The present invention relates to ventilation of an interior space such as one or more rooms within a building.

During recent years the general trend, driven by C02 reduction legislation in the construction industry, has been for residential and commercial buildings to become more airtight, this being the result of efforts to decrease the leakage of heat through exfiltration. Although this trend has led to increases in the energy efficiency of buildings, preventing exchange of air with outside spaces can lead to low indoor airflow and unhealthy indoor air quality (IAQ) for occupants and create moisture induced decay in the building fabric. While opening windows and doors provides a certain level of ventilation, doing so allows trapped heat to escape and generally does not provide adequate ventilation rates.

Many buildings include a means of mechanical ventilation to allow contaminated air within spaces to be extracted and replaced with makeup air via infiltration from unintended gaps in the building envelope or via purpose provided means. A simple solution is to provide an extraction fan in e.g. a wet room such as a kitchen or bathroom which draws moist or contaminated air out of the space. The extracted air will be replaced with air drawn from other parts of the building and/or through any existing infiltration. This uncontrolled infiltration of air is undesirable since unsuitable air can be inadvertently drawn into the space, replacing e.g. warm air within the building with cold air from outside in the winter condition, or replacing cool air with warm air from outside in the summer condition. While problems of air contamination may have been addressed, the air inside the space will need to be re-heated or re-cooled in order to maintain habitable conditions, leading to increased energy consumption and CO2 emissions. There exists a need for a ventilation system that can provide whole-house controlled ventilation that can control IAQ on a room-by-room basis and which can choose and/or control the condition of the ventilation make-up air.

Whole-house ventilation solutions, such as Mechanical Ventilation with Heat Recovery (MVHR), typically use a central heat recovery unit connected ductwork to ventilate a building while transferring heat from the outgoing warm air to the incoming cooler air. Although MVHR systems can partially reduce the effects of ventilation heat loss, they require extensive ductwork to link rooms with the heat recovery unit, which impinges on living space, as well as a high degree of building envelope airtightness, to work effectively. The variety of design and construction of buildings means that such systems are often onsite designed and bespoke for the intended building, which often results in error-prone installation and poor performance. Such systems are therefore impractical to install in existing buildings and problematic to install in new buildings. Furthermore, sizable fans which consume sizeable amounts of energy and that can create significant levels of noise are required to transport air along the ductwork. These drawbacks mean that ducted ventilation systems such as MVHR are often switched off by occupants, exacerbating the problems of poor IAQ.

It is an object of the invention to obviate or mitigate one or more the problems outlined above. In particular, it is an object of the invention to provide an improved ventilation system that can easily be installed or retrofitted within an existing building or within a new building.

It is an additional or alternative object of the invention to provide a ventilation system that avoids the requirement of ductwork for air transport.

It is an additional or alternative object of the invention to provide a ventilation system that is compact and does not impinge on living space.

It is an additional or alternative object of the invention to provide a ventilation system which can provide whole-house ventilation.

It is an additional or alternative object of the invention to provide a ventilation system which can provide modulation of ventilation dependent on indoor airborne pollution loads.

It is an additional or alternative object of the invention to provide a ventilation system which can provide modulation of ventilation dependent on outdoor airborne pollution loads.

It is an additional or alternative object of the invention to provide a ventilation system that is not dependent on building envelope airtightness level to operate efficiently.

It is an additional or alternative object of the invention to provide a ventilation system which can provide controlled ventilation on a room-by-room basis.

It is an additional or alternative object of the invention to provide a ventilation system that can provide space heating on a room-by-room basis.

It is an additional or alternative object of the invention to provide a ventilation system that can provide passive cooling on a room-by-room basis.

It is an additional or alternative object of the invention to provide a ventilation system which can dynamically choose suitable makeup air to ventilate a building with.

It is an additional or alternative object of the invention to provide a ventilation system that can facilitate smart-grid demand side response.

According to a first aspect of the present invention, there is a ventilation system for use in a building having a first group of rooms and a second group of rooms, the ventilation system comprising: one or more air intake arrangements each comprising an intake passage for mounting in communication with a respective room of the first group and with the exterior, and an intake fan configured to draw air through the intake passage from the exterior into said room of the first group at a controlled rate, the air intake arrangement being provided with a first sensor arrangement for sensing pollutant concentration in the air in said room of the first group; one or more air extraction arrangements each comprising an extraction passage for mounting in communication with a respective room of the second group and with the exterior, and an extraction fan configured to draw air through the extraction passage from said room of the second group to the exterior at a controlled rate, the air extraction arrangement being provided with a second sensor arrangement for sensing pollutant concentration in the air of said room of the second group; and a control arrangement for controlling the intake fan(s) and the extraction fan(s) such that: in the event that a sensed pollutant concentration in any of said rooms of the first group exceeds a threshold, the intake fan of the intake arrangement mounted in that room is activated; in the event that a sensed pollutant concentration in any of said rooms of the second group exceeds a threshold, the extraction fan of the extraction arrangement associated with that room is activated; and a balance is maintained between the total rate of air intake and the total rate of air extraction.

The first group or rooms and / or the second group of rooms may comprise a single room or a plurality of rooms.

The invention provides a means of actively managing air flow through the building without need of a network of connected ducts.

The first group of rooms may comprise “dry rooms”, expected to have lower humidity, such as hallways, living rooms, bedrooms and so on.

The second group of rooms may comprise “wet rooms” - rooms containing apparatus which can raise humidity in those rooms. Examples are bathrooms and shower rooms, since baths and showers form a source of atmospheric water vapour, and possibly also kitchens, where cooking can raise humidity, as can for example the use of a kitchen sink. The term “pollutant” as used herein must be understood to cover a range of air-borne materials, and in particular (and wholly without limitation) to include: air-borne water vapour and moisture; excess atmospheric carbon dioxide. Of course, CO ₂ is a natural constituent of air, but the respiration of the occupants of a room can raise its concentration, and a high level of CO ₂ is undesirable, in terms of IAQ; nitrogen oxides (NO _x ), a widespread pollutant created for example by internal combustion engines and other industrial processes involving combustion; air-borne organic compounds and especially volatile organic compounds (VOCs), which are widespread in the modern world; excess atmospheric ozone (O ₃ ), which is toxic and which is thought to be a factor I health conditions including asthma; radon and other gases not normally found in atmospheric air; excess air-borne particulate matter.

Either of the first and second sensor arrangements may be sensitive to one or more of the above pollutants.

The intake passage(s) and the extraction passage(s) can be formed as short through- wall pipes or other conduits leading from the relevant room to the exterior of the building. They are not connected to one another and unlike a conventional MVHR system, the invention is not reliant on a network of ducts leading from one room to another, making it straightforward to retro-fit in an existing building or to install in a new building. By managing both active intake of air and active extraction of air, the invention makes it possible to control the flow of air through the building without need of such a network of ducts.

The total rate of air intake and the total rate of air extraction may be balanced in the sense that the sum of the rates of air intake through the air intake arrangement(s) is maintained at a level equal to the sum of the rates of air extraction through the air extraction arrangement(s).

In a preferred embodiment, the control arrangement is configured to maintain a balance between the total rate of air intake and the total rate of air extraction by: activating an additional air intake arrangement, or increasing the rate of air intake through an active air intake arrangement, in the event that the total rate of air extraction through the extraction arrangement(s) would otherwise exceed the total rate of air intake; activating an additional air extraction arrangement, or increasing the rate of extraction through an active air extraction arrangement, in the event that the total rate of air intake through the intake arrangement(s) would otherwise exceed the rate of air extraction.

It is sometimes appropriate to activate ventilation of a room in response to occupation of the room. In a preferred embodiment, at least one of the air extraction arrangements and/or at least one of the air intake arrangements is further provided with a motion sensor responsive to motion in its respective room, or with a proximity or people counter sensor, the control arrangement being configured to activate that air extraction arrangement or air intake arrangement in response to detection of motion or people in that room. The motion sensor may for example take the form of a passive infra-red sensor (a “PIR”).

It may be desirable to regulate the rate of air intake or extraction in a room in response to sensed pollutant level.

