Outdoor heat pump unit and housing therefor

Abstract

The invention relates to a housing for an outdoor heat pump unit using a flammable refrigerant, wherein the housing is a volumetric body defined by a plurality of panels, and wherein at least one panel of the plurality of panels is at least in part made of expanded polypropylene that has a density of at least 55 kg / m3.

Description

Field of the Invention

[0001] The invention relates to a housing for an outdoor heat pump unit using a flammable refrigerant and to a system comprising the housing and a heat pump unit arranged inside the housing.Background

[0002] In view of environmental issues and a collective desire to reduce greenhouse gas emissions and fossil fuel consumption, heat pumps are one of the most appropriate solutions for ensuring thermal comfort in residential homes. This technology heats and / or cools a fluid by exchanging calories with another fluid commonly referred to as a refrigerant or as a heat transfer fluid. Among the most widely used systems are air / water heat pumps, which exchange calories, for cooling or heating, between the air in the environment and the water in the heating circuit, for heating / cooling the home and / or heating domestic hot water. Alternatively, air-to-air heat pump systems exchange calories between the outside air and the air in the building.

[0003] Changes in environmental regulations are forcing changes in the use of refrigerant classes in heat pumps, necessitating use of refrigerants with a low global warming potential (GWP). Even better is the use of a GWP no greater than 150 (GWP<150, the reference 1 being the global warming potential of CO2), compared with 2100 for previously used refrigerants such as R410a, 1430 for R134a and 675 for R32.

[0004] Manufacturers are therefore finding ways to switch to fluids that meet these GWP conditions such as R454c or R454, and in particular natural fluids such as propane R290 with a GWP of 3 or butane R600 with a GWP of 4 have become the preferred refrigerants of choice.

[0005] However, these fluids are flammable, and it is therefore necessary to put in place measures to guarantee the safety of users, e.g. to prevent ignition and / or explosion of the refrigerant when sources of ignition (electrical elements, hot spots etc.) are present nearby, and / or designs, wherein the risks are limited to an acceptable level.

[0006] To operate, these solutions require a flow of outside air through a refrigerant / air heat exchanger. This flow must be driven by a fan to ensure that a sufficient flow of outside air, and therefore calories, is transferred to the heat exchanger. As a result, this type of system requires the use of a fan and access to outside air. Given the noise generated by the fan and compressor, and the considerable dimensions of the product, particularly the air duct, it is much preferable to install the system in question directly outdoors. The outside air is therefore directly present, without the need for a duct. This reduces fan power and noise. Moreover, the noise generated by the system is less disturbing for users when it is installed outdoors rather than indoors because it is further away from living areas and is also more dissipated into the environment.

[0007] However, as a result, such heat pump units are confronted with the constraints of the external environment, in particular: i) a risk of multiple impacts like rain, hail, various mechanical shocks and stresses (balloons, bikes placed on them, people leaning on them, weight of accumulating snow, etc.) for example; ii) a wide temperature range, generally from -10°C to 50°C; iii) moisture or even water that can freeze; iv) the presence of rodents and other animals that may attack the structure of the unit; v) solar radiation, especially UV, which can damage or alter materials; and vi) the presence of multiple, uncontrolled people, who can damage the structure, open it or gain access to it, which may represent risks to themselves (electrical or contact with moving parts such as fans, a pipe with (flammable) fluid under pressure, etc.) or to the integrity of the product.

[0008] At the time, it was thus customary for heat pump units to be structured and / or covered with steel panels. This material has the advantage of being very robust and well suited to these constraints.

[0009] Then, the use of thermosetting polymer was introduced, through the use of injected plastic panels. Heat pump units were then generally made up of a steel structure and covered with plastic panels.

[0010] Based thereon, an architecture came up, which consists of a structure made of foamed plastic, in particular expanded polypropylene (EPP), which supports a set of internal components. This structure is covered by a set of steel and / or plastic panels. These cover panels are necessary to protect the plastic foam structure, to ensure the integrity of the assembly, to prevent the entry of external elements (like leaves, animals, humidity, etc.) and to prevent access to active and dangerous parts. However, the plastic foam is not configured to withstand an external environment, nor is it able to ensure non-penetration inside the heat pump unit. Moreover, the longevity of the foamed plastic does not ensure its integrity over the product's lifetime, i.e. at least 10 years on average, preferably 15 years. Thus, steel and / or plastic panels to cover the plastic foam structure was there needed.

[0011] In view of the above, it is known to build outdoor heat pump units using an internal steel structure covered with panels of plastic or steel. Less frequently, panels are used to create a self-supporting steel structure. Even rarer is the use of a plastic foam structure to which steel or plastic panels are attached. At the same time, the use of plastic foam parts is known for the use of technical parts positioned inside products, i.e. protected by an outer casing of another material. Very rarely, foamed plastic is used as part of the exterior wall of certain heating products such as water heaters, which was made possible however by the fact that the foamed plastic is in a controlled, indoor environment.

[0012] Hence, whatever solutions are nowadays used, they are usually relatively expensive, require the use of numerous parts and generate substantial pollution or are limited to indoor usage. Moreover, the multiplication of parts means that assembly time and difficulty are significant, thus increasing the cost of the product, its maintenance and therefore reducing the democratization of heat pump systems. Further, the multiplication of parts also leads to a multiplication of part numbers, and therefore of storage areas, parts management, spare parts referencing, transport flows, etc. All of which tends to increase the cost of the product. All of which tends to reduce the non-democratization of heat pumps units, despite their environmental virtues.

[0013] Hence, there is room and need for improvement regarding the development and usage of outdoor heat pump units, in particular of heat pump units using a flammable refrigerant.Summary

[0014] In view of the above, it is an object of the present disclosure to overcome at least part of the drawbacks available regarding the development and usage of outdoor heat pump units, in particular of heat pump units using a flammable refrigerant.

[0015] The term flammable is used with reference to the ASHRAE standards for refrigerants and EN 378-2:2016, defining the following classes: 1, 2L, 2, or 3, ranging from no flame propagation to high flame propagation and high heat of combustion.

[0016] The term flammable is used to refer to refrigerants that are highly flammable, class 3, such as R290 (propane), R600 (butane) and R600a (isobutane). Class 3 refrigerants, when tested, exhibit flame propagation at 140°F (60°C) and 14.7 psi (101.3 kPa) and that either has a heat of combustion of 19,000 kJ / kg (8,174 BTU / lb) or greater or an LFL of 0.10 kg / m3 or lower.

[0017] The term flammable may also be used here to refer to refrigerants from class 2 (less flammable), such as R-152a or class 2L (mildly flammable) such as R-32, R-1234yf, R-1234ze.

[0018] Therefore, to address one or more of these drawbacks, there is provided, in a first aspect, a housing for an outdoor heat pump unit using a flammable refrigerant, wherein the housing comprises a plurality of panels, and wherein at least one panel of the plurality of panels is made of expanded polypropylene (EPP) that has a density of at least 55 kg / m 3<

[0019] Density is the mass per unit volume of EPP material. The formula for density is d = M / V, where d is the density, M is the mass (in kg) and V is the volume (in m 3< ). Therefore, to determine the density, a sample of EPP measuring, for example, 10cm x 10cm x 2cm can be cut and its weight measured. Knowing the weight and volume of the EPP, its density can be determined. Similarly, the standard ISO 845:2006, which specifies a method for determining the apparent overall density and the apparent core density of cellular plastics and rubbers, can be used as well. In this standard, each specimen shall be of such a shape such that its volume can be easily calculated. The total volume of a specimen shall be at least 100cm 3< . A minimum of 5 specimen shall be tested. The specimen may be a manufactured object whose mass and volume can be measured accurately. Its total mass and total volume may be used to determine the specimen density. The procedure consists of measuring the dimensions, in millimeters, of the specimen in accordance with ISO 1923. Then make a minimum of three separate measurements of each dimension. And calculate the mean values for each dimension and from these measurements calculate the volume of the specimen. Finally weigh each specimen to an accuracy of 0.5% and record its mass in grams.

[0020] The term "outdoor" in "outdoor heat pump unit" indicates where the heat pump unit may be (intended to be) installed but does not limit the heat pump unit as such. For example, in case a heat pump unit is (intended to be) installed outside (i.e. exposed to an outside environment), i.e. in a housing for the heat pump unit that is provided outside, the heat pump unit may be understood as representing an outdoor heat pump unit. Hence, the term "outside" rather refers to a feature of the housing, namely that the housing is suitable to be exposed to an outside environment and to endure or resist the environmental conditions. However, this does not mean that the housing necessarily has to be exposed to an outside environment. Rather, in case the same heat pump unit is (intended to be) installed inside a building (basement, garden sheds for example), i.e. not exposed directly to an outside environment, i.e. in a housing for the heat pump unit that is provided inside a building (basement, garden sheds for example), throughout the present specification the heat pump unit may still be named "outdoor heat pump unit" even if installed inside a building

[0021] Further, it shall be noted that the housing may be understood as a volumetric body that is determined, in particular the geometric shape of which is determined by at least some of the plurality of panels. The volumetric body may be understood as comprising a hollow space inside the volumetric body, i.e. a hollow space determined by the at least some of the plurality of panels. Further, the housing may in general be of any geometric shape that allows to house the outdoor heat pump unit, and that the housing may be installed outdoor. The outdoor heat pump unit is a heat pump unit that may be installed outdoor, and the flammable refrigerant may be propane (R290) for example. By at least one panel it is meant that also two or more panels, for example all panels, of the housing are made of EPP. By the expression "made of EPP" it is meant that at least a structural element or a structural arrangement of a panel is made of EPP, preferably the panel is fully made of EPP. When all panels of the housing are made of EPP it may thus also be covered the case that the housing is fully made of EPP. Each panel may be understood to have an outer surface and an inner surface. The inner surface faces towards an inside of the housing and the outer surface faces towards a surrounding outside the housing, i.e. towards an outside of the housing. An inner surface of a panel may comprise one or more predetermined shapes and / or elements arranged to or being part of the panel, like ribs, grooves, countershapes or protrusions for example. Such one or more predetermined shapes and / or elements may be understood as representing structural elements or structural arrangements. Additionally or alternatively, also an outer surface of a panel may comprise such one or more predetermined shapes and / or elements arranged to or being part of the panel, like ribs, grooves, countershapes or protrusions for example.

