WO2014009688A2

WO2014009688A2 - A passive ventilation and/or humidity control unit

Info

Publication number: WO2014009688A2
Application number: PCT/GB2013/051514
Authority: WO
Inventors: Michael Massey
Original assignee: Bailcast Limited
Priority date: 2012-07-09
Filing date: 2013-06-10
Publication date: 2014-01-16
Also published as: WO2014009688A3; GB201212187D0

Abstract

A passive ventilation and/ or humidity control unit for an enclosure, the unit comprising: at least one extract circuit through which extract air can be drawn from said enclosure to an extract outlet; at least one supply circuit through which supply air can be drawn into the enclosure from a supply inlet to a supply outlet; and a roof mounting component, wherein the extract outlet is adapted to facilitate a Venturi effect on said extract circuit, and wherein the (or each) supply outlet is arranged relative to said roof mounting component to dispense a supply air stream proximal to a ceiling of the enclosure to create a Coanda effect with said ceiling of said enclosure.

Description

A PASSIVE VENTILATION AND/OR HUMIDITY CONTROL UNIT

BACKGROUND

Technical Field

The present invention relates generally to the field of ventilation of indoor environments. More particularly, but not exclusively, the present invention concerns a passive ventilation and/ or humidity control unit for enclosures.

Description of the Related Art

It is a well-known fact that enclosed un-heated and relatively unventilated spaces have high levels of humidity due to the temperature differential between the inside and the outside of the space. When the temperature in such a space drops below the dew point (the temperature at which the water vapour in a volume of humid air at constant barometric pressure condenses into liquid water), objects in the space become covered in condensed water. The moisture damages objects and the overall fabric of the enclosure through mould and damp. Furthermore, the moisture can contribute to pulmonary conditions, such as asthma, and encourage the proliferation of allergen-creating organisms, such as dust mites and mould.

It is currently considered that one half air changes per hour (ACH) will prevent the humidity reaching a level where dew point occurs. The ideal humidity level is thought to be RH55% relative to the external temperature.

It has been found that opening a window only facilitates air exchange local to the window. Therefore, an open window does not provide the required balanced air flow throughout the space to meet the one half air changes per hour (ACH) standard.

Furthermore, when an enclosure is left for significant periods of time without being occupied, it is not secure to leave a window open. Neither is it recommended, nor safe, to leave powered ventilation or heating systems running. Therefore, enclosures such as caravans, mobile homes, boats, holiday homes, Portakabins^®, site huts, workshops, garages, classic vehicle storage, green houses and HGV sleeper cabs that are not used regularly are particularly affected by this problem.

Accordingly, a number of ventilation systems have been devised for enclosures. Unfortunately, many of these systems use a fan and/or other PCB controlled components, which require a power supply.

The unit described in CA 1258398 A provides ventilation and heat and humidity recovery for an indoor environment of an enclosure. The unit provides natural (passive) ventilation and latent heat and humidity ratio recovery of an indoor environment. The unit can be placed on a surface, partially above a surface and partially below a surface or in a subsurface, and it comprises a duct having an opening near the ceiling (inside opening) and an opening above the roof (outside opening). The duct extends downwardly from the outside opening, through the roof and downwardly in the enclosure near to the floor. The duct loops and then rises upwardly to terminate adjacent to the ceiling with said inside opening. The duct conducts a central core of flow and an outer annulus of flow. The central core can provide inflow from the outside opening to the inside opening whilst the outer annulus can provide contra outflow from the inside opening to the outside opening, or vice versa. An intermediate zone between the core and the annulus allows for mixing of the inflow air with the outflow air. The arrangement has a drain provision at the lowermost point of the duct that is connected to a drain and when the temperature and humidity differences are big enough to create condensation, the drain provision is used to remove the water.

CA 1258398 A takes up a large amount of space and is not practical for accommodation enclosures.

Alternative passive ventilation systems are known, which comprise ducts that connect extract grilles, usually located in kitchens and bathrooms of a building with outlet roof terminals. When the air inside the building is warmer than that outside, it rises up the ducts by natural convection, carrying moisture with it. Wind blowing across the roof provides additional suction to draw out the moisture laden air via the Venturi effect. As the warm stale air rises, replacement fresh air is normally drawn into the building through either wall or window background ventilators which are usually sited in the habitable (dry) rooms. Such systems do not require additional input energy, but are not always practical or simple to fit since multiple extensive components are required.

It is an object of the present invention to provide an improved arrangement for a passive ventilation and/ or humidity control unit for enclosures.

SUMMARY OF THE INVENTION

In a first aspect of the present invention there is provided a passive ventilation and/ or humidity control unit for an enclosure, the unit comprising:

at least one extract circuit through which extract air can be drawn from said enclosure to an extract outlet;

at least one supply circuit through which supply air can be drawn into the enclosure from a supply inlet to a supply outlet; and

a roof mounting component,

wherein the extract outlet is adapted to facilitate a Venturi effect on said extract circuit, and wherein the (or each) supply outlet is arranged relative to said roof mounting component to dispense a supply air stream proximal to a ceiling of the enclosure to create a Coanda effect with said ceiling of said enclosure.

