WO2012041330A2

WO2012041330A2 - Roofing elements

Info

Publication number: WO2012041330A2
Application number: PCT/DK2011/050371
Authority: WO
Inventors: Karsten Bro; Bo Serwin; Kaj Erik JØRGENSEN
Original assignee: Connovate Aps
Priority date: 2010-09-30
Filing date: 2011-09-30
Publication date: 2012-04-05
Also published as: WO2012041330A3

Abstract

Roofing element (1) having upper (10) and inner (20) shell sections made from high strength concrete, where said shells are arranged on either side of an insulating core (30), where one or more reinforcement lattices (40) are arranged, said reinforcement lattice (40) being embedded both in the upper (10) and inner (20) concrete sections.

Description

Roofing elements

Field of the Invention

The present invention is related to a roofing element and a method of providing a roofing using such elements where special advantageous features and properties of high strength concrete are advantageously used in order to provide extremely strong waterproof and relatively light elements which provides the invention with numerous advantages.

Background of the Invention

In the art many different systems have been described which provide roof coverings in various materials and embodiments, and especially for industrialized construction it is well-known to use roof cassettes which are basically timber constructions in a box shape surrounding insulation. The roof cassettes are arranged on a load-carrying structure, and after being placed a relatively flexible roof covering such as for example a bitumen impregnated membrane is applied to the upper side of the roof cassettes. In this manner a relatively factory-made solution is provided which is lightweight and with good insulation properties. However, it is not desirable to use organic materials in a roof construction due to the fact that organic materials may rot, be targeted by fungus and the like. From a strength perspective the timber roof cassettes are not very strong and are susceptible to the influence of moisture in that wood being a natural material will absorb and deform when exposed to moisture.

Naturally some basic features shall be provided by a roof structure such as a coherent waterproof covering, resistancy to external influences from precipitation, wind, temperature, the ability to anchor the roof to the underlying construction etc.

In the art AU 2009202728 describes a concrete panel which may be used as a wall and roofing element. The element is especially developed in order to avoid heat transfer through the element due to thermal bridges. The element has an insulating core sandwiched between two boards, against which the concrete outer shells are cast. The con- crete is an aerated concrete. In each concrete shell is arranged a reinforcement, where the reinforcement in the two shells are connected by stringers through the insulating core. The aerated concrete is typically not very dense and as such requires either ann exterior roof membrane or a special treatment in order to render the upper surface wa- terproof. Furthermore, although aerated concrete to a certain degree contributes to the insulation properties of the entire element, the concrete shells and the embedded corrugated metal reinforcing sheets requires a relatively heavy construction in order to be able to provide any covering span (as a roofing element), and as such the insulating properties of an element is relatively limited, compared to its thickness and weight. Furthermore the element lacks rigidity, in that the ties connecting the corrugated metal reinforcing sheets are connected to the sheets by means of a connection where a polymeric sleeve is used, such that the sheets are not in direct contact. This creates a number of connection points where the polymeric sleeve will be exposed to loads, which may not be transferred to the reinforcement. Object of the Invention

It is therefore an object of the present invention to provide a very strong and still lightweight and well-insulating roofing element. A further object is to provide the best price/quality un-organic roofing element.

Description of the Invention

The invention addresses this by providing a roofing element having upper and inner shell sections made from high strength concrete, where said shells are arranged on either side of an insulating core, where one or more reinforcement lattices are arranged, said lattice being embedded both in the upper and inner concrete sections. As regards the present invention high strength concrete shall mean concrete with a compressive strength between 65 and 300 MPa as will be further elaborated in an embodiment of the invention. Traditional concrete will usually have compressive strength between 20 and 40 MPa. In addition to being extremely strong, i.e. having a very high compressive strength, high strength concrete is usually also very dense such that even a thin layer of concrete will be waterproof and as such no further cladding is needed in order to obtain a waterproof roof.

It is however possible during manufacture i.e. in the mould or after de-moulding to coat the roofing elements with a waterproofing agent, if desired.

The reinforcement lattices arranged between the upper and inner concrete sections provide for a relatively stiff structure, and furthermore in embodiments where the lattice is made from stainless steel and the insulation is for example a foam product which is relatively rigid such as PUR foam, a very stiff roofing element is provided which in addition has excellent characteristics with respect to carrying capability and thereby the distance at which the elements must be supported may be substantive.

