WO2015094102A1

WO2015094102A1 - Construction comprising a building structure and a ground-based heat storage

Info

Publication number: WO2015094102A1
Application number: PCT/SE2014/051524
Authority: WO
Inventors: Frans Kodeda
Original assignee: Kodeda Group Ab
Priority date: 2013-12-20
Filing date: 2014-12-17
Publication date: 2015-06-25

Abstract

The invention relates to a construction (1 ) comprising a building structure (2, 3, 5, 6, 7) and a ground-based heat storage (4). The invention is characterized in that the building structure (2, 3, 5, 6, 7) is located essentially above the ground-based heat storage (4) in the vertical direction and that the building structure (2, 3, 5, 6, 7) has approximately the same or greater expanse than the heat storage (4) in a direction perpendicular to the vertical direction, wherein the building structure comprises at least one house body (2, 3) arranged in connection to the heat storage (4) and an enclosed space (5) located above the heat storage (4) adjacent to the house body (2, 3); wherein the enclosed space (5) has a limiting surface in the form of a wall (7) or a roof (6) being at least partially transparent to solar radiation and being arranged to allow heating of the enclosed space (5) by means of solar radiation; wherein an air heat pump system (21, 22, 23, 24, 26, 27) is arranged in connection to the enclosed space (5); wherein the air heat pump system (21, 22, 23, 24, 26, 27) is adapted to extract heat from the air in the enclosed space (5); wherein the air heat pump system is furthermore adapted to give off heat to both the heat storage (4) and to a heating system and/or domestic hot water system arranged in the house body (2, 3); and wherein the heat storage (4) is located in connection to a ground level in the enclosed space (5).

Description

Construction comprising a building structure and a ground-based heat storage

TECHNICAL FIELD

The invention relates to a construction comprising a building structure and a ground-based heat storage, wherein air heat pump technology is used for taking heat from a solar-heated, enclosed space above the heat storage, which heat is given off to the heat storage and to, for example, a domestic hot water system belonging to a building within the construction. The purpose of the invention is increased energy efficiency for buildings through improved storing of solar heat.

STATE OF THE ART

There is a desire to be able to seasonally store heat in ground-based heat storages to be used as heating in homes and other buildings during the colder part of the year. Known variants of such heat storages are rock cavities, rock ground, accumulator tanks, pits with water, and clays. As heat source use can be made of solar heat, district central heating etc., and in winter the heat can be extracted from the storage by means of, for example, a heat pump system. Typically, a heat medium is allowed to circulate through a pipe system, which is buried or in other manner disposed in the heat storage so that heat can be supplied and withdrawn.

Existing constructions for seasonal storing of heat in so-called sensible heat storages are generally unprofitable due to large heat losses or high insulation costs. In particular small heat storages are unprofitable since the capacity is related to the storage volume, while the heat losses are related to the storage surface, which, proportionally, is larger for small storages. Thus, there is a need for improvements in the field of constructions which utilize ground-based heat storages.

DESCRIPTION OF THE INVENTION

The invention relates to a construction comprising a building structure and a ground-based heat storage according to the appended claim 1 . The dependent claims set forth various embodiments, improvements, and variants of the invention.

According to the invention, the building structure is located essentially above the ground-based heat storage in the vertical direction and has approximately the same or greater expanse than the heat storage in a direction perpendicular to the vertical direction. Thus, viewing the construction from above, the heat storage is located inside, or near, the external frames of the building structure. It is an advantageous effect of such a construction that the heat leaving a heat storage in an upward direction, and which as regards conventional, detached, ground-based heat storages constitutes a heat loss, is transferred to the building structure, and hence is useful. Even the loss conventionally occurring in the horizontal direction from a heat storage in the ground partially goes up in the building construction and is useful in a construction according to the invention, i.e. the heat which is least partially transported upwards towards the ground surface after leaving the heat storage in the horizontal direction.

Overall, this considerably reduces the heat losses as compared with conventional constructions with ground-based heat storages. As regards small-sized heat storages, that advantageous effect is even stronger. Thereby constructions with (small) heat storages can be made commercially interesting. According to the invention, the building structure comprises at least one house body arranged in connection to the heat storage and an enclosed space located above the heat storage in connection to the house body.

