WO2012110505A1

WO2012110505A1 - Filling station with roof designed for recovering rainwater

Info

Publication number: WO2012110505A1
Application number: PCT/EP2012/052502
Authority: WO
Inventors: Stefan Boettle; Roland Luick
Original assignee: Stefan Boettle; Roland Luick
Priority date: 2011-02-14
Filing date: 2012-02-14
Publication date: 2012-08-23
Also published as: DE102011000709A1

Abstract

The invention relates to a filling station with a filling region, which is covered by a roof, and with operation buildings. The problem addressed by the invention is that of providing a filling station in which the operating costs can be significantly reduced. This problem is solved in that the rain water falling on the roof is conducted by means of a conduit system to a vehicle washing installation and/or to a WC unit of an operation building.

Description

Gas station

The invention relates to a gas station with a tank area, which is covered by a roof, and with operating buildings, in particular a vehicle wash and / or a toilet unit.

Such gas stations are operated in a variety of constellations and serve to provide nationwide fuel supply. In addition, petrol stations are increasingly selling additional services and a freely available assortment. This should provide an additional customer benefit. A significant influence on the operating costs of such a gas station is the need for energy as well as water. In particular, a high water consumption is generated for the vehicle washing systems and the toilet units. The vehicle washing systems therefore require complex tank systems that are integrated into a cycle. This circulation system also has a treatment plant, with which the washing water is cleaned and recycled. It is an object of the invention to provide a gas station of the type mentioned, in which the operating costs can be significantly reduced.

This object is achieved in that the rainwater accumulating on the roof is fed by means of a line system to a vehicle washing installation and / or a toilet unit of an operating building. The gas station roof, which usually covers a large area of land, is now used as a water collector, and the water supplied to the further use of the vehicle wash or toilet unit. This is a simple and effective way of accommodating the green-building idea and significantly reducing operating costs and, in particular, reducing maintenance and servicing costs by significantly reducing reprocessing efforts. In the context of the invention, it is also conceivable that the collected gray water (rainwater) is supplied to the vehicle washing system via an intermediate storage system and a continuous metering into the circulatory system of the vehicle washing system takes place from the temporary storage device, in which way a part of the water is always exchanged and therefore does not have to be prepared separately and intensively.

According to a preferred embodiment variant of the invention, provision may be made for a water treatment plant to be integrated in the line system. The rainwater usually has only a slight contamination, so that it can be converted with a simple design water treatment plant in a state that allows use in the vehicle wash or in the toilet unit. Particularly preferably, a gas station is designed such that the roof has two or more supports that support a roof construction, and that the supports enclose a receiving space in which a water-bearing downpipe is integrated. Thus, the columns are assigned two functions, namely the support function and the water supply function. This has advantages, especially in the creation of the gas station roof, and less space is required for the installation of the drainage systems.

A gas station according to the invention may be characterized in that the roof construction has at least two mutually inclined roof surfaces, which dewater together in a collecting channel, and that the collecting channel is connected to the water-bearing downpipe. In this way, an orderly water removal can be achieved with simple measures. Particularly preferably, it can be provided that the roof of the roof construction is at least partially formed by sheet-like photovoltaic elements. This first minimizes the design effort to create the roof. In addition, with the photovoltaic elements on the large roof of the gas station, an effective power generation is possible. The integration of the photovoltaic elements into the gas station roof further takes into account the "green building idea".

In this case, it can preferably be provided in particular that the photovoltaic elements are designed as format elements having the same format size, and that the photovoltaic elements are arranged in the form of a matrix. By using the same format elements, a reduction of the parts expenditure is made possible. In addition, depending on the property requirements, a module-like expansion of the roof can be achieved via the modular arrangement of the photovoltaic elements. surface can be easily made. In particular, further format elements can be added in the row and / or column direction.

In this case, a simple roof drainage succeeds in that the photovoltaic elements are arranged in rows or columns such that two or more rows or columns together form an inclined roof part surface, and that the transition between the photovoltaic elements of adjacent rows or columns with a water-bearing cover are bridged. The use of several rows or columns within a roof part area creates a generous drainage area, which can be used to realize even flat roof pitches. In this roof part surface, the individual photovoltaic elements form sub-assemblies, which can be designed in terms of their capacity so that they can withstand normal stresses acting on the roof top. In particular, the format sizes can be chosen such that it is possible to walk on the roof surface for maintenance or cleaning purposes.