In a further advantageous embodiment end walls are provided at least in the upper and/or inner section, where said end walls are provided adjacent the edges of the section, and where said end walls projects towards the opposite section, without connecting to said section or opposing end wall.

The end walls provide the roofing element with added stiffness in that an end wall ar- ranged substantially perpendicular to the roofing surface or the inner section surface will dramatically improve the moment of resistance such that a much stiff er panel is achieved. Furthermore, by arranging end walls two roofing elements being placed next to each other in a roofing structure will have a larger concrete surface facing each other such that any sealing may be attained much more effectively in that the seal has a larger concrete surface to be placed against. By not having the end walls connecting the front and the inner sections it is ensured that the end wall does not act as a thermal bridge whereby the insulating properties of the panel is maintained.

In a still further advantageous embodiment the upper surface of the upper section is slanted relative to the lower surface of the inner section, where the slant is between 1 :20 and 1 :75, more preferred between 1 :30 to 1 :50 and most preferred 1 :40. In this manner the upper surface and the lower surface are not parallel. This in turn provides for one side edge being lower than the other side edge. When the roofing elements are arranged in a roofing construction the lower side edges will be arranged uppermost such that water flowing down the roof s surface will drop from the highest point down towards the lower point on an adjacent roofing element. Due to the slant of the roof, the water will not fall in the joint between two adjacent roofing elements, but fall on the roofing surface as such.

In a still further advantageous embodiment the edge of the upper section extends be- yond the end wall in the thicker end of the element, such that when two identical roofing elements are positioned adjacent to each other, the upper section of one will extend a distance over the surface of the adjacent roofing element.

In this manner it is ensured that water on the roofing element will be transferred to the downstream roof element in a manner where the water is transferred from the upper to the lower element a distance away from the joint between the two adjacent roofing elements. It is also contemplated that a very thin seal may be arranged between the extension of the upper section and the upper surface of the adjacent roofing panel, such that any water driven by wind upwards against the natural flow of water will not be able to enter the construction. Also with respect to wind protection a thin seal between the extension and the upper surface of the roofing element will serve to make the roof surface substantially wind-tight and thereby preserve the integrity of the insulation.

In a still further advantageous embodiment the shells are 5-35 mm thick, and the high strength concrete has a compressive strength between 65 MPa and 300 MPa, more preferred between 100 MPa and 250 MPa and most preferred around 150 MPa.

The very thin concrete shells being made from a very strong concrete provides very stiff panels which are at the same time very light. For this reason in combination with the insulation the roofing elements are extremely lightweight and at the same time very strong such that it is possible to make the roof elements self-carrying and spanning a substantial distance without load-bearing support. In this context it is also important to note that the minimum concrete cover, covering reinforcement in traditional concrete constructions according to most building codes is to be 35 - 50 mm (depending on the environment into which the construction is introduced), whereas with high strength concrete and non-corrosive reinforcement/fibres, the density of the high strength concrete is such that only very few mm concrete cover is required.

In order to further strengthen the roofing elements the invention in a further advantageous embodiment provides the roofing elements with ribs such that either the upper or the inner or both shell sections, on the surface facing the insulation, is/are provided with reinforcement ribs made from high strength concrete and integral with the high strength concrete of the shell(s), where non-corroding rebars or other reinforcement is provided in the ribs. As concrete has a high compressive strength and a substantially lower tensile strength, it will be necessary to introduce measures in order to increase the tensile strength of the constructions. This is done in an advantageous embodiment by providing ribs where said ribs will encapsulate the reinforcement bars, for example in the shape of glass fibre, carbon fibre or Kevlar fibre ropes ars which have very high tensile strength, good adhesion to the concrete and are non-corroding. Furthermore, the entire concrete matrix may be add-mixed with fibres both in order to improve the tensile properties of the concrete matrix as such, but also in order to provide improved ductility to the very thin concrete structures. With roofing elements having a size as disclosed in a further advantageous embodiment of the invention without dimensions such that the length of an element is between 2000 to 16000 mm, the width between 600mm to 4000 mm and the thickness between 100 mm to 600 mm it is possible to lift and mount the roofing elements without the use of heavy lifting equipment, but rather the crane mounted on most trucks will be able to lift and handle the roofing elements. The 100 mm thickness will typically be high strength concrete shells of 10-20 mm and an insulating core of 60 - 80 mm. In many instances transport considerations will limit the overall size of the roofing elements.