Thus, said enclosed space constitutes no house body in the ordinary sense, but is conveniently constituted of a simpler roof and wall structure enclosing the air above the heat storage. Preferably, walls of an adjacent house body or house bodies are used as limiting surfaces to contribute to the enclosure of said space. It is an advantage of placing this space, and not a house body, above the heat storage that the heat storage with associated pipe system etc. becomes easily accessible for overhaul and repair. It is a further advantage that the heat storage is not required to sustain any (major) weight/load, which simplifies the design of the construction. The vertical heat leakage from the heat storage does not lead to a heat loss, as in conventional ground-based heat storages, but to heating of the air in the enclosed space. This spontaneous heat transfer from the heat storage is an intended effect of the construction and is favourable for direct heat transfer to adjacent house bodies, and also because it promotes the heat pump function described in more detail below.

In order to obtain a suitable transfer of heat from the heat storage to the enclosed space, the heat storage is positioned in connection to a ground level in the enclosed space. This is in contrast to many conventional ground- based heat storages, which may lie deep below ground level, perhaps 10 metres or more, sometimes precisely to avoid heat transfer to what is above ground level. However, even though a relatively shallow position is suitable in the construction according to the present invention, it is not desirable normally that the heat storage is exposed or positioned right up at the ground surface. If so, the heat transfer to the enclosed space might become too large, and the storage capacity in the heat storage become too small. Typically, the upper surface of a clay-based heat storage may be positioned from a few decimetres up to one metre below ground level with, for example, mould or gravel placed on top. The exact position of the heat storage can be adapted to the construction in point. In many cases it is expedient to lay out walkways, recreation areas, meeting places, plantation, etc. on top of the heat storage.

Also, the enclosed space has a limiting surface in the form of a wall or a roof being at least partially transparent to solar radiation and being arranged to allow heating of the enclosed space by means of solar radiation. Thereby, the air in the enclosed space will be heated, not only from the heat storage, but also by solar radiation, especially via ground and walls which absorb and then transfer the energy/heat from the solar radiation. This is true even in winter (sunny days). Such an enclosed space serves as a heated and bright courtyard. Alternatively, it may serve as an indoor plaza, or be a covered street. Furthermore, according to the invention an air heat pump system is arranged in connection to the enclosed space, wherein the air heat pump system is adapted to extract heat from the air in the enclosed space; wherein the air heat pump system is furthermore adapted to give off heat to both the heat storage and to a heating system and/or domestic hot water system arranged in the house body.

The air heat pump system may include one or more heat pumps of conventional type with evaporator, compressor, condenser, and throttle valve, wherein a cold medium circulates and takes up (extracts) heat at the evaporator and gives off heat at the condenser. By using various additional heat exchange systems, it is possible to let the heat pump give off its heat in more than one place. Thus, the air heat pump system according to the inventive construction is arranged such that heat is taken from the air in the enclosed space, which heat is subsequently given off to a heating system or domestic hot water system in a building in the building structure, or to the heat storage. Suitably, the setup is such that heat can be distributed simultaneously between the various recipients. How the extracted heat is to be distributed depends on, for example, heat requirements in buildings and the current temperature in the heat storage.

In the event heating and domestic hot water systems in buildings are not in need of additional heat, heat is preferably given off to the heat storage until it has reached the current max temperature. If the heat storage is not in need of more heat either, the air heat pump system can be shut down until heat demand arises. Alternatively, an additional unit may be connected to the air heat pump system to which heat can be given off. Such a unit could be e.g. a swimming pool, or an additional building not included in the primary building structure. For example, the construction may relate to primarily office buildings, while the extra unit might be a residential building, which usually has heating requirements at other times of the day than an office building. Such additional unit being supplied with heat, the air heat pump system can be used simultaneously for cooling the enclosed space or a house body in the primary building structure. Such operation is probably most desirable in summer.

Expediently, the construction includes awnings or other means to limit the solar radiation to the enclosed space when the heat content in the enclosed space and the heat storage is sufficient, typically a warm and sunny summer's day. Furthermore, regulatable ventilation means, such as openings and fans, are expediently installed to make possible ventilation of the enclosed space.