By "passive device", what is meant is a single device using natural forces to drive the ventilation and/or humidity control of an enclosure with no additional input energy being required to drive the device.

With the above arrangement, substantially the full air volume of an enclosure can be effectively changed over to the required level as follows: as a prevailing wind moves across the top of the extract outlet, the air speed accelerates, which creates a vacuum acting on the extract circuit, which draws air up and out of the extract outlet (the Venturi effect); the vacuum correspondingly causes air to be drawn in through the supply circuit to maintain the pressure in the enclosure; furthermore, the positioning of the supply outlet delivers the incoming air stream close to the ceiling of the enclosure and since such fluid streams have a tendency to be attracted to a nearby surface (the Coanda effect), the supply air travels along the ceiling of the enclosure displacing still air; through convention, as the supply air cools, it air falls to displace cooler air below, which is then drawn into the extract circuit.

Preferably, the (or each) supply outlet is arranged to dispense the supply air stream in a direction substantially parallel with the ceiling of the enclosure to further facilitate a Coanda effect with said ceiling of said enclosure.

Preferably, the extract circuit and the supply circuits are mutually exclusive of one another within said device.

Preferably, the extract circuit and the supply circuit are arranged relative to one another to further induce one or more convection paths in said enclosure. More preferably, an extract inlet of the extract circuit and the (one or more) supply outlet(s) are arranged relative to one another to further induce one or more convection paths in said enclosure.

Preferably, therefore, the extract inlet is positioned so as not to impede the operation of the supply outlet(s). More preferably, the extract inlet is distanced from the supply inlet(s). Most preferably, the extract inlet is arranged behind each supply outlets(s).

Preferably also, the extract inlet is arranged substantially perpendicularly to the supply outlets(s).

The unit may comprise a substantially cylindrical form, comprising multiple substantially cylindrical modules and components.

Preferably, the extract circuit is arranged in a central core of the unit. Preferably, the extract circuit comprises a substantially vertical extract channel between the extract inlet and the extract outlet. Preferably therefore, the extract inlet is located centrally in a base of the unit.

Preferably, the extract inlet is annular. The annular extract inlet may be provided by a cover mounted at a spaced distance over said extract inlet. Alternatively, the inlet may comprise an insert suspended within the mouth of the extract inlet, or suspended within the channel at at least the extract inlet end. With an annular extract inlet the convection streams are not drawn together and remain relatively separate, which keeps turbulence within the enclosure to a minimum.

Alternatively, the extract inlet comprises either a single discrete opening, one or more continuous annular (concentric) openings, or a series of discrete openings in annular arrangement in the base of the unit.

Preferably, the extract outlet comprises either a single discrete opening, one or more continuous annular (concentric) openings, or a series of discrete openings in annular arrangement in a top of the unit. The annular extract outlet may be provided by an extract cover mounted at a spaced distance over said extract outlet. Preferably, the extract cover comprises a columnar mount suspended within the mouth of the extract outlet.

Preferably, the extract cover is arranged to provide a constriction in the space between the mouth of the extract outlet and the extract cover. Preferably, therefore, the extract cover comprises an inverted shallow dome shape. With this arrangement, the air speed is increased as it passes through the constriction, thereby increasing the vacuum effect.

Preferably, the extract cover further provides a weather shield and is therefore, wider than the extract outlet. Preferably, the extract cover comprises downwardly turned edge portions to minimise ingress of water, snow, debris. Preferably, the extract cover comprises a flat upper surface in order to reduce turbulence there over.

Preferably, the one or more supply circuits are arranged substantially around the central core. Preferably, at least the supply inlet(s) and the supply outlet(s) are peripheral to the core, although a part of the extract circuit may pass through the core (but remain separate from the extract pathway). Preferably, the supply circuits comprise a substantially horizontal supply inlet channel. Preferably, the supply inlet channel merges into a supply chamber. Preferably, the supply chamber comprises the at least one supply outlet. Preferably therefore, the extract inlet is located centrally in a base of the unit.

In one aspect, the unit comprises a single supply circuit. The single supply circuit may comprise a single supply chamber disposed around the core.

The single supply circuit may comprise a single supply outlet. The single supply outlet may comprise either a single discrete opening, one or more continuous annular (concentric) openings around the unit, or a series of discrete openings in annular arrangement around the unit. With a single supply circuit and the employment of one or more continuous annular openings around the unit or a series of discrete openings in annular arrangement, the supply air streams can be discharged around the periphery of the unit in order to maximise the coverage of the convection paths created within the enclosure.

The single supply circuit may comprise a single supply inlet. The single supply inlet may comprise either a single discrete opening, one or more continuous annular openings around the unit, or a series of discrete openings in annular arrangement around the unit. With a single supply circuit and the employment of one or more continuous annular openings around the unit or a series of discrete openings in annular arrangement, it will not matter from which direction the prevailing wind comes, since the a portion of the supply inlet will always be in the path of the prevailing wind.

In another aspect, the unit comprises two supply circuits.