A filling station according to the invention may be characterized in that two or more mutually inclined roof part surfaces are pitched against each other, each dehydrate from a high to a low point, and that connect to the inclined roof surfaces in the region of the low point more inclined roof surfaces, the the low points inclined to further high points inclined. In this case, a butterfly roof construction is achieved, which can be extended in a kit-like manner, in particular for use at filling stations, and effective drainage areas can be created with a low roof construction height. In the low point, which serves the drainage, a collection channel may be laid for this purpose. A particularly preferred embodiment of the invention is such that the roof construction has a grid composed of mutually parallel longitudinal and transverse beams. In this roof construction can be done by Anaddieren of longitudinal and / or cross members, a size variation of the roof in a simple manner.

In order to reduce the parts and assembly costs and for an improved optical design, it can be provided in particular that at least a part of the longitudinal and / or cross member has drainage channels.

The invention will be explained in more detail below with reference to an embodiment shown in the drawings. Show it:

Figure 1 is a roof in perspective view;

Figure 2 is a cross-sectional view through a support of the roof according to

Figure 1 (see section line II-II in Figure 1);

FIG. 3 shows an isometric view of a crossing node according to the detail labeled III in FIG. 1;

Figure 4 is a plan view of the unit shown in Figure 3;

FIG. 5 shows an isometry of the crossing point marked IV in FIG. 1;

FIGS. 6 to 8 show a side view of a crossing node according to FIGS

Figure 1 with VI to VIII marked details and at various roof positions; Figure 9 is a side view of the junction node of Figure 3 with a roof structure; FIG. 10 is a plan view of the roof according to FIG. 1;

Figure 1 1 is a sectional view along that marked in Figure 2 with Xl-Xl

Section line; and FIG. 12 is a side view of the attic of the roof according to the invention.

FIG. 1 shows a roof for a filling station, which has a plurality of vertical supports 10. The supports 10 are anchored to the floor with a foot plate or embedded in concrete in the ground. At their end facing away from the bottom of the supports 1 0 carry a roof construction. This roof construction is composed in the form of a framework of longitudinal beams L and cross beams Q. In this case, the longitudinal members L and the cross member Q are each arranged parallel to each other at a distance, wherein the pitch is respectively identically identical. In this way, the roof construction forms a matrix-like structure in which the longitudinal and transverse beams L, Q enclose compartments of the same size. The compartments are arranged in rows and columns in the longitudinal and transverse directions.

With reference to Figures 2 and 3, the design of the supports 10 will be explained below.

As Figure 2 shows, the supports 10 are formed as closed hollow sections. In this case, identical double-T-carriers 12 are used on the profile sides. These double T-beams 12 have two mutually parallel spaced straps 12.2 over a connecting portion 12.1 are interconnected. The straps 12.2 are welded in the region of their inner cross section of the support 10 facing region with angle profiles 1 1. In this way, a cross-shaped structure, as shown in FIG 2 clearly shows.

Figure 3 illustrates the connection of the longitudinal and transverse beams L, Q to the vertical supports 1 0. As this illustration reveals, 10 connecting pieces 14 are welded in the form of plates in the head region of the supports. These are used for detachable coupling of the longitudinal members L and cross member Q with fixing screws 24.1. The side members L and cross members Q are basically constructed identically to reduce the parts cost. They each have a top flange 21 and a bottom flange 22. Upper and lower belt 21, 22 are again each formed as a double-T carrier, and thus have a connecting portion 21 .1, at the end two straps 21 .2 are connected. The double-T-beams are aligned so that the connecting portions 21 .2 are arranged horizontally. To bridge the distance range between the upper and lower belt 21, 22 struts 23 are used in the form of flat steel. In the connection area to the support 1 0, the upper flange 21, the lower flange 22 and the struts 23 are welded to the front side of a flange 24. The flange 24 can be placed flat on the connector 1 4. In this case, fastening receptacles of the flange 24 are in alignment with fastening receptacles of the connecting piece 1 4. Through the fastening receptacles fastening screws 24.1 can be passed and countered by means of nuts. In this way, can be connected to the support 10 at all four sides defined by the double-T-beam 12 side members L and cross member Q.

