WO2009071958A1

WO2009071958A1 - Building structure with active heat insulation

Info

Publication number: WO2009071958A1
Application number: PCT/HU2008/000141
Authority: WO
Inventors: László NAGYLUCSKAY; Tamás BÁRKÁNYI
Original assignee: Nagylucskay Laszlo; Barkanyi Tamas
Priority date: 2007-12-04
Filing date: 2008-11-28
Publication date: 2009-06-11
Also published as: HU227029B1; EP2231952A1; HU0700778D0; HUP0700778A2

Abstract

The building structure with active heat insulation according to the invention is used for limiting walls and/or slabs of buildings. It comprises a frame structure formed by at least two steel mesh sheets (1, 2) fixed to each other with steel wires (3) welded to the steel meshes, a heat insulation layer (6 ) arranged in the centre of the frame structure, where the internal steel mesh 2 is encased in a first concrete layer (4), and the external steel mesh 1 is encased in a second concrete layer (5). A coil-pipe (7) is fixed on the external steel mesh 1, encased in the second concrete 5 and covered by the heat insulation layer (6), said coil-pipe (7) is connected to another coil-pipe (9) arranged under the surface of the soil in a depth of 1 - 150 m. The two coil-pipes (7, 9) form a common circuit, said circuit being provided with a pump (10) circulating the heat insulating fluid and an expansion tank (11).

Description

Building structure with active heat insulation

Field of the Invention

The subject of the present invention is a building structure with active heat insulation for limiting walls of building and/or for slab, according to preamble of claim 1. This kind of solutions are outlined for instance in documents US 6,272,805 Bl, as well as US 7,067,588 B2. The State of Art:

The building elements disclosed in US 6,272,805 Bl and US 7,067,588 B2 are heat insulated panels. These building elements provide solution of cost efficient, durable, easily and quickly executable buildings, but their heat insulation properties are not competitive with other building elements and systems meeting up to date heat insulation requirements. The outer concrete layer of this panel is exposed to high temperature fluctuation that can cause cracking of concrete surface and, in this way, damage of the structure. The building element itself doesn't provide the cooling of the building. HU-185052 describes a wall structure made from U-shaped glass elements, creating vertical channels near to each other. Fresh air or the used air of the room circulate in these channels. The structure is usually proposed to apply in ventilation systems. The disadvantage of the solution is the very narrow scope of utilisation as it may only be applied in case of walls made from U-shaped elements. Furthermore, air has low specific heat and can transfer suitable heat quantity only in case of special circumstances, and the flow of large air quantities is very noisy. The air channels do not provide suitable sound damping between the rooms of the building. From DE 3843067, a structure is known, where the buildings have hollow walls. One part of the heat streaming through the walls are taken up in the holes by the fresh air, sucked from environment. The air preheated in this way is mixed with the air of the internal area and the mixture is heated further with a heat-pump. The disadvantage of this technical solution is the utilization of air with low specific heat as heat transfer media, as well as applying an expensive heat-pump.

The heat of the earth, as renewable energy source is used expansively, especially as the starting energy source of heat-pumps. The heat-pumps produce high temperature media for heating by using electric power. The disadvantage of this solution is the high investment cost and the high power demand. To feel well in flats, suitable temperature, humidity and oxygen are needed. For this reason nearly constant temperature between 20-22⁰C and fresh air are necessary. That is why flats have to be ventilated and heated in winter and cooled in summer. The energy necessary for heating, is taken mainly from fossil energy, which is more and more expensive and pollutes the environment.

The heat insulation of so called "passive houses" is nearly perfect, but very thick and extremely expensive walls are required for this reason. Artificial ventilation is also needed in order to have always fresh air. Recuperators have been developed for this purpose, to heat incoming fresh air with the air stream flowing out, during winter. In this way, fresh air is coming in, and the heat remains inside. In summer, the incoming warm air is cooled by the cool air flowing out, meanwhile external heat can not flow in. It is also known that nature has energy for both heating and cooling, but it is a problem how to use it with low costs and without polluting the environment. The free energy of nature is available, but not in the time and in the way it is needed. For heating it is necessary to have a medium with 22⁰C temperature, but this kind of mediums is available in a relatively cheap way in the nature only in summer, but that time cold is needed rather.

