Infrared Occupancy Detection for Zone-Based HVAC Energy Control
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Solution Overview
Problem
Existing HVAC systems in commercial buildings lack the ability to accurately determine occupant locations and densities, leading to inefficient operation as they often turn on or off for entire spaces regardless of occupant presence or number, necessitating a need for advanced detection technologies to enhance control efficiency.
Innovation Solution
A system utilizing infrared sensors and artificial intelligence classifiers to determine occupant locations and densities, creating thermal models, predicting thermal comfort using PMV models, and adjusting HVAC systems to maintain comfort while minimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PIR motion sensors are used for occupancy detection, then occupancy presence can be detected, but specific information about exact location and number of occupants cannot be obtained
Solution Approach 1:
The patent replaces traditional PIR motion sensors with infrared cameras to detect occupants. The infrared camera captures thermal images that provide both occupancy detection and precise location information through image processing, transforming mechanical sensor detection into optical field-based detection that preserves spatial information.
Solution Approach 2:
The patent transitions from point-based PIR sensor detection to area-based infrared image detection. By capturing two-dimensional thermal images and processing them to extract occupant locations and densities, the system adds spatial dimensionality to occupancy detection, enabling precise tracking of multiple occupants across different positions in the space.
2Ease of operation
If HVAC systems operate on an all-or-nothing basis for entire spaces, then system control is simplified, but energy efficiency deteriorates due to unnecessary operation in unoccupied areas
Solution Approach 1:
The patent divides the entire space into multiple zones based on detected occupant locations and densities. The infrared camera identifies specific areas with occupants, and the HVAC system adjusts temperature and ventilation independently in each zone, allowing occupied areas to receive full HVAC service while unoccupied areas are reduced or shut off, significantly improving energy efficiency.
Solution Approach 2:
The patent implements different HVAC control strategies for different spatial locations based on local occupancy conditions. Occupied zones receive appropriate temperature and ventilation control, while unoccupied zones receive reduced or no HVAC service. This localized quality approach maintains comfort where needed while minimizing energy consumption in unoccupied areas.
3Productivity
If advanced detection technologies are implemented to accurately determine occupant locations and densities, then HVAC control efficiency improves, but system complexity increases
Solution Approach 1:
The patent uses infrared cameras that serve multiple functions: occupancy detection, location tracking, density calculation, and thermal environment monitoring. This single device performs what would traditionally require multiple separate systems, reducing overall system complexity while maintaining high HVAC control efficiency through accurate spatial occupancy information.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides precise control of HVAC systems, reducing energy consumption by up to 44% compared to traditional methods, ensuring occupant comfort and flexibility in energy usage, and preventing brown-outs by optimizing energy distribution across buildings.
Implementation Method 1
the system may use one or more sensors, such as low resolution infrared (IR) sensors
Implementation Method 2
creating a thermal model of the space based on the number of occupants, data about an outside temperature from an outside surface of one or more walls of the space, data about an inside temperature from an inside surface of one or more walls of the space
Implementation Method 3
data about wall insulation for one or more walls of the space
Data Source
AI summary
The system may include determining a number of occupants in a space, based on input from one or more sensors and an artificial intelligence classifier; creating a thermal model of the space based on the number of occupants, data about an outside temperature from an outside surface of one or more walls of the space, data about an inside temperature from an inside surface of one or more walls of the space and data about wall insulation for one or more walls of the space; predicting, using the thermal model, a temperature in the space for a period of time to create a predicted temperature; predicting a thermal comfort using a predicted mean vote (PMV) model and based on the predicted temperature; creating adjustment instructions for a building management system (BMS) based on the thermal comfort; and sending the adjustment instructions to the BMS.