In a preferred embodiment of the present invention, at least one of the air extraction arrangements and/or at least one of the air intake arrangements comprises a fan configured to provide a variable throughput, and in which the control arrangement is configured to control the throughput of that fan in closed-loop manner, using a sensed pollutant level as the control variable.

A problem can arise where the air external to the building carries an undesirable level of one or more pollutants - in that case increasing ventilation of the building in an uncontrolled manner may worsen air quality, or at least fail to improve it. In certain embodiments, the control arrangement may be configured to select where intake air is drawn from, in order to obviate this problem.

In a preferred embodiment of the present invention, the ventilation system comprises an external sensor arrangement for sensing pollutant concentration in a zone outside the building, the control arrangement being configured to de-activate air intake arrangement(s) drawing air from that zone in the event that sensed pollution concentration in that zone exceeds a threshold.

The external sensor arrangement needs to be exposed to the external air in the said zone. To that end, it may be placed outside the building. It may instead by placed in or adjacent the intake passage of one of the air intake arrangement(s), since it will thereby be exposed to the air entering from outside the building. More than one external sensor arrangement many be provided, monitoring more than one external zone. Each of the air intake arrangements may be provided with a respective external sensor arrangement, in order that any of them is able to be shut down in the event that the external air in the zone form which it draws air is of poor quality.

Ventilation involves an exchange of air with the exterior of the building. On a cold day (or to be more specific, on a day when the exterior air temperature is lower than the air temperature of a room in the building) this can mean that heat is lost to the exterior, which can add to the building’s energy usage if it is being heated. On a warm day (when the exterior air temperature is higher than that of the air in a room), the intake of air may undesirably increase the temperature in the building which can add to the building’s energy usage if it is being cooled.

The ventilation system to the present invention may be configured to preferentially expel air from cold rooms of the building, in order to minimise heat loss.

The ventilation system may be configured to preferentially expel air from warm rooms in the building, in order to minimise heat loss.

In a preferred embodiment of the present invention, the ventilation system comprises at least two air extraction arrangements each provided with a respective temperature sensor, whereby the control arrangement is able to determine which of the air extraction arrangements is in the colder room, the control arrangement being operable in a first mode in which, when air extraction is required, it activates the air extraction arrangement in the colder room in preference to the air extraction arrangement in the warmer room.

The control arrangement may, in a further preferred embodiment, be operable in a second mode in which, when air extraction is required, it activates the air extraction arrangement in the warmer room in preference to the air extraction arrangement in the colder room.

The first mode may be selected on cold days, in order to minimise heat loss. The second mode may be selected on warm days, when the priority is to minimise the building’s interior temperature.

A further problem can arise where external air quality is locally poor, in that intake of air to a certain room or rooms from an exterior zone having poor air quality may not be able to provide an improvement of indoor air quality in the relevant room(s). The control means may be configured, in response to this condition, to cause air to be expelled through one or more air intakes of the ventilation system. In this mode of operation, the requirement for balancing of airflow is suspended. In a preferred embodiment of the present invention, the control arrangement is configured to be operable in a contingency mode to cause air to be expelled from a selected room or rooms in the first group by suspending the balancing of airflow, causing the air intake arrangement(s) in the said at least one room(s) to be inactivated, causing the air extraction arrangements to be inactivated, and operating the air intake arrangement(s) in one or more rooms of the first group other than the selected room(s), thereby causing air to be expelled through the air intake arrangement(s) of the selected room(s).

In this operating mode, air may be taken into the building through certain rooms in the first group, and expelled through others. The system may in particular exploit variations in outdoor air quality in the vicinity of the building to provide the best possible indoor air quality. In particular, the system may activate those air intake arrangements drawing air from less polluted zones outside the building, inactivating those that would be drawing air from more polluted zones.

According to a second aspect of the present invention, there is a method of operating a ventilation system in a building having a first group of rooms and a second group of rooms, the ventilation system comprising: one or more air intake arrangements each comprising an intake passage for mounting in communication with a respective room of the first group and with the exterior, and an intake fan configured to draw air through the intake passage from the exterior into said room of the first group at a controlled rate, the air intake arrangement being provided with a first sensor arrangement for sensing pollutant concentration in the air in said room of the first group; one or more air extraction arrangements each comprising an extraction passage for mounting in communication with a respective room of the second group and with the exterior, and an extraction fan configured to draw air through the extraction passage from said room of the second group to the exterior at a controlled rate, the air extraction arrangement being provided with a second sensor arrangement for sensing pollutant concentration in the air of said room of the second group; and the method comprising controlling the intake fan(s) and the extraction fan(s) such that: in the event that a sensed pollutant concentration in any of said rooms of the first group exceeds a threshold, the intake fan of the intake arrangement mounted in that room is activated; in the event that a sensed pollutant concentration in any of said rooms of the second group exceeds a threshold, the extraction fan of the extraction arrangement associated with that room is activated; and a balance is maintained between the total rate of air intake and the total rate of air extraction.

According to a further aspect of the invention there is provided a ventilation system for ventilation of an interior space, the ventilation system comprising: an air extraction means for extracting air from a primary space within the interior space; an air supply means for providing a supply of air to the primary space; and a control means for controlling the operation of the air extraction means and/or air supply means. Advantageously, using such a ventilation system, the air supply means can supply fresh makeup air into the space and the air extract unit can extract stale air from the space while being dynamically controlled by the control means.

Ideally the airflow through the interior space is balanced such that air entering the interior space through the air supply means is substantially equal to the air leaving the interior space through the air extraction means. Advantageously, this allows the ventilation system to maintain a neutral air pressure in the space during ventilation, reduces the amount of unwanted makeup air entering the primary space during ventilation, reduces the amount of airborne pollution entering the primary space from conjoined buildings through porous party walls and floors, and reduces radon gas being drawn in via the sub-floor.

The interior space may be divided into N spaces where N is greater than or equal to 1.

The air supply means may provide a supply of air directly to the primary space.

The air supply means may provide a supply of air indirectly to the primary space.

The air supply means may provide a supply of air to the primary space indirectly via one or more spaces within the interior space.

The air supply means may provide a supply of air directly to a secondary space within the interior space.

The secondary space may be in direct fluid communication with the primary space, or in indirect fluid communication with the primary space via one or more spaces such as an intermediate space.

The air supply means may provide a supply of air directly to a further space within the interior space.

The further space may be in direct fluid communication with the primary space, or in indirect fluid communication with the primary space via one or more spaces such as an intermediate space. The air supply means and air extraction means may be physically separate units. Advantageously having separate units allows for there to be e.g. a large distance between the air extraction means and air supply means such that they may be located on opposite sides of a building without any connecting ductwork.

The ventilation system may include a plurality of air extraction means for extracting air from the interior space.

The ventilation system may include a plurality of air supply means for supplying air to the interior space.

The control means may be operable to select a subset of the available air extraction means and/or air supply means for activation and/or deactivation.

The control means may be operable to activate and/or deactivate a plurality of air extraction means and/or air supply means in order to ventilate the interior space.

The control means may be operable to activate and/or deactivate a subset of the plurality of air extraction means and/or air supply means in order to ventilate the interior space.

The ventilation system may be a de-central ised ventilation system.

The interior space may correspond to space within a building.

The interior space may correspond to space within a container, hospital, house, dwelling or non-domestic building.

The primary space, secondary space and/or further space may be defined by partitions, walls, ceilings, roofs, floors, doors, doorways and/or windows within the interior space.

The primary space may be in fluid communication with the secondary space and/or any further space such as an intermediate space via a doorway, door, window, aperture, channel or path.

The primary space, secondary space and/or further space such as an intermediate space may each be one or more spaces, rooms or floors within a container, building, hospital, house, dwelling or non-domestic building.

The or each of the primary space, secondary space, and/or further space such as an intermediate space may be any combination of one or more rooms such as wet rooms, bathrooms, lavatories, ensuites, shower rooms, kitchens, living rooms, treatment rooms, waiting rooms, lounges, dining rooms, bedrooms, attics, porches, hallways, corridors or stairwells. The or each air extraction means may be in fluid communication with one or more exhaust spaces.

The or each exhaust space may be an external region or space outside of the interior space.