Under the surface of the earth, in the depth of 1,5-2,0 meters, there is a nearly constant temperature of about + 8 -12 ⁰C. In this depth, unrestricted quantity of a medium at this temperature is available with low cost. This source is renewable, does not pollute the environment and is free. As it is not possible to heat with any medium of this temperature, it should be heated to about 50 ⁰C in heat pumps, which use considerable electric energy.

To make different renewable energy suitable for heating, it is necessary to use complicated equipments. The refunding period of such systems can be 15-20 years. That is the reason of the limited use of this new technology.

Summary of the Invention

The object of the present invention is therefor to provide a structure which enables creating buildings with small structural thickness, in an easy way, quickly, and with remarkable energy saving, due to the use renewable energy of the soil. The present invention overcomes the problems of the building structures according to the state of art with active heat insulation, as described in the characterizing part of claim 1 , where the temperature of fluid streaming in the coil-pipes is lower than the desired internal temperature of the building. The construction, at the same time, maintains all advantages of the prior art structures.

The invention is based on the recognition that using the low temperature renewable energy of the earth not for heating, but for active heat insulation results in a significant energy saving, compared to the known solutions.

The operation of the active heat insulation of the structure requires only the minimal energy of a pump circulating the fluid.

The solution according to the invention provides active heat insulation of a building, as well as cooling without noise and draught, since heat-exchange is solved without air movement.

The heating of the internal areas of a building requires a medium with higher temperature than the temperature of the internal area, but from renewable energy sources, a medium of such temperature is only available in a minimum quantity. Due to this reason, it is available only with expensive investments (e.g. sun collector, geothermic heat sources from deep wells, heat-pump, etc.). The low temperature, renewable, free energy for the solution according the invention is available in unrestricted quantity and continuously, in winter and in summer, day and night, and can be obtained in an easy way (with a coil-pipe placed in the soil in depths of maximum

150, preferably 1,5 -2,0 m under the surface, or with soil probe).

Brief description of the drawings

Further details, features and advantages will become more readily apparent from the following description accompanied by a set of drawings, in which

Fig. 1. shows a section of a preferred embodiment of a building element with active heat insulation, according to the invention, in perspective view, Fig 2. is a schematic elevational view of the structure with active heat insulation according to the invention,

Fig. 3. shows the heat transmission system of the structure in winter, Fig. 4. shows the heat transmission system of the structure in summer and Fig. 5. is a diagram showing the heat transmission of the wall structure with active heat insulation as function of temperature, Detailed description of a preferred embodiment Fig. 1. shows a preferred embodiment of a prefabricated panel, with active heat insulation according to the invention.

The panel contains steel meshes 1 and 2 welded with steel web wires 3 to create a continuous frame structure. The frame structure is equipped with a heat insulation layer

6 between the meshes and the internal steel mesh is covered with a first concrete layer

4, and the external steel mesh 1 is covered with a second concrete layer 5. The panel is covered from the outside with a second heat insulation layer 8.

The insulated structure according to the invention consisting of load-bearing steel meshes can be produced in large series on automatic production lines. The weight of such panels is insignificant compared to common building materials, so it is not necessary to use cranes at building. The building procedure is very quick, due to the big panel sizes. It is possible to make fittings (electricity, water, etc.) in the erected walls without demolish and repair before applying heat bearing concrete layers 4 and 5. It is not necessary to use cross-beams over the windows and doors due to the stability of the structure. The heat insulation layer 6 in the load-bearing structure provides good heat insulation for the internal part of the panel. Due to the steel structure, buildings made from this structure withstand earthquakes and hurricanes, and the internal concrete layer

4 provides suitable fire-resisting properties.