Preferably, the two supply circuits are mutually exclusive of one another. The two supply circuits may each comprise a single supply outlet. Again, each single supply outlet may comprise either a single discrete opening, one or more continuous part-annular openings around the unit, or a series of discrete openings in part-annular arrangement around the unit. Each single supply inlet may comprise either a single discrete opening, one or more continuous annular openings around the unit, or a series of discrete openings in annular arrangement around the unit.

Alternatively, where there is more than one supply circuit, the supply circuits may be partially integrated with one another. The supply circuits may therefore, share a supply chamber, but comprise separate supply outlets and/or a separate inlet channels and or discrete supply outlet channels from said supply chamber.

The unit may comprise a plurality of mutually exclusive supply circuits, with the appropriate options described above. Preferably, these supply circuit(s) are arranged substantially equally spaced around the perimeter of the core.

Most preferably, the mutually exclusive supply outlets of the two or more mutually exclusive supply circuits are organised in alternate arrangement around the unit. With this above arrangement, the supply outlets of a single supply circuit will be discharged around the periphery of the unit in order to maximise the coverage of the convection paths created within the enclosure.

With multiple mutually exclusive supply circuits, volume of the supply circuits can be reduced, which improves the air pressure and air speed moving through each supply circuit and in turn improves the efficiency of the convection currents in the enclosure. The unit preferably comprises a core extract module comprising the features of the extract circuit. The unit preferably comprises a supply module comprising the features of the supply circuit arranged around the extract module. The unit preferably comprises a mounting module arranged around the supply module.

The supply module preferably comprises a weather shield in the form of a hood.

Preferably, the supply inlets are disposed in an underside of the hood.

The unit is preferably aerodynamic to reduce turbulence and external buffering of the enclosure.

Preferably, the unit comprises a heat recovery device. The heat recovery device preferably comprises a passive heat exchanger.

Preferably, the heat exchanger is fitted within a lower portion of the unit. More preferably, the heat exchanger extends across at least a lower portion of the extract channel and a portion of the supply chamber(s). Most preferably, the heat exchanger extends across at least a lower portion of the extract channel and a significant part of the supply chamber(s).

Preferably, the heat exchanger comprises discrete extract and supply exchange pathways. Preferably, the configuration of the heat exchanger generates two opposing airflows (supply and extract).

Preferably, the heat exchanger comprises at least one heat exchange member. Most preferably, the heat exchanger comprises a plurality or a stack of heat exchange members.

Preferably, the heat exchange members comprise an internal (exchange) airflow pathway. Preferably, therefore, the heat exchange members comprise hollow members and most preferably, hollow plates.

Preferably, the heat exchanger provides an external (exchange) airflow pathway. Preferably, therefore, the heat exchanger comprises a containment member around said heat exchange member(s).

Preferably, said internal (exchange) airflow pathway comprises the extract exchange pathway as part of the extract circuit of the unit. Preferably, therefore, said external (exchange) airflow pathway comprises the supply exchange pathway as part of the supply circuit of the unit.

Preferably, each of said plates comprises a plurality of interconnected disc members. Preferably, each plate comprises two hollow disc members.

Preferably, the hollows of the disc members are connected by at least one channel extending there between and preferably, a plurality of hollow channels extending there between. Preferably, the channels are located around a peripheral region of the discs. Preferably, therefore, each plate comprises an upper hollow disc and a lower hollow disc in spaced stacked arrangement.

The channel(s) preferably extend between an upper wall of the lower disc and a lower wall of the upper disc.

Preferably, the upper disc is upwardly convexly curved. Even more preferably, the lower disc is downwardly convexly curved.

Preferably, the discs are spaced from one another to allow for air flow there between.

The outermost wall of each disc preferably comprises an access aperture to the hollow within. Most preferably, the upper wall of the upper disc and the lower wall of the lower disc comprise a central aperture therein.

Preferably, each plate is adapted to be stacked atop another plate. Preferably, the apertures are adapted to communicate with the aperture of an adjacent plate in stacked arrangement.

Preferably, edge regions of the apertures of the plates are adapted to be fixed together, by permanent or temporary fixing means. Preferably, each plate comprises one part of a cooperative snap-fit or clip mechanism.

The stack may comprise between three and five individual plates.

Preferably, the plates are arranged such that extract airflow through the stack is generally upward and circular (or spiral) through the discs.

Preferably, the containment member provides a plurality of pathways around said periphery of the plate(s).

Preferably, the containment member comprises a wall around said stack of plates. Preferably, therefore, the wall is provided by a main body and a passage there through. Preferably, the passage is substantially cylindrical.

Preferably, the passage comprises at least one wide groove cut into the wall of the passage, more preferably, a plurality of grooves. Preferably, the groove(s) take(s) a spiral path down the inside of the cylindrical wall. The grooves may be uniformly spaced from one another.

Preferably, each groove comprises an inlet located proximal to a top of the containment member. Preferably, each groove comprises an outlet located proximal to a bottom of the containment member. Preferably, the inlets and the outlets of a plurality of grooves are uniformly spaced from one another. Preferably, the plates and the grooves are arranged such that supply airflow through the stack is generally downward and circular (or spiral) between the discs.

Preferably, the outlets comprise generally lateral elongate slots, promoting a laminar supply airstream out of the heat exchanger.