The or each exhaust space may be an external region or space outside of the building.

The or each exhaust space may be an external region or space outside of the container, hospital, house, dwelling or non-domestic building.

The or each exhaust space may be a space, room or floor within the building.

The or each exhaust space may be a space, room or floor within the hospital, house, dwelling or non-domestic building.

The or each air supply means may be in fluid communication with one or more air intake spaces.

The or each air intake space may be an external region or space outside of the interior space.

The or each air intake space may be an external region or space outside of the building. The or each air intake space may be an external region or space outside of the container, house, dwelling or non-domestic building.

The or each air intake space may be a space, room or floor within the interior space.

The or each air extraction means may provide a fluid exit from the interior space. The or each air extraction means may provide a fluid exit from the primary space.

The or each air extraction means may provide a fluid path between the interior or primary space and an exhaust space.

The or each air extraction means may be installed at the boundary of the interior or primary space.

The or each air extraction means may be installed in a wall, partition, ceiling, roof, door, doorway and/or window.

The or each air extraction means may comprise one or more exhaust apertures. The or each air extraction means may comprise one or more exhaust paths.

The or each air extraction means may comprise at least one exhaust pipe. The or each exhaust pipe may be a through-wall pipe. The or each exhaust pipe may be a telescopic pipe. Advantageously, providing a telescopic pipe allows the system to be installed in a variety of walls of various thicknesses and designs.

The or each exhaust pipe may be cylindrical. The or each exhaust pipe may have a first end.

The first end of the or each exhaust pipe may be located within or adjacent to the interior space.

The or each exhaust pipe may have a second end located opposite the first end thereof. The or each air extraction means may comprise one or more extraction fans.

The or each extraction fan may cause air to flow through the or each exhaust pipe from the first end to the second end thereof.

The or each extraction fan may be positioned within or adjacent to an exhaust path, aperture, or pipe.

The or each extraction fan may be attached to the first end of an exhaust pipe. One or more extraction fan(s) may be positioned within the interior space.

One or more extraction fan(s) may be positioned outside the interior space. Advantageously, positioning extraction fans outside of the interior space can provide a reduction in noise transmission into the interior space created by the air extraction means.

One or more extraction fan(s) may be positioned in an exhaust space.

One or more extraction fan(s) may be externally mounted extract fan(s). The or each externally mounted extract fan may incorporate a cowl.

The or each extraction fan may be a centrifugal fan.

The or each extraction fan may be an axial fan.

The or each extraction fan may be a variable-speed fan.

The or each extraction fan may be a variable-speed fan having one or more predefined speed settings. Advantageously, having a plurality of stepped speeds provides a plurality of preset flow rates of air that can be used to extract air from a space.

The air extraction means may comprise a cowl. Advantageously, the use of a cowl can provide reduction of air draughts through the air extraction means. The cowl may be located proximal to the second end of an exhaust pipe. The cowl may be attached to the second end of an exhaust pipe.

The cowl may be hinged. Advantageously, hinged attachment of the cowl allows access to the interior of the air extraction means for cleaning and maintenance/replacement of parts.

The air extraction means may include a filter. Advantageously the filter may protect components within the air extraction means such as the air extraction fan from any extracted airborne pollutants.

The filter may be a pleated, disc, cylindrical, canister or electrostatic filter. The or each filter may be provided within an air exhaust pipe.

The or each filter may be provided outside an air exhaust pipe. The or each filter may be removable and replaceable.

The air supply means may provide a fluid path into the interior space.

The air supply means may provide a fluid path into the primary space, secondary space and/or further space such as an intermediate space.

The air supply means may provide a fluid path between the intake space and the interior space.

The air supply means may provide a fluid path between the primary space, secondary space and/or further space such as an intermediate space. The air supply means may be installed at the boundary of the interior space.

The air supply means may be installed at the boundary of the primary space, secondary space and/or further space such as an intermediate space.

The air supply means may be installed in a partition, wall, ceiling, roof, floor, door, doorway and/or window. The air supply means may comprise one or more intake apertures.

The air supply means may comprise one or more intake paths.

The air supply means may comprise at least one intake pipe.

The or each intake pipe may be a through-wall pipe.

The or each intake pipe may be a telescopic pipe. The or each intake pipe may be cylindrical.

The or each intake pipe may have a first end.

The first end of the or each intake pipe may be located within or adjacent to the interior space.

The or each intake pipe may have a second end located opposite the first end thereof.

The air supply means may comprise one or more supply fans. Advantageously, the supply fans may be used to draw air into the interior space, primary space, secondary space and/or further space such as an intermediate space to create a balanced airflow therein.

The or each supply fan may cause air to flow through the or each intake pipe from the or each second end to the or each first end thereof.

The or each supply fan may be positioned within or adjacent to an intake path, aperture, or pipe.

The or each supply fan may be positioned within the interior space. The or each supply fan may be a centrifugal fan.

The or each supply fan may be an axial fan.

The or each supply fan may be a variable-speed fan.

The or each supply fan may be a variable-speed fan having one or more predefined speed settings. Advantageously, having a plurality of speed settings provides a plurality of preset flow rates of air.

The ventilation system may comprise a filter.

The air supply means may include a filter. Advantageously the filter can protect occupants within the interior space and components within the air supply means (such as the air supply fan) from any makeup air airborne pollutants.

The filter may be a pleated, disc, cylindrical, canister or electrostatic filter. The or each filter may be provided within an air intake pipe.

The or each filter may be provided outside an air intake pipe.

The or each filter may be removable and replaceable.

The or each air supply means may include a heating element such as a resistive heating element. Advantageously, the heating element can be used to warm the air from the air intake space prior to it being brought into the interior space. The or each air supply means may comprise a cowl. Advantageously, the cowl can provide reduction of air draughts through the air supply means.

The cowl may be attached to the second end of the pipe of the air supply means.

The cowl may be hingedly attached to the second end of the pipe of the air supply means. Advantageously, hinged attachment of the cowl allows access to the interior of the air supply means for cleaning and maintenance/replacement of parts such as the filter.

The or each air supply means may comprise a nozzle.

The or each nozzle may be a Coanda nozzle. Advantageously, the use of a Coanda nozzle causes the three-dimensional jet of air expelled from the air supply means to adhere to and travel along an upper surface or ceiling of the interior space.

The control means may be in wireless communication with the air extraction means and/or air supply means.

The air extraction means, air supply means and/or control means may include wireless communication means.

The wireless communication means may comprise a wireless transmitter, wireless transmitter-receiver, wireless transceiver or wireless router.

The air extraction means, air supply means and/or control means may be connected via a wireless network.

Preferably, the wireless network is one of a wireless personal area network (WPAN), a wireless local area network (WLAN), a cellular network, the internet, an intranet, a long range wireless area network (LoRaWAN), a low power wireless area network (LPWAN), GSM, NFC, Bluetooth or WiFi. Any suitable wireless network may be used.

The control means may comprise a processing unit.

The control means may comprise a memory. Advantageously the memory is adapted to store program instructions and/or algorithms to control operation of the ventilation system. Furthermore, the memory can be adapted to store sensor data measured by sensing means within the ventilation system.

The control means may comprise a control hub.

The control means may be in wireless communication with the air extraction means and/or air supply means via a wireless local area network (WLAN), and a cellular network, the internet, an intranet, a long range wireless area network (LoRaWAN), a low power wireless area network (LPWAN), GSM, NFC, Bluetooth or WiFi.

The control means may be connectable to the cloud via the internet. Advantageously it is possible to store program instructions and/or algorithms to control operation of the ventilation system and/or sensor data in the cloud.

The control means may be connectable to an electricity utility grid network operation, via the internet, a cellular network or LoRaWAN. Advantageously, connection to a utility grid network operation allows the control hub to facilitate smart grid demand-side response.

The control means may be connected to third party data services via the internet, cellular network or LoRaWAN. Advantageously, connection to third party data services allows the control means to facilitate efficient energy consumption, ensure the quality of outside makeup air and non-IAQ costs (such as thermal discomfort or noise) of the ventilation system.

The control means may comprise, or be connectable to, a mobile computing device.

The control means may be integrally connected to the air supply means or air extraction means.

