EP3800305A1

EP3800305A1 - Tile convection construction

Info

Publication number: EP3800305A1
Application number: EP20198645.2A
Authority: EP
Inventors: Ole Frederiksen
Original assignee: Excellent Holding ApS
Current assignee: Excellent Holding ApS
Priority date: 2019-10-03
Filing date: 2020-09-28
Publication date: 2021-04-07

Abstract

The present invention relates to a tile convection construction as well as a method of cooling buildings utilizing such a roof comprising a tile convection construction.It is the object of the invention to provide a solution for cooling of an interior climate in a house during warm periods, and thereby reducing the costs of cooling. The present invention presents a low cost solution, especially for cooling of houses. The present invention provides a tile convection construction comprising a substantially horizontal roof having at least one barrier extending away from said roof, where said barrier encircles wholly or partly a tile layer, where said tile layer is arranged a distance above said roof, where at least one limited space is provided between said roof and said tile layer, where the barrier is provided with said at least one aperture, where said aperture provides an air communication between an ambient space and said limited space, which provides an air flow from said ambient space through said tile layer.

Description

Field of the Invention

The present invention relates to a tile convection construction as well as a method of cooling buildings utilizing such a roof comprising a tile convection construction.

Background of the Invention

With the increasing focus on energy consumption, there is a desire to lower the energy consumption and thereby the cost of energy in connection with among other things buildings, living quarters, etc.
To maintain an interior climate in houses, which is neither too cold nor too hot, and as such during winter periods it is necessary to heat the houses and during summer periods it is desirable to cool the houses.
In a number of regions the costs of cooling houses exceed by far the costs of heating houses. Furthermore, it is more energy consuming to cool the interior of houses than it is to heat the same house.

Object of the Invention

It is the object of the invention to provide a solution for cooling of an interior climate in a house during warm periods, and thereby reducing the costs of cooling.

