Air conditioning system

Abstract

To provide an air conditioning system excellent in overall aspects including energy efficiency, comfort, room temperature adjustment, and maintainability.SOLUTION: In an air conditioning system capable of providing heating and cooling in an entire house interior of multiple floors, an air conditioning machine is installed at each floor or in the attic or under floor; each room is provided with an air supply and exhaust vent for the air conditioning machine around a door and / or on the floor or ceiling; the air supply and exhaust vent on the floor at upper floors connects to an inter-floor space to circulate air inside the house; the inter-floor space is configured from an assembly wooden floor beam; the assembly wooden floor beam is formed from multiple web members arranged in a row with a space between them, an upper flange member formed from a pair of plate members that connect and fix the multiple web members with upper sides of the multiple web members clamped, and a lower flange member formed from a pair of plate members that connect and fix the multiple web members with lower sides of the multiple web members clamped; and the air passes between the multiple web members arranged in the row with the space between them to circulate the air inside the house.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an air conditioning system capable of heating and cooling the entire interior of a multi-story house. [Background technology]

[0002] 2. Description of the Related Art Conventionally, air conditioning systems having various structures and functions have been proposed for air conditioning the entire interior of a building such as an ordinary house by supplying air from an air conditioner.

[0003] For example, Patent Document 1 describes a central air conditioning system that includes an air conditioner, a number of ducts for transporting air conditioned by the air conditioner to a number of rooms, at least one fan for pressurizing the air conditioned by the air conditioner through the number of ducts to the number of rooms, and a control unit for controlling the operation of the fan.

[0004] Furthermore, Patent Document 2 describes a method of air conditioning a room that is connected to a vertical space that runs vertically through the interior of a building by a gap, opening, or duct, in which a portion of the return air from the room is mixed with outside air introduced from an outside air inlet by a return air fan, and after temperature adjustment through heat exchange in a heat exchanger, the mixed air is supplied to the room as conditioned air, and the remaining portion of the return air is exhausted from an exhaust port.

[0005] However, the method of using multiple ducts to transport air to each room, as described in Patent Document 1, has issues with the ease of installation of the ducts, is expensive, and has issues with low energy-saving performance due to the large difference between the room temperature and the outlet temperature.

[0006] Furthermore, in the case of an air conditioning method using a vertical space such as a pipe shaft, as described in Patent Document 2, a large number of fans are required and continuous operation of the entire building is required, which makes it difficult to adjust the temperature in each room. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2023-33681 A [Patent Document 2] JP 2013-113452 A Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been proposed in light of the above circumstances, and has an object to provide an air conditioning system that is excellent in terms of all aspects, including energy saving, comfort, room temperature control, and ease of maintenance. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, one aspect of the present invention is an air conditioning system capable of heating and cooling the entire interior of a multi-story house, in which an air conditioner is installed on each floor or in the attic or under the floor, and each room is provided with air intake and exhaust vents for the air conditioner around the door and / or on the floor or ceiling, and the intake and exhaust vents on the floor of the upper floors are connected to the inter-floor space, thereby circulating air inside the house, and the inter-floor space is formed by prefabricated wooden floor beams, which comprise a plurality of web members arranged in a row with a gap between them, an upper flange member consisting of a pair of plate-shaped members that connect and fix the plurality of web members while sandwiching the upper sides of the plurality of web members, and a lower flange member consisting of a pair of plate-shaped members that connect and fix the plurality of web members while sandwiching the lower sides of the plurality of web members, and air circulates inside the house through between the plurality of web members arranged in a row with a gap between them.

[0010] In this case, in one aspect of the present invention, a blower fan may be provided at the air supply and exhaust port on the top of the door, the ceiling, or the floor.

[0011] In addition, one aspect of the present invention may further include a heat exchange type ventilation device that exchanges heat between outside air and indoor air and supplies the heat-exchanged outside air to the inside of the house.