As a result of the horizontal orientation of the connecting portions 21 .2 and 22.2 of upper and lower belt 21, 22 results in a cable guide between the straps 21 .2, 22.2. As FIG. 3 illustrates, cables 86 can be connected by appropriate cable be removed 24.2 in the connector 14, the flange 24 and the support 10 from the interior of the support 10. In the region of the upper flange 21, a recess 12.3 is provided for the cable guide. To stiffen the support 10 in the head area, a top plate 13 is used. This top plate 1 3 is inserted into the inner cross section of the support 1 0 and welded here (see welds 1 8). The top plate 1 3 has an opening 13.1, which serves to receive a downpipe 1 7, as will be explained later in detail.

The design of the top plate 13 can be seen more clearly in FIG. As this illustration shows, the top plate 13 in the outer corner areas notches, which are required for welding reasons. FIG. 5 shows a crossing node in which the longitudinal and transverse beams L, Q meet one another off the supports 10. As can be seen from this illustration, the cross member Q is formed continuously and continuously. The longitudinal members L, however, are interrupted in the region of the crossing node as a result of the continuous configuration of the cross member Q and therefore connect with their carriers designed as longitudinal member sections 20 on both sides of the cross member Q on. For this purpose, the upper flange 21 and the lower flange 22 of the longitudinal member L are each closed at the end with a connecting piece 32. The connector 32 is welded to the upper and lower chords 21, 22, respectively. It has two fastening receptacles which are aligned with fastening receptacles of the cross member Q. Through the fastening receptacles fixing screws 33 can be passed and countered by a nut. For stiffening the intermediate node 30 transverse struts 31 are used. These are welded between the straps 21 .2, 22.2. A further stiffening of the intermediate node 30 is achieved with a connecting piece 34. The connector 34 is also a double T-beam formed, with its profile longitudinal extent is vertical. In the region of its front ends, the connecting piece 34 is welded at its connecting portion 34.1 and its straps 34.2 with the upper flange 21 and the lower 22. The connecting piece 34 is provided with a central opening 34.3 in its connecting portion 34.1. This can be passed through the breakthrough 34.3 cable.

The roof shown in Figure 1 can now be dimensioned to the plot of land. The width of the roof is determined as a result of the continuous cross member Q between the supports 1 0. In the present case, a roof width is selected that allows a four-lane gas station use. The length of the roof can now be easily varied by the side members L are extended with straps 20. This is easily achieved via the detachable coupling in the region of the crossing nodes (intermediate nodes 30) and on the supports 1 0. The extension of the roof can be made in a modular manner, in each case as the smallest size a column is added.

With reference to Figures 6 to 9, the roof structure will now be further explained. As illustrated in these drawings, supporting pieces 50 can be placed on the upper belts 21 of the longitudinal and transverse beams L, Q. In this case, the support pieces 50 are formed as hollow chamber profiles, which may have one or more chambers 51 depending on the embodiment. In the area of their underside, the support pieces 50 have molded fastening screws. These are for fixing the support pieces 50 by fastening receptacles of support plates 21 .3 passed and countered by means of nuts. The support plates 21 .3 are welded to the belts 21 .2 of the upper belts 21. The support pieces 50 are placed on the support plates 21 .3 with the interposition of a neoprene seal 21 .4. The connecting pieces 50 have an open towards the top hollow chamber, are inserted into the support bar 52. The Support bars 52 have on their upper side a connecting element 55 and sealing elements 53. On the sealing elements 53 photovoltaic elements 60 can be placed in the form of glass plates. For fixing the photovoltaic elements 60 clamping elements 54 are placed on top of the photovoltaic elements 60 and clamped to the connecting element 55. At the same time a cover 56 is clamped by means of the clamping element 54, which bridges the gap between the support pieces 50.

