JP4580955B2 - Underfloor ventilation control member and building structure using the same - Google Patents

Description

  The present invention relates to an underfloor ventilation control member disposed in a building provided with an internal ventilation layer that allows communication between an underfloor space and an attic, and a building structure including the same.

  The present inventor has adopted so-called ventilating heat insulation that can prevent the steaming of structural materials such as timber, improve the durability of the building, and maintain the living environment suitably by taking outside air into the ventilation layer of the building. It proposed about the building structure provided with the structure (refer patent document 1, 2). This ventilation insulation structure is provided with an external ventilation layer and an internal ventilation layer along the outside and inside of the wall structure material of the building, and controls the ventilation of the external ventilation layer and the internal ventilation layer according to the season etc. The indoor dwelling environment is suitably maintained by utilizing the moisture absorbing and exhausting action and the ventilation action of the wall (wall surface).

In this ventilation insulation structure, by taking outside air under the floor, venting it from the underfloor space to the internal ventilation layer provided inside the wall structure material, and letting the airflow rising up the internal ventilation layer flow out from the back of the hut to the outdoors, It is configured to discharge hot air and moisture in the living room to the outside. In other words, when the outside air temperature is high as in the summer, the outside air is passed through the external ventilation layer and the inside ventilation layer, and a comfortable environment is provided by discharging hot air, moisture, etc. from the living room, and the outside air temperature is as in the winter. By lowering the ventilation of the outer ventilation layer and the inner ventilation layer when the temperature is low, the heat insulation effect of the living room is enhanced, and a comfortable living space can be provided throughout the year.
Japanese Patent Application Laid-Open No. 11-181901 JP 2006-207126 A

In this way, the ventilation and heat insulation structure is intended to create a comfortable living space by providing a ventilation layer in the building and exhausting hot air and moisture by using air permeability and moisture permeation on the walls of the living room. Structure. In order to realize such a living space, a ventilation control member having an opening / closing mechanism which is formed of a shape memory alloy and operates based on the temperature of the outdoor air is used for the communication state between the ventilation layer and the outdoor.
Such a ventilation control member is used for communication between the entrance portion of the outer ventilation layer formed between the outer wall of the building and the wall structure material, and the communication between the inner ventilation layer formed between the wall structure material and the indoor wall and the underfloor space. It is arranged on the part, the eaves part communicating with the attic, the ridge part of the attic, the foundation part of the building, and the like.

  However, in the case where floor heating or the like is used as a heating means for a building provided with the ventilation control member, when the floor heating is operated, the air in the underfloor space is heated by residual heat or the like, and the shape is an opening / closing mechanism The temperature of the memory alloy may be considerably higher than the temperature of the outdoor air. In such a situation, the temperature of the outdoor air is low, and the underfloor space and the internal ventilation layer should be closed normally, but the shape memory alloy misrecognizes the temperature of the outdoor air, and the underfloor space and the internal ventilation layer There was a problem that the living room would get cold.

  The present invention has been made to solve the above-described problems, and is under a situation where the temperature of the air in the underfloor space is higher than the temperature of the outdoor air due to floor heating or the like (regardless of the facility state of the building). The underfloor ventilation control member capable of accurately controlling the communication state between the underfloor space and the internal ventilation layer based on the temperature of outdoor air, and a building structure including the same For the purpose.

The present invention has the following configuration in order to achieve the above object.
That is, an underfloor ventilation control member disposed in a building in which an internal ventilation layer communicating with the underfloor space and the attic is provided between the wall structure material and the indoor wall, the underfloor space and the internal ventilation layer The communication part and the main body part in which the air passage is formed, and the communication part is opened by the position of the through hole that is disposed on at least one side of the communication part and is formed to penetrate in the plate thickness direction. A shielding plate that switches to a closed state; and an opening / closing mechanism that slides a through-hole position of the shielding plate between a closed position and an open position, and the opening / closing mechanism is disposed in a lower space of the main body. And a spring body made of a shape memory alloy and a bias spring, and the spring body made of the shape memory alloy is in direct contact with outdoor air from a gap formed between the foundation portion and the base portion of the building. It is disposed so as,該Ba The body and the bias spring are slid between the open position and the closed position by the difference in spring pressure generated between them according to the outside air temperature, and the ventilation between the underfloor space and the internal ventilation layer is controlled. It is an underfloor ventilation control member characterized by being made.