[0022] It should be noted that the panels of the housing may be exposed to the exterior environment.

[0023] Referring back to the flammable refrigerant in more detail, it shall be noted that natural heat transfer fluids have the disadvantage of being flammable and therefore require additional precautions. In particular, leakage has to be prevented as much as possible to prevent ignition and explosion of the refrigerant. Leakage can easily result in an explosion, as sources of ignition (electrical elements, hot spots etc.) may be present nearby, inside the product or at the installation site.

[0024] One reason for leakage to occur is upon production, installation or maintenance of the refrigerant piping used in the heat pump unit (in the heat pump unit's heat exchanging circuit in more detail). During maintenance, the refrigerant circuit may need to be opened when one of the heat pump components need replacement or repair. This involves emptying all the heat transfer fluid, carrying out modifications (possibly involving brazing and the presence of fire), and refilling the heat transfer fluid after ensuring that the system is leakproof. Any misalignment or improper connection at any joint can cause a leakage. Any installation or maintenance is therefore done by a certified professional, which in practice is not always the case. Heat pump installation or maintenance on-site, especially when installed in domestic housing, isn't always installed or maintained by a certified professional.

[0025] To address one or more of these issues, in general, by providing an unopenable enclosure, heat pump components in which heat transfer fluid may be present, are guarded off. The term unopenable should be understood in the sense of a limited access from the outside environment of the heat pump unit to the internal components such as the refrigerant circuit. This significantly reduces the risk of safety issues as such heat transfer fluid carrying heat pump components (or also written as heat-transfer-fluid-carrying-heat-pump-components) are not easily accessible to users without opening the enclosure. The enclosure cannot be easily dismantled and it is thus ensured that no damage may be done to the heat pump components and refrigerant piping and there is no risk of any connections being misaligned or not closed properly after opening. This ensures that the risk of explosion is minimized, either due to an existing refrigerant leak or due to handling of the system. Specifically, the enclosure cannot be opened at the installation site of the heat pump without tools. Having a non-openable enclosure requires the user in order to remove it to have the necessary equipment to carry out the opening and maintenance. This ensures that the enclosure is not opened at the installation site, which is not a controlled environment. Thus, all components and connections inside the enclosure and people working on the product during maintenance or installation are protected.

[0026] It shall be noted that the housing as outlined above according to the first aspect may be designed to be such "unopenable enclosure without tools", for example by screwing one or more of the panels together. Additional and / or alternative fixing means may also be used to fix one or more of the panels together to obtain such "unopenable enclosure without tools".

[0027] The density may be determined in different ways. For example, a part, panel, portion or module that is made of the EPP may be measured to determine the volume of the part, panel, portion or module. Then, the weight of the part, panel, portion or module is determined. From the determined volume and the determined weight, the density can be determined or calculated. In more detail, the density of EPP (EPP foam) refers to the mass of the material per unit volume. In simpler terms, it indicates the amount of mass contained in a given volume of EPP. Density is usually measured in kilograms per cubic meter (kg / m 3< ). The density of a part, panel, portion or module made of EPP can thus be checked by measuring the weight of the part, panel, portion or module. Knowing the volume of the part, panel, portion or module, the density can be determined and verified.

[0028] The housing according to the first aspect is advantageous in that it may participate in enabling to reduce a number of parts and to thus achieve lower assembly, logistics, transport and parts management costs. In detail, parts may be spared, supplier contracts may be reduced, etc. Further, recycling is facilitated. It is further enabled a reduction in the cost of parts and therefore the cost of the product, and the resulting democratization of heat pump technology, based on a massive cost reduction potential. It is further achieved reduced part tooling costs, like reduced molds, and a slight flexibility of the EPP part, which offers a little tolerance during assembly for example. Moreover, there is the further advantage to achieve a lighter overall unit or housing, which allows for reduced transport costs and a reduced associated ecological footprint, and which further allows for ergonomics for the various users handling the housing for example, like an assembly operator, logistics, an end customer, an installer, a carrier, etc. Moreover, there is enabled the possibility of integrating recycled material, like recycled EPP, which even further reduces the ecological footprint. There is a reduced risk of injury from sharp edges during handling, there is reduced or no metallic ringing when rigid parts, like steel or plastic for example, come into contact with each other, as the heat pump unit's compressor's vibrations may cause the housing or the housing's structure to vibrate.

[0029] Furthermore, due to the relatively low thermal conductivity of EPP ( 0.28 W m ⋅ K ), for example in comparison to the thermal conductivity of a metal sheet ( 46 W m ⋅ K for steel), the temperature is kept within the housing's environment, thanks in particular to the thermal insulation capacity of the EPP. On the other hand, such thermal conductivity of EPP further avoids (at least reduces the risk of) an overheating inside the housing from the housing's outdoor environmental condition. For example, solar radiation that falls on the EPP does not heat the inside of the housing as much as if the solar radiation was falling on a metal sheet. Therefore, EPP also allows to reduce safety hazards in case of a flammable refrigerant. This may keep the heat pump unit's compressor warm during operation. Additionally, there is enabled a greater flexibility in terms of geometry and aesthetics, since the use of EPP parts may make it possible to create curves, also complex curves with sheet-metal parts, as well as large steps without draft, which is impossible with sheet-metal or injected plastic parts. The use of EPP also makes it possible to achieve different surface finishes, like more or less smooth, rough, matt, glossy, etc. on a same surface, which would be complex and / or costly with sheet metal parts for example.

[0030] According to several examples of the present disclosure the housing may be fully made of the EPP. Additionally and / or alternatively, according to several examples of the present disclosure, for a first panel and a second panel of the plurality of panels, the first panel and the second panel may be different panels, the first panel may be made of the EPP having a first density and the second panel may be made of the EPP having a second density different from the first density, wherein the first panel and the second panel fulfil different structural requirements of the housing.

[0031] It should be noted that the panels may comprise on its inner and / or outer surfaces one or more structural components or structural arrangements and / or that the panels may comprise varying thicknesses to ensure a robustness and resilience of the housing for example. For example, a higher density may be required for portions of the housing that are intended to carry or withstand a predetermined minimum load. For example, a portion, at which one or more components may be fastened by use of fastening means, for example by screwing the one or more components into the portion. A lower density may be used for portions that are not intended to carry the predetermined minimum load, for example for a portion that functions as a cover element.

[0032] Hence, the housing may be made even more lighter, even more environmental friendlier and even more flexible and safer, in particular even safer regarding the usage of flammable refrigerants.

[0033] According to several examples of the present disclosure, the EPP may have a thickness in a range between 6mm and 25mm, preferably in a range between 6mm and 20mm. Accordingly, from the plurality of panels, a panel made of the EPP may have a thickness in a range between 6mm and 25mm, preferably in a range between 6mm and 20mm. Referring to the minimum thickness in more detail, for economic reason it is preferable to have the minimum of thickness. However, such minimum is defined by several aspects. For example, by the mechanical strength of the EPP part, by the filling of the mold during the fabrication of the EPP part, and by "safety" reason, as it is required to respect the Low Voltage Direction standards (EN 60335-1 & EN 60335-2-40). There are several tests in these standards (i.e. glow wire test, chock tests, sharp tools tests, etc.) which make necessary to have a certain minimum of thickness in order to pass all these standard tests. Moreover, also the density, for example the density of the EPP part in combination with the thickness of the EPP part, has an effect on all these several aspects and a balance needs to be found between the density and / or the thickness of an EPP part and eventually other treatment on such EPP part. Further, in case the panel made of the EPP may have, toward an inside of the housing for example, one or more structural elements or structural arrangements, i.e. said in other words, in case an inner surface of the panel made of the EPP may comprises one or more structural elements or structural arrangements, these one or more structural elements or structural arrangements may also be made of the EPP. Then, these one or more structural elements or structural arrangements made of the EPP may also have a thickness in the range between 6mm and 25mm, preferably in the range between 6mm and 20mm. In general, a thickness of the EPP may not be uniform or constant but may vary in the desired range. For example, in case at least part of two or more panels of the housing are made of the EPP and are connected by structural elements and / or structural arrangements made of the EPP, these connected at least part of the two or more panels may be understood as representing one portion made of the EPP. By structural elements it may be meant elements for connecting at least part of two or more panels, so that a connection between the at least part of the two or more panels may be strengthened and a predetermined geometric body may achieved. A rib may be an example for a structural element. By structural arrangement, it may be meant elements for carrying or supporting components of an outdoor heat pump unit. However, such distinction is for reasons of understandability only and there may not be a strict distinction between structural element and structural arrangement when outlined in relation to the housing, i.e. and a structural element may also function and be understood as a structural arrangement, and a structural arrangement may also function and be understood as a structural element. Such portion (including the panel(s), panel sections and / or its structural elements and / or structural arrangements for example) may also have a thickness, i.e. a thickness of the EPP that forms the portion, in the range between 6mm and 25mm, preferably in the range between 6mm and 20mm. However, for reasons of understandability, it shall be noted that a dimension (length, width, height) of the portion may be in a range of several centimeters or meters.

[0034] Hence, a total amount of used EPP may be reduced and efficiency may thus be increased, while the thermal insulating capabilities of the EPP due to the EEP's thermal conductivity (as outlined above) for example may still be maintained, which is advantageous in particular when flammable refrigerants are used.

[0035] According to several examples of the present disclosure, the EPP may have a density of at least 60 kg / m 3< . A density of at least 60 kg / m 3< in comparison to the density of at least 55 kg / m 3< may allow for an increased stability and resilience of the EPP part, but at the same time may make it more time consuming and / or more energy consuming to process such EPP parts with increased density. However, the density of at least 60 kg / m 3< is still low enough to be easily operable and to allow for avoiding an unnecessary higher amount of EPP.