As FIGS. 6 to 8 show, three differently high connection pieces 50 can be installed. In this case, the connecting piece 50 according to FIG. 6 has the largest and the connecting piece 50 according to FIG. 8 the smallest overall height. The connecting piece 50 according to FIG. 7 has an intermediate height. The intermediate node 30 marked with VI in FIG. 1 represents the intermediate node 30 shown in FIG. 6. Accordingly, in this roof position the connecting piece 50 having the highest overall height 50 is used. Following in the longitudinal beam direction now connecting pieces 50 are installed with a Zwischenbauhöhe according to Figure 7. Accordingly, in Figure 1, the intermediate node 30 is marked with the intermediate height with VII according to Figure 7. The intermediate nodes 30 according to FIG. 8 adjoin the intermediate nodes 30 in accordance with FIG. 7 in the longitudinal beam longitudinal direction, so that these intermediate nodes 30 are labeled VIII correspondingly in FIG. With the different height support pieces 50, the photovoltaic elements 60 abandoned a roof pitch, which is used for drainage. Accordingly, this gradient runs starting from the high point HP shown in FIG. 6 via the intermediate point ZP shown in FIG. 7 to the low point TP shown in FIG. In the longitudinal beam direction, this gradient structure is repeated. As FIG. 8 shows, a rising gradient correspondingly then again follows, which leads via an intermediate point ZP to a high point HP. Accumulating rainwater can thus be dewatered via the photovoltaic elements 60 and the covers 56 in the direction of the low point TP (according to FIG. 8). There, the photovoltaic elements 60 form a rain water drain, which opens into a collecting channel 58. The collection channel 58 is in the form of a U-profile having a bottom and two side walls rising therefrom and parallel to one another. The side walls are provided at the ends with bends 58.1. This fold 58.1 is overlapped by a drip edge of a drip strip 57. In the area between the underside of the photovoltaic element 60 and the top of the drip strip 57 and the top of the support bar 52, a sealing element 53 is placed. The collected in Sam melkanal 58 water is discharged along this collecting duct 58 supporting cross member Q. For this purpose, the collecting channel 58 is laid in the gradient and fed to the supports 10, as can be seen in more detail in FIG. Accordingly, the collection channel 58 extends to a foliage basket 15 with a 2% gradient. The leaf basket 15 is inserted into the collecting channel 58. The collecting channel 58 is sealingly connected to a drop tube 1 7 with the interposition of a neoprene seal 21 .4. The downpipe 1 7 is laid vertically in the interior of the support 1 0. Accordingly, the water flowing from the collection channel 58 through the leaf basket 1 5 flows into the downpipe 17 and can be discharged centrally there. In addition, above the laubkorbes 1 5 an inlet piece 70 is used, drained from the water, which flows off at the top of the photovoltaic elements 60. The inlet piece 70 is fixed with clamping profiles 71. The rainwater drained from the roof surface can thus be removed centrally via all supports 10 of the roof. This water is fed to one or more collection containers. It can then be passed through a water treatment. There, it is transferred to a state that allows use in the car wash and possibly in the toilet facility of the gas station.

In Figure 10, the principle of dewatering is shown again schematically. This drawing shows the roof according to Figure 1 in plan view. As can be seen from this drawing, in each case an intermediate node 30 in the form of an intermediate point ZP adjoins a support S on both sides and an intermediate node 30 in the form of an intermediate point ZP. design as high point HP. This results in the form of a flat butterfly roof, an alternating gradient structure in the longitudinal beam direction. In the transverse support direction, the drainage channel 58 is laid in the support plane, the intermediate nodes 30 forming the low points TP between the supports.