By the inventive combination of the enclosed and solar-heated space, the heat storage, and the air heat pump system, a very energy efficient construction is obtained with respect to the energy requirement of the building structure. The incoming energy to the construction is essentially solar energy as the heat for the water systems (heating, domestic hot water) is taken from the air in the enclosed space, which, in turn, is primarily heated by solar energy, partly directly via solar radiation into the space, and partly indirectly via the heat storage, which in turn is heated by radiated solar energy. A certain amount of incoming electrical energy is necessary to drive the air heat pump system. However, that operation can be made very electricity efficient because the energy conversion that normally gives rise to heat losses can be largely eliminated as such "losses" result in heating of the air in the enclosed space. In conventional ground-based heat storages, storing of heat takes place during summer and withdrawal of heat during winter. Such heat transfer cycle is possible, in principle, even for a construction according to the invention. However, the heat transfer to and from the storage may be allowed to have significantly faster fluctuations, and the fluctuations can be adapted to, for example current weather variations. For example, net storing of heat can take place in the heat storage during a/some sunny day(s) or week(s) in winter with warmer weather, or net withdrawal of heat can take place from heat storages during an/some overcast day(s) or week(s) in summer with cooler weather. Furthermore, the heat transfer can be adapted to the hours of the day so that net storing takes place in (parts of) the daytime, and net withdrawal in (parts of) the night. According to the above description, a more flexible and dynamic heat transfer to and from the heat storage is of particular interest for small-sized heat storages, which have less capacity.

In one embodiment of the invention, the heat storage is arranged for connection to an external heat source, such as waste heat from heat- generating processes or return heat in a district heating network, for supplementary or alternative heating of the heat storage.

In the event it has, for a prolonged period, been cold and sunlight scarce, it may be that the heat storage heat content is too small to heat the air in the enclosed space sufficiently for the air heat pump system to operate sufficiently efficiently. Then it is expedient to have the possibility to couple in an external heat source for supplemental heating of the heat storage and thus, with some delay, the air in the enclosed space.

Utilization of such an external heat source is also expedient when the price of electricity is so high that the costs of running the air heat pump system, and to thereby give off heat to the heat storage, will be higher than heating the heat storage via the external heat source. Return heat from the district heating networks is often obtainable at relatively low cost, which makes that alternative very interesting.

Furthermore, the possibility to couple in the external heat source is desirable in the event the heat pump system, or parts thereof, does not operate satisfactorily. Thus, the external heat source can act as backup system.

In one embodiment of the invention, the heat storage comprises a first duct system for connection to, and heating via, said air heat pump system. The first duct system is adapted for through flow of a heat medium and allows heating of the heat storage via direct or indirect coupling to the air heat pump system.

In one embodiment of the invention, the heat storage comprises a second duct system for connection to, and heating via, said external heat source. The second duct system is adapted for through flow of a heat medium and allows heating of the heat storage via direct or indirect coupling to the external heat source.

The first and the second duct system may well consist of one and the same duct system, which is made connectable to the air heat pump system and, via valves and fittings outside the heat storage, possibly even to the external heat source, if present.

The duct system may consist of pipes or tubes distributed in a kind of loop over the length and width, and perhaps even depth, of the heat storage at a depth of perhaps 1 -3 metres from ground level. As heat medium, use may be made of, for example, water, which during recirculation takes up heat by heat exchange with air heat pump system or external heat source and gives off heat to the heat storage.

In one embodiment of the invention, the house body is located next to the heat storage. According to the above, advantages hereof are that the heat storage is accessible and is not required to sustain any weight.

In one embodiment of the invention, the house body constitutes a limiting surface of the enclosed space. This simplifies construction work as well as reduces the heat losses to the surroundings.