The control means may comprise a user interface. Advantageously the user interface can be used to establish and adjust one or more settings for the ventilation system. The user interface may comprise a touch screen. The user interface may have antimicrobial properties.

The ventilation system may include a sensing means. The sensing means may be selectively activated and/or deactivated.

The air extraction means, air supply means and/or control means may be in operable communication with the sensing means.

The sensing means may be physically connected to or integrated with the air extraction means, air supply means and/or control means. The sensing means may be located proximal to the air extraction means and/or air supply means.

The sensing means may be located distal to the air extraction means, air supply means and/or control means.

The sensing means may comprise one or more sensors. The sensing means may comprise a plurality of sensors distributed throughout the interior space and/or within or adjacent to the air intake space(s).

The sensing means may comprise one or more environmental condition sensors.

The sensing means may comprise one or more relative humidity sensor(s), absolute humidity sensor(s), vapour pressure sensor(s), air quality sensor(s), temperature sensor(s), carbon dioxide sensor(s), carbon monoxide sensor(s), total volatile organic compounds (TVOCs) sensor(s), nitrogen dioxide sensor(s), sulphur dioxide sensor(s), ozone sensor(s), formaldehyde sensor(s), methane sensor(s), radon sensor(s), particulate matter sensor(s), smoke sensor(s), environmental tobacco smoke sensor(s) or pressure sensor(s) or any other suitable type of sensor.

The sensing means may comprise a presence sensor or motion sensor for detecting the presence or movement of a person within a space or room. Advantageously, the sensing of presence or motion in the space may be used to infer occupancy of the space and can be used to decide whether or not or how quickly to vent the space.

The sensing means may be adapted to measure air condition or presence within the interior space, primary space, secondary space and/or further space such as an intermediate space.

The sensing means may be adapted to measure air condition in the air intake space and/or exhaust space. Advantageously measuring air condition or quality in the or each intake space allows the ventilation system to select the most appropriate air for drawing into the space.

The air extraction means and/or air supply means may be electrically powered.

The air extraction means and/or air supply means may receive power from a circuit of the building.

The air extraction means and/or air supply means may receive power from a battery.

According to yet a further aspect of the invention, there is provided a method of ventilating an interior space, the method comprising: extracting, by an air extraction means, air from a primary space within the interior space; and supplying, by an air supply means, air to the primary space, wherein the air extraction means and/or air supply means are wirelessly controlled by a control means. Advantageously the air supply means is operable to supply makeup air into the space while the air extraction means extracts stale air from the space. Ideally the method includes balancing the airflow through the interior space such that air entering the interior space through the air supply means is substantially equal to the air leaving the interior space through the air extraction means. Advantageously, this allows the ventilation system to maintain a neutral air pressure in the space during ventilation and reduces the amount of unwanted air entering or exiting the primary space during ventilation.

The method may include activating the air extraction means to cause air to flow out of the interior space.

The method may include activating the air supply means to cause air to flow into the interior space.

The method may include deactivating the air extraction means and/or air supply means.

The method may include increasing the flow of air through the air extraction means and/or air supply means. Advantageously, increasing the flow of air can cause a change in the rate at which the interior space is ventilated, when required.

The method may include decreasing the flow of air through the air extraction means and/or air supply means.

The method may include increasing or decreasing the flow of air through the air extraction means and/or air supply means by altering the speed of one or more fans.

The method may include increasing or decreasing the flow of air through the air extraction means and/or air supply means in order to compensate for infiltration or exfiltration in any part of the interior space.

The method may include controlling the air extraction means and air supply means independently.

The method may include controlling the air extraction means and air supply means in a dependent manner.

The method may include activating and/or deactivating the air extraction means and air supply means simultaneously.

The method may include altering the speed of one or more fans simultaneously.

The method may include activating and/or deactivating the air extraction means and air supply means at different times.

The method may include extracting air from the primary space at an extraction rate. The method may include extracting air at an extraction rate which corresponds to a volume of air being extracted from the primary space in a predetermined amount of time.

The method may include extracting air at an extraction rate which corresponds to one of one or more predetermined extraction rates.

The method may include extracting air at an extraction rate which corresponds to a speed of one or more extraction fans.

The method may include supplying air to the interior space at a supply rate.

The method may include supplying air to the primary space, secondary space and/or further space such as an intermediate space at a supply rate.

The method may include supplying air at a supply rate which corresponds to a volume of air being supplied to the primary space, secondary space and/or further space such as an intermediate space in a predetermined amount of time.

The method may include supplying air at a supply rate which corresponds to one of one or more predetermined supply rates.

The method may include supplying air at a supply rate which corresponds to a speed of one or more supply fans.

The method may include supplying air and extracting air at equal rates.

The method may include supplying air and extracting air at rates which correspond to the air in the primary space being completely replaced in a predetermined amount of time.

The method may include supplying air to and/or extracting air from the interior space continuously.

The method may include supplying air to and/or extracting air from the interior space intermittently.

The method may include supplying air to and/or extracting air from the interior space according to a duty cycle.

The method may include controlling the air extraction means and/or air supply means based on one or more conditions or properties of the interior space.

The method may include controlling the air extraction means and/or air supply means based on occupancy of the interior space. The method may include controlling the air extraction means and/or air supply means based on a change to one or more conditions or properties of the interior space.

The method may include controlling the air extraction means and/or air supply means based on a change in electricity grid properties such as frequency, voltage and demand.

The method may include measuring, by a sensing means, one or more conditions or properties of the interior space, air intake space and/or air exhaust space.

The method may include measuring, by a sensing means, one or more conditions or properties of the primary space, secondary space and/or further space such as an intermediate space.

The method may include controlling the air extraction means and/or air supply means based on one or more conditions or properties of the interior space air intake space and/or air exhaust space measured by the sensing means.

The method may include activating or deactivating the sensing means.

The method may include selectively activating or deactivating the sensing means based on one or more conditions of the interior space, air intake space and/or air exhaust space.

The method may include activating or deactivating one or more air extraction means when one or more conditions or properties of the interior space increases, decreases, exceeds a pre- determined threshold, falls below a predetermined threshold or equals a predetermined threshold.

The method may include activating or deactivating one or more air supply means when one or more conditions or properties of the interior space, air intake space, primary space, secondary space and/or further space such as an intermediate space increases, decreases, exceeds a pre-determined threshold, falls below a predetermined threshold or equals a predetermined threshold.

The method may include activating or deactivating the one or more air extraction means and/or air supply means after a predetermined amount of time has elapsed since the one or more air extraction means and/or air supply means was last activated or deactivated.

The method may include activating or deactivating the one or more air extraction means and/or air supply means when a person is present in the interior space, in particular the primary space, secondary space and/or further space such as an intermediate space. According to a further aspect of the invention there is provided a ventilation system for an interior space, the ventilation system comprising: an air extraction means for extracting air from a space wherein the air extraction means is wirelessly controllable.

According to a yet further aspect of the invention there is provided a ventilation system for an interior space, the ventilation system comprising: an air supply means for providing a supply of air to the space, wherein the air supply means is wirelessly controllable.

It will be appreciated that optional features applicable to one aspect of the invention can be used in any combination, and in any number. Moreover, they can also be used with any of the other aspects of the invention in any combination and in any number. This includes, but is not limited to, the dependent claims from any claim being used as dependent claims for any other claim in the claims of this application.

The invention will now be described with reference to the accompanying drawings which show, by way of example only, two embodiments of an apparatus in accordance with the invention, wherein:

Figure 1 is a plan view of an embodiment of a ventilation system in accordance with the present invention.

Figure 2a is a schematic side view of an air supply unit for use in the present invention.

Figure 2b is a schematic side view of an alternative air supply unit for use in the present invention.

Figure 3a is a schematic side view of an air extraction unit for use in the present invention.

Figure 3b is a schematic side view of an alternative air extraction unit for use in the present invention.

Figure 4 is a schematic view of a control unit for use in the present invention.

Figure 5 is a plan view of a further embodiment of a ventilation system in accordance with the present invention.

Figure 6 is a picture of a heating element suitable for use in the ventilation system of the present invention.