Preferably, each groove completes a full turn of the cylindrical wall of the passage between its inlet and its outlet.

Preferably, the stack is a snug fit within the passage of the containment member. Preferably, therefore, the outer circumference of the stack substantially abuts the wall of the passage leaving the grooves unobstructed.

Preferably, the grooves are arranged relative to the stack such that at a number of points, the grooves communicate with the spaces between the plates and/or the discs of said plates. Preferably therefore, the grooves and the plates provide a plurality of intercommunicating external pathways between external surfaces of the stack within the confines of the containment member.

Preferably, the heat exchanger comprises a wind director. Preferably, the wind director comprises a plurality of radial arms located adjacent one or more of the groove inlets. Preferably, the arms are spaced configured to direct air into said inlets.

Preferably, the heat exchanger comprises an adaptor to link said extract channel with said extract pathway of the plates. Preferably, the adaptor comprises an open-ended conduit configured to bridge the gap between the aperture of the uppermost plate and the extract channel.

Most preferably, the wind director and the adaptor comprise a single component. Preferably, therefore, the arms project from a base of the conduit of the adaptor.

Preferably, the wind director is configured to sit on top of the stack and the containment member, such that the arms rest on an upper face of the containment member.

In a second aspect of the present invention there is provided a passive heat exchanger for a ventilation and/ or humidity control unit, comprising discrete and opposing extract and supply exchange pathways, the heat exchanger comprising at least one heat exchange member, wherein the heat exchanger comprises a containment member around said heat exchange member(s) and the heat exchange member(s) is/ are hollow, wherein the configuration of the containment member and the heat exchange member(s) provides an internal (exchange) airflow pathway through said hollow heat exchange member(s) and an external (exchange) airflow pathway around said heat exchange member(s).

The above described features relating to the heat exchanger also apply to the second aspect of the invention. The unit may comprise one or more modules or components capable of transmitting light there through. Therefore, one or more components of the unit may be transparent or translucent. Preferably, a core portion of the unit is capable of transmitting light there through. Most preferably, the outlet cover, the extract channel, any heat exchanger and any extract inlet cover is capable of transmitting light there through.

The unit may comprise an alternative outlet cover suspended over the extract outlet comprising a lens. The outlet cover may, therefore, comprise an inner domed member and an outer domed member that are configured as a lens. The lens may be focussed onto a diffused Fresnel lens.

The extract circuit may comprise a passive condensation control. The passive condensation control may comprise a water retaining foam, such as that known as Oasis foam'.

The unit may comprise a number of adaptors suitable for use of the unit on different roof profiles, such as flat, inclined, slated, etc. The unit may be fitted with a roof void adaptor where an attic space is present.

Preferably, the components of the unit are coated with a photo catalytic compound to minimise mould, bacteria, etc.

The unit may comprise an insect deter/ killing means or device.

Furthermore, the unit may incorporate one or more humidity and/ or temperature sensors.

The supply inlets may comprise downwardly disposed guide vanes.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show how exemplary embodiments may be carried into effect, reference will now be made to the accompanying drawings in which:

Figure 1 is a schematic cross-sectional view of an exemplary embodiment of a passive ventilation and/ or humidity control unit for an enclosure;

Figure 2 is a cross-sectional view of the unit of Figure 1 ;

Figure 3 is a schematic cross-sectional view of the unit of Figure 1 showing air circuits;

Figure 4 is a schematic cross-sectional view of the unit of Figure 1 mounted on the roof of an enclosure and demonstrating the air paths induced by the unit; Figure 5 is a schematic cross-sectional view of another exemplary embodiment of a passive ventilation and/ or humidity control unit for an enclosure comprising a passive heat exchanger;

Figure 6 is a perspective exploded view of the heat exchanger of Figure 5;

Figure 7 is a cross-sectional view of stacked heat exchange members of the heat exchanger of Figure 5;

Figure 8 is a perspective cross-sectional view of the heat exchanger of Figure 5; and

Figure 9 is a perspective exploded cross-sectional view of the heat exchanger of

Figure 5.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Figure 1 is a perspective view of a passive ventilation and/ or humidity control unit according to an exemplary embodiment.

As shown in Figure 1 , the passive ventilation and/ or humidity control unit (1 ) for an enclosure (2), comprises: at least one extract circuit through which extract air can be drawn from said enclosure (2) to an extract outlet (13); at least one supply circuit through which supply air can be drawn into the enclosure (2) from a supply inlet (22) to a supply outlet (23); and a roof mounting component (31 ), wherein the extract outlet (13) is adapted to facilitate a Venturi effect on said extract circuit, and wherein the (or each) supply outlet (23) is arranged relative to said roof mounting component (30) to dispense a supply air stream proximal to a ceiling (2a) of the enclosure (2) to create a Coanda effect with said ceiling (2a) of said enclosure (2).

By "passive device", what is meant is a unit (1 ) using natural forces to drive the ventilation and/or humidity control of the enclosure (2) with no additional input energy being required to drive the unit (1 ).

The unit (1 ) therefore, comprises an extract module (1 0), a supply module (20) and a mounting module (30).

