ISLS: IoT-Based Smart Lighting System for Improving Energy Conservation in Office Buildings

TL;DR

This paper tackles office energy waste by proposing ISLS, a DIY IoT-based smart lighting system that uses occupancy and daylight sensing with remote monitoring to optimize lighting. It casts the problem as a constrained optimization that minimizes total power $\sum_{n=1}^{N} P_n d_n$ while achieving target illuminance $E_T$, solved via the simplex algorithm. A two-luminaire linear model with a dimming vector $\mathbf{d}$ is estimated through least-squares regression and implemented with PWM to avoid flicker, enforcing illumination constraints and Weber's law-based perceptual limits. Validation includes MATLAB simulations and a real-world prototype, showing substantial energy savings across occupancy scenarios and demonstrating real-time monitoring and data analytics capabilities. The approach offers a scalable, low-cost pathway for energy-efficient, IoT-enabled office lighting systems with potential for broader deployment in smart buildings.

Abstract

With the Internet of Things (IoT) fostering seamless device-to-human and device-to-device interactions, the domain of intelligent lighting systems have evolved beyond simple occupancy and daylight sensing towards autonomous monitoring and control of power consumption and illuminance levels. To this regard, this paper proposes a new do-it-yourself (DIY) IoT-based method of smart lighting system featuring an illuminance control algorithm. The design involves the integration of occupancy and presence sensors alongside a communication module, to enable real-time wireless interaction and remote monitoring of the system parameters from any location through an end-user application. A constrained optimization problem was formulated to determine the optimal dimming vector for achieving target illuminance at minimal power consumption. The simplex algorithm was used to solve this problem, and the system's performance was validated through both MATLAB simulations and real-world prototype testing in an indoor office environment. The obtained experimental results demonstrate substantial power savings across multiple user occupancy scenarios, achieving reductions of approx. 80%, 48%, and 26% for one, two, and four user settings, respectively, in comparison to traditional basic lighting installation systems.

Figures (2)

• Figure 1: Floor plan illustrating an indoor space projecting the luminaire
• Figure 2: Block diagram illustration of the closed loop system.