Figure 1 shows an example embodiment of a ventilation system 1. The ventilation system 1 can be used to ventilate an interior space within a building. In this example embodiment, the interior space is made up of a wet room 4, a habitable room 6, and a transfer zone 5. The transfer zone 5 connects the wet room 4 to the habitable room 6. The interior space of figure 1 is divided into N spaces where N is equal to 3. The rooms are within a building and are defined by walls 11 , 12 and 13, as well as ceilings (not shown), floors (not shown) and doors/doorways 9 and 10. The transfer zone 5 is in fluid communication with the wet room 4 and habitable room 6 through air transfer slots created by door threshold undercuts in doorways 9 and 10, respectively, or through other purpose provided air transfer apertures.

The skilled person will appreciate that the invention can be applied to any room(s) or spaces inside a building. For example, the wet room 4 may be a kitchen or bathroom, the habitable room 6 may be a bedroom or living room and the transfer zone 5 may be a hallway between the two.

An air extraction unit 2 in the wall of the wet room 4 can extract air from the wet room

4.

The air extraction unit 2 provides a fluid exit path from the wet room 4 to an exhaust space 7.

An air supply unit 3 in the wall of the habitable room 6 can supply makeup air directly to the habitable room 6. The air supply unit 3 can supply makeup air to the wet room 4 via the transfer zone 5. The air supply unit 3 provides a fluid entry path from an air intake space 8 to the habitable room 6.

As can be seen in figure 1, the air extraction unit 2 and air supply unit 3 are physically separate units and the ventilation system 1 is de-centralised. The air extraction unit 2 and air supply unit 3 are electrically powered. For example, the units 2 and 3 may be powered using any suitable electrical circuit of the building e.g. the lighting circuit, or using battery power.

Figure 2a shows an example air extraction unit 2. This example air extraction unit 2 has an exhaust pipe 20 which allows air to pass through. The exhaust pipe 20 can take any suitable shape and have any suitable diameter such as from 50 mm to 600 mm and beyond. In this example the exhaust pipe 20 is cylindrical.

When the air extraction unit 2 is installed in a wall, the exhaust pipe 20 is a through- wall pipe having a first end 21 and a second end 22. When installed in a wall, the first end 21 of the exhaust pipe 20 is located near the interior surface of the wall (e.g. the interior surface of wall 11 which is inside the building) and the second end 22 of the exhaust pipe 20 is located near the exterior surface of the wall. By using short through-wall pipes such as exhaust pipe 20 the present ventilation system 1 requires less energy compared to prior art whole-house systems which use extensive ductwork and require large fans for air transportation.

The first end 21 of the exhaust pipe 20 may be attached to an extract grille or diffuser 24. The second end 22 of exhaust pipe 20 may be attached to a cowl 23 which is used to reduce draughts through the air extraction unit 2 and prevent ingress of moisture/rain into exhaust pipe 20. The cowl 23 and extract grille or diffuser 24 are attached to the pipe 20 in a way which allows access to the interior of the air extraction unit 2 for the purpose of cleaning, maintenance and/or replacement of parts. The cowl 23 and extract grille or diffuser 24 both include apertures to allow air to pass through. The air extraction unit 2 may include an extraction fan 25 which can be used to draw air out of the wet room 4 through exhaust pipe 20. During operation of the extraction fan 25, air flows through the exhaust pipe 20 towards exhaust space 7. The extraction fan 25 is a variable-speed centrifugal fan or an axial fan. The speed of the extraction fan 25 corresponds to a flow rate of air through the exhaust pipe 20.

Operation of the air extraction unit 2 is controlled by a processor 28 which is connected to a wireless transmitter 29a and a wireless receiver 29b. The wireless transmitter 29a and wireless receiver 29b can be used to exchange wireless communication signals with the other components of the ventilation system 1 , especially control hub 50.

The air extraction unit 2 has a sensing unit 27 which is attached to the extract grille or diffuser 24, or contained within the extract unit 2. The sensing unit 27 can be used to measure properties of the air in the wet room 4 and/or the presence of occupants in the wet room 4. In the example embodiment, sensing unit 27 includes an air condition sensor which measures the relative humidity (RH) of air within the wet room 4 and a PIR (passive infrared) sensor which measures motion within the wet room 4. Operation of the air extraction unit 2 can be based on measurement signals sent from the sensing unit 27 to processor 28.

Figure 2b shows an alternative air extraction unit 102 for use with the ventilation system

This example alternative air extraction unit 102 has an exhaust pipe 120 having first and second ends 121, 122, an extract grille or diffuser 124 attachable to the first end 121 of the exhaust pipe 120, a sensing unit 127 and a processor 128 which is connected to a wireless transmitter 129a and a wireless receiver 129b.

The alternative air extraction unit 102 figure 2b may be generally similar to air extract unit 2 shown in figure 2a. However, the alternative air extraction unit 102 does not include an extraction fan within the exhaust pipe 120. Instead, the second end 122 of exhaust pipe 120 may be attached to an external extraction fan 125. The external extraction fan 125 can incorporate a cowl which is used to reduce draughts through the air extraction unit 102 and prevent ingress of moisture/rain into exhaust pipe 120. The external extraction fan 125 is locatable in the exhaust space 7.

The external extraction fan 125 may be located in the exhaust space 7 in order to draw air out of the wet room 4 through exhaust pipe 120. Positioning extraction fans outside of the interior space can provide a reduction in noise transmission into the interior space created by the air extraction fan 125. During operation of the extraction fan 125, air flows through the exhaust pipe 120 towards exhaust space 7. The extraction fan 125 is a variable-speed centrifugal fan or an axial fan. The speed of the extraction fan 125 corresponds to a flow rate of air through the exhaust pipe 120.

The skilled person will appreciate that where the following discussion of the invention refers to the air extraction unit 2 of figure 2a or any sub-components of air extraction unit 2, the system could equally use the alternative air extraction unit 102 shown in figure 2b or corresponding sub-components of alternative air extraction unit 102.

Figure 3a shows an example air supply unit 3. This example air supply unit 3 has an intake pipe 30 which allows air to pass through. Intake pipe 30 provides a path for air to pass through wall 13 of the habitable room 6. The intake pipe 30 can take any suitable shape and have any suitable diameter such as from 50 mm to 600 mm and beyond. In this example the intake pipe 30 is cylindrical.

When the air supply unit 3 is installed in a wall, the intake pipe 30 is a through-wall pipe having a first end 31 and a second end 32. When installed, the first end 31 of the intake pipe 30 is located near the interior surface of wall 13 (e.g. the surface of wall 13 which is inside the building) and the second end 32 of the intake pipe 30 is located near the exterior surface of the wall.

The first end 31 of the intake pipe 30 may be attached to a nozzle 34. The second end 32 of the intake pipe 30 may be attached to a cowl 33 which can be used to reduce draughts through the air supply unit 3 and prevent ingress of moisture/rain into intake pipe 30.

A filter 36 is locatable within the air intake pipe 30 and can be used to remove particulate matter or other airborne pollution such as oxides of nitrogen from the air which flows through the intake pipe 30. The filter 36 may be a pleated, disc, cylindrical, canister or electrostatic filter. The cowl 33 and nozzle 34 are attached to the pipe 20 such that the interior of the air extraction unit 3 can be accessed for the purpose of cleaning, maintenance and/or replacement of e.g. filter 36. In optional embodiments the filter 36 can be located outside of the air intake pipe whilst being used to remove particulate matter or other airborne pollution from the air which flows through the air supply unit 3. The cowl 33 and nozzle 34 both include apertures to allow air to pass through.

The air supply unit 3 may include a supply fan 35 which is used to supply air to the habitable room 6 through the intake pipe 30. During operation of the supply fan 35, air flows from the intake space 8 and into the habitable room 6. The supply fan 35 is a variable-speed fan. Each speed setting of the supply fan 35 corresponds to a flow rate of air through the intake passage 30.

