Ventilation system and ventilation method

Abstract

The objective of the present invention is to provide a ventilation system, a ventilation method and a program capable of sufficiently reducing the concentration of a chemical substance in a room while suppressing ventilation in consideration of adsorptive building materials.　A ventilation system (10) includes a ventilation facility (20) for ventilating a room (40), an adsorptive building material (41) installed in the room (40) to adsorb a chemical substance, a chemical substance concentration sensor (52) installed in the room (40) to detect the concentration of the chemical substance, and a control device (21), in which the control device (21) includes: a required ventilation amount calculating means for calculating an amount of ventilation required to suppress the concentration of the chemical substance to or below a predetermined reference concentration, on the basis of a concentration detected by the chemical substance concentration sensor (52); a corresponding ventilation amount calculating means for calculating a corresponding ventilation amount that is a ventilation amount corresponding to an effect of reducing the concentration of the chemical substance by means of the adsorptive building material (41); and a control means for controlling the operation of the ventilation facility (20) on the basis of the amount of ventilation required and the corresponding ventilation amount.

Description

Title of Invention: VENTILATION SYSTEM AND VENTILATION METHOD Technical Field The present invention relates to a ventilation system and a ventilation method, and more particularly, to reduction in concentration of a volatile organic compound in a room. Background Art In order to reduce a concentration of a volatile organic compound such as formaldehyde in a room, in Patent Literature 1, there is disclosed an apparatus which includes a sensor for detecting a concentration of a chemical substance, and controls a ventilation amount of a 24-hour ventilation system based on a detection value obtained by the sensor. With this apparatus, the concentration of the chemical substance in the room can be reduced through ventilation. Citation List Patent Literature [PTL 1] JP 2010-266102 A Summary of Invention Technical Problem For reduction in concentration of a volatile organic compound, not only ventilation but also a building material that chemically adsorbs a volatile organic compound is effective. At present, adsorptive building materials made of various raw materials can be used in various forms such as a wall material and a ceiling material. Incidentally, when the above-mentioned related art is applied to a room using such an adsorptive building material, over-ventilation occurs because no consideration is given to reduction in concentration of a chemical substance by the adsorptive building material. However, such over-ventilation is not preferred from the viewpoint of energy saving. The present invention has been made in view of the above-mentioned problem, and has an object to provide a ventilation system and a ventilation method with which a concentration of a chemical substance in a room can be sufficiently reduced while suppressing ventilation in consideration of an adsorptive building material. Solution to Problem (1) In order to solve the above-mentioned problem, a ventilation system according to one aspect of the present invention includes: ventilation equipment configured to ventilate a room; an adsorptive building material, which is installed in the room, and is configured to adsorb a chemical substance; a first sensor, which is installed in the room, and is configured to detect a concentration of the chemical substance; required ventilation amount calculating means for calculating, based on the concentration detected by the first sensor, a required ventilation amount required for reducing the concentration of the chemical substance to a predetermined reference concentration or less; corresponding ventilation amount calculating means for calculating a corresponding ventilation amount that is a ventilation amount corresponding to an effect of reducing the concentration of the chemical substance by the adsorptive building material; and control means for controlling an operation of the ventilation equipment based on the required ventilation amount and the corresponding ventilation amount. (2) In the ventilation system according to Item (1), the required ventilation amount calculating means may be configured to calculate a current or future generation amount of the chemical substance based on the concentration detected by the first sensor. The required ventilation amount calculating means may also be configured to calculate the required ventilation amount based on the current or future generation amount and the predetermined reference concentration. (3) The ventilation system according to Item (2) may further include a second sensor configured to detect at least one of a temperature or a humidity in the room. The required ventilation amount calculating means may be configured to calculate the future generation amount of the chemical substance further based on the at least one of the temperature or the humidity in the room. (4) In the ventilation system according to any one of Items (1) to (3), the corresponding ventilation amount calculating means may be configured to calculate the corresponding ventilation amount based on an adsorption area of the adsorptive building material and a value of the corresponding ventilation amount per unit area of the adsorptive building material. (5) The ventilation system according to Item (4) may further include: a sub-adsorptive building material, which is provided in a circulation path provided in the room, and is made of the same raw material as a raw material of the adsorptive building material; and a third sensor, which is provided on a downstream side of the sub-adsorptive building material in the circulation path, and is configured to detect the concentration of the chemical substance. The corresponding ventilation amount calculating means may be configured to calculate the value of the corresponding ventilation amount per the unit area based on the concentration of the chemical substance on an upstream side of the sub-adsorptive building material