In one embodiment of the invention, the building structure comprises at least two house bodies arranged in connection to the heat storage on opposite sides thereof, wherein said house bodies are joined via said wall or roof, alternatively via additional walls, house bodies and/or roofs, which house bodies, walls and roofs thereby define said enclosed space. Two or more house bodies can thus be arranged along the heat storage sides, or one house body is allowed to surround the entire or almost the entire heat storage. In this way, a larger portion of the heat is used in the enclosed space. In addition, the enclosed space can easily be arranged by attaching a roof (for example partially made of glass), and, if the house body does not surround the entire storage, one or more walls (for example partially made of glass) between the surrounding house bodies. In one embodiment of the invention, the air heat pump system is arranged such as to extract, in operation, heat from an airflow, wherein the system is arranged to allow regulating of the airflow, at least after heat has been extracted by the air heat pump system, wherein said regulating is arranged such that, in a first regulating position, the airflow is discharged into the enclosed space, whereby the air is thus allowed to recirculate in the enclosed space, and that, in a second control position, the airflow is discharged outside the enclosed space. In the event an airflow from the enclosed space is contacted with an evaporator in the heat pump, the energy content and the temperature of the airflow drop. By regulating how this cooled airflow is to be conducted, back to the enclosed space; out into the surroundings; to the house body (for cooling); or distributed among these options, it is possible to obtain further technical effects.

During winter in a cold country like Sweden, it is often a problem that the outside air becomes so cold that conventionally positioned air heat pumps sharply drop in efficiency. By allowing, as in the current construction, the air heat pump system to operate with air heated in a solar-heated space, e.g. by simply placing a conventional air heat pump fan and evaporator in the enclosed space, it is avoided in most situations to have to work with extremely cold air. By controlling the airflow such that the air in the cooled airflow is allowed to recirculate in the enclosed space only when its temperature is higher than the ambient air outside the enclosed space, it is possible to maintain to a higher degree a higher temperature inside the enclosed space. When the temperature of the airflow after contact with the heat pump's evaporator is lower than the ambient air, the airflow may be discharged to the surroundings, and the relatively warmer outside air may be allowed to enter the enclosed space instead.

If, instead, there is a need to cool the building structure, the airflow may be allowed to be discharged into the enclosed space as it has a lower temperature than the ambient air. If there is a need to cool apartments or offices in the house body, the cooled airflow may, as alternative or supplement, be passed directly to the house body.

In order to conduct ambient air into the enclosed space in the event the airflow is discharged from the enclosed space, the enclosed space may be provided with one or more openings which may be located in different places depending on the construction in point. Conveniently, such openings are relatively small, at least if they are not regulatable, so as to prevent a major uncontrolled air exchange. The openings may be part of a system for ventilation of the enclosed space.

In one embodiment of the invention, the air heat pump system comprises an air duct and an airflow regulator, in the form of e.g. a damper, arranged to accomplish said regulating.

In one embodiment of the invention, the air heat pump system comprises: a first temperature sensor adapted to sense a temperature T1 in the airflow after heat has been extracted by the air heat pump system; a second temperature sensor adapted to sense a temperature T2 in ambient air outside the enclosed space; and a control unit adapted to control said airflow regulating in dependence of the temperatures T1 and T2.

Preferably, the control unit is adapted to activate the first regulating position (recirculation in enclosed space) where T1 > T2 and by activating the second regulating position (the airflow is discharged outside the enclosed space) where T2 > T1 . According to the above, it is possible in this way to keep the temperature as high as possible to increase the efficiency of the heat pump in winter. Expediently, the control unit is also adapted to control regulators which distribute the airflow between surroundings and ventilation system in the house body in the event the airflow is discharged from the enclosed space.

The air heat pump system may include additional temperature sensors coupled to the control unit, for example with regard to the temperature at various sites in the enclosed space and in the house body, and the temperature in the heat storage and at various sites where cold medium or heat medium flows. The control unit can be configured to control, in various ways, airflow, heat pump effect, etc. In one embodiment of the invention, the air heat pump system comprises pipes for transferring heat from the air heat pump system to the heat storage. Such pipes may be coupled together with the duct system or duct systems, which according to the above is/are disposed in the heat storage. Conveniently, the heat is transferred by circulating water or other heat carrying medium through the pipes and on to the duct system where heat is transferred to the heat storage.

In one embodiment of the invention, the enclosed space is provided with one or more openings allowing at least a small amount of air to pass in and out between the enclosed space and the surroundings.