The nozzle 34 is a Coanda nozzle having a nozzle housing 34 and first and second nozzle portions 37a and 37b. The first and second nozzle portions 37a, 37b are attached to the nozzle housing 34 such that they are spaced apart from each other to define an elongate aperture 40 between them. The aperture 40 may have an aspect ratio of approximately 20:1. The first and/or second elongate nozzle portions 37a, 37b may be attached to the nozzle housing 34 in such a way that allows the width of the aperture 40 to be increased or decreased. The first and/or second elongate nozzle portions 37a, 37b may be attached to the nozzle housing 34 in such a way that allows the width of the aperture 40 to be dynamically increased or decreased during system operation. The first and/or second elongate nozzle portions 37a, 37b may be attached to the nozzle housing 34 in such a way that allows the major axis angle of aperture 40 to be adjusted or dynamically increased or decreased during system operation.

When the air supply unit 3 is installed in e.g. the wall 13 of the habitable room 6, the aperture 40 is located a distance of approximately 200 mm from the ceiling. This short distance between the ceiling and the aperture 40 means that air jets ejected from the aperture 40 adhere to and travel along the ceiling, this being the result of the shape of the nozzle 34, the angle of trajectory and the Coanda effect. Using the Coanda effect, the three-dimensional jet of air expelled from the air supply unit 3 tends to adhere to and travel along the ceiling of the habitable room 6. As the air jet diffuses along the ceiling the buoyancy of the air beneath the diffused jet of air holds it up for a time before it is warmed by the air within the habitable room 6. The jet of air exchanges energy with the ceiling of the habitable room 6, warming or cooling the jet of air. The jet of air can also provide a heat insulating effect by breaking the consistent thermal path between the volume of air within the habitable room 6 and the ceiling thereof.

The operation of the air supply unit 3 is controlled by a processor 38 which is connected to a wireless transmitter 39a and a wireless receiver 39b. The wireless transmitter 39a and wireless receiver 39b can be used to exchange wireless communication signals with the other components of the ventilation system 1 such as the control hub 50. The air supply unit 3 has interior and exterior sensing units 41a and 41b which can be used to measure conditions in the interior space and the intake space 8, respectively.

The interior sensing unit 41a may be attached to the nozzle housing 34. The interior sensing unit 41a can be used to measure properties of the air in the habitable room 6 and/or the presence of occupants in the habitable room 6. In the example embodiment the interior sensing unit 41a includes air condition sensors to measure the RH and temperature of air within the habitable room 6 and a PIR sensor which measures motion within the habitable room 6. The exterior sensing unit 41b may include a temperature sensor which can be used to measure the temperature of air in the air intake space 8. The exterior sensing unit 41b may include a range of sensors which can be used to measure the properties of air in the air intake space 8. Operation of the air supply unit 3 can be based on measurement signals sent from the sensing units 41a, 41b to processor 38.

Figure 3b shows an alternative air supply unit 103 for use with the ventilation system 1. The alternative air supply unit 103 has an intake pipe 130 having first and second ends 131 , 132, a nozzle 134 attachable to the first end 131 of the exhaust pipe 130, sensing units 141a and 141b and a processor 138 which is connected to a wireless transmitter 139a and a wireless receiver 139b. The nozzle 134 is a Coanda nozzle having a nozzle housing and first and second nozzle portions 137a and 137b. The first and second nozzle portions 137a, 137b are attached to the nozzle housing 34 such that they are substantially parallel and spaced apart from each other to define an elongate aperture 140 between them.

The alternative air supply unit 103 shown in figure 3b may be generally similar to air supply unit 3 shown in figure 3a. However, the alternative air supply unit 103 does not include a supply fan within the intake pipe 130. Instead, the second end 132 of exhaust pipe 130 may be attached to an external supply fan 135. The external supply fan 135 can incorporate a cowl which is used to reduce draughts through the air supply unit 103 and prevent ingress of moisture/rain into intake pipe 130. The external supply fan 135 is beatable in the intake space 8.

The external supply fan 135 may be located in the intake space 8 in order to supply air to the habitable room 6 through the intake pipe 130. Positioning supply fans outside of the interior space can provide a reduction in noise transmission into the interior space created by the supply fan(s). During operation of the external supply fan 135, air flows from the intake space 8 and into the habitable room 6. The external supply fan 135 is a variable-speed centrifugal fan with multiple speed settings. Each speed setting of the external supply fan 135 corresponds to a flow rate of air through the intake pipe 130. The skilled person will appreciate that where the following discussion of the invention refers to an air supply unit 3 of figure 3a or any sub-components of air supply unit 3, the system could equally use an alternative air supply unit 103 shown in figure 3b or corresponding sub components of alternative air supply unit 103.

The ventilation system 1 includes a control hub 50, shown in figure 4, for wirelessly controlling the operation of the air extraction unit 2 and air supply unit 3. The air extraction unit 2 and air supply unit 3 are connected over a local area wireless network such as the LoRa wireless network to the control hub 50.

Control hub 50 includes a processing unit 51, a memory 52, a wireless transceiver 53 and a user interface 54. Memory 52 stores program instructions and/or algorithms for execution by processing unit 51 to communicate with and control the operation of the components of the ventilation system 1, in particular the air supply unit(s) 2,102 and air extraction unit(s).

User interface 54 may include an antimicrobial touch screen and may be used to establish and/or adjust one or more settings of the ventilation system 1 , view current or historic sensor values and/or manually activate the air supply unit(s) and air extraction unit(s).

In use, the ventilation system 1 of figure 1 ventilates the interior space by creating a balanced airflow through the interior space. The air extraction unit 2 extracts air from the wet room 4 and the air supply unit 3 supplies air to the wet room 4 (by way of the habitable room 6 and the transfer zone 5). During ventilation, the air extraction unit 2 and air supply unit 3 are wirelessly controlled by the control hub 50. Stale and moist air in the wet room 4 is exhausted into the exhaust space 7 and replaced with makeup air from the transfer zone 5, habitable room 6 and intake space 8.

In broad terms, the basic method of controlling the air extraction units 2 and the air supply units 3 can be characterised as follows. Individual air extraction/supply units 2,3 are controlled based on sensed conditions in the room where they are mounted. Individual units may be activated (and de-activated) in response to levels of any given pollutant in the air of the room in which they are mounted. Their throughput may be varied in response to sensed level of that pollutant. So a base level of ventilation demand is established based on local air quality. That base level of demand is modifiable in order to maintain a balance of air flow between air intake and air extraction. This may be because the sum of the throughputs of the air supply units 3 is equal to the sum of the throughputs of the air extraction units 2. To maintain this equality, the system must determine - based on the base level demands applicable to each of the air extraction/supply units 2,3 - whether the base level demands would create an imbalance. If so, the system corrects for the imbalance by: adding throughput to one or more of the air extraction units 2, if their collective throughput would otherwise be exceeded by the throughput of the air supply units 3. This may be done by activating additional air extraction units 2, or by increasing the throughput of an already active air extraction unit 2; or adding throughput to one or more of the air supply 3, if their collective throughput would otherwise be exceeded by the throughput of the air supply extraction units 2. This may be done by activating additional air supply units 3, or by increasing the throughput of an already active air supply unit 3.

The control hub 50 activates the air extraction unit 2 and air supply unit 3 by sending signals over the wireless network to the processors 28 and 38, respectively. The extraction fan 25 and supply fan 35 are activated simultaneously to create a balanced airflow through the interior space. Once the interior space has been sufficiently ventilated, the control hub 50 deactivates the air extraction unit 2 and air supply unit 3 by sending signals over the local area wireless network to the processors 28 and 38, respectively.

In a non-limiting example, stale and humid air may be extracted from the wet room 4 by the air extraction unit 2 at a predetermined extraction rate. Makeup air may be supplied to the habitable room 6 by the air supply unit 3 at a predetermined supply rate. Since the volume of air entering and exiting the interior space is substantially equal, a balanced airflow through the interior space is created. This allows the ventilation system 1 to maintain a neutral air pressure in the interior space and reduces the amount of unwanted air entering the interior space via infiltration.

In example embodiments a balanced airflow can be achieved by matching the airflow, fan speed and/or operating time of the extraction unit 2 and the supply unit 3. Where the ventilation system 1 includes unequal numbers of air supply units and air extraction units, a ratio of fan speeds for each particular unit can be used to provide a balanced airflow through the interior space.