[0012] In one aspect of the present invention, the prefabricated wooden floor beam may be formed from a plurality of laminated veneer lumber pieces. Effect of the Invention

[0013] According to the present invention, it is possible to provide an air conditioning system which is excellent in terms of energy saving, comfort, room temperature control, ease of maintenance, etc. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an air conditioning system according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the intake and exhaust ports at the top of the door for an air conditioning system according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing the configuration of an air conditioning system according to another embodiment of the present invention. [Figure 4] FIG. 4 is a perspective view of a prefabricated wooden floor beam according to one embodiment of the present invention. [Diagram 5] FIG. 5(A) is a front view, FIG. 5(B) is a plan view, and FIG. 5(C) is a side view of a prefabricated wooden floor beam according to one embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing an inter-floor space constructed with prefabricated wooden floor beams according to one embodiment of the present invention. [Figure 7] FIG. 7(A) is a diagram showing the temperature distribution at each height in a room during heating when an air conditioning system according to one embodiment of the present invention is applied, and FIG. 7(B) is a diagram showing the temperature distribution at each height in a room during cooling when an air conditioning system according to one embodiment of the present invention is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A preferred embodiment of the present invention will be described in detail below. Note that the embodiment described below does not unduly limit the content of the present invention described in the claims, and all of the configurations described in the embodiment are not necessarily essential as the solution of the present invention.

[0016] Fig. 1 is a schematic diagram showing the configuration of an air conditioning system according to an embodiment of the present invention. One aspect of the present invention is an air conditioning system 100 capable of cooling and heating the entire interior of a multi-story house, in which an air conditioner (e.g., air conditioner) 10 (11, 12) is installed on each floor (first and second floors in Fig. 1), and each room is provided with supply and exhaust ports 20 (21, 22, 23, ...) for air A supplied from the air conditioner around the door and / or on the floor or ceiling, and the supply and exhaust ports 22, 23 on the floor of the upper floor communicate with an inter-floor space 30, circulating air A inside the house through the upper or lower parts of the rooms and the inter-floor space 30 as shown by the arrows in Fig. 1.

[0017] FIG. 2 is a schematic diagram showing the intake and exhaust port at the top of the door in an air conditioning system according to an embodiment of the present invention. In one aspect of the present invention, it is preferable that the intake and exhaust port 20 at the top of the door D is provided with a blower fan 35. In this way, the blower fan 35 is provided to enable ON / OFF and air volume change, and room temperature control for each room is also possible. In addition, by providing the blower fan 35 at the top of the door, it is possible to prevent the airflow from directly hitting people, and the blower fan 35 acts as a circulator to stir the air in the room, preventing temperature unevenness. For example, as shown in the second floor room in FIG. 1, cold air is taken in from the blower fan 35 provided at the intake and exhaust port 21 at the top of the door, and is discharged and circulated outside the room through the intake and exhaust port 22 on the floor through the inter-floor space 30. The blower fan 35 may be installed on the ceiling or floor surface as described below.

[0018] Taking Fig. 1 as an example, an air conditioner (air conditioner) 12 is installed in the second floor hall, and air heated and cooled by the air conditioner 12 is blown out from air supply and exhaust vent 21, which has a blower fan 35 installed on the wall (above the door) of the second floor room, which is the room to be air conditioned, to the room to be air conditioned (the room on the second floor) by the power of the blower fan 35. The air coming out of the air supply and exhaust vent 21 flows along the ceiling surface of the room to be air conditioned in a diagonal direction to the air supply and exhaust vent 21. The conditioned air that is blown out then passes through an intake port (air supply and exhaust vent 22) on the floor surface located approximately diagonally from the air supply and exhaust vent 21, passes through the inter-floor space 30, and returns to the second floor hall through the air supply and exhaust vent 23, repeating the circulation.

[0019] In one embodiment of the present invention, the air conditioning system 100 is preferably further provided with a heat exchange type ventilation device 40 that performs heat exchange between the outside air and the indoor air and supplies the heat-exchanged outside air to the inside of the house. By installing the heat exchange type ventilation device 40, for example, when taking in outside air for ventilation in winter, the heat can be absorbed from the warm air in the room and discharged to the outside, and heat can be given to the cold air taken in from the outside and taken in as warm air, thereby improving energy saving and comfort. It is desirable to install a filter in the heat exchange type ventilation device 40 to remove polluting particles such as pollen and PM2.5. Regarding the heat exchange type ventilation device 40, air is discharged from each room through a duct or the like, and air from the outside is supplied to the underfloor, inter-floor space, etc.

