Smart Passive Infrared Sensor–Enabled Building Access Control System with Energy Harvesting UWB Positioning for Occupancy-Based HVAC Optimization in Smart Buildings

Project Abstract

This study presents a novel integrated building access control system that leverages passive infrared (PIR) sensing, energy harvesting, and ultra-wideband (UWB) positioning to enable occupancy-aware HVAC optimization in smart buildings. The core objective is to enhance security and energy efficiency by synchronizing entry control with accurate, low-power occupancy detection and precise location tracking, while eliminating reliance on wired power supplies through energy harvesting methods. The proposed system architecture comprises three synergistic subsystems a PIR-based presence sensing module for intrusion detection and room-level occupancy confirmation, an energy harvesting unit that converts ambient light and thermal gradients into usable electrical energy to power the sensors and low-power microcontroller, and a UWB-based localization framework that determines user position within a building footprint with centimeter-level accuracy. The integration of UWB positioning enables not only secure access control by validating authorized occupants at entry points but also supports dynamic HVAC strategies by mapping occupancy distribution and movement patterns across zones. A multi-layer control algorithm orchestrates access decisions, energy budgeting, and HVAC operations, prioritizing occupancy comfort while minimizing energy waste during off-peak hours or in unoccupied zones. The system employs a lightweight cryptographic protocol and a rolling token-based authentication scheme to mitigate unauthorized access, with data privacy preserved through edge processing and local decision making to reduce cloud exposure. The research encompasses design, prototyping, and field testing in a representative smart-building environment, evaluating performance metrics such as PIR detection accuracy, energy harvesting efficiency, UWB localization precision, access latency, and HVAC energy savings. A rigorous experimental methodology includes controlled experiments to quantify false positives/negatives in occupancy detection, energy budget simulations under varying lighting conditions, and localization error analyses under multipath and non-line-of-sight scenarios. Results indicate that the energy harvesting unit sustains continuous operation of sensing modules with minimal battery intervention, while the UWB system maintains sub-meter tracking accuracy critical for occupancy-aware HVAC adaptation. The occupancy-based HVAC optimization model demonstrates measurable reductions in peak power demand and improvements in thermal comfort indices, especially during transitional periods of occupancy influx or exodus. The study also investigates resilience aspects, including spoofing risks, sensor fusion robustness, and failure modes under partial system outages, proposing mitigation strategies such as redundant sensing and secure handover protocols. Scalability analyses reveal that the integrated approach can be deployed across multiple floors and modular zones with achievable costs comparable to conventional wired systems, and the energy-neutral operation enhances long-term maintenance and sustainability. The work contributes to the body of knowledge on secure, energy-efficient building automation by presenting a cohesive framework that melds presence sensing, autonomous power harvesting, precise localization, and occupancy-driven HVAC control, with potential extensions to integrate indoor air quality sensing and adaptive lighting.

Project Overview

What This Project Is About

---

This project explores a smart building system that controls access using a passive infrared (PIR) sensor, which detects when people are nearby, combined with energy harvesting and ultra-wideband (UWB) positioning to manage occupancy-based heating, ventilation, and air conditioning (HVAC). The aim is to improve security and energy efficiency by knowing exactly when a space is occupied and by whom, without relying on constant power or wired infrastructure. The system should be practical, safe, and easy to install in real buildings.

---

---

The Problem It Addresses

---

Buildings waste energy when HVAC runs in empty rooms, and traditional access control often provides only doors unlocked/locked without knowing occupancy inside. This project addresses both energy waste and the need for reliable, low-power access and presence data by combining PIR sensing, energy harvesting to power sensors, and UWB positioning for precise location tracking within a facility.

---

---

Objectives of the Project

---

1. Design a PIR-based presence detector that can determine room occupancy.
2. Incorporate energy harvesting techniques to power sensors and radios sustainably.
3. Implement UWB positioning to locate people/furniture inside a building with high accuracy.
4. Develop an access control mechanism linked to occupancy data for secure entry.
5. Create an HVAC control strategy that uses occupancy information to save energy.

---

---

What You Will Do Step by Step

---

1. Review relevant literature on PIR sensing, energy harvesting, UWB positioning, and smart HVAC control.
2. Prototype a PIR sensor module with a small energy-harvesting circuit.
3. Integrate a UWB module and test location accuracy in a controlled space.
4. Develop a simple access control workflow tied to occupancy data.
5. Model HVAC control rules based on occupancy results.
6. Collect data from experiments and perform basic analysis of energy savings and accuracy.
7. Evaluate system reliability, power consumption, and user impact.
8. Document design, tests, and potential improvements for deployment.

---

---

Expected Outcome

An integrated, low-power access and occupancy system that coordinates with building HVAC to reduce energy use while maintaining security and comfort. The project should provide a working prototype, performance metrics (occupancy accuracy, energy savings, UWB precision), and recommendations for real-world deployment.