Description of the Invention

The present invention presents a low cost solution, especially for cooling of houses. The present invention provides a tile convection construction comprising a substantially horizontal roof having at least one barrier extending away from said roof, where said barrier encircles wholly or partly a tile layer, where said tile layer is arranged at a distance above said roof, where the tile layer is provided with at least on opening, where at least one limited space is provided between said roof and said tile layer, where the barrier is provided with said at least one aperture, where said aperture provides an air communication between an ambient space and said limited space, which provides a convection when an air flow is provided from said ambient space through the aperture into the limited space and upwards through said tile layer.
The tile convection construction uses air cooling for lowering air temperature by dissipating heat. The air cooling process, e.g. natural or forced convection cooling, provides an air flow, which reduces temperature by dissipating the heat out of the limited space through the openings/gabs between the tiles in tile layer and/or along the sides of the tile layer. The heated perforated tile layer, which is heated by the solar energy, will create a cooling mechanism using convection.
The air inside the limited space will be heated and the heated air will move upwards, i.e. away from the roof surface through the gaps between the tiles and/or along the sides of the tile layer adjacent to the barrier and/or the building construction. During this movement an under-pressure will occur in the limited space, which will cause air at a lower temperature to be sucked into the limited space through the apertures in the barrier.
The tile convection construction has a roof construction, which may be a substantially horizontal roof. A tile layer is arranged a distance above said roof. The tile layer may be encircled wholly or partly by a barrier. The tile layer may also be encircled wholly or partly by at least one wall of a building construction, or similar. An limited space may be provided between barrier and/or a wall of a building construction, the roof and the tile layer. The limited space may be connected outside ambient space through apertures in the barrier and/or a wall of a building construction. The aperture provides an air flow from the outside ambient space, which may be the ambient surrounding, into said limited space and through said tile layer. A convection of air is provided, when air from the ambient surrounding is guided into the space between the roof and the tile layer, where the air is heated by the roofs upper surface and the heated air is rising upwards through the gaps between the tiles in the tile layer. This will provide a lower temperature on the roofs upper surface and thereby also a lower temperature on the roof's interior surface. The present invention thereby provides a solution for natural cooling of an interior climate in a house during warm periods, and at the same time reducing the costs of cooling.
The invention is especially used for buildings having a flat or substantially flat roof. The roof may also have other shapes, e.g. one or more slopes. The roof or part of the roof may be provided with a substantially horizontal terrace provided by the tile convection construction. The terrace may be encircled by a barrier. The barrier may be integrated into and/or a part of the building construction or simply added as a railing etc. When encircling the terrace and thereby also the tile convection construction, the limited space between the roof, the tile layer and the barrier may accumulate heat, when the sun is shining. The heat accumulated may not be able to escape the limited space, and the heat may damage the roof.
The accumulated heat may be transferred through the roof causing the temperature to rise inside the building construction. This may be preferred if the intention is to increase the temperature inside a room in the building construction, but not if the intention is to lower the temperature inside a room. In a number of regions the costs of cooling houses exceed by far the costs of heating houses. So the heating of the building construction may not be preferable in many regions.
By using forced or natural convection method comprising heat transfer, the heat on the roof may be led away from the roofs upper surface, causing the temperature to drop. The limited space cannot unmanageably accumulate the heat, because the airflow due to the convection, may maintain the temperature with in a predefined range.
In an advantageous embodiment of the invention, at least one tile in the tile layer is a perforated tile.
The air inside the limited space will be heated and the heated air will move upwards, i.e. away from the roof surface through the perforations in the tiles. During this movement an under-pressure will occur in the limited space, which will cause air at a lower temperature to be sucked into the limited space through the apertures in the barrier. In this invention the effect of cooling the roof using natural air cooling, will apply for both a tile layer and/or a perforated tile layer likewise. By natural air cooling means the air cooling is a passive ventilation system providing cooling to a building.
In an advantageous embodiment of the invention, said aperture is provided with at least one valve.
The valves may be simple dampers, plates or the like which may be brought from a position where the air may flow freely to a position obstructing the air from flowing through the aperture, to any position in between. The valve may be a one-way valve.
The valve may be controlled by temperature controlled valve means. The temperature controlled valve means may comprise one or more sensors to detect one or more temperatures in the limited space. The temperature controlled valve means may control one or more valve and thereby control the airflow through the apertures. The means for controlling the valves may alternatively be, but not limited to, metal springs which are made from materials having specific temperature expansion/contraction properties, such as the valves are set to remain closed and only open when the temperature in the volume between the roof and the tiles rises above 20 degrees centigrade. The valves themselves may be simple dampers, plates or the like which may be brought from a position obstructing the conduit to a position where the air may flow freely through the conduit, and any position in between.