[0020] FIG. 3 is a schematic diagram showing the configuration of an air conditioning system according to another embodiment of the present invention. In another embodiment of the present invention, as shown in FIG. 3, air conditioners 10 (15, 16) may be installed in the attic and under the floor in an air conditioning system 200. In this way, the air flow is less likely to directly hit people, and in the case of heating, it is possible to heat from under the floor. In the case of FIG. 3, a blower fan 35 is installed on the ceiling or floor (for example, at the supply and exhaust ports 25, 26), and the cooled and heated air from the ceiling or under the floor is supplied to the room. The heat exchange type ventilation device 40 may be installed in the space between floors as shown in FIG. 1, or may be installed under the floor as shown in FIG. 3.

[0021] In the example of Fig. 3, an air conditioner (air conditioner) 15 is installed in an attic space (roof), and the air heated and cooled by the air conditioner 15 is blown out from an air supply and exhaust vent 25 installed on the ceiling surface to a room on the second floor, which is the room to be air-conditioned. At this time, for example, a method can be used in which the air is blown out along the ceiling surface of the room on the second floor by using a guide of an outlet grill installed on the air supply and exhaust vent 25. The air coming out of the air supply and exhaust vent 25 flows along the ceiling surface of the room to be air-conditioned in a diagonal direction to the air supply and exhaust vent 25, and the blown out conditioned air returns from an intake port (air supply and exhaust vent 27) on the floor surface through the inter-floor space 30 to the second floor hall through the air supply and exhaust vent 28, and then returns to the ceiling space through the air supply and exhaust vent 29, repeating the circulation.

[0022] The present invention is characterized in that the inter-floor space 30 is constructed with prefabricated wooden floor beams, allowing air to pass through the inter-floor space 30. Next, the configuration of a prefabricated wooden floor beam in one aspect of the present invention will be described. Fig. 4 is a perspective view showing a prefabricated wooden floor beam according to one embodiment of the present invention, Fig. 5(A) is a front view of a prefabricated wooden floor beam according to one embodiment of the present invention, Fig. 5(B) is a plan view, and Fig. 5(C) is a side view.

[0023] As shown in Fig. 4, a prefabricated wooden floor beam 50 in one embodiment of the present invention is composed of a plurality of web members 70 (71-75) arranged in a row with a gap therebetween, an upper flange member 60U (61, 62) made of a pair of plate-like members that connect and fix the plurality of web members 70 (71-75) while sandwiching the upper side sides of the plurality of web members 70 (71-75), and a lower flange member 60L (63, 64) made of a pair of plate-like members that connect and fix the plurality of web members 70 while sandwiching the lower side sides of the plurality of web members 70. In the following, for convenience of explanation, the direction in which the flange members 60U, 60L extend is defined as the X direction, the plate thickness direction of the flange members 60U, 60L is defined as the Y direction, and the direction perpendicular to both the X direction and the Y direction is defined as the Z direction. In the following description, when the flange members 61-64 are not differentiated, they will be simply referred to as flange members 60 (60U, 60L), and when the web members 71-75 are not differentiated, they will be simply referred to as web member .

[0024] In the prefabricated wooden floor beam 50 according to one embodiment of the present invention, as shown in Figs. 4 and 5, each flange member 61, 62, 63, 64 is a long plate-like member extending in the X direction and formed in a straight line in front view. The flange members 61, 62 are upper flange members 60U that connect and fix the multiple web members 70 (71-75) by sandwiching the upper side of the multiple web members 70 (71-75), and the flange members 63, 64 are lower flange members 60L that connect and fix the multiple web members 70 (71-75) by sandwiching the lower side of the multiple web members 70 (71-75). The flange members 61, 62, 63, 64 may be the same length or different lengths. The flange members 61, 62 arranged on the upper side and the flange members 63, 64 arranged on the lower side are arranged parallel to each other while being vertically spaced apart from each other through the web member 70. The interval between the flange members 70 (the distance between them in the Z direction) is not particularly limited.

