Patent ID: 9470670
Filing Date: 2016-10-18
CPC Classification: G01N,G08B

Claim Text:
1. A method for detecting recent human presence in a space, the method comprising the steps of: measuring, using a carbon dioxide sensor, the concentration of carbon dioxide within said space to obtain a first carbon dioxide measurement; measuring, using the carbon dioxide sensor, the concentration of carbon dioxide within said space after a first period of time elapses to obtain at least a second carbon dioxide measurement; calculating the carbon dioxide rate of decay using at least said first and said second carbon dioxide measurements; determining a carbon dioxide concentration of interest; extrapolating the time at which the concentration of carbon dioxide in said space was approximately equivalent to said carbon dioxide concentration of interest; and correlating said carbon dioxide rate of decay to a level of human presence in said space at said extrapolated time; wherein the carbon dioxide sensor is an infrared gas sensor.