The inventive roofing elements according to the invention may be arranged so that one element spans from the lower edge of the roof to the ridge, or such that a number of roofing elements are arranged next to each other in order to provide the roofing surface between the lower and upper edge of a roof. The panels are also suitable to be used for so-called flat roofs. In reality "flat roofs" will have a inclination of 1 :50 - 1 :40. In some embodiments the extended member has been provided with a GRC shoe/profile along a free edge, in order to protect the edge and in order to be able to fit/fastened weather strips or other joint materials. Although GRC is preferred, other materials such as for example stainless steel or other corrosion resistant materials may be used, as long as their thermal expansion coefficient is similar to that of the concrete.

The invention is also directed to a method of providing an insulated roof construction by mounting roofing elements according to any of claims 4 to 8 comprising the following steps :

a) providing a load transferring substructure, where said substructure has support members spaced a distance corresponding to the length of the roofing elements or less; b) arranging a first row of roofing elements lengthwise end to end lowermost on the roof construction;

c) arranging subsequent rows of elements end to end, where the roof elements' projecting edge of the upper section extends beyond the end wall in the thicker end of the element, such that the upper section of one element will extend a distance over the surface of the adjacent roofing element.

This method takes advantage of the advantages provided by the novel and inventive roofing element as discussed above.

When producing the elements, they may be manufactured by any suitable method. Traditionally moulds are made to the desired shape and size. Thereafter concrete, insulation and/or/comprising reinforcement is placed and finally the second layer concrete is placed, after which a finishing procedure is carried out. The panels are thereafter left to cure/set.

A coating, either providing surface characteristics not provided in the moulding process or colour or waterproofness are all of the above, may be applied at this stage.

The invention is also directed to an advantageous method of casting the roofing elements described above, which method comprises the following steps:

a) in a concrete casting mould a first quantity of substantially liquid high strength concrete is placed;

b) arranging a pre-shaped insulation section, said insulation section having upper and lower substantially planar surfaces, where said insulation section comprises reinforcement lattice extending from both surfaces of the insulation section, such that the lower surface of the insulation and part of the reinforcement lattice is embedded in the liquid concrete;

c) pouring a second pre-defined quantity of substantially liquid high strength concrete on top of the insulation section, thereby embedding the upper surface of the insulation section, and part of the reinforcement lattice.

The method provides further advantages in further method steps where the concrete casting mould is provided with channels, such that as the first quantity of concrete is poured it will fill the channels and create a number of ribs and a continuous high strength concrete plate. and where the insulation section prior to being introduced into the mould is provided with one or more channels in either upper or lower surface or both surfaces, such that as the concrete is poured and comes into contact with the insulation section, the channels are filled with high strength concrete.

In particular the additional method step of providing channels in the casting mould such that the ribs formed when pouring the first quantity of concrete are established projecting away from the insulating core provides a number of advantages. When casting the roofing elements as suggested in this embodiment the upper surface of the roof will be cast downwards against the mould. This in turn provides the possibility to provide the weather-exposed surface of the roof with any desired pattern or characteristic. Furthermore, the reinforcement ribs will from an aesthetic point of view provide the possibility to design the visible roof surface with special features. Furthermore, as the ribs project away from the insulating section the entire cross section of the roofing element is provided with the same thermal insulation value in that the ribs which would otherwise be projecting inwards towards the insulation section would diminish the insulation characteristics of a finished element.

As the mould is provided with the channels in the bottom, all roofing elements will be provided with ribs and as such a work process is saved in that the channels which could otherwise be provided in the insulating material does not have to be created. These channels shall be created in each and every insulating section used for casting concrete roofing panels wherein the channels are desired in that the insulating section when the channels are shaped in the insulation material will act as a last shuddering.