and the concentration detected by the third sensor. (6) In the ventilation system according to Item (5), the concentration of the chemical substance on the upstream side of the sub-adsorptive building material may be the concentration detected by the first sensor. (7) A ventilation method according to one aspect of the present invention includes: a required ventilation amount calculating step of calculating, based on a concentration of a chemical substance detected by a first sensor installed in a room, a required ventilation amount required for reducing the concentration of the chemical substance to a predetermined reference concentration or less; a corresponding ventilation amount calculating step of calculating a corresponding ventilation amount that is a ventilation amount corresponding to an effect of reducing the concentration of the chemical substance by an adsorptive building material which is installed in the room and is configured to adsorb the chemical substance; and a control step of controlling, based on the required ventilation amount and the corresponding ventilation amount, an operation of ventilation equipment configured to ventilate the room. (8) A program according to one aspect of the present invention is a program for causing a computer to execute: a required ventilation amount calculating step of calculating, based on a concentration of a chemical substance detected by a first sensor installed in a room, a required ventilation amount required for reducing the concentration of the chemical substance to a predetermined reference concentration or less; a corresponding ventilation amount calculating step of calculating a corresponding ventilation amount that is a ventilation amount corresponding to an effect of reducing the concentration of the chemical substance by an adsorptive building material which is installed in the room and is configured to adsorb the chemical substance; and a control step of controlling, based on the required ventilation amount and the corresponding ventilation amount, an operation of ventilation equipment configured to ventilate the room. Advantageous Effects of Invention According to the present invention, it is possible to sufficiently reduce the concentration of the chemical substance in the room while suppressing ventilation in consideration of the adsorptive building material. Brief Description of Drawings FIG. 1 is a configuration diagram of a ventilation system according to an embodiment of the present invention. FIG. 2 is a functional block diagram of a control device. FIG. 3 shows graphs of variations of a change in concentration of a chemical substance. FIG. 4 is a flow chart for illustrating ventilation amount changing processing. FIG. 5 is a flow chart for illustrating ventilation amount increasing processing. FIG. 6 is a flow chart for illustrating ventilation amount decreasing processing. Description of Embodiments Now, an embodiment of the present invention is described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a ventilation system according to the embodiment of the present invention. A ventilation system 10 illustrated in FIG. 1 is used to reduce a concentration of a volatile organic compound such as formaldehyde in a room 40 of a house or the like through ventilation. That is, the ventilation system 10 includes ventilation equipment 20 for ventilating the room 40. Further, an adsorptive building material 41 for adsorbing the chemical substance is installed in the room 40 on, for example, a wall surface, a ceiling, or a floor surface. That is, the ventilation system 10 is to reduce the concentration of the volatile organic compound in the room 40 by both of the ventilation equipment 20 and the adsorptive building material 41. A user device 50 formed mainly of a computer is installed in the room 40. This user device 50 includes a display unit 51 such as a display for issuing an alert or the like to a user who is a resident, a chemical substance concentration sensor 52 for detecting the concentration of the chemical substance in the room 40, a temperature sensor 53 for detecting a temperature in the room 40, and a humidity sensor 54 for detecting a humidity in the room 40, and those components are connected to the computer (not shown) included in the user device 50. Further, the user device 50 can perform wireless or wired data communication to and from a control device 21 to be described later. The chemical substance concentration sensor 52 is an example of a first sensor. Further, the temperature sensor 53 and the humidity sensor 54 are each an example of a second sensor . The ventilation equipment 20 includes the control device 21 and a heat exchanger 22. The heat exchanger 22 is connected to an outside air introducing duct 23 for taking in outside air, an exhaust duct 24 for exhausting air in the room to the outside, an intake duct 25 for taking in air in another room, and a ventilation duct 26 for introducing outside air into the room 40. A distal end of the ventilation duct 26 reaches the room 40, and the outside air introduced by the outside air introducing duct 23 is guided into the room 40 via the ventilation duct 26 (first path). The air in another room passes through the heat exchanger 22 to be discharged to the outside through the exhaust duct 24 (second path) . At this time, the heat exchanger 22 performs heat exchange between the above-mentioned two paths so that the outside air is introduced into the room 40 with its temperature being brought close to the temperature in the room 40. The ventilation equipment 20 is provided with a ventilation fan in at least one of the first path or the second path. In this case, the ventilation equipment 20 may perform balanced ventilation, or perform exhaust ventilation. The ventilation equipment 20 is further provided with a circulation path formed of an intake duct 27 and an exhaust duct 28. In the middle of the circulation path, a chemical substance adsorption space 31 is provided between the intake duct 27 and the exhaust duct 28, and an adsorptive building material 29 (sub-adsorptive building material) for adsorbing the chemical substance is arranged in this space. Further, a fan (not shown) is provided in the middle of the circulation path so that air in the room 40 is forced to circulate. The adsorptive