In a further advantageous embodiment of the invention, said aperture is provided with an inlet opening arranged on an outer side of the barrier and an outlet opening arranged on an inner side of the barrier, where said inlet opening has a cross-sectional area and said outlet opening having a cross sectional area, where the cross-sectional area of the inlet opening is larger than an cross-sectional area of an outlet opening.
The air inside this limited space will be heated by the solar influx, i.e. solar energy and due to the basic principles of hot air rising relative to cool air the air in the space will move upwards, i.e. away from the roof surface through the perforations in the tiles. During this movement an under-pressure will occur between the perforated tiles and the roof surface, which will cause the ambient air to be sucked into the limited space through the aperture.
In regards to the cool air, it is in the sense that the cool air has a lower temperature relative to the heated air. The cool air has substantially the same or lower temperature than the ambient air. The heated air is the air heated in the limited space and raising from the convection construction. The heated air has a temperature higher than the cool air. The cool air may for example be obtained from the ambient space. The cool air may for example alternatively be obtained from a basement, cellar, ground well or a shadow section behind the building, and led through one or more conduits to the inlet/inlets of the apertures in the barrier.
When the ambient air flows into the limited space, the air must preferably be circulated and thereby distributed evenly in the limited space, before the air gets heated and leave the limited space. The aperture may have at least one inlet opening arranged on the outer side of the barrier and at least one outlet opening arranged on the inner side of the barrier. To provide an efficient natural flow, the cross sectional area of the inlet opening may be larger than the cross sectional area of the outlet opening. This may provide a nozzle effect blowing the air further into the limited space. Especially if there is a wind, the wind may then blow into the inlet of the aperture arranged on the outer side of the barrier and build up a pressure on the inlet cross-sectional area providing nozzle effect on the outlet cross-sectional area. The nozzle effect may also be controlled using a valve in the convergent aperture.
As the ambient air has not been heated by the solar influx, the result will be that air in the limited space will have a substantially lower temperature than air immediately above a tile convection construction. Therefore, the perforated tile layer will create a cooling mechanism whereby the solar influx, i.e. the solar energy, will not be able to penetrate into the roof construction.
In a still further advantageous embodiment of the invention, the perforated tile layer is assembled from a plurality of tiles, where the tiles are elevated relative to said roof by means of one or more risers.
By using a plurality of tiles the elevated tile layer is relatively easy to install in that it is possible to select tiles, which have a size that may easily be carried and manually handled on the roof surface. The risers are provided to elevate the perforated tile layer from the roof. The risers are also used to levelling the perforated tile layer. The risers may be provided in many different shapes and heights.
Tiles or tiles may be provided with many different holes patterns and/or size of the perforations. The tiles or tiles may also be solid, where the gap between the tiles may provide the air communication needed for the heated air to escape from the limited space providing the convection of the tile convection construction.
The advantages of using the risers under the elevated tile layer with great versatility in that different tile sizes may be used and the tile layer may be arranged horizontally regardless of the slant of the underlying roof structure, naturally within limits, simply by using more or less risers. In this manner it is possible to convert a relatively useless slanting/flat roof into a useful outdoor space.
In a further advantageous embodiment of the invention, the risers have different height.
The risers may be constructed so that the risers may be used by superposing a plurality of risers, or as single elements having various heights. The risers may be arranged, such that the tile layer may be arranged on a slanted or horizontal surface. Some roof construction may have a slope, so it is necessary to compensate in order to have a substantially horizontal tile layer.
In a still further advantageous embodiment of the invention, the ambient space to which the inlet opening of said aperture is connected is in a lower elevated position than said tile layer.
It might be preferred that the inlet opening of said aperture is in the same elevated position as the limited space arranged between said roof and said tile layer. This will lead the air flow directly into the limited space. Optional the inlet opening is in a lower position than the limited space, or maybe even connected to a cooler environment through a conduit.
Due to the solar energy heating the air trapped between the perforated tile layer and the roof, an air movement is created by the influx of solar energy. By providing apertures to the limited space, the air movement caused by an under-pressure in the limited space will cause air movement through the aperture. The inlet of the aperture may be in communication with cool air from the nearby surroundings. The inlet of the aperture may be in communication with cool air from for example a lower elevation or a cooler space such as for example an area which will be in shadow or a cellar space, ground well or the like, cool air will be sucked into the limited space. This will further improve the lowering of the temperature on the roof and thereby the influx of heat into the interior of the building, which will again lower the cost of cooling the interior of the building.
In a further advantageous embodiment of the invention, said outlet opening of said aperture is connected to at least one air distributing channel which is arranged between said roof and said tile layer.