In one embodiment of the invention, a biofilter is disposed in the enclosed space, preferably on top of the heat storage, which biofilter comprises plants with the ability to clean the air in the enclosed space. Thereby, air from the building structure can be recirculated via the enclosed space. To recirculate the air from the surrounding building structure by means of biofilters is especially favourable in winter because the need to heat cold outside air is avoided. In one embodiment of the invention, the ground-based heat storage comprises a heat-storing medium with high specific heat capacity in the form of water, clay, soil, and/or rock. Combinations of these materials are also possible. Clay is a particularly suitable material as clay contains much water, which has a very high specific heat capacity, and holds the water in place. If the ground under the enclosed space consists of clay, such clay can largely be left and constitute the heat storage. DESCRIPTION OF FIGURES

The invention will now be described in more detail with reference to the following figures, in which: Figure 1 shows a perspective view, from the southeast, of an embodiment of a construction according to the invention;

Figure 2 shows a view, from the south, of the embodiment according to

Figure 1 ; and

Figure 3 shows a view, from the southwest, of the embodiment according to

Figure 1 .

PREFERRED EMBODIMENTS

Figures 1 -3 show an example of a construction 1 comprising a building structure 2, 3, 5, 6, 7 and a ground-based heat storage 4 (dashed line). Figure 1 shows the construction 1 viewed in perspective from the southeast;

Figure 2 shows the construction 1 viewed from the south; and Figure 3 shows the construction viewed from the southwest.

The building structure includes, in turn, a first and a second house body 2, 3 disposed in connection to, and on opposite sides of (west and east of) the ground-based heat storage 4. A simpler building portion 10, including stairs etc., connects the house bodies 2, 3 at their north side. The house bodies 2, 3, and the building portion 10 are all equally high (three levels) and form a U- shaped formation. Additional apartments 15 are arranged on top of the house bodies 2 and 3. An enclosed space 5 is arranged between the house bodies

2, 3. The heat storage 4 is arranged in connection to a ground level in the enclosed space 5, more specifically, the heat storage 4 is arranged such that its upper surface is about half a metre below ground level. Mould covers the heat storage 4. In this example, the dimensions of the heat storage 4 are about 2^*20^*25 metres.

Extending between the house bodies 2, 3, are a roof 6 and a wall structure 7, which together with the simpler building portion 10 define the enclosed space 5, which in this case forms a courtyard located between the house bodies 2, 3, and the building portion 10 above the heat storage 4. The roof 6, which in this example is made partly of glass, and the wall structure 7, which in this example is made entirely of glass, allow solar radiation to pass and be given the possibility to provide light and warmth to the space 5. The enclosed space 5, which together with the roof 6 and the wall structure 7, constitutes a part of the building structure, is thus positioned on top of the heat storage 4, which entails that the heat storage 4 is easily accessible and is not encumbered by the weight of a house body.

The wall structure 7 covers the entire south facade of the building structure, which gives a highly effective inflow of solar radiation (e.g. in Sweden) to the enclosed space 5 located inside the wall structure 7.

The construction 1 further comprises a first and a second air heat pump system, illustrated by a first and a second heat pump part 21 , 22, arranged at their respective house body 2, 3 inside the enclosed space 5. Each of the air heat pump systems is adapted to extract heat from the air in the enclosed space 5, via an evaporator in the respective heat pump part 21 , 22, and to give off heat both to the heat storage 4 and to heating system (not shown) and domestic hot water system (not shown) arranged in the house bodies 2, 3. The systems are designed to be able to distribute the heat among these recipients, as needed.

The heat from the air heat pump systems is given off in respective condensers placed inside respective house bodies 2, 3. Heat exchange systems are coupled to these condensers for further heat transfer to, inter alia, the heat storage 4.

Each of the air heat pump systems is arranged such as to extract, in operation, heat from an airflow and to allow regulating of the airflow after heat has been extracted by the air heat pump system. Said regulating is arranged in such manner that, in a first regulating position, the airflow is discharged into the enclosed space 5, whereby the air is thus allowed to recirculate in the enclosed space 5, and that, in a second regulating position, the airflow is discharged outside the enclosed space 5, where outside air from the surroundings is allowed to flow into the enclosed space 5 via an opening (not shown). For this purpose, each of the heat pump parts 21 , 22 is provided with an air duct 26, 27 and an airflow regulator (not shown), in the form of, for example, a damper, arranged to accomplish said regulating. Change or adjustment of regulating position is done by changing the angle or position of the airflow regulator in the air duct 26, 27 so that the airflow is conducted in the intended direction.