[0025] Each flange member 60 in the prefabricated wooden floor beam 50 is composed of a pair of plate-like members. For example, as shown in FIG. 5(B), the flange member 61 is composed of plate-like members 61a and 61b, and the flange member 62 is composed of plate-like members 62a and 62b. The pair of plate-like members are formed to have the same shape and are arranged opposite each other with a web member 70 in between. Note that the flange member 60 only needs to have plate-like members 61a, 61b, 62a, 62b, etc., of different lengths, arranged alternately in the front-rear or up-down direction. Furthermore, the plate-like members 61a, 62a, etc. and the plate-like members 61b, 62b, etc. may be formed from the same wood material.

[0026] As shown in Fig. 5(A), the beam depth h (dimension in the Z direction) of the prefabricated wooden floor beam 50 can be changed by changing the height (length in the Z direction) of the web member 70. The overall length of the flange members 60 is determined according to the location where they are placed. The length of the upper flange members 60U (61, 62) is made longer than the length of the lower flange members 60L (63, 64). This leaves spaces below both sides of the prefabricated wooden floor beam 50. Members such as beams and columns that support the prefabricated wooden floor beam 50 from below are placed in these spaces.

[0027] Each of the plate-like members 61a, 61b, etc. that make up the flange member 60 is made of wood, for example, LVL (Laminated Veneer Lumber), but is not limited thereto and may be made of wood such as lumber or steel. LVL has a layered structure in which multiple veneers are laminated, and is obtained, for example, by thermocompression bonding the veneers together. By laminating multiple veneers, the strength of the flange member 60 can be improved and the occurrence of warping or bending in the longitudinal direction can be suppressed.

[0028] The material of the plate-like members 61a, 61b, ... (flange member 60) is not particularly limited, but the flange member 60 may be made of a relatively soft wood such as cedar. However, the material is not limited to wood such as cedar, and any wood may be used as long as the bending Young's modulus value is within the range specified for bending Young's modulus classification 60E of the JAS standard.

[0029] The web member 70 is a plate-like member formed in a square shape when viewed from the front. The web member 70 is arranged so as to be sandwiched between the upper and lower flange members 60 (between the upper chord member and the lower chord member), and connects the plurality of flange members 60 together. Specifically, as shown in Figs. 4 and 5, the web member 70 is composed of a first web member 71, a second web member 72, a third web member 73, a fourth web member 74, and a fifth web member 75, and is arranged at equal intervals along the X direction in a state of being sandwiched between the flange members 61 and 62 and the flange members 63 and 64 in this order (first to fifth order), for example, to connect the flange members 60 together. Note that the intervals between the web members 70 are not limited to equal intervals. Also, the number of web members 70 is not limited to five, and is not particularly limited.

[0030] As shown in Fig. 5(B), each web member 70 is sandwiched between a pair of plate-like members 61a, 61b, ... in the Y direction and is disposed at a fixed interval in the X direction. Note that each web member 70 is formed to have the same size, but the dimensions of some of the web members 70 may be different. For example, only the first web member 71 and the fifth web member 75 located on both sides in the longitudinal direction of the prefabricated wooden floor beam 50 may be formed to be narrower than the second web member 72, the third web member 73, and the fourth web member 74.

[0031] The thickness of the web member 70 only needs to be approximately the same as that of the flange members 60, and may be changed as appropriate depending on the strength required for the prefabricated wooden floor beam 50. The height (dimension in the Z direction) of the web member 70 is, for example, approximately 20 to 40 centimeters, but can be changed as appropriate taking into consideration the location where the prefabricated wooden floor beam 50 is placed. As the height of the web member 70 changes, the beam depth h of the prefabricated wooden floor beam 50 also changes. The web member 70 is made of wood, and may be made of the same material as the flange members 60, or may be made of a different material.

[0032] Fixing members 5 for fixing the flange member 60 to the web member 70 are disposed at the four corners of the web member 70. Specifically, fixing members 5 such as screws are inserted and fixed at positions in the vicinity of the four corners of the web member 70, penetrating the web member 70 from the plate-like member 61a side until they reach the plate-like member 61b. Note that the fixing members 5 may also be inserted and fixed by penetrating the web member 70 from the plate-like member 61b side until they reach the plate-like member 61a.