[0036] According to several examples of the present disclosure, wherein a third panel of the plurality of panels comprises a first portion, wherein the first portion may be made of the EPP and an outer surface of the first portion, preferably the outer surface of the third panel or the housing, may have: a water non-permeability over at least one month at 3kPa, and / or an inherent permeability lower than 4.5E-18 m 2< , and / or a superficial melting level (or "surface fusion") of the EPP of more than 99%, preferably 100%. Indeed thanks to the use of a very specific graining system enabling the steam (i.e. the steam for melting or fusing a surface of the EPP part to which the steam is applied) to be correctly distributed over the entire surface of the EPP part, it is possible to achieve a superficial melting level of 100% over the surface of the EPP part.

[0037] It should be noted that the first portion may have any shape and may represent a part of the housing or may even be understood to represent the entire housing. The first portion may be at least part of one or more panels. For example, the first portion may form an upper section of a panel, an entire panel, two panels, two panels and a lower section of a third panel, etc. The outer surface of the first portion may be at least part of the outer surface of one or more panels.

[0038] The water non-permeability was determined as follows. An outer flat portion / surface made of the EPP (i.e. an EPP portion that may represent at least part of the first portion as outlined above) was glued and sealed below a PVC tube having a diameter of 100mm. The tube was then filled with 30cm of water, which corresponds to a pressure of 3kPa, i.e. a pressure of 3kPa was applied to the surface of the outer flat portion / surface made of the EPP. The water level in the PVC tube was recorded over time. A thickness of the EEP portion (having the flat / surface made of the EPP) was 10mm. The water level of 30cm did not decrease over a period of one month. Hence, it was determined that the flat portion / surface made of the EPP was non-permeable for water over at least one month at 3kPa.

[0039] In more detail, the inherent permeability k [in m 2< ] is defined as follows: k = μ ⋅ K ρ ⋅ g wherein µ represents a dynamic viscosity [in Pa · s], K represents the permeability coefficient in m s , ρ represents a fluid density in kg m 3 , and g represents gravity acceleration in m s 2 .

[0040] For the above-outlined determination regarding the thickness of the flat EPP portion being 10mm and the water applying the pressure of 3kPa to the flat EPP portion, a value of k = 8E-22 m 2< is obtained for the flat EPP portion.

[0041] For a housing for an outdoor heat pump unit using a flammable refrigerant, the value of the inherent permeability k of the EPP should be lower than 4.5E-18 m 2< .

[0042] By the melting level it may be understood that, during manufacturing of an EPP part, EPP beads are welded to each other during the EPP injection and fusion process, leaving gaps of less than 10% and preferably of less than 5% of the total surface area of the EPP part, or less than 1% and preferably 0% of the total surface area of the outer surface of the EPP part. The melting level can, for example,. be measured by a traction test (ISO 1798 or ISO 1926 for example), which is more relevant for the mechanical resistance point of view but may also be applied to measure a level of impermeability.

[0043] In more detail, two methods can be used for controlling or measuring the melting level (or melting rate). First, a tensile test to ISO standard (ISO 1798 or 1926) may be performed. In doing so, specimens need to be cut from the EPP part and need to be tested on a calibrated machine. Second, a fracture test may be performed. In doing so, there is no need to cut from an EPP part an EPP sample. There is no need to have a calibrated machine either. The fracture test is used by some OEMs (in the automotive field) for low densities (30g / l). A lower limit value for the melting level (or melting level rate) may need to be defined according to an EPP part's function and / or density for example. However, the value of 1% of gaps of the total outer surface area of an EPP part (the outer surface area may be understood to represent the surface of an EPP part that is exposed to the environment) was determined to still represent an acceptable compromise between resources (like energy or time) needed to achieve at least such melting level and characteristics the EPP part may then have (like its inherent permeability for example).It is preferred that there are no gap to achieve the level of water-permeability desired.

[0044] Hence, robustness and resilience of the housing is even further increased.

[0045] According to several examples of the present disclosure, an inner surface of at least a fourth panel of the plurality of panels may comprise a structural arrangement, wherein the at least fourth panel and the structural arrangement may represent at least part of a second portion made of the EPP. The second portion may be configured to support, via, i.e.by use of the structural arrangement, a component, preferably a fan of the outdoor heat pump unit. The structural arrangement, i.e. the second portion, may comprises a counter-shape to at least part of a shape of the component.

[0046] The second portion may be at least part of one or more panels. For example, the second portion may form an upper section of a panel, an entire panel, two panels, two panels and a lower section of a third panel, etc. It should be noted that the inner surface of the second portion may be at least part of the inner surface of one or more panels.

[0047] Hence, in addition to just housing or accommodating a heat pump unit, the housing may at the same time also allow to support or arrange the heat pump unit in a certain or predetermined way. Thus, the housing may also comprise structural elements and / or structural arrangements for arranging the heat pump unit correctly and more securely. In doing so, an operation of the heat pump unit is made more secure, for example in view of reducing the risk of leakages when flammable refrigerants are used, and additional elements for such arrangement of the heat pump unit may be avoided. Thus, costs may be further decreased, and efficiency is further increased.

[0048] According to several examples of the present disclosure, an outer surface of a third portion of the housing, the third portion made of the EPP and may be part of at least a fifth panel of the plurality of panels, may comprise at least one of grooves, recesses, handles and protuberances.

[0049] The third portion may be at least part of one or more panels. For example, the third portion may form an upper section of a panel, an entire panel, two panels, two panels and a lower section of a third panel, etc. It should be noted that the outer surface of the third portion may be at least part of the outer surface of one or more panels.

[0050] Hence, the third portion may be easily gripped or held. Thus, a user may easier handle the third portion as intended and more accurately.

[0051] According to several examples of the present disclosure, a fourth portion of the housing, the fourth portion made of the EPP and may be part of at least a sixth panel of the plurality of panels, may be dismantlable and / or openable from the outside of the housing and / or may be rotatable around a rotation axis.

[0052] The fourth portion may be at least part of one or more panels. For example, the fourth portion may form an upper section of a panel, an entire panel, two panels, two panels and a lower section of a third panel, etc. For example, said in other words, the fourth portion may be understood to represent a door or flap or element that may be swung open to easily gain access into the inside of the housing.

[0053] Hence, to accessing the inside of the housing is made more comfortable and to completely dismantle the housing may thus be avoided for example.

[0054] According to several examples of the present disclosure, when the housing houses the heat pump unit, i.e. the heat pump unit is arranged inside the housing, the fourth portion, that may be dismantlable and / or openable from the outside of the housing and / or may be rotatable around a rotation axis, may be configured to cover at least part of a refrigerant circuit and / or at least part of an electronic control box of the heat pump unit. Furthermore, the fourth portion may further be configured to be at least one of dismantlable, openable and rotatable to expose the at least part of the refrigerant circuit. In particular, the fourth portion may be arranged so that parts of the refrigerant circuit are accessible where leakages of the flammable refrigerant may occur more likely.

[0055] Hence, maintenance of the refrigerant circuit is made easier and more comfortable, in particular regarding the handling of potential leakages of the flammable refrigerant.

[0056] According to several examples of the present disclosure, a fifth portion of the housing, the fifth portion made of the EPP and may be part of at least a seventh panel of the plurality of panels, preferably the housing that is made of the EPP, may comprise an opening into which a refrigerant-air heat exchanger associated with the outdoor heat pump unit is arrangeable. Additionally or alternatively, a sixth portion of the housing, the sixth portion made of the EPP and may be part of at least an eighth panel of the plurality of panels, may comprise an opening, wherein the opening is configured to be arranged below the refrigerant-air exchanger, when the housing houses the outdoor heat pump unit.

[0057] The opening below the refrigerant-air exchanger may allow for condensate drainage.

[0058] The sixth portion may be at least part of one or more panels. For example, the sixth portion may form an upper section of a panel, an entire panel, two panels, two panels and a lower section of a third panel, etc. In doing so, said in other words, the refrigerant-air heat exchanger when arranged in the opening may be understood to form part of the outer surface of the housing.

[0059] Hence, adapting the housing to specific requirements of the heat pump unit is easily applicable. In particular, to have the refrigerant-air exchanger in the opening allows for an improved air-exchange.

[0060] According to several examples of the present disclosure, at least part of each of at least two of the plurality of panels may form three or more EPP modules made of the EPP, and wherein the three or more EPP modules may be detachably connected to each other. According to several examples of the present disclosure, the housing may comprise two such EPP modules.

[0061] It should be noted that, said in other words and for explanation purposes, the EPP modules may be understood as a three-dimensional puzzle that may be set together to create the housing or at least part of the housing. Hence, the EPP modules may not necessarily allow to create the entire housing, but preferably the entire housing and at least part of the housing. For example, the housing that may result from arranging the EPP modules together may comprise an opening. In such opening a component associated with the outdoor heat pump unit may be arranged or positioned.

[0062] Hence, a flexible and easy to manufacture solution is achieved. In addition, access to the inside of the housing and the heat pump unit may be realized quite easily, i.e. the inside of the housing or the heat pump unit may be accessible quite easily.

[0063] According to several examples of the present disclosure, it shall be noted that in general, a portion of the housing, wherein the portion is made of the EPP, may be at least part of one or more panels of the plurality of panels. Thus, said in other words, the portion may in general be a section of one or more panels, for example the portion may even represent one or more entire panels, and may be of arbitrary size and / or shape.

[0064] Hence, it is enabled to design the housing in an efficient way to be suitable according to individual requirements, like technical requirements and / or environmental requirements for example. For example, portions may be designed so that components of the heat pump unit that are vulnerable for occurrences of leakages of a flammable refrigerant are easily accessible and / or are supported more safely.

[0065] According to several examples of the present disclosure, it shall be noted that in general, a portion of the housing, wherein the portion is made of the EPP, may represent an EPP module of the two or more, preferably three or more EPP modules. Thus, said in other words, the portion may in general be an EPP module, and may be of arbitrary size and / or shape.

[0066] Hence, it is enabled to design the housing in an efficient way to be suitable according to individual requirements, like technical requirements and / or environmental requirements for example.

