Air-conditioning control system

Abstract

An air-conditioning control system includes a ventilation fan; a human sensor for human presence detection; a gas sensor for measuring concentration of carbon dioxide; and a control panel as a control device. The control panel controls the ventilation fan based on an output signal of the human sensor and an output signal of the gas sensor. The control panel controls the ventilation fan to change an amount of ventilation by the ventilation fan based on the output signal of the human sensor when the concentration of carbon dioxide measured with the gas sensor is below a first threshold.

1 . An air-conditioning control system, comprising:
 a ventilation fan;   a human sensor configured to perform human presence detection;   a gas sensor configured to measure concentration of carbon dioxide; and   a control device configured to control the ventilation fan based on an output signal of the human sensor and an output signal of the gas sensor, wherein   the control device is configured to control the ventilation fan to change an amount of ventilation by the ventilation fan based on the output signal of the human sensor when the concentration of carbon dioxide measured with the gas sensor is below a first threshold.   
     
     
         2 . The air-conditioning control system of  claim 1 , wherein the control device is configured to control and operate the ventilation fan regardless of the output signal of the human sensor when the concentration of carbon dioxide measured with the gas sensor is the first threshold or more. 
     
     
         3 . The air-conditioning control system of  claim 1 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is below the first threshold, to control the ventilation fan so that the amount of ventilation by the ventilation fan when the human sensor detects human absence becomes smaller than that by the ventilation fan when the human sensor detects human presence. 
     
     
         4 . The air-conditioning control system of  claim 3 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is below the first threshold, to control to stop the ventilation fan when the human sensor detects human absence. 
     
     
         5 . The air-conditioning control system of  claim 1 , wherein the control device is configured to control the ventilation fan to change the amount of ventilation by the ventilation fan based on the output signal of the human sensor when the concentration of carbon dioxide measured with the gas sensor is below a second threshold that is lower than the first threshold. 
     
     
         6 . The air-conditioning control system of  claim 5 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is below the second threshold, to control the ventilation fan so that the amount of ventilation by the ventilation fan when the human sensor detects human absence becomes smaller than that by the ventilation fan when the human sensor detects human presence. 
     
     
         7 . The air-conditioning control system of  claim 6 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is below the second threshold, to control to stop the ventilation fan when the human sensor detects human absence. 
     
     
         8 . The air-conditioning control system of  claim 1 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is the first threshold or more, to control the ventilation fan so that the amount of ventilation by the ventilation fan when the human sensor detects human presence becomes greater than that by the ventilation fan when the human sensor detects human absence. 
     
     
         9 . The air-conditioning control system of  claim 5 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is the second threshold or more, to control the ventilation fan so that the amount of ventilation by the ventilation fan when the human sensor detects human presence becomes greater than that by the ventilation fan when the human sensor detects human absence. 
     
     
         10 . The air-conditioning control system of  claim 1 , wherein the gas sensor comprises:
 a light source;   a photodetector comprising
 a first optical filter which has a transmission band for transmitting infrared light containing an absorption wavelength of carbon dioxide, 
 a first light receiver which is disposed at an opposite side of the first optical filter from the light source, 
 a second optical filter which has a transmission band, without overlapping with the first optical filter, for transmitting infrared light having a reference wavelength as a non-absorption wavelength of carbon dioxide, and 
 a second light receiver which is disposed at an opposite side of the second optical filter from the light source; 
   a sample cell disposed between the light source and the photodetector; and   a signal processor configured to acquire the concentration of carbon dioxide based on a difference or a ratio between an output signal of the first light receiver and an output signal of the second light receiver.   
     
     
         11 . The air-conditioning control system of  claim 10 , wherein
 the sample cell is shaped like a tube of which inner face is a reflection surface for reflecting infrared light emitted from the light source,   the inner face is in a shape of a spheroid of which rotation axis is a major axis defined as a central axis of the sample cell, both ends of the spheroid in a direction of the major axis being cut by two planes perpendicular to the major axis,   the light source is disposed in vicinity of one focal point of the spheroid on the central axis, and   the photodetector is disposed at a position nearer to the light source than another focal point of the spheroid on the central axis.   
     
     
         12 . The air-conditioning control system of  claim 1 , wherein the control device is configured, when operating the ventilation fan, to more decrease the amount of ventilation as the concentration of carbon dioxide measured with the gas sensor is lower. 
     
     
         13 . The air-conditioning control system of  claim 1 , wherein the first threshold is set to permissible concentration of carbon dioxide in a room in which the gas sensor is installed. 
     
     
         14 . The air-conditioning control system of  claim 2 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is below the first threshold, to control the ventilation fan so that the amount of ventilation by the ventilation fan when the human sensor detects human absence becomes smaller than that by the ventilation fan when the human sensor detects human presence. 
     
     
         15 . The air-conditioning control system of  claim 14 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is below the first threshold, to control to stop the ventilation fan when the human sensor detects human absence. 
     
     
         16 . The air-conditioning control system of  claim 2 , wherein the control device is configured to control the ventilation fan to change the amount of ventilation by the ventilation fan based on the output signal of the human sensor when the concentration of carbon dioxide measured with the gas sensor is below a second threshold that is lower than the first threshold. 
     
     
         17 . The air-conditioning control system of  claim 16 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is below the second threshold, to control the ventilation fan so that the amount of ventilation by the ventilation fan when the human sensor detects human absence becomes smaller than that by the ventilation fan when the human sensor detects human presence. 
     
     
         18 . The air-conditioning control system of  claim 17 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is below the second threshold, to control to stop the ventilation fan when the human sensor detects human absence. 
     
     
         19 . The air-conditioning control system of  claim 2 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is the first threshold or more, to control the ventilation fan so that the amount of ventilation by the ventilation fan when the human sensor detects human presence becomes greater than that by the ventilation fan when the human sensor detects human absence. 
     
     
         20 . The air-conditioning control system of  claim 6 , wherein the control device is configured, when the concentration of carbon dioxide measured with the gas sensor is the second threshold or more, to control the ventilation fan so that the amount of ventilation by the ventilation fan when the human sensor detects human presence becomes greater than that by the ventilation fan when the human sensor detects human absence.