The operation of the ventilation system 1 can depend on conditions within and/or outside the interior space, such as in the wet room 4 or the intake space 8. The control hub 50 can activate and/or deactivate the air supply unit 3 and air extraction unit 2 according to sensor measurements made by the sensing units 31, 41a and 41b.

In an example, the sensing unit 31 , which is located in the wet room 4, includes a RH sensor, a motion sensor and a C02 sensor. When the RH in the wet room 4 exceeds a threshold, the control hub 50 activates the air extraction unit 2 to extract humid air from the wet room 4. The control hub 50 simultaneously activates the air supply unit 3 to create a balanced airflow through the interior space. The control hub 50 continually monitors the RH in the wet room 4. When the RH in the wet room 4 falls below a desired level, the control hub 50 deactivates the air supply unit 3 and the air extraction unit 2.

As will be appreciated by the skilled person, it is possible to effectively decrease the vapour pressure and thereby the humidity within the interior space when the air being brought in from the intake space 8 is of a lower vapour pressure. This can be difficult during summer months for example, when ambient relative humidity can be high. Programming the ventilation system 1 to turn on when e.g. the humidity in the wet room 4 is above a threshold could mean that the ventilation system 1 is always on.

The ventilation system 1 can overcome the above problem by selectively activating and deactivating sensors. For example, when the outdoor air temperature (ODAT) is greater than a pre-determined temperature dependent on local climate conditions, or the outdoor vapour pressure is lower than the indoor vapour pressure, the RH sensor in sensing unit 27 can be switched off. During this time, the operation of the ventilation system 1 would be based on measurements made by the presence or motion sensor. The control unit 50 can activate the air supply unit 3 and air extraction unit 2 when presence or motion is detected in the wet room 4 for e.g. a predetermined amount of time. In contrast, when the ODAT is less than a pre-determined temperature dependent on local climate, or the outdoor vapour pressure is higher than the indoor vapour pressure, the presence or motion sensor is switched off and the system is controlled based on measurements made by the RH sensor. The CO2 sensor is kept on irrespective of ODAT. The ventilation system 1 therefore ensures that any air brought into the interior space with the intention of reducing the vapour pressure within the interior space will have a lower vapour pressure.

In another example, the air extraction unit 2 and air supply unit 3 can be activated based on rises in measured quantities in e.g. the wet room 4. For example, if a significant rise in RH is detected in the wet room 4 then the air extraction unit 2 and air supply unit 3 can be activated until the level of RH in the wet room 4 falls below a certain threshold.

In another example, the air extraction unit 2 and air supply unit 3 can be activated based on occupancy of the interior space. For example, if an occupant or movement is detected in the wet room 4, then the air extraction unit 2 and air supply unit 3 can be activated to ventilate the interior space. The air extraction unit 2 and air supply unit 3 can be activated based on movement or occupancy being detected in the primary space for a pre-set duration.

Figure 5 shows a second embodiment of the ventilation system, indicated generally by the numeral 201. The ventilation system 201 is used to ventilate an interior space within a building having a first wet room 204, a second wet room 224, a first habitable room 206, a second habitable room 226, and a transfer zone 205. The transfer zone 205 connects the first wet room 204, second wet room 224, first habitable room 206 and second habitable room 226.

The interior space of figure 5 is divided into N spaces where N is equal to 5. The rooms are within a building and are defined by walls 211 , 212, 213, as well as ceilings (not shown), floors (not shown) and doors/doorways 209, 210, 229 and 230. The transfer zone 205 is in fluid communication with the first wet room 204, second wet room 224, first habitable room 206 and second habitable room 226 through air transfer slots created by door threshold undercuts in doorways 209, 210, 229 and 230, respectively, or through other purpose provided air transfer apertures.

The skilled person will appreciate that the invention can be applied to any room(s) or spaces inside a building. For example, the first wet room 204 may be a bathroom, the second wet room 224 may be a kitchen, the first habitable room 206 may be a bedroom, the second habitable room 226 may be a living room and the transfer zone 205 may be a hallway between them.

A first air extraction unit 202 (similar to the air extraction unit 2 shown in figure 2a or alternative air extraction unit 102 shown in figure 2b) in the wall of the first wet room 204 can extract air from the first wet room 204. The first air extraction unit 202 provides a fluid exit path from the first wet room 204 to a first exhaust space 207.

A second air extraction unit 222 (similar to the air extraction unit 2 shown in figure 2a or alternative air extraction unit 102 shown in figure 2b) in the wall of the second wet room 224 can extract air from the second wet room 224. The second air extraction unit 222 provides a fluid exit path from the second wet room 224 to a second exhaust space 227.

A first air supply unit 203 (similar to the air supply unit 3 shown in figure 3a or alternative air supply unit 103 shown in figure 3b) in the wall of the first habitable room 206 can supply makeup air directly to the first habitable room 206. The first air supply unit 203 can also supply makeup air to the first wet room 204 and/or second wet room 224 via the transfer zone 205. The first air supply unit 203 provides a fluid entry path from a first air intake space 208 to the first habitable room 206.

A second air supply unit 223 (similar to the air supply unit 3 shown in figure 3a or alternative air supply unit 103 shown in figure 3b) in the wall of the second habitable room 226 can supply makeup air directly to the second habitable room 226. The second air supply unit 223 can also supply makeup air to the first wet room 204 and/or second wet room 224 via the transfer zone 205. The second air supply unit 223 provides a fluid entry path from a second air intake space 228 to the second habitable room 226. As can be seen in figure 5 first air extraction unit 202, second air extraction unit 222, first air supply unit 203 and second air supply unit 223 are physically separate units and the ventilation system 201 is de-centralised.

In use, the ventilation system 201 can ventilate part or all of the interior space, creating a balanced airflow through the interior space. The ventilation system 201 includes a control hub 150 (similar to the control hub 50 shown in figure 4) for wirelessly controlling the air extraction units 202, 222, and air supply units 203, 223. The control hub 150 can selectively and dynamically control the air extraction units 202, 222 and air supply units 203, 223 to maintain a balanced airflow through the interior space. If for example the volume flow rate into the interior space is increased then the volume flow rate out of the interior space will also increase. Similarly, if the volume flow rate into the interior space is decreased then this will result in a corresponding reduction in the volume flow rate out of the interior space.

If sensors in the first habitable room 206 detect poor IAQ, or the occupant sensor detects movement over a given period, the control hub 150 can trigger the supply fan of the first air supply unit 203 to supply fresh filtered makeup air into that room. The first air supply unit 203 simultaneously sends a message to the control hub 150 that fresh air is required and at what volume flow rate (i.e. speed of supply fan).

If sensors in the second habitable room 226 detect poor IAQ, or the occupant sensor detects movement over a given period, the control hub 150 can trigger the supply fan of the second air supply unit 223 to supply fresh filtered makeup air into that room. The second air supply unit 223 simultaneously sends a message to the control hub 150 that fresh air is required and at what volume flow rate (i.e. speed of supply fan).

In order to provide a balanced airflow while fresh filtered makeup air is being supplied to the first habitable room 206 and/or second habitable room 226, the control hub 150 can select, activate and control either or both of the air extraction units 202, 222 to ensure that the volume flow rate of air into the interior space is equal to the volume flow rate of air out of the interior space.

For example, if the supply fan in the first habitable room 206 is running at x litres per second and the extract fan in the first wet room 204 is running at x litres per second also, and no other supply fans or extract fans are running, then the airflow through the interior space is in balance. If sensors in the second habitable room 226 then trigger the supply fan in that room to start running at x litres per second also, the control hub 150 will need to balance the airflow by increasing the volume flow rate of air out of the interior space. The control hub 150 can do this by, for example, doubling the speed of the extract fan in the first wet room 204 to 2x litres per second, or by activating the extract fan in the second wet room 224 such that both extract fans run at x litres per second. In either case, the airflow through the interior space will be balanced. If whilst both supply fans are running at x litres per second, one of the supply fans is called on to run at 1.5x litres per second because the sensors in that room have detected poor IAQ, the other supply fan may throttle back to 0.5x litres per second to balance the airflow.