[0033] In this way, by fixing the flange members 60 to the four corners of the web member 70, the strength of the prefabricated wooden floor beam 50 can be increased. Note that the locations where the fixing members 5 are arranged are not limited to the four corners of the web member 70, and may be any location as long as the flange members 60 can be fixed to the web member 70. Furthermore, the fixing members 5 are not limited to screws, and may be any configuration that has the function of fixing the flange members 60 and the web member 70, such as fastening structural screws, combinations of bolts and nuts, nails, rivets, etc.

[0034] In the prefabricated wooden floor beam 50, a plurality of openings 80 are formed by a plurality of flange members 60 and a plurality of web members 70. Specifically, as shown in Figs. 4 to 5, a plurality of openings 80 are formed in a line along the X direction of the prefabricated wooden floor beam 50. Each opening 80 is formed in a rectangular shape in a plan view, and each opening 80 is formed to have approximately the same size. As shown in Figs. 4 and 5(A), the width of the opening 80 is formed to be approximately the same length as the width of the web member 70. This is because the web members 70 are arranged at equal intervals in the X direction, spaced apart by the width dimension of the web member 70. Note that the web members 70 do not need to be arranged at equal intervals, and may be arranged at intervals sufficient to form the openings 80.

[0035] In this way, the prefabricated wooden floor beam 50 has a plurality of openings 80 formed by combining a plurality of flange members 60 extending laterally and a plurality of web members 70 extending vertically. That is, the prefabricated wooden floor beam 50 is formed in a Vierendeel beam shape in which plate-shaped members are combined vertically and horizontally and gaps are formed between the plate-shaped members. This allows the amount of material used to be reduced by the amount of the gaps, making it possible to reduce the weight of the prefabricated wooden floor beam 50.

[0036] FIG. 6 is a schematic diagram showing an inter-floor space formed by prefabricated wooden floor beams according to an embodiment of the present invention. As shown in FIG. 6 as an example, the inter-floor space 30 is arranged in parallel with a plurality of prefabricated wooden floor beams 50 spaced apart from each other along the X direction between the horizontal members 90 installed at a predetermined interval, and both ends of these prefabricated wooden floor beams 50 are supported by the horizontal members 90. In the inter-floor space 30 thus formed, the prefabricated wooden floor beams 50 have a plurality of gaps (openings 80) formed therein, so that the conditioned air can pass freely between the gaps (openings 80) and can circulate freely within the house. In addition, there is no need to install a duct for circulating the air. In FIG. 6, a plurality of prefabricated wooden floor beams 50 are arranged between two horizontal members 90, but depending on the size of the inter-floor space 30, for example, a total of three horizontal members 90, one at each end and in the middle, may be arranged, and a prefabricated wooden floor beam 50 may be arranged between each of the horizontal members at each end and in the middle.

[0037] Even if it becomes necessary to pass a duct when installing the heat exchange ventilation device 40, construction work can be improved by passing piping or pipes through the gap (opening 80) in the prefabricated wooden floor beam 50. Furthermore, since the web member 70 is fixed while being sandwiched between a pair of plate-like members 61a, 61b, ..., sufficient strength can be ensured even if the prefabricated wooden floor beam 50 is made of wood.

[0038] Thus, according to the present invention, if at least one air conditioner (air conditioner) is installed on each floor, the entire house can be cooled or heated, which is economical, and the air conditioner (air conditioner) can operate efficiently and achieve energy saving. In addition, by forming the inter-floor space with the prefabricated wooden floor beams related to the present invention, it is possible to distribute fresh air throughout the entire house through the inter-floor space and under-floor space. In addition, by adjusting the ON / OFF and output of the blower fans installed in the rooms, it is possible to adjust the temperature to your preference for each room, and energy saving can be achieved by turning off the blower fans in rooms that are not being used. In addition, for example, air can be taken in from the top of the room door and exhausted through the inter-floor space from the intake and exhaust vents on the floor diagonally positioned, which can eliminate temperature unevenness without the air flow hitting people, and a synergistic effect can be obtained by the so-called Coanda effect and the inter-floor space formed by the prefabricated wooden floor beams. EXAMPLES

[0039] Figure 7(A) is a diagram showing the temperature distribution at each height in a room during heating when an air conditioning system according to one embodiment of the present invention is applied, and Figure 7(B) is a diagram showing the temperature distribution at each height in a room during cooling when an air conditioning system according to one embodiment of the present invention is applied.