Air distributing channels may be arranged in some degree between said roof and said tile layer. The tile convection construction may be optimized by using air distributing channels to distribute the airflow from the ambient space into the limited space. It is preferred that the air from the ambient space is evenly distributed throughout the entire limited space, to provide an efficient cooling effect. This can be accomplished by using the air distributing channels as guides, and thereby controlling the air flow accordantly.
The air distributing channels may be provided as perforated conduits, tubes or pipes. The air distributing channels may be of metal, plastic or similar.
In a still further advantageous embodiment of the invention, said tile convection construction comprises at least one forcing means.
Convection provides a heat transfer between the surface of the roof and the air in the limited space. The convection brings the heated air in motion, such as an airflow. The faster the heated air is brought in motion, the higher the convection of heat transfer from the roof becomes. In the absence of airflow, heat transfer between the roof and the adjacent air is low. To cool the roof it is preferred that the heat transfer between the roof and the adjacent air is high.
The heat transfer between the roof and the adjacent air may be forced using forcing means, which forces a higher airflow over the roof. The air flow may be controlled by using forcing means, such as fans, pumps compressors or even the use of natural wind from the surroundings.
In a further advantageous embodiment of the invention, the forcing means is a fan arranged in said aperture.
The fan may be arranged in the aperture forcing the air to flow through the aperture into the limited space. The inlet of the aperture may furthermore be connected to a pump or a container with compressed air. Controlling means may be controlling the forcing means and/or the vent to control the convection.
In a still further advantageous embodiment of the invention, the tiles and/or risers are made from plastics, preferably in an injection moulding process.
By using the risers, air distributing channels and tiles suggested above these are plastic moulded elements which are constructed such that they will be able to provide the necessary load carrying characteristics in order to provide a useful surface. However, this is not necessary in all instances and as such also weaker tile elements and smaller risers may be used in order to provide the same advantages as already described above. The injection moulding process is a relatively cheap manufacturing process and as such together with the relatively low cost of installing such a roof an over-all cheap but very effective cooling installation may be achieved.
The present invention also provides a method of cooling a building, where said building comprising a roof, arranging at least one perforated tile at a distance above the roof, creating an limited space between the roof and the perforated tile, guiding cool air by means into the limited space between the roof and the perforated tile.
Having a roof, maybe a substantially flat, with perforated tiles at a distance above the roof, where a limited space is provided between the roof and the perforated tile, the tile convection construction for cooling a building has been achieved. By guiding cool air by into the limited space between the roof and the perforated tile the air may be heated and lead away through the perforated tiles.
Furthermore, the invention provides a method of cooling a building, e.g. roofs, arranging at least one perforated tile at a distance above the roof, where said barrier encircles wholly or partly said perforated tiles, creating a limited space between the roof and the perforated tile, providing the barrier with said at least one aperture, guiding cool air by means of an aperture into the limited space between the roof and the perforated tile.
When the ambient air from an ambient space is guided into the limited space, the air must preferably be circulated and evenly distributed in the limited space, before the air gets heated and leave the limited space through the perforated tiles and/or the gap between the tiles. The aperture may have at least one inlet opening arranged on the outer side of the barrier and at least one outlet opening arranged on the inner side of the barrier.
As the ambient air has not been heated by the solar influx, the result will be that air in the limited space will have a substantially lower temperature than air immediately above a tile convection construction. Therefore, the perforated tile layer will create a cooling mechanism whereby the solar influx, i.e. the solar energy, will not be able to penetrate into the roof construction.
The invention may furthermore be based on the principle that the sun will heat the flat roof surfaces whereby the solar heating will penetrate the roof construction and into the building thereby increasing the interior temperature. In this connection the invention provides a cooling roof by using a tile convection construction.
In an advantageous method, the cool air is obtained from a lower elevation relative to the perforated tile layer, and by convection transported to the limited space between the roof and the perforated tile layer, where the cool air is heated due to the exposure to solar heating of the tile surface, where after the heated air escapes upwards through the perforations in the tiles creating under-pressure in the limited space between the roof and the perforated tile layer, thereby creating air flow movement.
Method where the cool air is transported along at least one air distributing channel to at least one predefined limited space between the roof and the perforated tile layer, where the cool air is heated due to the exposure to solar heating of the tile surface, where after the heated air escapes upwards through the perforations in the tiles creating under-pressure in the limited space between the roof and the tiles, thereby creating air flow movement.
One or more air distributing channel may be arranged as an extension to the aperture. The air distributing channel may be attached to the outlet opening arranged on the inner side of the barrier. The air distributing channel may have a plurality of apertures, where the air flow of cool air alternatively may be transported along the air distributing channel to at least one predefined part of the limited space. The air distributing channel may be made of polymers or fabrics or similar.