The extract module (10) comprises a substantially vertical extract channel (1 1 ) extending between an extract inlet (12) and the extract outlet (13). The extract channel (1 1 ) is substantially cylindrical and free of internal contours, but narrows slightly in an upper part to provide the mouth of the extract outlet (13).

An inlet cover (14) is suspended at a distance from the extract inlet (12) and provides an annular opening to the extract channel (1 1 ). The means for suspending the inlet cover (14) can be any suitable means, such as one or more struts or vanes extending from a base of the extract module (10) that do not substantially obstruct the annular opening. An outlet cover (15) is suspended over the extract outlet (13). The outlet cover (15) comprises an inverted shallow dish (16) with flat central portion (16a) and a downwardly turned peripheral edge portion (16b). The dish (16) is larger than the extract outlet (13). A shallow dome (17) extends downwardly from the flat central portion (1 6a) of the dish (16).

The outlet cover (15) is suspended above the extract outlet (13) such that the lowermost point of the dome (17) is positioned centrally over the outlet (13) and almost enters the mouth of the outlet (13). The cover (15) and the outlet (13) therefore, provide a curved and constricted air passage there between.

As shown in Figure 3, the extract circuit comprises the extract inlet (12), the extract channel (1 1 ), the extract outlet (13) and the extract cover (15). Extract air is drawn from an enclosure (2), through the extract inlet (12) and out of the extract outlet (13) via the extract channel (1 1 ). This is achieved by prevailing wind passing between the extract cover (15) and the top of the extract outlet (13), through the constriction, which causes the prevailing air flow to speed up and cause a vacuum in the extract circuit, which draws extract air from the enclosure (2). This is known as the Venturi effect.

The supply module (20) is located around the periphery of the extract module (1 0).

The supply module (20) and the extract module (10) are configured so that the extract and the supply circuits are mutually exclusive of one another.

The supply module (20) and comprises a supply chamber (21 ) located between the supply inlet (22) and the supply outlet (23). The supply chamber (21 ) provides a continuous cavity around the extract module (1 0).

The mounting module (30) is located around a periphery of the supply module (20), which determines a lower room-side part (21 a) and an upper external part (21 b) of the chamber (21 ).

The lower room-side part (21 a) of the chamber (21 ) is therefore, positioned below the mounting module (30) and can project through the ceiling of an enclosure (2), whereas the upper external part (21 b) is positioned above mounting module and can sit on the roof of the enclosure (2).

The lower room-side part (21 a) of the chamber (21 ) comprises a substantially vertical outer wall comprising the supply outlet (23) at a location just below the mounting module (30). The supply outlet (23) comprises a continuous annular aperture around the part 21 (a). The supply outlet (23) is optimally positioned and orientated to dispense the supply air stream in a direction substantially parallel with the ceiling (2a) of the enclosure (2) to further facilitate a Coanda effect with said ceiling (2a) of said enclosure (2). Since the extract inlet (12) is located in a base of the extract module (10), it is arranged substantially perpendicularly to the supply outlets (23). Accordingly, with the positioning and orientation of the supply outlet (23) the vacuum drawing the air flow into the extract inlet (12) does not to impede the operation of the supply outlet(s). However, the extract inlet (12) and the supply outlet (23) are optimally arranged relative to one another to induce effective convection paths in the enclosure (2) by providing space for the supply air stream to travel laterally and fall naturally to cause upward displacement of the lowermost air.

The upper part (21 b) of the chamber (21 ) narrows and then widens into a hood (24). The supply inlet (22) is provided in a substantially horizontal lower wall of the hood (24). The supply inlet (22) comprises a continuous annular aperture around the lower wall of the hood (24).

As shown in Figure 3, the supply circuit comprises the supply inlet (22), the supply hood (24), the supply chamber (21 ) and the supply outlet (23). Supply air is drawn from outside environment, through the supply inlet (22) and out of the supply outlet (23) via the supply chamber (21 ). This is achieved partly by the prevailing wind passing across the roof of the enclosure (2) and partly by the vacuum effect created by the extract circuit.

The unit (1 ) is installed in a roof of an enclosure (2) such that the part (21 a) projects through the ceiling (2a) of the enclosure (2) to be disposed substantially within the enclosure (2). The part (21 b) sits on top of the roof of the enclosure (2) along with the majority of the extract channel (1 1 ), the extract outlet (13) and the extract outlet cover (1 5) to be exposed to the outside environment.

The external contours of the unit (1 ) are arranged to be aerodynamic and reduce turbulence and external buffering of the enclosure (2).

The supply inlets may comprise downwardly disposed guide vanes.