FIGS. 6 to 8 show that luminous elements 40 can be arranged in the region of the intermediate nodes 30. For example, such luminous elements 40 may be mounted on each intermediate node 30. In this case, the luminous element 40 is mounted in the region of the lower flange 22 which is enclosed between the connecting section 22.1 and the straps 22.2. The light-emitting element 40 is designed as a so-called "down-light", in particular "LED-down light", and thus radiates a light with a wide beam in the direction of the bottom of the gas station. The light element 40 is supplied via a transformer 41, which is mounted on the top of the connecting portion 22.1. For an optical cover 20 covers 43, for example made of sheet metal, are provided on both sides of the carrier. The transformer 41 are associated with terminals 42, can be connected via the power supply cable. The power supply cables may be routed on top of the connecting portions 22.1 of the lower chords 22. As a result of the rust-like design of the roof construction, the lighting elements 40 can be mounted in the region of the intermediate nodes 30 with constant luminaire spacing. In this way, a uniform basic illumination of the gas station can be made. The light-emitting elements 40 can also be controlled via a dimmer circuit. In this case, for the purpose of saving energy, the luminosity of the luminous element 40 is controlled down or turned off when not using the gas station. If a retracting car is detected via a switching unit, in particular an induction loop incorporated in the roadway, the control circuit then regulates the lighting elements 40 back into the operating state. The driver interactively influences the lighting control. It can also be provided that some crossing points are equipped with speakers that emit their sound towards the ground in the form of a sound column. Through this sound output a background sound is possible, which radiates only slightly laterally, without disturbing the neighbors. The power supply to the lighting elements 40 via the vertical supports 10, as will be explained in more detail with reference to Figure 1 1. As this illustration shows, a cable channel 80 is arranged laterally in the region of the interior of the support. In the cable channel 80 cables 81, 83, 86 are guided. In the area of the flanges 24 (see FIG. 3), the cables 86 are fed to the underbelts 22 through cable bushings 24. For orderly wiring terminals 82 are housed in the interior of the support 10. The cables 86 lead to a central control unit, which may be housed for example in the technical room of the gas station. From there, the control of the light elements 40 can then be made. Furthermore, cable 83 are guided in the cable channel 80, which lead to a terminal 84. This clamp 84 is disposed between the support pieces 50. To this terminal 84 are connected cables leading to a terminal 86. The clamp 85 is mounted on the inside of one of the support pieces 50. From this terminal 85, cables 86 lead to the photovoltaic elements 60. Via the cables 86, the current generated by the photovoltaic elements 60 can be dissipated in a collective manner. It is then assigned via the cable 83 to a central unit, in which the inverters are arranged to generate alternating current. For example, this implementation can be carried out in a central technical room.

From the foregoing, it follows that both the water drainage and the power supply is carried out centrally in the supports 1 0. For this purpose, in the supports 1 0 a clear system separation in the water-bearing area and in the current-carrying area. Within the support 10, the water-bearing area is delimited by the downpipe 17. The remaining interior of the support 10 can be used for the power supply. In the area above the Upper belts 21, the electrically conductive components on the one hand by means of photovoltaic elements 60 and the other by means of sealed mounted covers 56 between the photovoltaic elements 60 are protected (see, for example, Figures 6 and 7). The clear water drainage is ensured via the collecting channels 58 in defined areas.

The photovoltaic elements 60 are designed as translucent glass elements with an integrated perforated thin-film PV cell. The perforated thin film offers the daytime ideal use of daylight with additional sun protection effect. In this way, at daytime a sufficiently high incidence of light can be guaranteed down to the bottom of the gas station. At night, as described above, the basic illumination by means of the light elements 40 is made. In addition, a so-called "ambi-light illumination" of the gas station roof is provided, which is symbolized on the underside of the longitudinal and transverse girders L, Q. Accordingly, LED strips are used here as strip lighting means 10. These strip illuminants 110 are preferably mounted on all longitudinal and transverse recesses L, Q on the underside in the region of the connecting sections 22.1 They emit a light in the direction of the gas station floor 10. In the case of controlled strip illuminants 1 1 0, a luminous effect is achieved in the area of the underside of the roof, which makes the underside of the roof appear as a luminous surface For example, at night the control can be switched such that the luminous elements 40 are out of operation and only the strip illuminants 1 10 is activated If a car enters the petrol station, it can be detected by a car In addition, activation of the lighting elements 40 for basic illumination or illumination of certain areas of the gas station are made ungsschaltung. In this way, special optical luminescent stimuli are offered, which invite the use of the gas station. As Figure 12 illustrates, the roof is provided in the area of its attic with a circumferential end construction. This attic is attached to the marginal longitudinal and cross beams L, Q, which form a circumferential lateral end frame. Hooks 98 are welded to fastening plates 21, 3 at predetermined longitudinally spaced, longitudinally spaced crossbars L, Q. The fastening plates 21, 3 are welded to the upper belts 21 as described above. Furthermore, 22.2 more hooks 98 are welded to the belts 22.2 in the area of the lower chords. At this hook 98, a screen support 90 can be hung in the form of an open housing. The screen support 90 has a bottom 91 from which side walls 92, 93 ascend circumferentially. The bottom 91 is provided with openings 95 which are arranged corresponding to the hooks 98. Accordingly, the screen support 90 can be hung on the hooks 98. By means of a fastening screw 98.2, which passes through the hook 98 and the bottom 91, a fixation de screen carrier 90 is achieved.