Each of the air heat pump systems further comprises a first temperature sensor adapted to sense a temperature T1 in the airflow after heat has been extracted by the air heat pump system; a second temperature sensor adapted to sense a temperature T2 in ambient air outside the enclosed space 5; and a control unit adapted to control said airflow regulating in dependence of the temperatures T1 and T2, preferably by activating the first regulating position where T1 > T2 and by activating the second regulating position where T2 > T1 .

To activate the second activating position where T2 > T1 , i.e. to discharge the cooled airflow outside the enclosed space 5 when the temperature of the airflow (after contact with the heat pump) is lower than the temperature of the ambient air, is particularly useful in winter time when it is of great importance to keep as high temperature as possible of the air in the enclosed space 5 in order not to lose heat pump efficiency. Then the airflow is discharged to the surroundings outside the enclosed space 5. Alternatively, the cooled airflow can be passed directly to the respective house body 2, 3 (by similar use of dampers and via not shown air ducts) to be used when there is a need for cooling in the house bodies 2 and 3.

After some time, heat stored in the heat storage 4 returns to the building structure, mostly to the air in the enclosed space 5 via vertical heat transport through the ground storage above the heat storage 4 and to a lesser extent to the house bodies 2, 3 via horizontal and vertical heat transport.

Pipes 23, 24 indicate in a simplified manner that heat can be transported via a heat carrying medium, for example water, from the heat pump parts 21 , 22 (actually from heat exchangers in contact with respective condensers) to the heat storage 4.

In this example, the heat storage 4 comprises two setups of a first duct system (not shown) for connection to each of said pipes 23, 24 to allow transfer of heat to the heat storage 4 from each of the air heat pump systems.

Furthermore, the heat storage 4 is arranged for connection to an external heat source (not shown), such as waste heat from heat-generating processes or return heat in a district heating network, for supplementary or alternative heating of the heat storage 4. Pipes 25 indicate that heat can be transported via a heat medium from said external heat source to the heat storage 4. For this purpose, the heat storage 4 includes a second duct system (not shown) arranged to be connected to pipes 25.

The duct systems in the heat storage 4 can be designed in various ways. For example, one and the same duct system can be used for alternative coupling to either heat pump system or external heat source.

In this case, the ground-based heat storage 4 consists of a clay, and despite its small size, as compared with e.g. a rock storage, the heat storage 4, together with the enclosed space 5 and the heat pump systems, gives the construction 1 high energy efficiency, i.a. because the heat losses from the heat storage 4 can be taken over by the building structure 2, 3, 5, 6, 7 in the construction 1 .

The invention is not limited to the above described embodiment but can be varied within what is defined by the appended claims.

For example, the solution with the heat storage 4 under under the enclosed space 5 creates preconditions of disposing a biofilter in the enclosed space 5. Such a filter consists of plants which effectively clean the air and hence regenerate the air ventilated out from the surrounding buildings. Such plants have been tested in, for example, NASA's space research program. The plants are disposed in the enclosed space 5, which thereby serves several functions: biofilter, solar collector, protection for heat storage 4, and conservatory. To clean recirculated air from surrounding buildings by means of biofilters is especially favourable in the winter time because the need to heat cold outside air is avoided.

The construction 1 also comprises a system for ventilation (not shown) of the enclosed space 5. Such a system may comprise fans and a number of openings in the enclosed space 5 allowing air to flow in or out. In the summer time, ventilation may be desirable in order to cool the enclosed space 5.

The construction may comprise additional heating systems. The construction may additionally be equipped with, for example, a second heat pump system adapted to extract heat from the heat storage 4 and to give off heat to the heating system and/or domestic hot water system of the house. However, normally it suffices to use only heat pump system, of which, in this case, there are two.

The heat pump parts 21 , 22 may be positioned further into the enclosed space 5 to be allowed to operate with somewhat warmer air during very cold winter nights where the air near the wall 7 is at risk of getting strongly cooled.