Description of the Drawing

The embodiments of the invention are described in the following with reference to:

Fig. 1: Illustrating a building construction with a tile convection construction.
Fig. 2: Illustrating a simple tile convection construction.
Fig. 3: Illustrating a tile convection construction comprising a valve in an aperture.
Fig. 4: Illustrating a terrace with a tile convection construction.

Detailed Description of the Invention

An embodiment of the invention is explained in the following detailed description. It is to be understood that the invention is not limited in its scope to the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways.
Fig. 1 illustrates a cross-section through a tile convection construction 1 in a building construction 2. The building construction 2 in this embodiment has a substantially horizontal roof 3. The roof may be provided with the normal membranes etc. in order to render it watertight. These features are not illustrated on fig. 1.
The tile convection construction 1 comprises also a barrier 6 extending upwards from said roof 3. The barrier 6 encircles wholly or partly a perforated tile layer 4, which may be used as a terrace. The perforated tile layer 4 is arranged at a distance above said roof 3. The elevated distance between the roof 3 and the perforated tile layer 4 is provided by means of one or more risers 5.
At least one limited space 10 is provided between the roof and the perforated tile layer 4. The volume of the limited space 10 is defined by the area of the roof, the area of the perforated tile layer 4, and the height or heights of the risers 5.
The perforated tile layer 4, which is arranged a distance above said roof 3 is partly encircled by the barrier 6. The perforated tile layer 4 is also partly encircled by at least one wall 9 of a building construction 2. A limited space 10 is delimited by the barrier 6, the wall 9, the roof 3 and the perforated tile layer 4. The limited space 10 is connected to the outside ambient space through apertures 7 in the barrier 6 and/or the wall 9 of a building construction 2.
The air cooling is based on the principle that the sun will heat the roof 3 surfaces whereby the solar heating will penetrate the roof 3 and into the building construction 2 thereby increasing the interior temperature in the rooms 8. The invention provides a cooling roof 3 by using a tile convection construction 1. The tile convection construction 1 uses the air cooling for lowering the roof 3 temperature by dissipating heat from the roof 3. The purpose of the air cooling is to cool the roof 3 by a flow of air, when passing over the roof 3. The apertures 7 provide an air flow from the outside ambient space, which may be the ambient surrounding, where the air flow is guided into the limited space 10 and upwards through said perforated tile layer 4.
A convection of air is then provided, when air from the ambient surrounding is guided into the limited space between the roof 3 and the perforated tile layer 4, where the air is heated by the roof 3 and/or the perforated tile layer 4. The heated air 11 then rises upwards through the perforated tile layer 4. This will provide a lower temperature on the roof s 3 upper surface and thereby also lower temperatures on the roofs interior surface in for example a room 8 in the building construction 2.
Fig. 2 illustrates a simple tile convection construction 1. The air cooling process provides an air flow, which reduces temperature by dissipating the heated air 11 out of the limited space 10 through the perforated tile layer 4 and/or the gap 12 between the tiles. The heated perforated tile layer 4, which is heated by the solar energy, will create an air cooling process.
The air inside this limited space will be heated by the solar influx, i.e. solar energy and due to the basic principles of hot air rising relative to cool air the air in the limited space will move upwards, i.e. away from the roof surface through the perforations in the tiles. During this movement an under-pressure will occur between the perforated tiles and the roof surface which will cause fresh air to be sucked into the space. As this air has not been heated by the solar influx, the net result will be that air in the space will have a substantially lower temperature than air immediately above a fully exposed roof surface. Therefore, the perforated tile layer 4 will create a cooling mechanism whereby the solar influx, i.e. the solar energy, will not be able to penetrate into the roof construction and thereby heat the interior of the building.
The convection used in the cooling process may be forced or natural. In a forced convection the air flow is caused by forcing means, such as by a fan, a pump, or atmospheric winds. The forcing means may comprise the use of a fan, pump and/or compressed air, not showed on the fig. 2, to provide forced convection air cooling of the roof.
In a natural convection, the flow is provided by density differences caused by temperature variations in the air. In natural convection heat transfer will occur from the roof into the air. Since the heated air is now lighter than the surrounding air, buoyancy forces induce a vertical motion for which heated air ascending from the roof is replaced by an inflow of cooler air from the ambient space.
Fig. 3 illustrates a tile convection construction comprising a valve in an aperture. The barrier 6 is provided with said at least one aperture 7. The aperture 7 is in air communication with an ambient space and said limited space 10, which provides an air flow from said ambient space into the limited space 10, and when heated through said perforated tile layer 4. The aperture has an inlet opening 13 arranged on the outer side of the barrier facing the ambient surrounding and an outlet opening 14 arranged on the inner side of the barrier facing the perforated tile layer 4.
As the solar energy impacts on the tiles in the perforated tile layer 4, air trapped in the limited spaces 10 will be heated and thereby move upwards through the perforations in the perforated tile layer 4. Consequently, an under-pressure will occur in the limited space 10, whereby air will be sucked through the aperture 7 into the limited space 10.
By arranging the inlet 13 of the aperture 7 in a suitable place where the air is cooler, e.g. from the ambient surrounding, the air introduced into the limited spaces 10 due to the suction created by the under-pressure will be substantially cooler and thereby hinder the solar energy in penetrating through the roof structure 3 and into the building 2. In this manner a very simple low-cost and no running cost cooling system is provided.