A still further advantage by this casting method is provided by the upstanding reinforcement ribs in that they will provide an integrated cornice along the edge of the roof. Also when creating water tight connexions between adjacent roofing elements advantages are achieved by the upstanding ribs. It is contemplated that the side edges of the roofing element in the direction in which the water will flow will be provided with upstanding ribs along the side edges. Therefore, by arranging two roofing elements adjacent to each other they will both have facing upstanding ribs which can be connected by an inversed U-shaped member which can be superposed the upstanding ribs and thereby create not only a connection between adjacent ribs but also a waterproof connection. By designing the top edge of the reinforcement rib, for example such that it has a smaller cross dimension than the rest of the upstanding rib it is possible to provide the U-shaped member such that it will be "invisible" from a distance in that the outer dimensions of the U may be corresponding to the dimensions of the adjacent reinforcement ribs. It is also possible to manufacture the elements in a continuous process, where the concrete is continuously sprayed onto a moving belt. An advantage of this procedure is that it is possible to integrate higher fibre % by this method, than be regular concrete casting. Insulation incorporating projecting reinforcement is thereafter placed in the still wet concrete. This is followed by a further spray station, applying the final layer of high strength concrete. The finished element may pass through a finisher, which will introduce any pattern or other surface characteristics (roughness, smoothness or the like) to the finished panel. Eventually the panels are cut in desired lengths. This method naturally requires that all elements have the same cross-sectional dimensions.

A similar process may be carried out, using extrusion techniques. Description of the Drawing

The invention will now be described with reference to the accompanying drawing wherein

Figure 1 illustrates the roofing element seen as a cross section

Figure 2 illustrates the inside face of the upper shell

Figure 3 illustrates a number of substantially identical roofing elements

Figures 4-8 illustrate constructive details of a construction

Figures 9-13 illustrate further embodiments of the roofing element.

Detailed Description of the Invention

The invention will now be explained with reference to the accompanying drawing wherein the figures of the drawing shall be seen as schematic, and depending on which project the roofing elements are to be used the roofing elements will vary as will the dimensions, thickness of concrete shell and insulation etc.

Turning to figure 1 a roofing element 1 according to the invention is illustrated. The roofing element comprises an upper high strength concrete shell 10 and an inner high- strength concrete shell 20. Between the concrete shells 10, 20 is arranged an insulation 30, which insulation may be selected among any types of insulation, but especially preferred are substantially rigid insulation materials such as for example PUR, PIR or relatively dense mineral wools. The upper and lower shells 10, 20 are provided with end walls 11, 12, 21, 22 the end walls 11, 12, 21, 22 are integral with the upper and inner sections 10, 20 and as illustrated it is important that the end walls 11, 12, 21, 22 do not connect such that a thermal bridge is created, but that the end walls are separated by insulating material 30.

The end walls serve to provide rigidity to the elements as such in that the bending moment of the entire panel in the longitudinal direction greatly increases due to the end walls 11, 12, 21, 22. In figure 1 the roofing element is seen as a cross section such that the longitudinal direction is perpendicular to the plane of the drawing.

Furthermore, a reinforcement lattice work 40 is provided which lattice work is embedded in the concrete shells 10, 20 and thereby rigidly connects the upper shell 10 with the inner shell 20. Typically the lattice work will be chosen from non-corrosive materials such as glass, carbon or Kevlar fibres or stainless steel. In the embodiments illustrated with reference to figures 4-8 stainless steel lattice work is used in an actual construction project. Turning to figure 2 the inside face of the upper shell 10, i.e. the face of the shell facing the insulation 30, is provided with reinforcement ribs 13 in which ribs additional reinforcement 14 is provided. Due to the very thin concrete cover the reinforcement may advantageously be chosen as non-corroding, but even where corroding material such as steel is used, the density of the concrete will be such that it is very unlikely that mois- ture will penetrate to the reinforcement 14 and create corrosive damage.

In the same manner the inner shell 20 is provided with reinforcement ribs 23 which are also provided with reinforcement. The reinforcement ribs are schematically illustrated and they may take any advantageous shape which both address ease of manufacture in the moulding process and the strength characteristics to which they are designed.

A roofing element according to the invention may in addition to the features described with reference to figure 1 also have the features of figure 2 such that it shall be under- stood that the reinforcement ribs 13, 23 do not exclude the use of other reinforcement, but may be combined with any other features of the invention.

The roofing elements illustrated with reference to figures 1 and 2 are furthermore pro- vided with an upper section 10 which has an extension 50 which extension extends beyond the end walls 11, 21. Furthermore, the upper section is provided with a slant such that the thickness of the entire roofing element in a first end (a) is smaller or equal to the distance between the lower section and the extending member 50 having the measurement (b). In this manner it is possible to arrange the roofing elements as illus- trated with reference to figure 3.