In use, as a prevailing wind moves through the constriction between the top of the extract outlet (13) and the outlet cover (15), the air speed accelerates, which creates a vacuum that acts on the extract circuit. This draws air up and out of the extract outlet (13) (the Venturi effect). The vacuum correspondingly causes air to be drawn in through the supply circuit to maintain the decreasing pressure in the enclosure (2). The positioning of the supply outlet (23) delivers the incoming air stream close to the ceiling (2a) of the enclosure (2) and since such fluid streams have a tendency to be attracted to a nearby surface (the Coanda effect), the supply air travels along the ceiling (2a) of the enclosure (2) displacing air downwardly. As the supply air cools, it falls downwardly to displace cooler air below, which rises as it increases in temperature. The rising air is drawn into the extract circuit. With the arrangement of the described unit (1 ) there is no requirement for a power supply since the unit (1 ) operates entirely passively to effectively provide the required air changes to the enclosure (2). By taking full advantage of the Venturi effect the unit (1 ) effectively extracts air and draws fresh air into the enclosure (2). Since the supply outlet (23) is arranged to dispense the supply air stream in a direction substantially parallel with the ceiling of the enclosure, the unit (1 ) further facilitates exploitation of the Coanda effect, which in turn improves the convection currents in the enclosure (2) to provide a thorough air changeover in the enclosure (2). By carefully arranging the relative positions of the extract inlet (12) and the supply outlet (23), the convection currents in the enclosure (2) can be maximised.

With the continuous annular supply inlet (22) around the unit (1 ) it does not matter from which direction the prevailing wind comes, since the a portion of the supply inlet (22) is always in the path of the prevailing wind.

With this above arrangement, since the supply outlet (23) extends around the periphery of the unit (1 ) convection flows created within the enclosure (2) are maximised.

In an alternative embodiment, as shown in Figures 5 to 8, the unit (1 ) comprises a heat recovery device in the form of a specially adapted heat exchanger (40).

As shown in Figure 5, the heat exchanger (40) is fitted within a lower portion of the unit (1 ) and extends across the supply chamber (21 ) and a lower portion of the extract channel (1 1 ).

The components and arrangement of the exchanger (40) are shown in Figure 6. The exchanger (40) comprises a wind director (41 ), a stack of exchange plates (44) and a containment member (50).

The stack (44) in the present embodiment comprises between three and five individual plates (45). Each plate (45) comprises an upper hollow disc (46) and a lower hollow disc (47) in spaced stacked arrangement. The hollow regions of the upper and lower discs (46, 47) of an individual plate (45) are interconnected via a plurality of hollow channels (48) extending there between, which also serve to space the discs (46, 47) from one another. The channels (48) extend between an upper wall (47a) of the lower disc (47) and a lower wall (46b) of the upper disc (46). The upper disc (46) is upwardly convexly curved, whereas the lower disc (47) is downwardly convexly curved. The upper wall (46a) of the upper disc (46) comprises a central aperture (49a) and the lower wall (47b) of the lower disc (47) comprises a central aperture (49b). Accordingly, each plate (45) comprises an internal pathway (shown by the cross-hatched region) between the central apertures (49a, 49b) of the upper and lower discs (46, 47) via the hollow region of the two discs (46, 47) and the channels (48) extending there between. The spaced arrangement of the discs (46, 47) allows for air flow between the discs

(46, 47).

When two or more plates (45) are stacked on top of one another, the apertures (49a, 49b) communicate with one another to provide an extended internal pathway. Accordingly, edge regions of the apertures (49a, 49b) of adjacent plates (45) are fixed together, by permanent or temporary fixing mechanisms. Ideally, the individual plates (45) comprise a cooperative snap-fit or clip mechanism.

Due to the convex arrangement of each plate (45), the stacked plates (45) have tapered spaces there between in their outer peripheral regions up to the edge regions of the apertures (49a, 49b) where the plates (45) are fixed together.

When the stack (44) is located between the extract inlet (12) and the extract outlet (13) of the previously described unit (1 ), extract airflow through the stack proceeds in an upwardly direction from entering the aperture (49b) of the lower disc (47) of the lowermost plate (45), to the aperture (49a) of the upper disc (46) of the uppermost plate (45).

Although extract airflow through the stack (44) is generally random, the mainstream airflow tends to take a generally upward and circular (or spiral) path through the discs (46, 47), the channels (48) and the apertures (49a, 49b), which is promoted by the Venturi effect.

The containment member (50) comprises a main body (51 ) of any suitable shape to fit within the unit (1 ) and comprises an upper face (51 a), one or more side faces (51 b) and a lower face (51 c). The stack (44) sits within a cylindrical hollow (52) of the containment member (50), the hollow (52) extending between the upper face (51 a) and the lower face (51 c) of the body (51 ).

The hollow (52) comprises four wide grooves (53) cut into the wall of the hollow (52), which take a spiral path down inside the cylindrical wall of the hollow (52). The grooves (53) are uniformly spaced from one another and each groove (53) comprises an inlet (53a) located in the upper face (51 a) of the body (51 ) and an outlet (53b) located in the side face(s) of the body (51 b). Again, the inlets (53a) and the outlets (53b) are uniformly spaced from one another. The outlets (53b) are provided as generally lateral elongate slots, which provide a laminar supply airstream out of the heat exchanger (40).

Generally, each groove (53) completes a full turn of the cylindrical wall of the hollow

(52) between its inlet (53a) and its outlet (53b), although it will be appreciated that this will depend on the height of the hollow (52), the stack (44) to be located therein and the tightness of the spiral.