The valve 15 may be controlled by temperature controlled valve means, not showed in fig. 3. The temperature controlled valve means may control one or more valve 15 and thereby control the air flow through the apertures 7. The means for controlling the valves 15 may alternatively be, but not limited to, metal springs which are made from materials having specific temperature expansion/contraction properties, such as the valves are set to remain closed and only open when the temperature in the volume between the roof 3 and the tile layer 4 rises above e.g. 20 degrees centigrade. The valve 15 may be brought from a position where the air may flow freely to a position obstructing the air from flowing through the aperture 7, to any position in between. The valve 15 may be a one-way valve.
The aperture/apertures 7 provide an efficient natural flow without using the valve 15 or when using the valve 15. The cross sectional area of the inlet opening 13 may be larger than the cross sectional area of the outlet opening 14. The form of the aperture 7 provides an efficient nozzle effect where the air is directed further into the limited space 10, due to the under pressure in the limited space 10. If furthermore there is a wind pressure on the inlet 13, the wind may then blow the air into the inlet 13 by building up a pressure on the inlet cross-sectional area and provide a nozzle effect on the outlet 14 cross-sectional area. The nozzle effect may also be controlled using a valve 15 in the convergent aperture 7.
Fig. 4 illustrates a square terrace with a tile convection construction from a top view. The terrace is arranged using a plurality of tiles forming a tile layer 4'. The tiles may be solid or perforated. A barrier 6 encircles three sides of the terrace and the building construction 2 is closing the fourth side, so the entire tile layer 4 is encircled. Gaps between the tiles are provided and are illustrated as lines forming the squares as tiles in the tile layer 4'. The heated air can escape upwards through the spaces in the tile layer 4'. The tile layer 4' is arranged in a distance above the roof, creating a limited space between the roof and the perforated tile, guiding cool air by means into the limited space between the roof and the perforated tile. This is illustrated in fig. 1.
By guiding cool air from the ambient surrounding through the apertures 7 in the barrier 6 into the limited space, cooling of the building has been achieved. The air must preferably be circulated and evenly distributed in the limited space under the entire squares terrace, before the heated air leaves the limited space.
The cool air is preferably obtained from a lower elevation relative to the tile layer 4', and by convection transported to the limited space between the roof and the tile layer 4'. The cool air is heated due to the exposure to solar heating of the surface of the tile layer 4', where after the heated air escapes upwards through the gaps between the tiles. An under-pressure occurs in the limited space thereby creating air flow movement.
One or more air distributing channel may be arranged as an extension to each of the apertures 7, attached to the outlet opening 14, fig. 3, arranged on the inner side of the barrier 6 facing the terrace. The air distributing channel may have a plurality of apertures. The air flow of cool air may alternatively be transported along the air distributing channel to at least one predefined part of the limited space through the apertures, where the cool air is heated due to the exposure to solar heating the surface of the tile layer 4', where after the heated air escapes upwards through the gaps between the tiles.
The valve 15 may be controlled by temperature controlled valve means. The temperature controlled valve means may comprise one or more sensors to detect one or more temperatures and arranged in predefined positions in the limited space 10.
Further the outlet 5" is provided with a valve 15. The valve 15 is activated by a temperature sensitive mechanism, which will not be further elaborated. Any suitable operation valve mechanism, mechanical or electrical, may naturally be employed. The valve mechanism may for example be programmed to be shut until the temperature in the limited space 6 rises above 20 degrees, after which the valve 11 opens and allows cool air to be sucked into the limited space through the conduit 5.
A test set up was installed on a normal housing type building in Dubai. Measurements were carried out in April-May. In fig. 5 is illustrated a sketch of the set-up.
On top of the normal/standard concrete roof 3 an elevated tile layer 4 was installed. The tiles were elevated approx. 100 mm above the concrete. The tiles and elevation system are of the type supplied by Excellent Systems, Denmark. The tiles are concrete tiles, but it is also contemplated that plastic tiles with a large number of apertures may be used. The roof was separated in three sections. A first section with the construction described above (tiles elevated above the concrete roof), a second zone with a bare concrete roof and a third section (as illustrated in fig 5) with elevated tiles and apertures 7 in the barrier surrounding the roof, such that it was possible to circulate ambient air into the limited space 10 between the tiles 4 and the concrete roof 3.
Temperature probes were arranged in all three zones. In the first and third zone probes were arranged on the concrete roof (underneath the tiles) and on top of the tiles (exposed to full sunshine). In fig 5 the arrangement of the probes in zone three is illustrated. Three probes 22,26,28 were arranged on the concrete roof 3, and an "out-side" probe 24 was placed on top of the tiles 4.
The first probe 22 was arranged approx. 20 cm from the aperture 7, the second probe 26 100 cm and the third probe 28 200 cm from the aperture. The outside probe 24 was arranged in a random position as substantially the same temperature was registered anywhere on the fully exposed upper surface of the tiles 4.
With this set-up the outside probe 24 registered 62°C. At the same time the first probe 22 registered 40 °C, the second probe 26 registered 44 °C and the third probe registered 45 °C.
The equipment used was THERMA2 Thermometer by ETI ltd and an IR type by Fluke IR 63 thermometer as second control.
The overall measurements are recited in table 1, where the temperature difference is given in %, such that the number represents the percentage by which the temperature was lower in comparison to and outside probe (comparable to probe 24 illustrated in fig. 5). The probe positioning and roof construction for the measurements disclosed in table 1 substantially corresponds to the schematic illustration in fig. 5. Table 1: Calculated temperature reduction in percentage of measured temperatures in Celcius.