[0067] According to several examples of the present disclosure, a seventh portion of the housing, the seventh portion made of the EPP and may be part of at least a ninth panel of the plurality of panels, may comprise a coating, preferably of a rigid material or metal. Additionally or alternatively, an outer surface of an eighth portion of the housing, the eighth portion made of the EPP and may be part of at least a tenth panel of the plurality of panels, may be a thermally-treated outer surface, for example applied by paint spraying or some other method that creates a superficial film on the EPP portion.

[0068] It should be noted that the coating may be, for example, one of urethane, acrylic acid ester and methacrylic, or may be a mixture of two of them.

[0069] Hence, robustness and resilience of the housing may be even further increased.

[0070] According to several examples of the present disclosure, a ninth portion of the housing, the ninth portion made of the EPP and may be part of at least an eleventh panel of the plurality of panels, may include a base material, preferably rigid plastic or metal, that is overmolded with the EPP.

[0071] It should be noted that the base material may allow for additional strength, robustness and resilience, for example of a panel that comprises such base material.

[0072] Hence, robustness and resilience of the housing may be even further increased. In doing so, a risk for the occurrence of a leakage of the flammable refrigerant is even further decreased.

[0073] According to a second aspect, there is provided a system comprising the housing according to the first aspect and a heat pump unit arranged inside the housing.

[0074] Moreover, according to several examples of the present disclosure, and at least one of the following may hold true: a) a fan of the outdoor heat pump unit may be supported by a tenth portion of the housing, the tenth portion made of the EPP, wherein the tenth portion functions as an outdoor heat pump unit panel, b) an air duct for the outdoor heat pump unit may be formed by or in an eleventh portion of the housing and is made of the EPP, c) a set of refrigerant circuit components of the outdoor heat pump unit may be fastened to a steel plate that is connected to a base of the outdoor heat pump unit, wherein the base is made of steel, wherein a fastening means for connecting the steel plate to the base passes through the base of the housing, the base of the housing made of the EPP, and d) the set of refrigerant circuit components of the outdoor heat pump unit may be fastened to portions of the housing that are made of EPP having a density different from portions of the housing that are made of EPP and to which the set of refrigerant circuit components are not fastened.

[0075] It shall be noted that the outdoor heat pump unit panel may be understood as a panel, casing or wall of the outdoor heat pump unit. Said in other words, the tenth and / or eleventh portion may serve or function as a functional element of the housing, i.e. as at least part of a panel of the housing for example, and as a functional element of the outdoor heat pump unit, i.e. as at least part of a panel, casing or wall of the outdoor heat pump unit for example. Similar, the tenth and / or eleventh portion may form part of the housing and, at the same time, may form (i.e. eleventh portion) the air duct for the outdoor heat pump unit. Hence, again, the tenth and / or eleventh portion may serve or function as a functional element of the housing, i.e. as at least part of a panel of the housing for example, and as a functional element of the outdoor heat pump unit, i.e. as the air duct for example. By fastening means it may be meant screws for example. Moreover, said in other words, different EPP portions that have different functions may have different densities, according to respective requirements that need to be satisfied. For example, a portion made of EPP that may have the function that one or more components of the outdoor heat pump unit may be held, carried or supported.

[0076] The system according to the second aspect is advantageous in that it may participate in enabling to reduced a number of parts and to thus achieve lower assembly, logistics, transport and parts management costs. In detail, parts may be spared, supplier contracts may be reduced, etc. Further, recycling is facilitated. It is further enabled a reduction in the cost of parts and therefore the cost of the product, and the resulting democratization of heat pump technology, based on a massive cost reduction potential. It is further achieved reduced part tooling costs, like reduced molds, and a slight flexibility of the EPP part, which offers a little tolerance during assembly for example. Moreover, there is the further advantage to achieve a lighter overall unit or housing, which allows for reduced transport costs and a reduced associated ecological footprint, and which further allows for ergonomics for the various users handling the housing for example, like an assembly operator, logistics, an end customer, an installer, a carrier, etc. Moreover, there is enabled the possibility of integrating recycled material, like recycled EEP, which even further reduces the ecological footprint. There is a reduced risk of injury from sharp edges during handling, there is reduced or no metallic ringing when rigid parts, like steel or plastic for example, come into contact with each other, as the heat pump unit's compressor's vibrations may cause the housing or the housing's structure to vibrate.

[0077] Furthermore, due to the relatively low thermal conductivity of EPP ( 0.28 W m ⋅ K ), for example in comparison to the thermal conductivity of a metal sheet ( 46 W m ⋅ K for steel), the temperature is kept within the housing's environment, thanks in particular to the thermal insulation capacity of the EPP. On the other hand, such thermal conductivity of EPP further avoids (at least reduces the risk of) an overheating inside the housing from the housing's outdoor environmental condition. For example, solar radiation that falls on the EPP does not heat the inside of the housing as much as if the solar radiation was falling on a metal sheet. Therefore, EPP also allows to reduce safety hazards in case of a flammable refrigerant. This may keep the heat pump unit's compressor warm during operation. Additionally, there is enabled a greater flexibility in terms of geometry and aesthetics, since the use of EPP parts may make it possible to create curves, also complex curves with sheet-metal parts, as well as large steps without draft, which is impossible with sheet-metal or injected plastic parts. The use of EPP also makes it possible to achieve different surface finishes, like more or less smooth, rough, matt, glossy, etc. on a same surface, which would be complex and / or costly with sheet metal parts for example.

[0078] According to a third aspect, there is provided a use of the housing according to the second aspect. In particular, there is provided a use of the housing according to the second aspect for housing, accommodating or protecting an outdoor heat pump unit, in particular an outdoor heat pump unit using a flammable refrigerant.

[0079] The use according to the third aspect is advantageous in that it may participate in enabling to reduced a number of parts and to thus achieve lower assembly, logistics, transport and parts management costs. In detail, parts may be spared, supplier contracts may be reduced, etc. Further, recycling is facilitated. It is further enabled a reduction in the cost of parts and therefore the cost of the product, and the resulting democratization of heat pump technology, based on a massive cost reduction potential. It is further achieved reduced part tooling costs, like reduced molds, and a slight flexibility of the EPP part, which offers a little tolerance during assembly for example. Moreover, there is the further advantage to achieve a lighter overall unit or housing, which allows for reduced transport costs and a reduced associated ecological footprint, and which further allows for ergonomics for the various users handling the housing for example, like an assembly operator, logistics, an end customer, an installer, a carrier, etc. Moreover, there is enabled the possibility of integrating recycled material, like recycled EEP, which even further reduces the ecological footprint. There is a reduced risk of injury from sharp edges during handling, there is reduced or no metallic ringing when rigid parts, like steel or plastic for example, come into contact with each other, as the heat pump unit's compressor's vibrations may cause the housing or the housing's structure to vibrate. Furthermore, due to the relatively low thermal conductivity of EPP ( 0.28 W m ⋅ K ), for example in comparison to the thermal conductivity of a metal sheet ( 46 W m ⋅ K for steel), the temperature is kept within the housing's environment, thanks in particular to the thermal insulation capacity of the EPP. On the other hand, such thermal conductivity of EPP further avoids (at least reduces the risk of) an overheating inside the housing from the housing's outdoor environmental condition. For example, solar radiation that falls on the EPP does not heat the inside of the housing as much as if the solar radiation was falling on a metal sheet. Therefore, EPP also allows to reduce safety hazards in case of a flammable refrigerant. This may keep the heat pump unit's compressor warm during operation. Additionally, there is enabled a greater flexibility in terms of geometry and aesthetics, since the use of EPP parts may make it possible to create curves, also complex curves with sheet-metal parts, as well as large steps without draft, which is impossible with sheet-metal or injected plastic parts. The use of EPP also makes it possible to achieve different surface finishes, like more or less smooth, rough, matt, glossy, etc. on a same surface, which would be complex and / or costly with sheet metal parts for example.

[0080] According to a fourth aspect, there is provided a use of the system according to the second aspect. In particular, there is provided a use of the system to heat and / or cool a space in a building, for example one or more rooms, or an entire building.

[0081] The use according to the fourth aspect is advantageous in that it may participate in enabling to reduce a number of parts and to thus achieve lower assembly, logistics, transport and parts management costs. In detail, parts may be spared, supplier contracts may be reduced, etc. Further, recycling is facilitated. It is further enabled a reduction in the cost of parts and therefore the cost of the product, and the resulting democratization of heat pump technology, based on a massive cost reduction potential. It is further achieved reduced part tooling costs, like reduced molds, and a slight flexibility of the EPP part, which offers a little tolerance during assembly for example. Moreover, there is the further advantage to achieve a lighter overall unit or housing, which allows for reduced transport costs and a reduced associated ecological footprint, and which further allows for ergonomics for the various users handling the housing for example, like an assembly operator, logistics, an end customer, an installer, a carrier, etc. Moreover, there is enabled the possibility of integrating recycled material, like recycled EPP, which even further reduces the ecological footprint. There is a reduced risk of injury from sharp edges during handling, there is reduced or no metallic ringing when rigid parts, like steel or plastic for example, come into contact with each other, as the heat pump unit's compressor's vibrations may cause the housing or the housing's structure to vibrate. Furthermore, due to the relatively low thermal conductivity of EPP ( 0.28 W m ⋅ K ), for example in comparison to the thermal conductivity of a metal sheet ( 46 W m ⋅ K for steel), the temperature is kept within the housing's environment, thanks in particular to the thermal insulation capacity of the EPP. On the other hand, such thermal conductivity of EPP further avoids (at least reduces the risk of) an overheating inside the housing from the housing's outdoor environmental condition. For example, solar radiation that falls on the EPP does not heat the inside of the housing as much as if the solar radiation was falling on a metal sheet. Therefore, EPP also allows to reduce safety hazards in case of a flammable refrigerant. This may keep the heat pump unit's compressor warm during operation. Additionally, there is enabled a greater flexibility in terms of geometry and aesthetics, since the use of EPP parts may make it possible to create curves, also complex curves with sheet-metal parts, as well as large steps without draft, which is impossible with sheet-metal or injected plastic parts. The use of EPP also makes it possible to achieve different surface finishes, like more or less smooth, rough, matt, glossy, etc. on a same surface, which would be complex and / or costly with sheet metal parts for example.