With the stack (44) located inside the hollow (52) of the containment member (50) is a snug fit and the outer circumference of the stack (44) substantially abuts the wall of the hollow (52) leaving the grooves (53) unobstructed. Accordingly, the grooves (53) provide a plurality of external spiral pathways around the outer circumference of the stack (44). However, since the plates (45) and the discs thereof (46, 47) are stacked in spaced arrangement, at a number of points, the grooves (53) also communicate with the spaces between the plates (45)/discs (47, 47) to provide a plurality of intercommunicating external pathways through/ between the external surfaces of the stack (44).

Although supply airflow around the stack (44) is guided in a generally downwardly direction from entering the inlets (53a) of the grooves (53) to the outlets (53b), the mainstream airflow tends to be forced between the plates (45) and the discs (46, 47) thereof. This means that the supply airflow is guided and forced across approximately 90% of the surface area of the plates (45).

Accordingly, the configuration of the heat exchanger (40) generates two opposing airflows (supply and extract). The two airflows never come into physical contact with one another, but since both airflows travel across opposing sides of the walls of the plates (45), where there is a temperature differential, heat exchange occurs between the two air flows.

The special arrangement of the exchanger (40) provides a number of advantages when compared with a conventional plate heat exchanger, including:

1 . The vertical stacked arrangement of the plates (45) of the heat exchanger (40) allows very low pressure air to pass through ;

2. The passive nature of the airflow allows for a long dwell-time over the surfaces of the heat exchanger (40) improving heat exchange and thermal efficiency;

3. The spiral grooves (53) distribute the air randomly over the exchanger (40) plates

(45) further improving thermal efficiency; and

4. The spiral grooves (53) slow the airflow through the exchanger (40) thus improving thermal efficiency.

The wind director (41 ) comprises an open ended conduit (42) and a plurality (four) of radial arms (43) projecting from a base of the conduit (42). The arms (43) are equally spaced around the base of the conduit (42).

The wind director (41 ) sits on top of the stack (44) and the containment member (50), so that the arms (43) are rest on the upper face (51 a) of the containment member (50). A bottom portion of the conduit (42) sits directly over the aperture (49a) of the upper disc (46) of the uppermost plate (45) in the stack (44), whilst an upper portion of the conduit (42) fits snugly with the extract channel (1 1 ). The wind director (41 ) is orientated such that the arms (43) are positioned on the upper face (51 a) of the containment member (50) between adjacent inlets (53a). The function of the wind director (41 ) is two-fold: to direct incoming wind in to the inlets (53a); and (b) to provide a link between the extract channel (1 1 ) and the internal extract pathways of the plates (45) of the heat exchanger stack (44).

As shown in Figure 5, the unit (1 ) comprises an alternative outlet cover (150) suspended over the extract outlet (13). The outlet cover (150) comprises an inner domed member (151 ) and an outer domed member (152) that are translucent in nature. The domes (151 , 152) are configured as a lens which is focussed onto a diffused Fresnel lens (not shown).

Additionally, or alternatively, one or more modules or components of the unit (1 ) are capable of transmitting light there through.

In yet another embodiment, the extract circuit comprises a passive condensation control in the form of water retaining foam, such as that known as oasis foam. Any water in the extract airflow will be condensed and retained by the foam, before the extract air is re- entrained to exit the unit (1 ).

The unit (1 ) can be fitted with a number of adaptors suitable for use on different roof profiles, such as flat, inclined, slated, etc. The unit (1 ) can also be fitted with a roof void adaptors where an attic space is present, by providing an extension kit.

Ideally, the individual components of the unit (1 ) are coated with a photo catalytic compound to minimise mould, bacteria, etc.

Furthermore, the unit (1 ) may comprise an insect deter/ killing means or device.

Furthermore, the unit (1 ) may incorporate a humidity and/ or temperature sensor.

Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention.

Claims

1 . A passive ventilation and/ or humidity control unit for an enclosure, the unit comprising:

a roof mounting component,

wherein the extract outlet is adapted to facilitate a Venturi effect on said extract circuit, and

wherein the (or each) supply outlet is arranged relative to said roof mounting component to dispense a supply air stream proximal to a ceiling of the enclosure to create a Coanda effect with said ceiling of said enclosure.

2. The unit according to Claim 1 , wherein the (or each) supply outlet is arranged to dispense the supply air stream in a direction substantially parallel with the ceiling of the enclosure to further facilitate a Coanda effect with said ceiling of said enclosure.

3. The unit according to Claim 1 or 2, wherein the extract circuit and the supply circuits are mutually exclusive of one another within said device.

4. The unit according to Claim 3, wherein an extract inlet of the extract circuit and the (one or more) supply outlet(s) are arranged relative to one another to further induce one or more convection paths in said enclosure.

5. The unit according to Claim 4, wherein the extract inlet is arranged behind each (of the) supply outlets(s).

6. The unit according to Claim 5, wherein the extract inlet is arranged substantially perpendicularly to the supply outlets(s).

7. The unit according to any one of Claims 1 to 6, wherein the unit comprises a substantially cylindrical form, comprising multiple substantially cylindrical modules and components.

8. The unit according to any one of Claims 1 to 7, wherein the extract circuit is arranged in a central core of the unit.

9. The unit according to Claim 8, wherein the extract circuit comprises a substantially vertical extract channel between the extract inlet and the extract outlet.