A coil-pipe 7 necessary for active heat insulation according to the invention is fixed to the external steel mesh 1. It is possible to fix it easily and quickly before applying the concrete layer 5. The steel mesh 1 under the coil-pipe 7, provides fast and even distribution of heat transported in the coil-pipe, besides the static tasks, accelerating heat-exchange in this way.

Fig. 2 shows a schematic elevational view of the structure with active heat insulation according to the invention. The coil-pipe 7 of the panel shown in Fig. 1. is connected to another coil-pipe 9. This coil-pipe 9 is arranged under the surface of the soil, in about one and the half meters depth, where the fluid circulating in it will take up a temperature of 8 - 12⁰C. A circulating pump 10 forwards this heated fluid having a temperature lower than the internal temperature of building into the coil-pipe 7. The system consisting of coil-pipes 7 and 9 is provided with an expansion tank 11, to buffer volume changes caused by temperature fluctuation.

This system can provide the heat insulation both of walls and slabs of the art.

The buildings made with the panel according to the invention, though it is of smaller thickness, has significantly less heat loss than solutions known up to now. The concrete layer 4 facing inside has suitable heat inertia for improving the internal comfort. The inner layer is firm and can be loaded, which is important for instance at cupboards and different objects to be fixed on the wall.

This structure according to the invention keeps all the advantages of the prior art structures, and at the same time, enables direct utilization of the low temperature (8-

12⁰C) earth heat, by leading it without any conversion to the coil-pipe fixed to the external steel mesh of the building element, and thus using the free energy of the soil not for heating, but for active heat insulation. The steel mesh under the coil-pipe provides, further to the load bearing function, the fast and even distribution of heat transported in the coil-pipe, accelerating heat-exchange in this way. The amount of heat flowing from the internal area through a unit area of the wall surface is significantly less with the active heat insulation, than without it. The energy saving can be even more than 50 - 80

%. The operation of the system requires only the minimal energy of a pump circulating the fluid.

It can be seen in Fig. 3, that in winter, when the external temperature (t_e ) is lower than the internal temperature (tj), the heat loss of the internal area (Q;) is determined by the temperature difference of internal temperature (tj) and the temperature of the earth (t_f), and the heat insulation factor of the internal wall part (Uj), independently from the external temperature (t_e), in case of the fluid circulating in coil-pipe provides constant earth temperature in the wall structure by proper fluid circulation.

The heat quantity (Q_f) taken by the low temperature fluid stream provides the heat loss of the external wall part (Q_e) determined by the difference of the earth temperature (t_t) and the external temperature (t_e ), together with the heat insulation factor (U_e) of the external wall part.

It can be seen in Fig. 4, that during summer, when t; < t_e, which means that the external temperature is higher, than the internal temperature, the active heat insulation structure does not allow heat loading (Q_e) into the internal area and transfers Qj heat from internal area to the soil.

Operating pump 10 is not practical, if heat quantity (Q) transferred through the whole wall structure is smaller than heat (Qj) transferred through the internal structural part with active heat insulation.

Fig. 5. graphically shows the operation of the active heat insulation structure as function of external temperature, wherein diagram part 2 shows that during summer (heat range between +35 and +22⁰C) the system does not allow the external heat loading into the internal area, but transfers it into the soil(Fig. 4: Q_e).

Diagram part 1 shows that, at the same time, the system transfers heat quantity (Qi) from the internal area into the soil. In this case the soil, as an endless heat accumulator, will be charged with heath energy, beside the heat energy given directly by the Sun. With the transfer of heat quantities (Q_e) and (Qi) into the soil, the icing of soil probe or soil absorber (which may occur by heat pumps) can be avoided.