[0082] According to a fifth aspect, there is provided a method of operating the system according to the second aspect. In particular, there is provided a method of operating the system to heat a space in a building, for example one or more rooms, or an entire building.

[0083] The method according to the fifth aspect is advantageous in that it may participate in enabling to reduced a number of parts and to thus achieve lower assembly, logistics, transport and parts management costs. In detail, parts may be spared, supplier contracts may be reduced, etc. Further, recycling is facilitated. It is further enabled a reduction in the cost of parts and therefore the cost of the product, and the resulting democratization of heat pump technology, based on a massive cost reduction potential. It is further achieved reduced part tooling costs, like reduced molds, and a slight flexibility of the EPP part, which offers a little tolerance during assembly for example. Moreover, there is the further advantage to achieve a lighter overall unit or housing, which allows for reduced transport costs and a reduced associated ecological footprint, and which further allows for ergonomics for the various users handling the housing for example, like an assembly operator, logistics, an end customer, an installer, a carrier, etc. Moreover, there is enabled the possibility of integrating recycled material, like recycled EPP, which even further reduces the ecological footprint. There is a reduced risk of injury from sharp edges during handling, there is reduced or no metallic ringing when rigid parts, like steel or plastic for example, come into contact with each other, as the heat pump unit's compressor's vibrations may cause the housing or the housing's structure to vibrate. Furthermore, due to the relatively low thermal conductivity of EPP ( 0.28 W m ⋅ K ), for example in comparison to the thermal conductivity of a metal sheet ( 46 W m ⋅ K for steel), the temperature is kept within the housing's environment, thanks in particular to the thermal insulation capacity of the EPP. On the other hand, such thermal conductivity of EPP further avoids (at least reduces the risk of) an overheating inside the housing from the housing's outdoor environmental condition. For example, solar radiation that falls on the EPP does not heat the inside of the housing as much as if the solar radiation was falling on a metal sheet. Therefore, EPP also allows to reduce safety hazards in case of a flammable refrigerant. This may keep the heat pump unit's compressor warm during operation. Additionally, there is enabled a greater flexibility in terms of geometry and aesthetics, since the use of EPP parts may make it possible to create curves, also complex curves with sheet-metal parts, as well as large steps without draft, which is impossible with sheet-metal or injected plastic parts. The use of EPP also makes it possible to achieve different surface finishes, like more or less smooth, rough, matt, glossy, etc. on a same surface, which would be complex and / or costly with sheet metal parts for example.

[0084] Optional features of the first aspect may form part of any of the second to fifth aspects, mutatis mutandis.

[0085] Regarding the multiple panels and portions as outlined above with reference to the first and second aspect the following shall be noted. Namely, the first to eleventh portions and the first to eleventh panels and not to be understood merely in that way that there are described elven different and individual portions and eleven different and individual panels.

[0086] Rather, as long as not outlined in detail to the contrary, the first to eleventh portions may represent one same portion of the housing, or any combination of the first to eleventh portions may represent one or more different portions of the housing. Similar, as long as not outlined in detail to the contrary, the first to eleventh panels may represent one same panel of the housing, or any combination of the first to eleventh panels may represent one or more different panels of the housing.

[0087] In general, according to several examples of the present disclosure, a portion may be understood as representing or being a panel, and a panel may be understood as representing or being a portion.

[0088] Thus, said in other words, the terms "first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth", "ninth", "tenth" and "eleventh" (in general, "Nth" or "Mth") in combination with the terms "panel" and "portion" are provided to increase readability and understandability. The terms "Nth" and "Mth" panel may refer to the same or to different panels. The terms "Nth" and "Mth" portion may refer to the same portion, different portion, the Nth portion being or comprising a portion of the Mth portion or vice versa, and alike.

[0089] The indefinite article "a" or "an" does not exclude a plurality. In addition, the articles "a" and "an" as used herein should generally be construed to mean "one or more" unless specified otherwise or clear from the context to be directed to a singular form.

[0090] Unless specified otherwise, or clear from the context, the phrases "one or more of A, B and C", "at least one of A, B, and C", and "A, B and / or C" as used herein are intended to mean all possible permutations of one or more of the listed items. That is, the phrase "A and / or B" means (A), (B), or (A and B), while the phrase "A, B, and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0091] The term "comprising" does not exclude other elements or steps. Furthermore, the terms "comprising", "including", "having" and the like may be used interchangeably herein.

[0092] The invention may include one or more aspects, examples or features in isolation or combination whether specifically disclosed in that combination or in isolation. Any optional feature or sub-aspect of one of the above aspects applies as appropriate to any of the other aspects.

[0093] The above-described aspects will become apparent from, and elucidated with, reference to the detailed description provided hereinafter.Brief Description Of The Drawings

[0094] A detailed description will now be given, by way of example only, with reference to the accompanying drawing, in which: Figures 1 to 8 illustrate from different views a heat pump system comprising a housing in which a heat pump unit is arranged according to several examples of the present disclosure; Figure 9 illustrates an exploded view of the heat pump system; Figures 10 to 13 illustrate from different views a heat pump system comprising a first type modular housing in which a heat pump unit is arranged according to several examples of the present disclosure; Figures 14 to 17 illustrate from different views a heat pump system comprising a second type modular housing in which a heat pump unit is arranged according to several examples of the present disclosure; Figures 18 to 24 illustrate from different views a heat pump system comprising a third type modular housing in which a heat pump unit is arranged according to several examples of the present disclosure; and Figures 25 to 31 illustrate different examples for portions of a housing for an outdoor heat pump unit that are overmolded with a protection layer according to several examples of the present disclosure. Detailed Description

[0095] According to several examples of the present disclosure, there is provided a housing for an outdoor heat pump unit using a flammable refrigerant. The housing comprises a plurality of panels and is a volumetric body defined by the plurality of panels. At least one panel of the plurality of panels is made of expanded polypropylene (EPP) that has a density of at least 55 kg / m 3< , preferably of at least 60 kg / m 3< .

[0096] However, currently (December 2024), the use of unprotected foamed plastic, like EPP for example, in outdoor applications is prohibited by standard 60335-2-40, in particular NEN-EN-IEC 60335-2-40:2023, published May 1, 2023, which defines special requirements for electric heat pumps. This reflects the fact that using such housing as disclosed herein according to several examples of the present disclosure involves a real technical challenge, which is neither natural nor obvious. Hence, the aim of the present disclosure is to go beyond the prohibition of the standard by proposing a solution which is made of plastic foam, in particular EPP, on the outside surface and which can be used outdoors. Although this is currently (December 2024) forbidden by the standard, the technical solution and its particular definition as disclosed herein according to several examples of the present disclosure may convince the standard-setting group to change its opinion in this regard.

[0097] Hence, according to several examples of the present disclosure, there is provided a housing for an outdoor heat pump unit, the housing made at least in parts of foamed plastic, for example of EPP. Unlike existing solutions, foamed plastic parts or portions alone, like parts or portions made of EPP alone, can fulfil one or more of the following functions: compartmentalization of different environments within the housing, like ventilation zone, electronics zone or refrigeration circuit zone for example, in particular so as to (substantially) separate spaces with flammable refrigerant or with possible refrigerant leakage from potential ignition sources thereby eliminating or at least reducing the risk for ignition or explosion; support for certain components of an outdoor heat pump unit, like plate heat exchangers, air heat exchangers, fans, refrigeration circuit components, electronic boards, wiring, acoustic damping devices such as foams or antivibration pads for example, in particular so as to (substantially) separate spaces with flammable refrigerant or with possible refrigerant leakage from potential ignition sources; as a guide for fluids or gasses, like for refrigerant discharge in the event of a circuit leak, allowing the flammable refrigerant to escape via a guided path to the exterior thereby reducing the risk for ignition or explosion; as a guide for other fluids, like for air in the ventilation duct and / or for condensate discharge from the heat exchanger; as an exterior wall of the heat pump unit, thus preventing the penetration of any element (like rodents, rain, dust, projectiles, human presence, etc.) into the heat pump unit's interior volume, and also potentially serving as an aesthetic exterior surface, in particular so as to prevent access to and tampering with the refrigerant circuit with the flammable refrigerant.

[0098] For this purpose, according to several examples of the present disclosure, a housing may be made in at least two portions or modules from foamed plastic like EPP for example. In general, the housing according to several examples of the present disclosure may have inner surfaces intended for technical use and outer surfaces visible from outside the product in operating position.

[0099] The housing or a portion of the housing may be made up of parts having a base material overmolded by a foamed plastic, the such parts that can be given complex shapes to accommodate components, in particular through the use of counter-forms. For example, such counter-forms may be counter-forms or counter-shapes to forms or shapes of one or more components of an outdoor heat pump unit that is to be arranged inside the housing.

[0100] The foamed plastic parts, like portions, panels or modules made of the foamed plastic like of EPP for example, may have a density of at least 55kg / m 3< , preferably of at least 60kg / m 3< . Minimum surface thicknesses may be greater than 25mm, preferably 30mm, wherein for smaller surface areas, like less than 100mm x 100mm for example, in particular smaller surface areas relative to the size of the housing for example, that may have dimensions of the order of 1m x 1m x 0.5m, lower thicknesses may also be possible. Such smaller surface areas may have thicknesses down to 6mm, preferably 9mm, or holes.

[0101] In particular, according to several examples of the present disclosure, the material used as the foamed plastic may be expanded polypropylene, noted PPE or EPP.

[0102] The mechanical characteristics as indicated above in combination with EPP may ensure a mechanical strength of the assembly, i.e. of the housing assembled at least in parts from portions made of EPP, that is adapted to external environmental conditions.

