CO2 Decay Rate Analysis for Post-Occupancy Presence Detection

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Solution Overview

Problem

Existing systems for detecting human presence in environments cannot determine recent human presence once the space is empty or in areas without pre-installed sensors, as they rely on real-time detection and fail to quantify past occupancy.

Innovation Solution

A method and system that measure carbon dioxide concentration levels over time to calculate the rate of decay, allowing for the extrapolation of past occupancy and departure times by correlating CO2 levels with human presence, using sensors and a computer program to analyze these measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If real-time sensor detection is used to detect human presence, then detection accuracy is improved, but the system cannot detect recent human presence after the space becomes empty

Engineering Contradiction:

Improvehuman presence detection accuracyVSAvoiddetection capability after occupancy ends

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary measurement of CO2 concentration before human departure, and uses this baseline to detect recent presence after the space becomes empty. By measuring and storing the CO2 level prior to occupancy end, the system can later determine if humans were recently present by comparing current levels against this preliminary data, extending detection capability beyond real-time occupancy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces CO2 concentration as an intermediary substance that remains in the environment after human departure. Instead of directly detecting humans in real-time, the system detects the residual CO2 signature left by occupants, allowing inference of recent presence without requiring continuous real-time human detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If sensors are pre-installed in spaces for real-time detection, then detection capability is improved, but the system cannot function in spaces without pre-installed sensors

Engineering Contradiction:

Improvedetection capabilityVSAvoidapplicability to spaces without sensors

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system is designed to work in two modes: (1) continuous monitoring mode for spaces with pre-installed sensors, and (2) retrospective detection mode using portable devices that can be brought to any space. This universal design allows the same technology to serve both permanently instrumented environments and ad-hoc locations without requiring permanent sensor installation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The portable detection device performs self-service by carrying its own sensing capabilities and computational resources. Instead of relying on pre-installed infrastructure, the device independently measures CO2 levels, processes the data, and generates occupancy reports, making the system adaptable to any space regardless of existing sensor infrastructure.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If multiple CO2 measurements are taken over time to calculate decay rate, then quantification of recent human presence is improved, but measurement time and system complexity increase

Engineering Contradiction:

Improverecent human presence quantificationVSAvoidmeasurement and calculation system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system monitors changes in CO2 concentration parameters over time to infer occupancy information. By tracking the decay rate of CO2 levels after occupancy ends, the system can quantify recent human presence. This approach transforms a complex multi-parameter problem into a simpler single-parameter measurement (CO2 concentration change over time) that provides rich occupancy information.

Inventive Principle:

Principle #35Parameter changes

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

Enables the detection and quantification of recent human presence in spaces without requiring real-time occupancy, providing a historical analysis of occupancy numbers and departure times based on CO2 concentration decay rates.

Implementation Method 1

measuring means configured to measure the concentration of carbon dioxide within the space

Methodology Applied

Scientific EffectGas concentration detection:

Data Source

PatentUS10145831B2Method and system for human presence correlation using carbon dioxide

Publication Date: 2018.12.04 SRC INC

AI summary

Method and system for detecting and/or quantifying recent human presence in an environment using a calculated rate of decay of carbon dioxide concentration levels within that environment. A sensor measures the change in carbon dioxide levels over time to calculate the rate of decay to equilibrium and extrapolate recent human presence. Also provided is a method and system for quantifying recent human activity in an environment using the calculated rate of decay to equilibrium.