Sensor/time 9:30 12:15 14:00

1 28 22,3 25,3

2 31,7 16 21,2

3 35,8 31,6 30,9

4 27,4 21,3 22,3

5 29,6 13 19

6 36,2 31,4 32
As is evident from table 1 there was registered a significant temperature difference between particularly the sensors arranged underneath the tiles in the first and third zones, clearly indicating that the ventilation openings in the barrier allowed air to circulate in the limited space thereby helping cooling the concrete roof. Consequently, rooms below the roof will experience less heating from the roof, and thereby a significantly lesser need for air condition. From surface temperatures on the tiles in the first and third zones and the exposed concrete roof in zone two of around 56 degree Celcius, to temperatures on the concrete in zone three down to 42-44 degrees Celcius.

Claims

Tile convection construction comprising a roof having at least one barrier extending away from said roof, where said barrier encircles wholly or partly a tile layer, where said tile layer is arranged at a distance above said roof, where the tile layer is provided with at least one opening, where at least one limited space is provided between said roof and said tile layer, where the barrier is provided with at least one aperture, where said aperture provides air communication between an ambient space and said limited space, allowing convection when air flow is provided from said ambient space through the aperture into the limited space and upwards through said opening in said tile layer.
Tile convection construction according to claim 1 wherein the roof is substantially horizontal and the aperture is provided through a substantially vertical part of the barrier.
Tile convection construction according to claim 1, where at least one tile in the tile layer is a perforated tile.
Tile convection construction according to claim 1, where said aperture is provided with at least one valve.
Tile convection construction according to any preceding claim, where said aperture is provided with an inlet opening arranged on an outer side of the barrier and an outlet opening arranged on an inner side of the barrier, where said inlet opening has a cross-sectional area and said outlet opening has a cross sectional area, where the cross-sectional area of the inlet opening is larger than an cross-sectional area of an outlet opening.
Tile convection construction according to any one of the preceding claims, wherein the perforated tile layer is assembled from a plurality of tiles, where the tiles are elevated relative to said roof by means of risers.
Tile convection construction according to claim 4, wherein the risers have different height.
Tile convection construction according to any one of the preceding claims, wherein the ambient space to which the inlet opening of said aperture is connected is in a lower elevated position than said tile layer.
Tile convection construction according to any one of the preceding claims, wherein said outlet opening of said aperture is connected to at least one air distributing channel which is arranged between said roof and said tile layer.
Tile convection construction according to any one of the preceding claims wherein the tiles and/or risers are made from plastics, preferably in an injection moulding process.
Tile convection construction according to any one of the preceding claims, where said tile convection construction comprises at least one forcing means.
Tile convection construction according to any one of the preceding claims, where the forcing means is a fan arranged in said aperture.
Method of cooling a building, where said building comprises a roof and arranging at least one tile in a tile layer at a distance above the roof, creating a limited space between the roof and the tile, guiding cool air by means of convection apertures arranged between the tiles and the roof from an ambient space through the apertures into the limited space and upwards through at least one opening in said tile layer.
Method according to claim 12, wherein cool air is obtained from a lower elevation relative to the tile layer, and by convection transported to the limited space between the roof and the tile layer, where the cool air is heated due to the exposure to solar heating of the tile layer, where after the heated air escapes upwards through the openings in or between the tiles creating under-pressure in the limited space between the roof and the tile layer, thereby creating air flow movement.
Method according to claim 12 or 13, where the cool air is transported along at least an air distributing channel to at least one predefined limited space between the roof and the tile layer, where the cool air is heated due to the exposure to solar heating of the tile surface, where after the heated air escapes upwards through the perforations in the tiles creating under-pressure in the limited space between the roof and the tiles, thereby creating air flow movement.