[0103] In an embodiment, an outer layer or surface of at least part of the housing has a relatively smooth surface finish, preventing particle stagnation and the acceptability of external friction, which could lead to degraded perceived quality and / or premature material degradation. In this case, most of the outer surface may have an average, or arithmetic average of profile height deviations from a mean line of between 50 µm and 500 µm, preferably between 100 µm and 400 µm. For example, a value for the surface state finish indicator Ra may be between 100 µm and 500 µm, preferably between 200 µm and 400 µm. An example method for obtaining such relatively smooth surface finish is the use of texture via laser grain on the mould cavity for the EPP part creation. A structural groove (for example a gap preventing EPP beads from passing through) may lead to microchannel(s) which allows steam to be transported and therefore to achieve a desired level of fusion, so it is advantageous that the mould used to make the EPP parts is grained.

[0104] The housing as disclosed according to several examples of the present disclosure may also feature wide recesses or openings, which may be covered by at least one fan and at least one air / refrigerant heat exchanger of the outdoor heat pump unit when arranged inside the housing, i.e. when the housing houses the outdoor heat pump unit.

[0105] It shall be noted that as extracted from 3.8.101 of standard 60335-2-40 version F, the definition of plastic foam material is particle foam material, that is a closed-cell material molded from thermoplastic particles (e.g. beads) with a blowing agent.

[0106] In an embodiment, the housing may have at least three external or outer surfaces formed by foamed plastic. The aim is to make the most of the advantages on a set of surfaces.

[0107] Similarly, according to several examples of the present disclosure, the lower base of the housing may be formed from foamed plastic and may form one of the foamed plastic outer surfaces, i.e. part of an outer surface of the housing.

[0108] Furthermore, unlike standard injection-molded plastic parts or metallurgy parts, foamed plastic parts may have large thicknesses and can be designed in such a way that large thickness variations can be achieved within the part (like portion, panel or module for example). For example, a same part can have a local thickness of 20mm in one area and a local thickness of around 50mm in another area. This flexibility is not possible with injection-molded plastics and steels, for which thickness variations are very small, less than a doubling of thickness, generally less than an increase of more than 50%, and for which the thicknesses considered are small, generally of the order of 0.8mm to 3.5mm. In general and according to several examples of the present disclosure, by using foamed plastic parts, it is possible to create counter-forms to accommodate and support various elements or components, for example from an outdoor heat pump unit when the outdoor heat pump unit is arranged inside the housing. Due to such improved support and arrangement of the various elements or components, also a risk that a leakage may occur is reduced, which is particular important if the refrigerant is a flammable refrigerant.

[0109] Furthermore, unlike other processes, the use of foamed plastic allows to produce shapes with no draft, or even with undercuts of the order of 2mm to 3mm without drawer.

[0110] In an embodiment, the fan of the outdoor heat pump unit may directly be housed or accommodated and supported by one or more foamed plastic parts of the housing.

[0111] In an embodiment, a heat pump module comprising a set of refrigeration circuit components, in particular compressor and plate heat exchanger for example, is fixed to a steel plate and rests on a base of the heat pump unit, where the base of the heat pump unit may be made of foamed plastic, like of EPP for example.

[0112] In an embodiment, steel feet are arranged under the heat pump unit to locally support the entire weight of the heat pump unit.

[0113] In an embodiment, the plate supporting the refrigeration module of the heat pump unit is connected to a steel base.

[0114] In an embodiment, a fastening means such as a screw secures the i) module plate of the heat pump unit to the ii) foamed plastic surface of the base of the housing and the iii) foot of the heat pump unit together, in this order (in a "sandwich" assembly).

[0115] The housing according to several examples of the present disclosure, in particular one or more panels or portions of the panels of the housing, can be fitted with handles for product handling.

[0116] In an embodiment, a set of parts of the foamed plastic casing can be disassembled from their closed position in order to gain access to the inside of the housing, i.e. to components of the heat pump unit for easier assembly, maintenance or inspection for example. These may be completely removable parts or parts mounted on hinges for example. Due to such improved accessibility to various elements or components of the heat pump unit, also a handling of potential leakages is improved and is made easier, which is particular important if the refrigerant is a flammable refrigerant.

[0117] Hinges, fasteners and / or closures can be integrated directly into the foamed plastic parts and produced solely by this means (clip system, for example), or interface parts or connections can be added (screws, additional hinges, plates, inserts, etc.).

[0118] The foamed material may incorporate different elements or have different configurations to improve its performance in the application in question, such as one or more of the following: addition of a treatment for resistance to solar radiation, particularly UV (surface or in-mold treatment), wherein the treatment may comprise to include components into the EPP that are appropriate for increasing such resistance; production of double-injection parts with different material densities, like zones at 80kg / m3 and zones at 60kg / m3 for example; integration of metal inserts or plastic inserts (inside a foamed plastic part), in particular for fastening means such as tappings in or screwing.

[0119] In short, according to several examples of the present disclosure, a range of configurations and alternatives are possible. The concept can be applied by separating the main elements of the housing into two or more parts or portions. The housing can be divided into two, three, four or more portions or modules. It is preferable to limit the number of modules in order to reduce assembly costs and the management of interfaces between each part (means of closure, sealing, aesthetics, etc.).

[0120] Now, to outline the above in more detail, reference is made to Figures 1 to 8, wherein Figures 1 to 8 illustrate from different views a heat pump system comprising a housing 100 in which a heat pump unit is arranged according to several examples of the present disclosure. The heat pump unit may be operable with a flammable refrigerant.

[0121] In particular, according to several examples of the present disclosure, the housing 100 is for an outdoor heat pump unit, wherein the outdoor heat pump unit uses a flammable refrigerant like, for example, R290 or propane. The housing 100 may in general be understood as a volumetric body that comprises a plurality of panels and / or that is defined by the plurality of panels. However, as outlined below in more detail, it shall be noted that the housing 100 may not be an entirely closed volumetric body. Rather, said in other words, the housing 100 may comprise openings and / or recesses, and it may even be preferred that the housing 100 comprises openings and / or recesses as functional elements for example. Further, the housing 100 in a most general way may be understood as representing a box into which an apparatus, device, equipment, unit or system may be placed or arranged. However, the housing 100 is not limited to such interpretation. Rather, as outlined below in detail, the housing 100 may comprise inner surfaces and / or an inner structure that provide one or more predetermined technical features, for example that fulfil one or more predetermined technical requirements and / or that may achieve a synergistic effect with one or more components of an apparatus, device, equipment, unit or system that is placed or arranged inside the housing 100. Thus, said in other words, the housing 100 may not be limited on housing or accommodating the apparatus, device, equipment, unit or system only, but at least part of the housing 100 may be understood as if it was functioning as being part of the apparatus, device, equipment, unit or system. In Figures 1 to 8, the housing is of a substantial cuboid shape and may thus be defined by panels and / or portions of panels, i.e. six geometric planes representing the six sides of a cuboid shape indicated by panels and / or portions of panels 101, 102, 103, 104, 105 and 106 in Figures 1 to 8, that may indicate the substantial cuboid shape. At least one panel of the plurality of panels 101, 102, 103, 104, 105 and 106 is made of EPP or comprises EPP that has a density of at least 55 kg / m 3< , preferably of at least 60 kg / m 3< . By the term "made" it is not intended to limit the panel as consisting of EPP only. Rather, by the term "made" is it meant that at least a structural element or a structural arrangement of a panel is made of EPP and, in doing so, may be fully made of EPP. In general, the housing 100 may be a volumetric body of any shape, like even a sphere for example, wherein the plurality of panels may then be understood as forming the sphere. Preferably, one or more panels of the housing 100 or the housing 100 is / are fully made of the EPP.

[0122] For example, with reference to Figures 1 to 8, reference signs 101 to 106 shall be understood as indicating the panels or walls of the volumetric body, in detail the six geometric planes that define the six planes of a cuboid shape. In particular, reference sign 101 may indicate a top panel or top wall of the housing 100 and reference sign 106 may indicate a bottom panel, bottom wall or base (panel or wall) of the housing 100. The top panel and the bottom panel may be arranged to face each other. Reference signs 103 and 105 may indicate side panels or side walls of the housing 100 that are arranged adjacent to the top and bottom panels and that are arranged to face each other. Reference sign 102 may indicate a front panel or front wall of the housing 100 and reference sign 104 may indicate a back panel or back wall of the housing 100. The front panel and the back panel are arranged adjacent to the top and bottom panels and may be arranged to face each other.

[0123] However, in more detail and with further reference to Figure 9, it shall be noted that the respective panels 101 to 106 may comprise or may be made or consist of several different individual elements or portions. For example, with regard to the top panel 101, the front panel 102, the bottom panel 106 and part of the side panel 105, it shall be noted that these panels and panel parts are made or provided by one portion 901 that is made of the EPP. This one portion 901 may be understood as representing a main housing portion 901. With regard to the side panel 103 and the back panel 104, the back panel 104 comprises a first portion 104-1 of a portion 902 made of the EPP, wherein a second portion 103-1 of the portion 902 forms at least part of the side panel 103. Thus, said in other words, the portion 902 forms or provides part of each of the side panel 103 and the back panel 104. The back panel 104 further comprises a first part 104-2 of an outer surface of an air heat exchanger 930. The air heat exchanger 930 may be fixed on the main housing portion 901, with or without an interface part such as a steel plate. A second part 105-1 of the outer surface of the air heat exchanger 930 forms part of the side panel 105. The back panel 104 further comprises a part 104-3 of an outer surface of a plate 940, wherein on the plate 940 a refrigerant circuit 920 of the outdoor heat pump unit can be fixed and the plate 940 can also include connection elements for fluid and electrical connection outside the heat pump unit. A fan 910 of the heat pump unit may be arranged or fixed in the main housing portion 901. In particular, the main housing portion 901, in more detail the front panel 102, comprises an opening that has (as part of its inner surface and / or arranged on its inner surface) a structural arrangement 901in, in particular a counter-shape 901c to the shape 910s of the fan 910 for supporting the fan 910 or for holding the fan 910 in position when the heat pump unit is arranged inside the housing 100. Reference sign 950 represents an electronic board 950 that may be fixed on a plate and may be inserted in the main housing portion 901. For example, the main housing portion 901 may comprise an inner structure comprising a surface at which the electronic board 950 may be attached or fixed. Reference sign 960-1 and 960-2 represent feet 960-1 and 960-2, which may be fixed bay use of a "sandwich assembly" with fixing means such as screws for example. Fixing means may hold together the feet 960-1 and 960-2, the bottom side of the main housing portion 901, wherein the bottom side may represent the bottom panel 106, and an associated upper plate that holds the refrigerant circuit 920 on one side. Reference sign 970 represents a plate 970 for fixing the feet 960-1 and 960-2.