building material 29 is made of the same raw material as that of the adsorptive building material 41, and has the same adsorption performance for the chemical substance. Further, the adsorptive building material 29 and the adsorptive building material 41 are in contact with the air in the same room 40, and have equal deterioration speeds of the adsorption performance. As described later, in this embodiment, the current adsorption performance of the adsorptive building material 41 is estimated by monitoring the adsorption performance of the adsorptive building material 29. Accordingly, in the middle of the exhaust duct 28, that is, on the downstream side of the adsorptive building material 29 in the circulation path, a chemical substance concentration sensor 30 for detecting the concentration of the chemical substance is provided. Detection results obtained by the chemical substance concentration sensor 30 are input to the control device 21. The chemical substance concentration sensor 30 is an example of a third sensor. The control device 21 receives, as input, detection results obtained by the chemical substance concentration sensor 52, the temperature sensor 53, and the humidity sensor 54 included in the user device 50 and the detection results obtained by the chemical substance concentration sensor 30, and controls a ventilation amount of the ventilation apparatus 20 (an amount of air to be replaced per unit time) as appropriate based on those pieces of information. At this time, over-ventilation is prevented in consideration of an effect of adsorbing the chemical substance by the adsorptive building material 41. FIG. 2 is a functional block diagram of the control device 21. The control device 21 is a computer mainly including a CPU and a memory, and executes a program according to one embodiment of the present invention to implement a group of functions illustrated in FIG. 2. That is, the control device 21 functionally includes a required ventilation amount calculation unit 210, a corresponding ventilation amount calculation unit 211, and a control unit 212. The required ventilation amount calculation unit 210 receives, as input, a room temperature detected by the temperature sensor 53, a humidity in the room 40 detected by the humidity sensor 54, and a concentration of a chemical substance in the room 40 detected by the chemical substance concentration sensor 52. Further, the required ventilation amount calculation unit 210 receives, as input, a current ventilation amount managed by the control unit 212. The required ventilation amount calculation unit 210 calculates a required ventilation amount required for reducing the concentration of the chemical substance to a predetermined reference concentration or less, based on the concentration of the chemical substance detected by the chemical substance concentration sensor 52. In this case, the required ventilation amount calculation unit 210 calculates a present or future generation amount of the chemical substance based on the concentration detected by the chemical substance concentration sensor 52. Specifically, the generation amount of the chemical substance is calculated in accordance with the following expression (1). (Generation amount of chemical substance)=(space concentration)x(ventilation amount) ••• (1) Here, the space concentration may be the weight of the chemical substance per unit volume, or may be a value measured by the chemical substance concentration sensor 52. Further, the value measured by the chemical substance concentration sensor 52 may be corrected based on at least one of the room temperature or the humidity. This correction value means the future generation amount of the chemical substance. The Berge formula or the Inoue formula may be adopted as the correction expression. As an example, the Inoue formula is expressed by the following expression (2) . Co=Cxl.O9A (To-T) / {1 + 0.01 (H-Ho) } ••• (2) Here, " / x" represents exponentiation. Co is a space concentration after correction, and C is a space concentration before correction. To is a predicted future room temperature, and T is a current room temperature. To may be obtained by, for example, extrapolation of a time series of T. Ho is a predicted future humidity, and H is a current humidity. Ho may be obtained by, for example, extrapolation of a time series of H. The future temperature or humidity may be more accurately predicted in consideration of the room layout of the construction, the position of the window, the heat insulation performance, the operation state of the heating and cooling equipment, the outside air temperature, the amount of insolation, and the like. Further, coefficients of 1.09 and 0.01 in the expression (2) may be updated to more likely values based on the transition of the actual concentration of the chemical substance, the actual room temperature, and the actual humidity. The ventilation amount is a current ventilation amount of the ventilation equipment 20, that is, a volume of air in the room 40 replaced with the outside air (having the concentration of the chemical substance of zero) per unit time. The current ventilation amount is managed by the control unit 212 as a function of the number of rotations of the ventilation fan of the ventilation equipment 20. The required ventilation amount calculation unit 210 calculates the required ventilation amount from the current or future generation amount of the chemical substance thus calculated. Specifically, the required ventilation amount is calculated by the following expression (3). (Required ventilation amount) = (generation amount) / (allowable space concentration) ••• (3) The allowable space concentration is an upper limit of the concentration of the chemical substance (predetermined reference concentration) allowed in the room 40. For example, 100 pg / m3 in a guideline from the Ministry of Health, Labour and Welfare of Japan may be adopted. The required ventilation amount calculation unit 210 may store the concentration detected by the chemical substance concentration sensor 52 in time series, and may monitor whether the concentration has suddenly increased. Then, when such sudden increase of the concentration is detected, the required ventilation amount may be obtained by obtaining the generation amount of the chemical