[0040] In the conventional example, for example, in the case of heating, when hot air is blown horizontally near the ceiling, the temperature near the ceiling becomes high and the temperature near the floor becomes low, resulting in an uncomfortable environment. On the other hand, when the air conditioning system according to the present invention is applied, the conditioned air flows efficiently along the ceiling to the diagonal side of the room and is sucked in from the floor. The low-temperature air near the floor of the room is sucked in from the floor intake, reducing the temperature difference between the top and bottom, and the temperature becomes uniform throughout the room. As shown in Figures 7(A) and (B), it has been demonstrated that by applying the air conditioning system according to the present invention, the temperature difference from the bottom to the top of the room is within 1°C even under harsh outdoor conditions in winter (outdoor temperature of about 0°C) and summer (outdoor temperature of about 30°C), and the temperature throughout the room is uniform.

[0041] In this way, the present invention can reduce the temperature difference between the top and bottom of an air-conditioned room without requiring a complex mechanism for changing and controlling the direction of the air from the air conditioning outlet, or a mechanism for reducing the temperature difference between the top and bottom by mixing the air separately in the room. In addition, since the air blown out from the air conditioning flows along the ceiling and is sucked in through a floor louver at a diagonal position, it is possible to perform air conditioning without blowing the conditioned air directly on the residents. It is also possible to provide an air conditioning system that reduces the phenomenon of cold feet and does not cause discomfort to residents due to the feeling of airflow from the blown out air.

[0042] Although one embodiment and examples of the present invention have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present invention. Therefore, all such modifications are intended to be included within the scope of the present invention.

[0043] For example, a term described at least once in the specification or drawings together with a different term having a broader or similar meaning may be replaced with the different term anywhere in the specification or drawings. In addition, the configuration of the air conditioning system is not limited to that described in the embodiment and examples of the present invention, and various modifications are possible. [Explanation of symbols]

[0044] 5 Fixed members, 10,11,12,15,16 Air conditioners, 20,21,22,23,25,26,27,28,29 Air supply and exhaust vents, 30 Inter-floor space, 35 Blower fans, 40 Heat exchange type ventilation equipment, 50 Assembled wooden floor beams, 60,61,62,63,64 Flange members, 60U Upper flange members, 60L Lower flange members, 61a,61b,62a,62b,63a,63b,64a,64b Plate members, 70,71,72,73,74 Web members, 80 Openings, 90 Cross members, 100,200 Air conditioning systems

Claims

1. An air conditioning system capable of heating and cooling the entire interior of a multi-story house, An air conditioner is installed on each floor, in the attic, or under the floor, and each room is provided with an intake and exhaust port for air supplied from the air conditioner around the door and / or on the floor or ceiling; The air intake and exhaust vents on the upper floors communicate with the inter-floor space to circulate air inside the house, The inter-floor space is formed by prefabricated wooden floor beams; The prefabricated wooden floor beam is A plurality of web members arranged in a row at intervals; an upper flange member consisting of a pair of plate-shaped members that connect and fix the plurality of web members in a state in which the upper side sides of the plurality of web members are sandwiched; a lower flange member comprising a pair of plate-like members that connect and fix the plurality of web members together while sandwiching the lower sides of the plurality of web members therebetween; It consists of: An air conditioning system characterized in that the air circulates inside the house through between the plurality of web members arranged in a row at intervals.

2. 2. The air conditioning system according to claim 1, wherein a blower fan is provided at an intake / exhaust port at the top of the door, at the ceiling, or at the floor.

3. 3. The air conditioning system according to claim 1, further comprising a heat exchange type ventilation device that exchanges heat between outside air and indoor air and supplies the heat-exchanged outside air to the inside of the house.

4. 4. The air conditioning system of claim 3, wherein said prefabricated wooden floor beams are formed from a plurality of laminated veneer lumber.

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