[0124] Moreover, according to several examples of the present disclosure, the portion 902 that forms or provides part of each of the side panel 103 and the back panel 104, may be dismantlable and / or openable from the outside of the housing 100 and / or may be rotatable around a rotation axis. This is indicated from different perspectives as an example in Figures 5 to 8, wherein the portion 902 is referred to with the reference sign 501 to highlight that in Figures 5 to 8 this is a portion that is openable and may be rotated around a rotation axis. In doing so, since the portion 902 (or 501) may cover (when in a closed position) at least part of the refrigerant circuit 920, an access to the refrigerant circuit 920 is facilitated.

[0125] Further, according to several examples of the present disclosure, the portion 902 (or portion 501) may comprise at least one of grooves, recesses, handles and protuberances. In particular, the portion 902 (or portion 501) comprises handles 902h-1 and 902h-2 to open the housing 100, i.e. to dismantle the portion 902 from the housing 100 (or to rotate the portion 501 around a predetermined rotation axis to open the housing 100). In particular, an outer surface 902out of the portion 902 of the housing 100 comprises the handles 902h-1 and 902h-2.

[0126] In addition, with further reference to Figure 9 and for reasons of understandability, it shall be noted that the housing 100 is made of the main housing portion 901 and the portion 902 (or portion 501), wherein these two portions are made of EPP for example. Further, the combination of the main housing portion 901 and the portion 902 (or portion 501) may be understood to comprise an opening or recess into which, for example, the air heat exchanger 930 is arrangeable so that outer surface parts 104-2 and 105-1 of the air heat exchanger 930 may be understood to extend or increase the outer surface of the housing 100. Hence, it may be said that the air heat exchanger 930, which is associated with the heat pump unit arranged inside the housing 100 and which may be understood to be part of the heat pump unit, also functions as providing at least part of the outer surface of the housing. However, still the air heat exchanger 930 shall not be understood as being part of the housing 100, but rather the air heat exchanger 930 is part of the heat pump unit and, at the same time, may function as if it was part of the housing. Further, below the air heat exchanger 930, an opening may be located in the main housing portion 901 for condensate drainage.

[0127] Moreover, with further reference to Figure 9, an outer surface 901out of the main housing portion 901 and an inner surface 901 in of the main housing portion 901 are indicated as an example. As derivable from Figure 9, an inner surface of an EPP portion of the housing 100, for example the inner surface 901in of the main housing portion 901, may comprise structural elements, like reinforcements and / or structural or special subdivisions for example. An EPP portion of the housing 100, for example the main housing portion 901 including its structural elements may have a thickness in a range between 6mm and 25mm, preferably in a range between 6mm and 20mm. Regarding the outer surface 901out as an example, may have a water non-permeability (inherent permeability k below 4.5E-18 m 2< ) over at least one month at 3kPa, and / or a superficial melting level of the EPP of more than 99%, preferably of 100%.

[0128] Referring now to Figures 10 to 13, Figures 10 to 13 illustrate from different views a heat pump system comprising a first type modular housing in which a heat pump unit is arranged according to several examples of the present disclosure.

[0129] According to the first type modular housing, the housing comprises two EPP modules, a top EPP module 1001-1 and a bottom EPP module 1002-1 that are made of the EPP, and the two EPP modules are detachably connected to each other. Said in other words, the housing is divided into two portions or two halves, a top portion and a bottom portion, that may be connected to each other to create or form the housing, similar to the housing 100 according to Figures 1 to 9. For example, in comparison to Figures 1 to 9, the front panel 102 comprises a first part 102-1 provided by the top EPP module 1001-1 and a second part 102-2 provided by the bottom EPP module 1002-1. Similar, in comparison to Figures 1 to 9, the side panels 103 and 105 each comprise a first part 103-1 and 105-1 provided by the top EPP module 1001-1 and a second part 103-2 and 105-2 provided by the bottom EPP module 1002-1. For example, the housing created by the top EPP module 1001-1 and the bottom EPP module 1002-1 also comprises an opening in the front panel for the fan 910, a space inside the housing for the refrigerant circuit 920, and an opening in the back panel for the air heat exchanger 930. Said in other words, instead of the main housing portion 901 and the portion 902 (or portion 501) used to form the housing 100 according to Figures 1 to 9, the top EPP module 1001-1 and the bottom EPP module 1002-1 are used to form a housing. In doing so, the elements or components of the heat pump unit may be easily accessible in that the top EPP module 1001-1 may simply be removed. This may allow for improved and safer maintenance in particular in case a flammable refrigerant is used.

[0130] Referring now to Figures 14 to 17, Figures 14 to 17 illustrate from different views a heat pump system comprising a second type modular housing in which a heat pump unit is arranged according to several examples of the present disclosure.

[0131] According to the second type modular housing, the housing comprises two EPP modules, a top EPP module 1001-2 and a bottom EPP module 1002-2 that are made of the EPP, and the two EPP modules are detachably connected to each other. Said in other words, the housing is divided into two portions of different size, a top portion and a bottom portion, that may be connected to each other to create or form the housing, similar to the housing 100 according to Figures 1 to 9. For example, in comparison to Figures 1 to 9, the front panel 102 comprises a first part 102-3 provided by the top EPP module 1001-2 and a second part 102-4 provided by the bottom EPP module 1002-2. However, the second type modular housing differs from the first type modular housing in that the top EPP module 1001-2 is designed to cover, enclose or house the refrigerant circuit 920 entirely. Thus, when removing the top EPP module 1001-2, the entire refrigerant circuit 920 may be accessible, wherein only the top halve may be accessible according to the first type modular housing. For example, the housing created by the top EPP module 1001-2 and the bottom EPP module 1002-2 also comprises an opening in the front panel for the fan 910, a space inside the housing for the refrigerant circuit 920, and an opening in the back panel for the air heat exchanger 930. Further, said in other words, instead of the main housing portion 901 and the portion 902 (or portion 501) used to form the housing 100 according to Figures 1 to 9, the top EPP module 1001-2 and the bottom EPP module 1002-2 are used to form a housing. In doing so, the elements or components of the heat pump unit may be easily accessible in that the top EPP module 1001-2 may simply be removed. This may allow for improved and safer maintenance in particular in case a flammable refrigerant is used.

[0132] Referring now to Figures 18 to 24, Figures 18 to 24 illustrate from different views a heat pump system comprising a third type modular housing in which a heat pump unit is arranged according to several examples of the present disclosure.

[0133] According to the third type modular housing, the housing comprises three EPP modules, a top EPP module 1001-3, a bottom EPP module 1002-3 and a side EPP module 1003-3 that are made of the EPP, and the three EPP modules are detachably connected to each other. Said in other words, the housing is divided into three portions, a top portion, a bottom portion and side portion, that may be connected to each other to create or form the housing, similar to the housing 100 according to Figures 1 to 9. For example, in comparison to Figures 1 to 9, the front panel 102 comprises a first part 102-5 provided by the top EPP module 1001-3, a second part 102-6 provided by the bottom EPP module 1002-3, and a third part 102-7 provided by the side EPP module 1003-3. However, the third type modular housing differs from the first and second type modular housings by the number of modules, and in that the side EPP module 1003-3 is designed to cover, enclose or house only a space inside the housing that is predetermined for the refrigerant circuit 920. Thus, when removing the side EPP module 1003-3, only the entire refrigerant circuit 920 may be accessible, wherein the space inside the housing and behind the fan 910 for example remains closed. For example, the housing created by the top EPP module 1001-3, the bottom EPP module 1002-3 and the side EPP module 1003-3 also comprises an opening in the front panel for the fan 910, the predetermined space inside the housing for the refrigerant circuit 920, and an opening in the back panel for the air heat exchanger 930. Further, said in other words, instead of the main housing portion 901 and the portion 902 (or portion 501) used to form the housing 100 according to Figures 1 to 9, the top EPP module 1001-3, the bottom EPP module 1002-3 and the side EPP module 1003-3 are used to form a housing. Thus, the design with the three EPP modules allows for access to the refrigeration circuit 920 independently of the ventilation and electronic board 950. This facilitates assembly and / or disassembly and provides greater security for components not involved during a maintenance phase. For example, the side EPP module 1003-3 may be designed to be removable for access to refrigeration components and circuit board. Similar, removal of the top EPP module 1001-3 may allow for access to the ventilation section or the fan 910 and air heat exchanger 930 without affecting the refrigeration circuit 920 and electronic board 950. In doing so, the elements or components of the heat pump unit may be easily accessible in that the side EPP module 1003-3 for example may simply be removed. This may allow for improved and safer maintenance in particular in case a flammable refrigerant is used.

[0134] Referring now to Figures 25 to 31, Figures 25 to 31 illustrate different examples for portions of a housing for an outdoor heat pump unit, the portions for example overmolded or coated with a protection layer according to several examples of the present disclosure. Figures 25 and 26 show portion 2500 that may represent a further processed bottom EPP module 1002-3 according to the third type modular housing, Figures 27 to 29 show a portion 2700 may represent a further processed top EPP module 1001-3 according to the third type modular housing, and Figures 30 and 31 may represent a further processed housing according to the third type modular housing.

[0135] Namely, according to several examples of the present disclosure, in order to ensure mechanical resistance, to guard against a series of brittleness of the foamed plastic in the face of external conditions, and to potentially act as a lever to exceed standard 60335-2-40 (NEN-EN-IEC 60335-2-40:2023, published May 1, 2023) and a wish on foamed plastic on the exterior facade of an exterior product, it is disclosed to integrate more rigid materials directly into the foamed plastic part on its outside surface. This may involve steel parts (e.g. thin sheet metal, i.e. less than 1 mm thick) or a layer of rigid plastic of low thickness, i.e. less than 1 mm, preferably less than 0.5 mm, more preferably less than 0.1 mm. The plastic used can be a polystyrene-type plastic (unexpanded in this case) or Acrylonitrile Butadiene Styrene (ABS) for example.