In figure 3 a number of substantially identical roofing elements are arranged such that the side face (a) of one roofing element is inserted underneath the extended section 50, whereby the extension 50 is covering part of the upper section 10 of an adjacent roof- ing element 1. In this manner it becomes possible to create an overlapping roof covering with a high degree of water-tightness in that the overlap ensures that water will flow from the upper surface of one element onto the upper surface of the adjacent element without penetrating the joint between the two elements. In the overlap may furthermore be provided a closure strip or joint material such that water or wind being forced into the joint between two adjacent elements is effectively stopped from penetrating further into the construction.

The lowermost element 2 is different from the other roofing elements 1 in that a gutter 51 is integrated in the element.

In figures 4-8 are illustrated various construction details.

In fig 4 the overlapping relationship between two adjacent elements is illustrated with the extension section (50) overlapping an adjacent element.

In fig. 5 is illustrated a detail, where a "standard" roofing element 1 is arranged adjacent a wall element 80. A traditional gutter 81 is arranged lowermost on the roof surface. An important aspect of all the details is the fact that no thermal bridges occurs in any of the constructual details, and that both wall and roof elements are made from thin shell high strength concrete.

In fig 6 a detail of a roof panel being connected to a wall panel is illustrated. In this detail a covering element 82, made from high strength concrete is fitted in order to bridge the gab between the wall element and the roof element. Fig 7 illustrates a roof ridge detail, where two roofing elements meet. Also in this detail a covering element 82 is used to assure watertightness.

In fig. 3 and 4 the connection details relating to horizontal details are illustrated. In fig 8 is illustrated a vertical detail, between adjacent roofing panels 1 being supported by a load carrying member, as for example a steel girder 83. Also in this embodiment a covering element 82 is used.

In fig. 9 is illustrated an alternative embodiment of the roofing element 100. The roofing element will of course comprise reinforcement as described above, but for the sake of clarity a reinforcement is not illustrated. The roofing element is cast upside down, i.e. the upper side 101 will during the casting process have been facing the bottom of the mould. In the mould has been provided cavities which have shaped the reinforcement ribs 102 such that these when the roofing element is in its use position as illustrated in figure 9 will be projecting upwards from the upper surface 101. In this par- ticular embodiment also the inner shell 120 is provided with reinforcement ribs 123. As is evident from the illustration in figure 9 the insulation thickness between the reinforcement ribs 123 and the projecting reinforcement ribs 102 is thicker than the corresponding insulation thickness in for example figure 2 and as such the overall insulation properties of the roofing element 100 are improved without increasing the thickness of the insulation material. In this context it is contemplated that the reinforcement ribs 123 may be offset from the projecting reinforcement ribs 102 on the upper shell 110. The side edges 111, 112 are also provided with upstanding ribs 102', 102" which may either serve to create a water-proof joint between two adjacent roofing elements as illus- trated with reference to figure 11 or may be part of an integrated cornice 114, see figure 10.

Turning to figure 10 three substantially identical roofing elements 100', 100", 100"' are arranged next to each other in order to illustrate a roof having a certain slant such that water will flow towards the lower edge. At the lower edge either a cornice 114' may be so low that the water will be able to run off the roof and be collected by gutter (not illustrated) or an integrated gutter as described with reference to figure 3 may be integrated,

In order to understand the connection details between adjacent roofing elements 100', 100" attention is directed to figure 11 and 12 in which an embodiment of a connection is illustrated. Two substantially identical roofing elements 100', 100" are arranged such that their side edges 111, 112 are placed next to each other. Thereby the rein- forcement ribs 102', 102" will also be places next to each other. In this embodiment the distal part of the reinforcement ribs 102', 102" have a material thickness smaller than the reinforcement ribs as such, such that a capping element 130 may be arranged which capping element 130 has a general inverted U-shape such that between the two flanges of the U the distal ends of the upstanding reinforcement ribs 102', 102" will fit inside the U, such that the U will create a substantially water-proof connection between the two adjacent roofing elements 100', 100".

In figure 12 a detail is illustrated where a joint pillar or a weather strip 131 have been arranged in order to further improve the water-tightness and/or adhesively bond the capping element 130 to the reinforcement ribs 102', 102".