Diagram part 3 shows the status when the heat quantity (Q) transferred through the whole wall structure is smaller than heat (Qi) transferred through the internal structural part with active heat insulation, when circulating pump does not work and the heat loss of internal area (Q,) is determined only by the heat transfer factor of the total structure (U), and the difference between external (t_e) and internal temperature (t;). At diagram part 4, (below -5⁰C temperature), the circulating pump is working again providing constant soil temperature (t_f) in the coil-pipe layer of the wall with the fluid stream. In consequence of this, the heat loss of internal area (Qi) is determined only by heat transfer factor (Uj) of wall part contacting with the internal area and difference between the internal temperature (ti) and the soil temperature (t_f) in the layer of coil- pipe. The quantity of liquid stream should be adjusted to provide continuous soil temperature in the wall even in case of lowest planned external temperature. This constant temperature of about +1O⁰C in the wall provides a constant low heat loss of internal area, independently from external temperature.

It is necessary to provide a heat quantity (Q_f) in the same range, determined by the difference between the external temperature (t_e) and the soil temperature (t_f) and by the heat transfer factor (U_e) of external wall part (diagram part 5).

The basic advantage of the invention is that this heat quantity is obtained not from the internal area, but from the soil, in an easy way.

In the following, the economy available by the invention will be illustrated by way of an example:

The dimensions of a wall structure shown in Fig. 2 are the following: ( 4 ) width of the concrete layer 5 cm

( 6 ) width of the heat insulation layer 10 cm EPS

( 5 ) width of the concrete layer with coil-pipe 7cm

( 8 ) width of the heat insulation layer 10 cm. EPS Accordingly, the total thickness of the wall structure is 32 cm.

On basis of the above data and in knowledge of materials of the wall layers, the following factors can be calculated:

The total heat transfer factor of the wall structure: U = 0,19 W/m , K

The heat transfer factor of the internal wall structure (the part between internal wall of concrete layer 4 and the middle of concrete layer 5) Uj = 0,37 W/m², K

The heat transfer factor of the external wall structure (see Figure 5) U_e = 0,46 W/m², K If the internal temperature (t; ) is +2O⁰C, the temperature of the concrete layer with coil- pipe 5 (tf) is +1O⁰C, and the eternal temperature is (t_e), than the heat transfer of unit wall surface from internal area without heat insulation is (Q) W/m , that can be calculated according to formula Q = (tj-t_e) U. The heat transfer of unit wall surface from internal area with heat insulation is (Q 0 W/m², that can be calculated according to formula Qj = (tj-t_f) Uj

There is a double advantage of the wall structure with active heat insulation in summer, in a temperature above +22⁰C, compared to the traditional wall structures, as the external heat loading Q₆ = (tj-t_e) U would not be transferred into the internal area, and a heat quantity Qi = (tj-t_e) Uj will be transferred from the internal area into the soil. In this way, the saving in summer is Q = Q_e + Qi, which need not to be removed from the internal area with a separate cooling equipment.

The following table (Table 1.) includes numeric data of the building structure with active heat insulation, for the above example. The table shows heat loss values calculated according to formulas in Figure 5. and the rate of heat quantity saving provided by the system. The saving marked with * is basically 100 %, since it is not necessary to remove this heat quantity from internal area by air condition.

It can be seen from above table that applying the building structure with active heat insulation according to the invention energy saving or even passive family houses, storied houses and also industrial buildings can be built with a simple and more effective way than with the existing technologies.

Claims

What we claim is:

1. Building structure with active heat insulation, for limiting walls and/or slabs of buildings comprising a frame structure formed by at least two steel mesh sheets (1, 2) fixed to each other with steel wires (3) welded to the steel meshes, a heat insulation layer (6 ) arranged in the centre of the frame structure, where the internal steel mesh (2) is encased in a first concrete layer (4), and the external steel mesh (1) is encased in a second concrete layer (5) characterized in that a coil-pipe (7) is fixed on the external steel mesh (1) encased in the second concrete (5) and covered by the heat insulation layer (6), said coil-pipe (7) is connected to another coil-pipe (9) arranged under the surface of the soil in a depth of 1 - 150 m; and the two coil-pipes (7, 9) form a common circuit, said circuit being provided with a pump (10) circulating the heat insulating fluid and an expansion tank (11).

2. The building structure according to claim 1 , characterized in that the temperature of fluid circulating in coil-pipe is lower than the desired internal temperature of the building.