[0136] These parts may therefore be produced using an overmolding process. The plastic sheet overmolded is in contact with the floor and it allows for translation of the product (and associated friction) without damaging and breaking the EPS. The same logic is proposed to create a shield around the foam-based plastic of the heat pump unit, if necessary.

[0137] Overmolding of a black PS sheet to ensure higher resistance to contact and friction and humidity may also be an option. Overmolding can be carried out on an entire outside panel of the housing. However, it can also extend a little beyond the inner parts, to ensure a better joint and better hold. It can also be slightly shorter than the outer panels, depending on industrial constraints.

[0138] In any case, a majority, like at least 95% of the outer surface of the housing, may be covered by a coating and / or the uncoated areas that are outer surfaces of the housing not covered by another element (such as the fan) are strips less than 5mm wide.

[0139] For example, in Figures 25 to 31, a dark grey zone corresponds to an area where rigid plastic (or steel) is overmolded to the EPP. The white or light-gray zone corresponds to an area without protection, i.e. foam plastic (EPP in particular) on the outside panel. There may not be any need to overmold a rigid part (or set of parts) on all the surfaces of the foamed plastic part. In Figure 30, the light grey portion indicates the air heat exchanger 930.

[0140] According to several examples of the present disclosure, as an alternative to overmoulding the surface of the foamed plastic like EPP for example, another process can be used to make such part more robust under certain conditions of use. This may involve heating a portion's (or panel's or module's) intended outer surface after the plastic foam has been expanded and shaped. Once the portion has been made in the conventional way, i.e. expansion with integration of steam in the mould, one or more surfaces of the portion may be heated to anneal and obtain a rigidified material. This process is known as "ironing" or "skin-forming". This heating can be applied directly on the portion with a hot surface or contact-free (hot air environment, laser, etc.).

[0141] Due to such process, the surface of the portion made of the EPP for example is made more rigid and may be more likely to be compatible with the constraints of the environment in which it is used, to the point of making it compatible with standard requirements. Alternatively, taking advantage of this surface rigidity could make it possible to reduce the density and / or thickness of the portion's surface while maintaining satisfactory rigidity.

[0142] The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features.

[0143] It has to be noted that embodiments of the invention are described with reference to different categories. In particular, some examples are described with reference to methods whereas others are described with reference to apparatus. However, a person skilled in the art will gather from the description that, unless otherwise notified, in addition to any combination of features belonging to one category, also any combination between features relating to different category is considered to be disclosed by this application. However, all features can be combined to provide synergetic effects that are more than the simple summation of the features.

[0144] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art, from a study of the drawings, the disclosure, and the appended claims.

[0145] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously.

[0146] Any reference signs in the claims should not be construed as limiting the scope.Reference Signs

[0147] 100housing 101top panel 102front panel 102-1front panel first part 102-2front panel second part 102-3front panel first part 102-4front panel second part 102-5front panel first part 102-6front panel second part 103side panel 103-1side panel first part 103-2side panel second part 104back panel 104-1back panel first part 104-2back panel second part 104-3back panel third part 105side panel 105-1side panel first part 105-2side panel second part 106bottom panel 501rotatable portion 901main housing portion 901instructural arrangement 901ccounter-shape 901outouter surface 902portion 902h-1handle 902h-2handle 902outouter surface 910fan 910sshape of the fan 920refrigerant circuit 930air heat exchanger 940plate 950electronic board 960-1foot 960-2foot 970plate 1001-1first module first type 1002-1second module first type 1001-2first module second type 1002-2second module second type 1001-3first module third type 1002-3second module third type 1003-3third module third type 2500coated portion 2700coated portion

Claims

1. A housing (100) for an outdoor heat pump unit using a flammable refrigerant, wherein the housing (100) comprises a plurality of panels (101, 102, 103, 104, 105, 106), and wherein at least one panel (101) of the plurality of panels (101, 102, 103, 104, 105, 106) is made of expanded polypropylene that has a density of at least 55 kg / m3.

2. The housing (100) according to claim 1, wherein the housing (100) is fully made of the expanded polypropylene; and / or for a first panel and a second panel of the plurality of panels, the first panel and the second panel are different panels, the first panel is made of the expanded polypropylene having a first density and the second panel is made of the expanded polypropylene having a second density different from the first density, wherein the first panel and the second panel fulfil different structural requirements of the housing.

3. The housing (100) according to claim 1 or 2, wherein the expanded polypropylene has a thickness in a range between 6mm and 25mm; and / or wherein the expanded polypropylene has a density of at least 60 kg / m3.

4. The housing (100) according to any of claims 1 to 3, wherein a third panel of the plurality of panels comprises a first portion (901, 902), wherein the first portion (901, 902) is made of the expanded polypropylene and an outer surface (901 out, 902out) of the first portion (901, 902), preferably the outer surface of the third panel or the housing, has: a water non-permeability over at least one month at 3kPa, and / or superficial melting level of more than 99%, preferably 100%, and / or an inherent permeability lower than 4.5E-18 m2.

5. The housing (100) according to any of claims 1 to 4, wherein an inner surface of at least a fourth panel of the plurality of panels comprises a structural arrangement (901in), wherein the at least fourth panel and the structural arrangement (901in) represent at least part of a second portion (901) made of the expanded polypropylene, wherein the second portion (901) is configured to support, via the structural arrangement (901in), a component, preferably a fan (910) of the outdoor heat pump unit, wherein the structural arrangement (901in) comprises a counter-shape (901c) to at least part of a shape (910s) of the component (910).

6. The housing (100) according to any of claims 1 to 5, wherein an outer surface (902out) of a third portion (902) of the housing (100), the third portion (902) made of the expanded polypropylene and being part of at least a fifth panel of the plurality of panels, comprises at least one of grooves, recesses, handles (902h-1, 902h-2) and protuberances.

7. The housing (100) according to any of claims 1 to 6, wherein a fourth portion (501) of the housing (100), the fourth portion (501) made of the expanded polypropylene and being part of at least a sixth panel of the plurality of panels, is dismantlable and / or openable from the outside of the housing (100) and / or is rotatable around a rotation axis.

8. The housing (100) according to claim 7, wherein, when the housing (100) houses the outdoor heat pump unit, the fourth portion (501, 902, 1001-1, 1001-2, 1003-3), that is dismantlable and / or openable from the outside of the housing (100) and / or is rotatable around a rotation axis, is configured to cover at least part of a refrigerant circuit (920) and / or at least part of an electronic control box of the outdoor heat pump unit, and the fourth portion (501, 902, 1001-1, 1001-2, 1003-3) is further configured to be at least one of dismantlable, openable and rotatable to expose the at least part of the refrigerant circuit (920) and / or the at least part of the electronic control box.

9. The housing (100) according to any of claims 1 to 8, wherein a fifth portion (901, 902; 1001-1, 1002-1; 1001-2, 1002-2; 1001-3, 1002-3, 1003-3) of the housing (100), the fifth portion (901, 902; 1001-1, 1002-1; 1001-2, 1002-2; 1001-3, 1002-3, 1003-3) made of the expanded polypropylene and being part of at least a seventh panel of the plurality of panels, preferably the housing (100) that is made of the expanded polypropylene, comprises an opening into which an air heat exchanger (930) associated with the outdoor heat pump unit is arrangeable, and / or wherein a sixth portion (901) of the housing (100), the sixth portion (901) made of the expanded polypropylene and being part of at least an eighth panel of the plurality of panels, comprises an opening, wherein the opening is configured to be arranged below the air heat exchanger (930) for condensate drainage, when the heat pump unit is arranged inside the housing.

10. The housing (100) according to any of claims 1 to 9, wherein at least part of each of at least two of the plurality of panels form two or more, preferably three or more expanded polypropylene modules (1001-1, 1002-1; 1001-2, 1002-2; 1001-3, 1002-3, 1003-3) made of the expanded polypropylene, and wherein the two or more, preferably three or more expanded polypropylene modules (1001-1, 1002-1; 1001-2, 1002-2; 1001-3, 1002-3, 1003-3) are detachably connected to each other.

11. The housing (100) according to any of claims 1 to 10, wherein a seventh portion (2500, 2700) of the housing (100), the seventh portion (2500, 2700) made of the expanded polypropylene and being part of at least a ninth panel of the plurality of panels, comprises a coating, preferably of a rigid material or metal; and / or wherein an outer surface of an eighth portion of the housing (100), the eighth portion made of the expanded polypropylene and being part of at least a tenth panel of the plurality of panels, is a thermally-treated outer surface.

12. The housing (100) according to any of claims 1 to 11, wherein a ninth portion of the housing, the ninth portion made of the expanded polypropylene and being part of at least an eleventh panel of the plurality of panels, includes a base material, preferably rigid plastic or metal, that is overmolded with the expanded polypropylene.

13. A system comprising the housing (100) according to any of claims 1 to 12 and a heat pump unit arranged inside the housing (100).

14. The system according to claim 13, a) wherein a fan (910) of the outdoor heat pump unit is supported by a tenth portion (901) of the housing, the tenth portion (901) made of the expanded polypropylene, wherein the tenth portion (901) functions as an outdoor heat pump unit wall, and / or b) wherein an air duct for the outdoor heat pump unit is formed by or in an eleventh portion of the housing and is made of the expanded polypropylene, and / or c) wherein a set of refrigerant circuit components (920) of the outdoor heat pump unit is fastened to a steel plate that is connected to a base of the outdoor heat pump unit, wherein the base is made of steel, wherein a fastening means for connecting the steel plate to the base passes through the base of the housing, the base of the housing made of the expanded polypropylene, and / or d) wherein the set of refrigerant circuit components (920) of the outdoor heat pump unit is fastened to portions of the housing that are made of expanded polypropylene having a density different from portions of the housing that are made of expanded polypropylene and to which the set of refrigerant circuit components (920) are not fastened.

15. Use of a housing according to any of claims 1 to 12 for a heat pump unit operable with a flammable refrigerant.

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