substance by substituting the concentration after the sudden increase into the expression and then substituting the value of the generation amount into the expression (3). In this manner, when the concentration of the chemical substance suddenly increases because, for example, a new piece of furniture has been installed in the room 40, the required ventilation amount can be appropriately calculated, and thus the required ventilation can be carried out. The corresponding ventilation amount calculation unit 211 calculates the corresponding ventilation amount that is a ventilation amount corresponding to an effect of reducing the concentration of the chemical substance by the adsorptive building material 41. When the adsorptive building material 41 adsorbs the chemical substance present in the room 40, this adsorption reduces the concentration to be detected by the chemical substance concentration sensor 52. The corresponding ventilation amount indicates by how much ventilation amount the ventilation equipment 20 is required to perform ventilation in order to achieve the same concentration reduction. Accordingly, the corresponding ventilation amount calculation unit 211 calculates the corresponding ventilation amount as expressed by the following expression (4), based on an adsorption area of the adsorptive building material 41, that is, an area in which the adsorptive building material 41 is exposed to the room 40, and the corresponding ventilation amount per unit area. (Corresponding ventilation amount) = (adsorption area)x(corresponding ventilation amount per unit area) ••• (4) Here, the adsorption area is stored in advance in the control device 21. Further, the corresponding ventilation amount calculation unit 211 calculates, through use of the following expression (5), the corresponding ventilation amount per unit area, based on the concentration of the chemical substance on the upstream side of the adsorptive building material 29 and the concentration detected by the chemical substance concentration sensor 30. (Corresponding ventilation amount per unit area)=((indoor concentration) / (blowout concentration)-1)x(circulation amount) / (adsorption area) ••• (5) Here, the indoor concentration is a concentration detected by the chemical substance concentration sensor 52 installed in the room 40, which is on the upstream side of the adsorptive building material 29. The blowout concentration is a concentration detected by the chemical substance concentration sensor 30. The circulation amount is a volume of air passing through the circulation path including the intake duct 27 and the exhaust duct 28 per unit time. Further, the adsorption area is an area in which the adsorptive building material 29 is exposed in the chemical substance adsorption space 31. After the required ventilation amount is calculated by the required ventilation amount calculation unit 210 and the corresponding ventilation amount is calculated by the corresponding ventilation amount calculation unit 211 as described above, the control unit 212 controls the ventilation amount of the ventilation equipment 20 based on those values. As illustrated in FIG. 2, the control unit 212 includes a determination unit 212a, and the determination unit 212a manages time-series data of the concentration of the chemical substance in the room 40 to determine a pattern of change in concentration of the chemical substance. FIG. 3 shows graphs of the patterns of the change in concentration of the chemical substance. In FIG. 3, the horizontal axis of each graph corresponds to a time axis, and the right direction represents the future. The vertical axis of each graph indicates the concentration of the chemical substance, and the upper direction represents high concentration. The broken line indicates the upper limit concentration. Further, the gray region has a lower limit corresponding to the lower limit space concentration set in the control unit 212 and an upper limit corresponding to the above mentioned allowable space concentration. The control unit 212 performs control so that the concentration of the chemical substance in the room 40 falls within the gray region, to thereby prevent the concentration of the chemical substance from becoming high and prevent over-ventilation. In FIG. 3, case (1) shows a pattern in which the future concentration of the chemical substance calculated based on the temperature and the humidity exceeds the above-mentioned allowable space concentration. When the determination unit 212a determines that the current change in concentration of the chemical substance is the pattern of case (1), the control unit 212 performs ventilation amount changing processing to be described later. Case (2) shows a pattern in which the (current) concentration of the chemical substance detected last has become greatly larger than the concentration detected immediately before and exceeds the allowable space concentration. Also when the determination unit 212a determines that the current change in concentration of the chemical substance is the pattern of case (2), the control unit 212 performs the ventilation amount performs changing processing to be described later. Case (3) shows a pattern in which, even after the amount of ventilation by the ventilation equipment 20 is increased, the (current) concentration of the chemical substance detected thereafter still increases. This pattern may include a pattern in which the future concentration calculated based on the (current) concentration of the chemical substance detected immediately after the ventilation amount is increased still increases. Also when the determination unit 212a determines that the current change in concentration of the chemical substance is the pattern of case (3), the control unit 212 performs the ventilation amount changing processing to be described later. Case (4) shows a pattern in which, even after the amount of ventilation by the ventilation equipment 20 is increased immediately before, the (current) concentration of the chemical substance detected thereafter is equivalent (the concentration does not decrease) . When the determination unit 212a determines current change in concentration of the chemical is the pattern of case (4), the control unit 212 ventilation amount increasing processing to be later. Case (5) is a pattern in which the detected (current) concentration of the chemical substance exceeds the upper limit space concentration. When the determination unit 212a determines that the current change in concentration of the chemical substance is the pattern of case (5), the control unit that the substance described 212 causes the ventilation fan of the ventilation equipment 20 to operate at the maximum air volume. When the pattern of case (5) occurs together with other patterns, priority is given to the pattern of case (5) so that the ventilation fan is operated at the maximum air volume. Case (6) shows a pattern in which the detected (current) concentration of the chemical substance falls below the lower limit space concentration. When the determination unit 212a determines that the current change in concentration of the chemical substance is the pattern of case (6), the control unit 212 performs the ventilation amount changing processing to be described later. Case (7) shows a pattern in which, even after the ventilation amount is changed after the detected (current) concentration of the chemical substance falls below the lower limit space concentration, the concentration does not increase. When the determination unit 212a determines that the current change in concentration of the chemical substance is the pattern of case (7), the control unit 212 performs ventilation amount decreasing processing to be described later. FIG. 4 is a flow chart for illustrating the ventilation amount changing processing performed by the control unit 212. In the ventilation amount changing processing, first, the required ventilation amount calculated by the required ventilation amount calculation unit 210 is acquired (Step S401). Next, the corresponding ventilation amount calculated by the corresponding ventilation amount calculation unit 211 is acquired (Step S402) . Then, when the required ventilation amount is equal to or lower than the corresponding ventilation amount, the ventilation fan of the ventilation equipment 20 is operated in a first control mode, that is, at the minimum air volume (Step S403) . When the required ventilation amount is larger than the corresponding ventilation amount, the maximum amount of ventilation by the ventilation equipment 20, which has been stored in advance, is acquired, and the maximum total ventilation amount is calculated by adding the corresponding ventilation amount to the maximum ventilation amount (Step S404). Then, when the required ventilation amount is equal to or lower than the maximum total ventilation amount, the air volume of the ventilation equipment 20 is determined to achieve a second control mode, that is, to achieve the least ventilation amount required to allow the sum of the amount of ventilation by the ventilation equipment 20 and the corresponding ventilation amount to become the required ventilation amount or more, and the ventilation fan of the ventilation equipment 20 is operated at the determined air volume (Step S405). Further, when the required ventilation amount is larger than the maximum total ventilation amount, the user is alerted by, for example, issuing an alert on the display unit 51 of the user device 50 (Step S406) . Then, the ventilation fan of the ventilation equipment 20 is operated in a third control mode, that is, at the maximum air volume (Step S407). FIG. 5 is a flow chart for illustrating the ventilation amount increasing processing performed by the control unit 212. In the ventilation amount increasing processing, first, the current air volume of the ventilation equipment 20 is acquired (Step S501) . When the current air volume is not the maximum air volume, the air volume is increased by one level (Step S502) . In contrast, when the air volume is the maximum air volume, the current air volume is maintained (Step S503). FIG. 6 is a flow chart for illustrating the ventilation amount decreasing processing performed by the control unit 212. In the ventilation amount decreasing processing as well, similarly, first, the current air volume of the ventilation equipment 20 is acquired (Step S601). When the current air volume is not the minimum air volume, the air volume is decreased by one level (Step S602). In contrast, when the air volume is the minimum air volume, the current air volume is maintained (Step S603). With the ventilation system 10 described above, the ventilation amount of the ventilation equipment 20 can be appropriately set in consideration of the effect of adsorbing the chemical substance by the adsorptive building material 41 installed in the room 40. Thus, over-ventilation can be prevented, and thus energy can be saved. Further, the circulation path in which the adsorptive building material 29 is arranged is provided so that the corresponding ventilation amount per unit area of the adsorptive building material 41 can be calculated. Thus, even when the adsorptive building material 41 deteriorates over time and the adsorption effect is reduced, the adsorption effect thereof can be appropriately evaluated. In this manner, the ventilation amount of the ventilation equipment 20 can be appropriately set. The present invention is not limited to the above-mentioned embodiment, and various modifications can be made thereto. The various modifications also fall within the scope of the present invention. For example, the ventilation equipment 20 is not required to be balanced ventilation equipment or exhaust ventilation equipment, and may be supply ventilation equipment. Further, the ventilation may be performed by an automatic opening / closing window. In this case, it is only required to control the opening degree of the automatic opening / closing window or control the release time thereof. Moreover, a kitchen ventilation fan may be used in place of the ventilation equipment 20, and the air volume of the kitchen ventilation fan may be controlled. Reference Signs List 10 ventilation system, 20 ventilation equipment, 21 control device, 22 heat exchanger, 30, 52 chemical substance concentration sensor, 40 room, 29, 41 adsorptive building material, 50 user device, 51 display unit, 53 temperature sensor, 54 humidity sensor, 210 required ventilation amount calculation unit, 211 corresponding ventilation amount calculation unit, 212 control unit, 212a determination unit