  In addition, by connecting the spring body made of the shape memory alloy and the bias spring in series, the structure of the opening / closing mechanism can be simplified, it can be provided at low cost, and maintenance is easy. Become.

As another invention, an internal ventilation layer communicating with the underfloor space and the attic is provided between the wall structure material and the indoor wall, the communication state between the underfloor space and the internal ventilation layer, and the attic and the outdoor The ventilation structure is provided with a ventilation insulation structure that controls the communication state according to the outside air temperature as an underfloor ventilation control member that communicates the underfloor space and the internal ventilation layer. The communication part is opened by the position of the main body part in which the communication part and the air passage for communicating with the layer are formed, and the through hole formed at least on one side of the communication part and penetrating in the plate thickness direction. A shielding plate that switches between a closed state and a closed state, and an opening / closing mechanism that slides a through hole position of the shielding plate between a closed position and an open position, and the opening / closing mechanism is disposed in a lower space of the main body. while being set, shape memory Spring body made of gold and has a bias spring, the spring body made of the shape memory alloy is disposed in direct contact with outside air from the gap section formed between the base portion and the base of the building The spring body and the bias spring are configured to slide the shielding plate between an open position and a closed position due to a difference in spring pressure generated between the spring body and the bias spring. The underfloor ventilation control member for controlling the ventilation state is attached.

According to the underfloor ventilation control member according to the present invention, it is possible to accurately control the flow of air from the underfloor space to the internal ventilation layer communicating with the attic according to the outdoor temperature. As described above, since the ventilation state is controlled based on the outdoor temperature, the communication between the underfloor space and the internal ventilation layer is surely cut off in the winter even in a house with floor heating. A comfortable living space with good heating efficiency can be provided.
Further, since the air circulation state in the building can be made suitable for each season, the consumption of energy required for air conditioning can be minimized, which is economical. Furthermore, the amount of energy used can be reduced, and the amount of carbon dioxide emissions associated with energy consumption can be reduced, so that global warming can be suppressed.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
(Ventilation insulation structure)
First, a building structure (ventilation heat insulation structure) using the ventilation control device according to the present invention will be described. In the building shown in FIG. 1, an outer wall 12 is provided outside the wall structure material 10 made of a heat insulating material by providing a ventilation layer between the wall structure material 10 and the wall structure material 10. A structure in which a ventilation layer is provided between and the indoor wall 14 is installed. A portion sandwiched between the outer wall 12 and the wall structure member 10 along the wall structure member 10 is the external ventilation layer 16, and a portion sandwiched between the wall structure member 10 and the indoor wall 14 is the inner ventilation layer 18.

  A ventilation control member 17 is provided at the lower end of the outer wall 12. The ventilation control member 17 is for controlling the ventilation in the external ventilation layer 16. By opening the ventilation control member 17, the ventilation layer 16 is vented upward from below to close the ventilation control member 17. As a result, ventilation in the external ventilation layer 16 is blocked. The ventilation control member 17 can be configured using, for example, a module using a shape memory alloy. The ventilation control member 17 is controlled to be opened when the outside air temperature is high as in the summer, and closed when the outside air temperature is low as in the winter.

On the other hand, the indoor wall 14 and the flooring 15 are attached to the base 22 supported by the foundation 20 with an opening. The internal ventilation layer 18 communicates with the underfloor space 23 through an opening provided between the base 22, the indoor wall 14, and the flooring 15.
The foundation 20 has an opening 20a communicating with the outside, and a ground window 21 with an opening / closing mechanism is attached to the opening 20a. The ground window 21 with the opening / closing mechanism includes a shielding plate that rotates between an open position and a closed position, and rotates the shielding plate to an open position and a closed position using a module using a shape memory alloy. Thus, it is controlled to be opened when the outside air temperature is high as in the summer, and closed when the outside air temperature is low as in the winter.