10. The unit according to Claim 9, wherein the extract inlet is located centrally in a base of the unit.

1 1 . The unit according to any one of Claims 4 to 1 0, wherein the extract inlet is annular and is provided by a cover mounted at a spaced distance over said extract inlet.

12. The unit according to any one of Claims 4 to 10, wherein the extract inlet comprises either a single discrete opening, one or more continuous annular (concentric) openings, or a series of discrete openings in annular arrangement in the base of the unit.

13. The unit according to any one of Claims 1 to 12, wherein the extract outlet comprises either a single discrete opening, one or more continuous annular (concentric) openings, or a series of discrete openings in annular arrangement in a top of the unit.

14. The unit according to Claim 13, wherein the annular extract outlet is provided by an extract cover mounted at a spaced distance over said extract outlet.

15. The unit according to Claims 14, wherein the extract cover is arranged to provide a constriction in the space between the mouth of the extract outlet and the extract cover.

16. The unit according to any one of Claims 8 to 15, wherein the one or more supply circuits are arranged substantially around the central core.

17. The unit according to Claim 16, wherein at least the supply inlet(s) and the supply outlet(s) are peripheral to the core, although a part of the extract circuit passes through the core (but remains separate from the extract pathway).

18. The unit according to any one of Claims 1 to 17, wherein the supply circuits comprise a substantially horizontal supply inlet channel that merges into a supply chamber comprising the at least one supply outlet.

19. The unit according to any one of Claims 4 to 18, wherein the extract inlet is located centrally in a base of the unit.

20. The unit according to any one of Claims 1 to 19, wherein the unit comprises a core extract module comprising the features of the extract circuit and a supply module comprising the features of the supply circuit arranged around the extract module, with a mounting module arranged around the supply module.

21 . The unit according to any one of Claims 1 to 20, wherein the unit is aerodynamic to reduce turbulence and external buffering of the enclosure.

22. The unit according to any one of Claims 1 to 21 , wherein the unit comprises a heat recovery device.

23. The unit according to Claim 22, wherein the heat recovery device comprises a passive heat exchanger.

24. The unit according to Claim 23, wherein the heat exchanger extends across at least a lower portion of the extract channel and a portion of the supply chamber(s).

25. The unit according to any one of Claims 23 to 24, wherein the heat exchanger comprises discrete extract and supply exchange pathways and the configuration of the heat exchanger generates two opposing airflows (supply and extract).

26. The unit according to any one of Claims 23 to 25, wherein the heat exchanger comprises a plurality or a stack of heat exchange members.

27. The unit according to Claim 26, wherein the heat exchange members comprise an internal (exchange) airflow pathway therefore, comprising hollow members and hollow plates.

28. The unit according to any one of Claims 26 to 27, wherein the heat exchanger provides an external (exchange) airflow pathway by comprising a containment member around said heat exchange member(s).

29. The unit according to any one of Claims 27 to 28, wherein, each of said plates comprises a plurality of interconnected disc members with each plate comprising two hollow disc members.

30. The unit according to Claim 29, wherein the hollows of the disc members are connected by at least one channel extending there between and a plurality of hollow channels extending there between and located around a peripheral region of the discs.

31 . The unit according to Claim 30, wherein each plate comprises an upper hollow disc and a lower hollow disc in spaced stacked arrangement with the channel(s) extending between an upper wall of the lower disc and a lower wall of the upper disc.

32. The unit according to Claim 31 , wherein an upper wall of the upper disc and a lower wall of the lower disc comprise a central aperture therein.

33. The unit according to Claim 22, wherein the apertures are adapted to communicate with the aperture of an adjacent plate in stacked arrangement.

34. The unit according to Claim 33, wherein the plates are arranged such that extract airflow through the stack is generally upward and circular (or spiral) through the discs.

35. The unit according to any one of Claims 28 to 34, wherein the containment member provides a plurality of pathways around said periphery of the plate(s).

36. The unit according to Claim 35, wherein the containment member comprises a wall around said stack of plates provided by a main body and a passage there through.

37. The unit according to Claim 36, wherein the passage comprises at least one wide groove cut into the wall of the passage, wherein each groove(s) take(s) a spiral path down the inside of the cylindrical wall.

38. The unit according to Claim 37, wherein each groove comprises an inlet located proximal to a top of the containment member and an outlet located proximal to a bottom of the containment member.

39. The unit according to Claim 37 or 38, wherein the grooves are arranged relative to the stack such that at a number of points, the grooves communicate with the spaces between the plates and/or the discs of said plates to provide intercommunicating external pathways between external surfaces of the stack within the confines of the containment member.

40. In a second aspect of the present invention there is provided a passive heat exchanger for a ventilation and/ or humidity control unit, comprising discrete and opposing extract and supply exchange pathways, the heat exchanger comprising at least one heat exchange member, wherein the heat exchanger comprises a containment member around said heat exchange member(s) and the heat exchange member(s) is/ are hollow, wherein the configuration of the containment member and the heat exchange member(s) provides an internal (exchange) airflow pathway through said hollow heat exchange member(s) and an external (exchange) airflow pathway around said heat exchange member(s).