Claims

1. A construction (1) comprising a building structure (2, 3, 5, 6, 7) and a ground-based heat storage (4);

characterized in

that the building structure (2, 3, 5, 6, 7) is located essentially above the ground-based heat storage (4) in the vertical direction and that the building structure (2, 3, 5, 6, 7) has approximately the same or greater expanse than the heat storage (4) in a direction perpendicular to the vertical direction;

wherein the building structure comprises at least one house body (2, 3) arranged in connection to the heat storage (4) and an enclosed space (5) located above the heat storage (4) adjacent to the house body (2, 3);

wherein the enclosed space (5) has a limiting surface in the form of a wall (7) or a roof (6) being at least partially transparent to solar radiation and being arranged to allow heating of the enclosed space (5) by means of solar radiation;

wherein an air heat pump system (21, 22, 23, 24, 26, 27) is arranged in connection to the enclosed space (5), wherein the air heat pump system (21, 22, 23, 24, 26, 27) is arranged to extract heat from the air in the enclosed space (5), wherein the air heat pump system is furthermore arranged to give off heat to both the heat storage (4) and to a heating system and/or domestic hot water system arranged in the house body (2, 3);

and wherein the heat storage (4) is located in connection to a ground level in the enclosed space (5).

2. A construction (1 ) according to claim 1 ,

characterized in

that the heat storage (4) is arranged for connection to an external heat source (25), such as waste heat from heat-generating processes or return heat in a district heating network, for supplementary or alternative heating of the heat storage (4).

3. A construction (1) according to claim 1 or 2,

characterized in

that the heat storage (4) comprises a first duct system for connection to, and heating via, said air heat pump system (21 , 22, 23, 24, 26, 27).

4. A construction (1) according to claim 2,

characterized in

that the heat storage (4) comprises a second duct system for connection to, and heating via, said external heat source.

5. A construction (1 ) according to any of the above claims,

characterized in

that the house body (2, 3) is located next to the heat storage (4).

6. A construction (1 ) according to any of the above claims,

characterized in

that the house body (2, 3) constitutes a limiting surface of the enclosed space (5).

7. A construction (1 ) according to any of the above claims,

characterized in

that the building structure comprises at least two house bodies (2, 3) arranged in connection to the heat storage (4) on opposite sides thereof, wherein said house bodies are joined via said wall (7) or roof (6), alternatively via additional walls, house bodies and roofs, which house bodies, walls and roof thereby define said enclosed space (5).

8. A construction (1 ) according to any of the above claims,

characterized in

that the air heat pump system (21, 22, 23, 24, 26, 27) is arranged such as to extract, in operation, heat from an airflow, wherein the system is arranged to allow regulating of the airflow, at least after heat has been extracted by the air heat pump system, wherein the regulating is arranged such that, in a first regulating position, the airflow is discharged into the enclosed space (5), the air thus being allowed to recirculate in the enclosed space (5), and that, in a second regulating position, the airflow is discharged outside the enclosed space (5).

9. A construction (1) according to claim 8,

characterized in that the air heat pump system (21, 22, 23, 24, 26, 27) comprises an air duct (26, 27) and an airflow regulator, in the form of e.g. a damper, arranged to accomplish said regulating.

10. A construction (1 ) according to claim 8 or 9,

characterized in

that the air heat pump system (21 , 22, 23, 24, 26, 27) comprises

- a first temperature sensor adapted to sense a temperature T1 in the airflow after heat has been extracted by the air heat pump system;

- a second temperature sensor adapted to sense a temperature T2 in ambient air outside the enclosed space (5); and

- a control unit adapted to control said airflow regulating in dependence of the temperatures T1 and T2.

11. A construction (1 ) according to any of the above claims,

characterized in

that the air heat pump system (21, 22, 23, 24, 26, 27) comprises pipes (23, 24) for transferring heat from the air heat pump system to the heat storage (4).

12. A construction (1 ) according to any of the above claims,

characterized in

that the enclosed space (5) is provided with one or more openings which allow(s) at least a small amount of air to pass in and out between the enclosed space (5) and the surroundings.

13. A construction (1 ) according to any of the above claims,

characterized in

that a biofilter is disposed in the enclosed space (5), preferably on top of the heat storage (4), which biofilter comprises plants with the ability to clean the air in the enclosed space (5).

14. A construction (1 ) according to any of the above claims,

characterized in

that the ground-based heat storage (4) comprises a heat-storing medium in the form of water, clay, soil, and/or rock.