An underfloor ventilation control member 24 that controls the communication state between the internal vent layer 18 and the underfloor space 23 is also provided at a portion that connects the internal vent layer 18 and the underfloor space 23. The underfloor ventilation control member 24 is also controlled to open and close using a module using a spring body made of a shape memory alloy. The underfloor ventilation control member 24 is connected to the inner ventilation layer 18 when the outside air temperature is high, such as in summer. The underfloor space 23 is communicated, and when the outside air temperature is low as in winter, the communication between the internal ventilation layer 18 and the underfloor space 23 is controlled to be closed.
Note that the opening / closing mechanism module using a spring body made of a shape memory alloy has a spring body 64A made of a shape memory alloy and a bias spring 64B made of a normal elastic material in opposite directions with respect to each other. When the outside air temperature becomes high as in the summer, the elastic force by the spring body 64A made of a shape memory alloy is set to exceed the elastic force of the bias spring 64B made of a normal elastic material. The difference in force can be used as a driving force.

The living room 13 is formed by an indoor wall 14, a flooring 15, and a ceiling 19 made of a material having moisture permeability, and the internal ventilation layer 18 communicates with the hut 25 above the ceiling 19 at the upper part of the indoor wall 14. The shed 25 is provided with a shed lining 28 made of a heat insulating material in the same form as the roof 26 below the roof 26. Thus, the living room 13 is surrounded by the inner ventilation layer 18 and the hut 25.
An opening 25a that connects the roof 26 and the roof 25 is provided at the top of the roof 25, and the roof 25 and the roof 30 communicate with each other through the opening 25a.

  A ventilation control member 34 using a spring body made of a shape memory alloy is also attached to an eaves 32 provided in communication with the attic 30. The ventilation control member 34 is attached to an opening provided in the eaves 32 and serves to communicate the inside and outside of the eaves 32 when the outside air temperature is high, and to block the inside and outside communication of the eaves 32 when the outside air temperature is low.

  The ridge portion of the attic 30 is provided with an opening 30a, and a hat member 36 is installed on the upper portion of the ridge of the roof 26 so as to cover the opening 30a. The hat member 36 protects the rain wind from entering the opening 30a, and is provided so that the attic 30 communicates with the outdoors via the opening 30a. Inside the hat member 36, there is provided a ventilation control member 37 using a spring body made of a shape memory alloy that opens and closes a shielding plate to interrupt communication between the attic 30 and the outdoors.

  As described above, in the building structure of the present embodiment, the internal ventilation layer 18 and the underfloor space 23 provided around the living room 13 can be communicated, and the internal ventilation layer 18 is communicated with the hut 25, so 25 and the attic 30 are connected to each other to provide a ventilation structure for the entire building, and the ventilation control members 17, 34, 37, the ground window 21 with an opening / closing mechanism, and the underfloor ventilation control member 24 are controlled to open and close to the living room 13. Can maintain a good environment throughout the year.

That is, at the time of high temperature and humidity such as the summer (shown in the left half of the line AA in FIG. 1), the underfloor ventilation control member 24, the ground window 21 with the opening / closing mechanism, and the ventilation control members 17, 34, 37 is opened, and in the external ventilation layer 16, the air heated in the ventilation layer becomes an updraft, and hot air is released to the outside. In the internal ventilation layer 18, the ground window 21 with an opening / closing mechanism is passed to the underfloor space 23. Outside air flows in and flows out from the hat member 36 through the underfloor ventilation control member 24, the attic 25 and the attic 30 to the outside. In the attic 30, air flows in from the eaves 32 and an upward flow is generated from the eaves 32 toward the ridge.
Thus, the entire building is in a ventilation circulation state, and in the living room 13, hot air and moisture are transmitted from the indoor wall 14 to the internal ventilation layer 18, and the indoor environment is maintained in a comfortable state.

  Further, when the outside air temperature becomes low as in winter (shown in the right half of the line AA in FIG. 1), the ground window 21 with an opening / closing mechanism, the underfloor ventilation control member 24, the ventilation control member 17, Both 34 and 37 are in a closed state, and the outer ventilation layer 16 and the inner ventilation layer 18 are not vented. When ventilation through the external ventilation layer 16 and the internal ventilation layer 18 is stopped, the ventilation layer acts as a heat insulating layer, and the air kept warm in the living room 13 is not discharged outside, and the whole building is kept warm. The underfloor space 23 is heated by geothermal heat and contributes to the heat insulation of the building. Thus, the living room 13 is kept warm and is maintained as a comfortable living space.