In fig. 3 was illustrated a lowermost module 2 incorporating a gutter. In fig. 13 is illustrated a variation, wherein a gutter is created by providing apertures 120 in the reinforcement ribs 102,102' 102" etc., across a lower roof edge 121 where the roof is made from elements as described with reference to fig. 9 to 12. The arrow 122 indicates the downward slant of the roof. The apertures 120 allow water to flow along the inner side of the lowermost rib 123, thereby leading the water away from the roof s surface. It should be clear that the system uses very simple and easy to execute assembly methods, which are very secure and relatively easy to carry out on site. The invention has been described with reference to illustrative examples, but it is clear that many modifications are possible, and the invention therefore shall only be limited by the scope of the appended claims.

Claims

1. Roofing element having upper and inner shell sections made from high strength concrete, where said shells are arranged on either side of an insulating core, where one or more reinforcement lattices are arranged, said lattice being embedded both in the upper and inner concrete sections.

Roofing element, according to claim 1, characterised in that end walls are provided at least in the upper and/or inner section, where said end walls are provided adjacent the edges of the section, and where said end walls projects towards the opposite section, without connecting to said section or opposing end wall.

Roofing element, according to claim 1, characterised in that the upper surface of the upper section is slanted relative to the lower surface of the inner section, where the slant is between 1 :20 and 1 :75, more preferred between 1 :30 to 1 :50 and most preferred 1 AO.

Roofing element, according to claim 2 and 3, characterised in that the edge of the upper section extends beyond the end wall in the thicker end of the element, such that when two identical roofing elements are positioned adjacent to each other, the upper section of one will extend a distance over the surface of the adjacent roofing element.

Roofing element, according to claim 2, characterised in that end walls does not connect, whereby the upper and inner shell always is separated by insulation.

Roofing element, according to claim 1, characterised in that the shells are 5 - 35 mm thick, and that the high strength concrete has a compressive strength between 65 MPa and 300 MPa, more preferred between 80 MPa and 250 MPa and most preferred around 150 MPa.

7. Roofing element, according to any preceding claim, characterised in that either the upper or the inner or both shell sections, on the surface facing the insulation, is/are provided with reinforcement ribs made from high strength concrete and integral with the high strength concrete of the shell(s), where non- corroding rebars or other reinforcement is provided in the ribs.

Roofing element according to any of claims 1 to 6 characterised in that the upper shell section is provided with reinforcement ribs projecting from the upper surface, and that the inner shell optionally is provided with reinforcement ribs on the surface facing the insulation, which reinforcement ribs are made from high strength concrete and integral with the high strength concrete of the shell(s), where non-corroding rebars or other reinforcement is provided in the ribs.

Roofing element, according to claim 1, characterised in that the roofing elements has outer dimensions such that the length of an element is between 2000 to 16000 mm, the width between 600mm to 4000 mm and the thickness between 100 mm to 600 mm.

10. Method of providing an insulated roof construction by mounting roofing elements according to any of claims 4 to 8 comprising the following steps:

a) providing a load transferring substructure, where said substructure has support members spaced a distance corresponding to the length of the roofing elements or less;

b) arranging a first row of roofing elements lengthwise end to end lowermost on the roof construction;

c) arranging subsequent rows of elements end to end, where the roof elements' projecting edge of the upper section extends beyond the end wall in the thicker end of the element, such that, the upper section of one element will extend a distance over the surface of the adjacent roofing element.

11. Method of casting roofing elements according to any of claims 1 to 8 comprising the following steps: a) in a concrete casting mould a first quantity of substantially liquid high strength concrete is placed;

b) arranging a pre-shaped insulation section, said insulation section having upper and lower substantially planar surfaces, where said insulation section com- prises reinforcement lattice extending from both surfaces of the insulation section, such that the lower surface of the insulation and part of the reinforcement lattice is embedded in the liquid concrete;

12. Method according to claim 11 wherein the concrete casting mould is provided with channels, such that as the first quantity of concrete is poured it will fill the channels and create a number of ribs and a continuous high strength concrete plate.

13. Method according to claims 11 or 12 wherein the insulation section prior to being introduced into the mould is provided with one or more channels in either upper or lower surface or both surfaces, such that as the concrete is poured and comes into contact with the insulation section, the channels are filled with high strength concrete.