Claims

1. A ventilation system, comprising:ventilation equipment configured to ventilate a room;an adsorptive building material, which is installed in the room, and is configured to adsorb a chemical substance;a first sensor, which is installed in the room, and is configured to detect a concentration of the chemical substance;required ventilation amount calculating means for calculating, based on the concentration detected by the first sensor, a required ventilation amount required for reducing the concentration of the chemical substance to a predetermined reference concentration or less;corresponding ventilation amount calculating means for calculating a corresponding ventilation amount that is a ventilation amount corresponding to an effect of reducing the concentration of the chemical substance by the adsorptive building material; andcontrol means for controlling an operation of the ventilation equipment based on the required ventilation amount and the corresponding ventilation amount.

2. The ventilation system according to claim 1, wherein the required ventilation amount calculating means is configured to :calculate a current or future generation amount of the chemical substance based on the concentration detected by thefirst sensor; andcalculate the required ventilation amount based on the current or future generation amount and the predetermined reference concentration.

3. The ventilation system according to claim 2, further comprising a second sensor configured to detect at least one of a temperature or a humidity in the room,wherein the required ventilation amount calculating means is configured to calculate the future generation amount of the chemical substance further based on the at least one of the temperature or the humidity in the room.

4. The ventilation system according to claim 1, wherein the corresponding ventilation amount calculating means is configured to calculate the corresponding ventilation amount of the adsorptive building material based on an adsorption area of the adsorptive building material and a value of the corresponding ventilation amount per unit area of the adsorptive building material.

5. The ventilation system according to claim 4, further comprising:a sub-adsorptive building material, which is provided in a circulation path provided in the room, and is made of the same raw material as a raw material of the adsorptive building material; anda third sensor, which is provided on a downstream side of the sub-adsorptive building material in the circulation path, and is configured to detect the concentration of the chemical substance,wherein the corresponding ventilation amount calculating means is configured to calculate the value of the corresponding ventilation amount per the unit area based on the concentration of the chemical substance on an upstream side of the sub-adsorptive building material and the concentration detected by the third sensor.

6. The ventilation system according to claim 5, wherein the concentration of the chemical substance on the upstream side of the sub-adsorptive building material is the concentration detected by the first sensor.

7. A ventilation method, comprising:a required ventilation amount calculating step ofcalculating, based on a concentration of a chemical substance detected by a first sensor installed in a room, a required ventilation amount required for reducing the concentration ofthe chemical substancetoa predeterminedreferenceconcentration or less;a corresponding ventilation amount calculating step of calculating a corresponding ventilation amount that is a ventilation amount corresponding to an effect of reducing the concentration of the chemical substance by an adsorptivebuilding material which is installed in the room and is configured to adsorb the chemical substance; anda control step of controlling, based on the required ventilation amount and the corresponding ventilation amount, an 5 operation of ventilation equipment configured to ventilate the room.

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