCTION The use of sensors is growing exponentially in all economic sectors. This growth can be attributed to some factors as the ease of use, the fexible compatibility with available microcontroller systems (i.e. such as Arduino and Raspberry Pi) and the ease of purchase and reduced costs of all required components to set-up a sensor network. Considering the wide range of technologies available, the correct choice on the type of sensors to use is key to spare time and resources, and instead dedicate them to achieve a reliable calibration and integration into the desired network. Nowadays, in the Architecture, Engineering, Construction and Operations (AECO), sensors are often installed to increase building performance Vol. 5, No. 1 (2019) e-ISSN 2421-4574 Fulvio Re Cecconi ABC Department - Politecnico di Milano, via Giuseppe Ponzio 31, Milano, 20133, Italia Tiziana Poli ABC Department - Politecnico di Milano, via Giuseppe Ponzio 31, Milano, 20133, Italia Nicola Moretti ABC Department - Politecnico di Milano, via Giuseppe Ponzio 31, Milano, 20133, Italia Juan Diego Blanco Cadena ABC Department - Politecnico di Milano, via Giuseppe Ponzio 31, Milano, 20133, Italia * Corresponding author e-mail: nicola.moretti@polimi.it