By the way, when cooking is done indoors or a large number of people gather, or in the rainy season, etc., the humidity in the living room 13 temporarily becomes high or the temperature becomes high, so forced ventilation is necessary. It may become.
For this reason, the exhaust fan 40 may be attached for indoor ventilation. When operating the exhaust fan 40, it is necessary to take in outside air, and it is possible to take outside air into the living room 13 through the internal ventilation layer 18 in a building having the ventilation structure of this embodiment. As a method for taking in outside air more directly, in this embodiment, a configuration in which the ventilation control member 42 for living room is attached so as to cross between the structural material 10 and the indoor wall 14 of the living room 13 is adopted.

The characteristic structure in the ventilation structure of the building of the present embodiment is that the living room 13 and the outside are directly connected by the ventilation control member 42 for the living room, and the outside air is easily taken into the living room 13, The living room ventilation control member 42 can be opened and closed as necessary, and is used in combination with ventilation control throughout the year to provide a more comfortable living space.
The opening / closing operation of the ventilation control member 42 for the living room is either manually operated or automatically activated based on a temperature change using a spring body made of a shape memory alloy as with other ventilation control members. Form may be sufficient.

(Underfloor ventilation control member)
The underfloor ventilation control member in this embodiment is shown in FIGS. FIG. 2 is a perspective view showing an arrangement state of the underfloor ventilation control member in the present embodiment. FIG. 3 is an explanatory view showing the flow of air in the underfloor ventilation control member in the present embodiment. FIG. 4 is an explanatory view showing a state of the underfloor ventilation control member in summer. FIG. 5 is an explanatory view showing a state of the underfloor ventilation control member in winter. Here, FIGS. 4 and 5 are drawings in which the display of the duct 60B is omitted.

  The underfloor ventilation control member 24 is formed with a communication portion 60 </ b> A communicating with each of the underfloor space 23 and the internal ventilation layer 18, and a main body portion 60 is disposed so as to bridge the internal ventilation layer 18 from the underfloor space 23. Yes. The main body 60 is attached to the base 22 with screws or the like. Each communication portion 60 </ b> A formed in the main body portion is formed so as to enter the underfloor space 23 and the internal ventilation layer 18. In the present embodiment, the opening portion of the communication portion 60A on the underfloor space 23 side is formed in a slit shape.

  As shown in FIGS. 2 and 3, a duct 60B is attached to the communication portion 60A on the inner ventilation layer 18 side. The duct 60B is attached by being inserted into the main body 60, but may be fixed to the base 22 by screwing. Further, the internal space of the main body 60 is formed in a hollow structure, and this hollow structure portion serves as a ventilation path 60C through which air flows between the underfloor space 23 and the internal ventilation layer 18 via the communication portion 60A. Yes. Depending on the structure of the building, the duct 60B may be formed integrally with the main body 60, or the duct 60B may not be used.

In the present embodiment, the shielding plate 62 is slidably disposed by the opening / closing mechanism 64 in the communicating portion 60 </ b> A on the underfloor space 23 side. The shielding plate 62 is held in a state of being erected along the side wall surface of the main body 60 by a holding piece 60 </ b> D disposed on the main body 60.
The shielding plate 62 is formed with a through hole 62A penetrating in the thickness direction. The through holes 62A of the shielding plate 62 are arranged in a slit shape with a required interval in the direction in which the shielding plate 62 slides. More specifically, the arrangement interval of the through holes 62A is formed to be the same as the slit interval of the opening in the communication portion 60A. The sliding amount of the shielding plate 62 is in a range from the state where the position of the through-hole 62A completely closes the opening formed in the slit shape of the communication portion 60A to the state where the opening is completely opened.

  Further, an engaging pin 62B for engaging the spring body 64A constituting the opening / closing mechanism 64 and the bias spring 64B is disposed at an intermediate portion of the shielding plate 62 in the sliding direction. A locking hole (not shown) is formed at the tip of the engaging pin 62B. The engagement pin 62B is inserted through an insertion hole (not shown) formed in the side wall of the main body 60. The insertion hole is formed as a long hole extending in the sliding direction of the shielding plate 62.

  The opening / closing mechanism 64 is disposed in the lower space 60 </ b> Z of the main body 60. The opening / closing mechanism 64 includes a spring body 64A made of a shape memory alloy and a bias spring 64B made of a normal steel material. One end of the spring body 64A and the bias spring 64B is engaged with an engagement pin 62B formed on the shielding plate 62, and the spring body 64A and the bias spring 64B are connected in series. Yes. The other ends of the spring body 64A and the bias spring 64B are engaged with the main body 60.