With the use of intermediate support elements 98.1 a reliable fixation is achieved. The screen support 90 has in the region of its lower horizontal side wall 93 on the front side a fold 94. An image-generating unit 100, namely a flat screen, preferably an LED screen, in particular an LED video screen, can be inserted in the screen carrier 90. In this case, the image forming unit 1 00 on the floor 93 behind the fold 94 is securely supported. In addition, the image forming unit 100 is fixed by means of a fixing member, not shown in the drawings, for example, on the image forming unit upper side. The energy and signal supply of the image generating unit 100 takes place again via the supports 10, wherein the ordered cable guide is made on the upper side of the lower chords 22. The screen support 90 is overlapped cover to protect against rainwater by means of a cover 99. This cover 99 has two connected legs 99.1 and 99.2. The legs 99.1, 99.2 form drip edges on the back or front side. The back The dripping edge dries on a cladding 97.2. The cladding 97.2 engages behind the leg 99.1 with a vertical connecting piece 97.1, which is fixed by means of a fastening element 96 on the bottom 91 of the screen carrier 90. The connector 97.1 merges into an inclined discharge surface 97.2, which ends in a downward drip edge 97.3. The drip edge 97.3 drains on the surface of the photovoltaic elements 60 edge. To produce an advertising space in the area of the attic, a multiplicity of screen carriers 90 are lined up with the corresponding image generation units 100. In this case, for example, only one side or a part of a side of the roof can be acted upon or it can screen support 90 are fixed circumferentially on the roof. It is also conceivable that two or three sides of the roof are equipped with screen carriers 90. The image generation units 100 are connected via control lines with a central switching electronics. Of these, preferably, the individual pixels of the image forming units 1 00 can be controlled individually or in groups. In this way, it is possible to generate images which are transferred to the image-forming units 100 that are lined up one after the other.

The central switching electronics can also be located away from the gas station and connected via the Internet to the gas station technology. In particular, a DMX control (FA E: cue) can be used. In this way, for example, centrally the ads of a variety of gas stations can be centrally recorded and varied.

The imaging units 100 are in turn housed in an explosion-proof housing. They can have an integrated cooling module, which can also be connected to the environment via a heat exchanger. In the context of the invention, a gas station is designed as a "green building", whereby in particular a focus is placed on energy-saving and resource-conserving construction, whereby a multimedia overall concept should also be integrated into the building construction.

Claims

claims

1 . Gas station with a tank area covered by a roof and with utility buildings,

characterized,

that the rainwater accumulating on the roof is fed by means of a conduit system of a vehicle washing system and / or a toilet unit of an operating building.

2. filling station according to claim 1,

characterized,

that in the line system, a water treatment plant is integrated.

3. filling station according to claim 1 or 2,

characterized,

in that the roof has two or more supports (10), which carry a roof construction, in that the supports (10) enclose a receiving space by integrating a drainage downpipe (17).

4. filling station according to claim 3,

characterized,

in that the roof construction has at least two mutually inclined roof surfaces which jointly dewater into a collecting channel (58), and in that the collecting channel (58) is connected to the water-discharging downpipe (1 7). Gas station according to one of claims 1 to 4,

characterized,

that the roof of the roof construction is at least partially formed by areal photovoltaic elements (60).

Gas station according to claim 5,

characterized,

that the photovoltaic elements (60) are formed as format elements with the same format size, and

the photovoltaic elements (60) are arranged in matrix form.

Gas station according to claim 6,

characterized,

that the photovoltaic elements (60) are arranged in rows or columns such that two or more rows or columns together form an inclined roof part surface, and

in that the transition between the photovoltaic elements (60) of adjacent rows or columns is bridged by a water-conducting cover (56).

Gas station according to one of claims 1 to 7,

characterized,

that in each case two or more mutually inclined roof part surfaces are set like a saddle roof against each other and each dewater from a high point (HP) to a low point (TP), and

in that further sloping roof part surfaces, which run from the low points (TP) to further high points (HP), adjoin the inclined roof part surfaces in the region of the low point (TP). Gas station according to claim 8,

characterized,

that in the region of the low point (TP) of the collecting channel (58) is laid.

0. filling station according to one of claims 1 to 9,

characterized,

the roof construction has a grid composed of mutually parallel longitudinal and transverse beams (L, Q).

1 . Gas station according to claim 10,

characterized,

in that at least some of the longitudinal and / or transverse beams (L, Q) have drainage channels.