A ventilation window 60Y communicating with the outdoor space is formed in the lower space 60Z in which the opening / closing mechanism 64 is disposed. The underfloor ventilation control member 24 in the present embodiment has a ventilation window 60Y that faces the gap portion S formed by disposing a spacer (not shown) between the upper end of the building foundation 20 and the building base 22. It is arranged to do. As described above, the spring body 64A made of a shape memory alloy is disposed so as to be brought into direct contact with (exposed to) the outdoor air.
In addition, since the communication between the underfloor space 23 of the building and the outdoor in this embodiment is made to communicate only through the underfloor ventilation control member 24, the upper end portion of the foundation 20 of the building that does not face the ventilation window 60Y and the base 22 of the building The gap portion S is hermetically sealed with a caulking material C.

The spring pressure of the bias spring 64B is substantially constant regardless of the temperature of the bias spring 64B, whereas the spring pressure of the spring body 64A is formed so as to change rapidly when the temperature of the spring body 64A reaches a predetermined temperature. Yes. Here, depending on the setting of the shape memory alloy that forms the spring body 64A, the spring body 64A gradually loses its spring property according to a setting that almost eliminates the spring property of the spring body 64A with a certain temperature as a boundary. The setting to be reduced can be selected as appropriate. If the setting that eliminates the spring property of the spring body 64A with a certain temperature as a boundary is adopted, the communicating portion 60A can be completely closed with the set temperature as a boundary, and the underfloor space 23 and the internal ventilation layer 18 can be shut off. .
On the other hand, if the setting of gradually reducing the spring property of the spring body 64A in accordance with the temperature change is adopted, the half-opening (in the spring, autumn, etc.) without completely blocking the underfloor space 23 and the internal ventilation layer 18 ( (Semi-communication) state. The setting of the shape memory alloy may be appropriately selected according to the climatic conditions of the district where the building is constructed and the resident's preference.

(Operation of underfloor ventilation control member)
Then, the effect | action of the underfloor ventilation control member 24 of this embodiment is demonstrated.
As described above, the opening / closing mechanism module (opening / closing mechanism) 64 using a spring body made of a shape memory alloy has a bias body made of a spring body 64A made of a shape memory alloy and a spring formed of a normal elastic material. The springs 64B are attached so that their elastic forces (tensile forces) are opposite to each other, and the difference between the elastic forces is used as a driving force.

In the present embodiment, in the outdoor outdoor air temperature state in summer, the elastic force by the spring body 64A made of a shape memory alloy is set so as to exceed the elastic force of the bias spring 64B made of a normal elastic material. When the outdoor temperature is high, the spring body 64A pulls the bias spring 64B and draws the shielding plate 62 toward the spring body 64A. On the contrary, in the winter season, the bias spring 64B pulls the spring body 64A and pulls the shielding plate 62 toward the bias spring 64B.
The elastic force of the spring body 64A and the bias spring 64B and the length of the spring are the positions where the opening of the communication portion 60A is opened in the summer (FIG. 4), and the positions where the opening of the communication portion 60A is closed in the winter ( FIG. 5).

  In addition, the ventilation control members 17, 34, 37 and the ground window 21 with the opening / closing mechanism operate in the same manner as the underfloor ventilation control member 24, and the ventilation portion of the building is opened in the summer, and the outside air actively circulates. Thus, a cool living space with low humidity can be obtained. On the other hand, in the winter season, the ventilation portion of the building is closed, and the air present in the ventilation portion becomes a heat insulating layer, so that a warm living space with good heating efficiency can be obtained.

Although the underfloor ventilation control member and the building structure using the same according to the present invention have been described based on the present embodiment, the present invention is not limited to the above embodiment.
For example, the spring pressure of the spring body 64A and the bias spring 64B of the opening / closing mechanism 64 is set to be a mode in which the spring pressure of the spring body 64A is larger than that of the bias spring 64B in the summer, but is a reverse spring pressure setting mode. Of course. The point is that the position of the through hole 62A of the shielding plate 62 can be slid with respect to the position of the communicating portion 60A of the main body 60 by making a difference in spring pressure between the spring body 64A and the bias spring 64B in summer and winter. It should be possible.

In the embodiment described above, as shown in FIG. 2, the independent duct 60 </ b> B is connected to each of the two communication parts 60 </ b> A on the inner ventilation layer 18 side of the main body part 60 of the underfloor ventilation control member 24. Although described, it is needless to say that the present invention is not limited to this form.
For example, as illustrated in FIG. 6, the duct 60 </ b> B may be shared by the communication portions 60 </ b> A and 60 </ b> A on the inner ventilation layer 18 side. When this configuration is employed, a notch for avoiding the duct 60B may be formed in the column or the like in a portion where the duct 60B and the column or the like in the wall surface interfere with each other. With such a configuration, the work burden of disposing the underfloor ventilation control member 24 in the wall surface (between the columns) is greatly reduced, so that the construction cost can be greatly reduced. Moreover, it is convenient because the mounting accuracy of the underfloor ventilation control member 24 can be improved.

It is explanatory drawing which shows the ventilation heat insulation structure of the building using the ground window with an opening / closing mechanism. It is a perspective view which shows the arrangement | positioning state of the underfloor ventilation control member in this embodiment. It is explanatory drawing which shows the flow of the air in the underfloor ventilation control member in this embodiment. It is explanatory drawing which shows the state of the underfloor ventilation control member in summer. It is explanatory drawing which shows the state of the underfloor ventilation control member in winter. It is a perspective view which shows an example of other embodiment of an underfloor ventilation control member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wall structural material 12 Exterior wall 13 Residential room 16 External ventilation layer 17, 34, 37 Ventilation control member 18 Internal ventilation layer 20 Foundation 20a Ground window hole 21 Ground window with opening and closing mechanism 22 Base 23 Floor space 24 Under floor ventilation control member 25 Back of hut 26 Roof 28 Hut Back Material 30 Attic 32 Eaves 36 Hat Member 40 Exhaust Fan 60 Main Body 60A Communication Portion 60B Engagement Pin 60C Ventilation Path 60D Holding Piece 60Y Ventilation Window 60Z Lower Space 62 Shielding Plate 62A Through Hole 62B Engagement Portion 64 Opening and closing mechanism 64A Spring body 64B Bias spring C Caulking S Clearance

Claims (3)

An underfloor ventilation control member disposed in a building in which an internal ventilation layer communicating with the underfloor space and the attic is provided between the wall structural material and the indoor wall,
A communication section that communicates the underfloor space and the internal ventilation layer, and a main body portion in which a ventilation path is formed;
A shielding plate that is disposed on at least one side of the communication portion and switches the communication portion between an open state and a closed state according to a position of a through hole formed so as to penetrate in the plate thickness direction;
An opening / closing mechanism that slides the through hole position of the shielding plate between a closed position and an open position,
The opening / closing mechanism is disposed in a lower space of the main body, and has a spring body and a bias spring made of a shape memory alloy, and the spring body made of the shape memory alloy includes a foundation portion and a base portion of a building. The spring body and the bias spring open the shielding plate by the difference in spring pressure generated between them according to the outside air temperature. An underfloor ventilation control member that is slid between a position and a closed position to control ventilation between the underfloor space and the internal ventilation layer. Wherein a spring body made of a shape memory alloy, underfloor ventilation control member according to claim 1 Symbol mounting said bias spring, characterized in that it is connected to the series arrangement. An internal ventilation layer communicating with the underfloor space and the attic is provided between the wall structural material and the indoor wall, and the communication between the underfloor space and the internal ventilation layer and the communication between the attic and the outside are outside air temperature. It is a building structure with a ventilation insulation structure that controls communication and shutoff according to
As an underfloor ventilation control member for communicating the underfloor space and the internal ventilation layer,
A communication section that communicates the underfloor space and the internal ventilation layer, and a main body portion in which a ventilation path is formed;
A shielding plate that is disposed on at least one side of the communication portion and switches the communication portion between an open state and a closed state according to a position of a through hole formed so as to penetrate in the plate thickness direction;
An opening / closing mechanism that slides the through hole position of the shielding plate between a closed position and an open position,
The opening / closing mechanism is disposed in a lower space of the main body, and has a spring body and a bias spring made of a shape memory alloy, and the spring body made of the shape memory alloy includes a foundation portion and a base portion of a building. The spring body and the bias spring open the shielding plate by the difference in spring pressure generated between them according to the outside air temperature. An underfloor ventilation control member for controlling an aeration state between the underfloor space and the internal ventilation layer by sliding between a position and a closed position is attached.