The control unit 150 can select the most suitable air extraction unit 202, 222 to use in order to reduce operational energy and CO2 emissions. For example, in the 'winter' condition when daytime temperatures are below 20°C, the air in the interior space may be heated by the space heating system of the building. If this warmed air is extracted then the replacement air entering the interior space will need to be heated in order to maintain a comfortable temperature for occupants. This will increase the heat load of the building. In order to reduce this problem, the control hub 150 can choose which extraction unit 202,222 to activate in order to extract the coolest air from the interior space (e.g. the air in first wet room 204 if this is coolest) during the winter condition. This reduces space heat demand. In contrast, in the ‘summer’ condition when outside temperatures are above 20°C, the control hub 150 can choose which extraction unit 202,222 to activate in order to extract the warmest air from the interior space (e.g. the air in second wet room 224 if this is the warmest). This helps to reduce overheating.

If sensors in the first wet room 204 detect poor IAQ, or the occupant sensor detects movement over a given period, the control hub 150 can trigger the extract fan of the first air extraction unit 202 to remove pollutants from the first wet room 204. The speed of the extract fan will dependent on the level of pollutants. The first air extraction unit 202 simultaneously sends a message to the control hub 150 that removal of pollutants is required and at what volume flow rate (i.e. speed of extract fan).

If sensors in the second wet room 224 detect poor IAQ, or the occupant sensor detects movement over a given period, the control hub 150 can trigger the extract fan of the second air extraction unit 222 to remove pollutants from the second wet room 224. The speed of the extract fan will be dependent on the level of pollutants. The second air extraction unit 222 simultaneously sends a message to the control hub 150 that removal of pollutants is required and at what volume flow rate (i.e. speed of extract fan).

In order to provide a balanced airflow while contaminated air is being extracted from the first wet room 204 and/or second wet room 224, the control hub 150 can select, activate and control either or both of the air supply units 203, 223 to ensure that the volume flow rate of air into the interior space is equal to the volume flow rate of air out of the interior space. The control hub 50,150 can choose to activate a subset of the air supply units 202,222 based on sensed external conditions. Looking at Figure 5, suppose that one side of the building faces toward some source of pollution such as a road, so that on that side of the building lies a zone of relatively high air pollution. In the present example, we will take that zone to lie adjacent the second wet room 224 and the second habitable room 226, at the lower part of the drawing. Suppose that the opposite side of the building faces toward a zone of relatively low air pollution, perhaps a garden. In the present example, that zone lies adjacent the first wet room 204 and the first habitable room 206, at the upper part of the drawing.

In this example, the air supply unit 223 of habitable room 226 receives, if activated, relatively polluted air. The air supply unit 203 of first habitable room 206 receives, if activated, air that is relatively high in quality (lower in pollution). The system according to the invention may be configured to sense external air quality in the two external zones, and in response to draw air preferentially from the zone with the better air quality. So in the present example it activates the air supply unit 203 of the first habitable room in preference to the air supply unit 223 of the second habitable room 226, which may be shut down or run at reduced capacity. In this way indoor air quality is improved.

In certain embodiments it may be desirable to actively expel air from one of the dry/habitable rooms (provided only with an air supply unit 202, 222) in order to improve air quality therein. This may be considered an emergency or contingency measure. It involves temporarily suspending the requirement to balance intake air and extracted air. Looking again at Figure 5, suppose that the air quality in the second habitable room 226 is so poor as to necessitate remedial action, but that the external air quality in the zone from which its air supply unit 223 draws air (which, as stated above, is a zone of poor air quality) is itself so poor that drawing external air into habitable room 226 will not improve its IAQ. The system is configured, in response to such conditions, to enter a contingency mode of operation, in which the air intake 223 in the affected room is de-activated, and a net influx of air is created in the building. To this end, air extraction units 202, 222 are de-activated. Air supply unit 203 is activated. The result is an unbalanced flow of air into the building, raising its internal air pressure, so that air is expelled through routes including the inactive air supply unit 223 of the polluted habitable room 226. This room therefore receives relatively high-quality air, driving out its polluted atmosphere and so improving its IAQ.

Figure 6 shows a heating element 61 which is able to be employed within an air supply unit 3,103,203,223 to warm air passing into the interior space. The heating element 61 may be a resistive heating element which is heated as electrical current passes through it. The control hub 50,150 may be operable to adjust and set the electrical current passing through the heating element in order to adjust and set the temperature of the heating element. In the example shown in figure 6 the heating element 61 can be located within a pipe 60 (similar to e.g. the air intake pipe 30 of figure 3a) in the path of air which travels through the pipe 60. The heating element 61 may have a coiled shape to maximise the contact area with the airflow. The heating element 61 can be connected to the pipe 60 (and e.g. the electrical components of an air supply unit 3, 103, 203, 223) via mechanical/electrical connections 62 and 63.

As will be understood by the skilled person, the example embodiments presented above can be modified in many ways without departing from the scope of the invention.

The ventilation system 1 ,201 may include any number of air extraction units 2,102,202,222 for extracting air from e.g. a wet room 4,204,224 or any other space within the interior space. Any number of air supply units 3,103,203,223 may be used to provide a supply of air directly to e.g. a wet room 4,204,224, transfer zone 5,105 or any other space within the interior space. Each wet room 4,204,224 may be in direct fluid communication with e.g. a habitable room 6,206,226 or any other space within the interior space.

The interior space may correspond to any space within a container, building, hospital, house, dwelling or non-domestic building. The interior space may be divided into any number of spaces N including a single space, two spaces, or five to ten spaces etc. The control unit 50,150 may control the operation of any number of air supply units 3,103,203,223 and air extraction units 2,102,202,222 to create a flow of air into, out of or between any of the N spaces. The interior space may be surrounded by a plurality of air intake spaces 8,208,228 and/or air exhaust spaces 7,207,227.

Wet room(s) 4,204,224 may be in fluid communication with a transfer zone 5,105, habitable room 6,206,226 and/or any other room via one or more doorway(s), door(s), window(s), aperture(s), channel(s) or path(s). Each wet room 4,204,224, transfer zone 5,105 or habitable room 6,206,226 may each correspond to one or more spaces, rooms or floors within the container, building, house, dwelling or non-domestic building and can be any combination of one or more rooms such as wet rooms, bathrooms, lavatories, ensuites, shower rooms, kitchens, living rooms, treatment rooms, lounges, dining rooms, bedrooms attics, porches, hallways, corridors or stairwells.

Exhaust space(s) may be any external region or space outside of a container, building, house, dwelling or non-domestic building or a further space, room or floor within the container, building, house, dwelling or non-domestic building. Air intake space(s) may be any external region or space outside of a container, building, house, dwelling or non-domestic building or a space, room or floor within the interior space. Air extraction unit(s) 2,102,202,222 may provide a fluid path between e.g. a wet room

4,204,224 and the transfer zone 5,105, or between any other rooms or spaces within the interior space. Air extraction unit(s) 2,102,202,222 may be installed in any partition, wall, ceiling, roof, floor, door, doorway and/or window of the building.

Air supply unit(s) 3,103,203,223 may provide a fluid path between e.g. a wet room 4,204,224 and a transfer zone 5,105, or between any other rooms or spaces within the interior space. Air supply unit(s) 3,103,203,223 may be installed in a partition, wall, ceiling, roof, floor, door, doorway and/or window of the building.

The or each pipe 20,120,30,130 may be telescopic and constructed from a number of interlocking tubes. Telescopic through-wall air transfer pipes can be used to cater for different wall thicknesses, reducing installation time and avoiding waste on-site from cutting pipes to length.

The or each fan 25,125,35,135 may be positioned within the interior space and/or adjacent to or within an exhaust aperture, path or pipe 20,30. The or each fan 25,125,35,135 may have any number of speed settings, for example two to ten speed settings. The speed of a fan, and the flow rate through the interior space, may correspond to the air in a room being completely replaced in a predetermined amount of time.

The speed of one or more fans 25,125,35,135 may be increased or decreased in order to compensate for infiltration or exfiltration in any part of the interior space resulting from e.g. open doors, windows or large draughts. Changing the speed of the fans 25,125,35,135 in this way keeps airflow through the interior space balanced during ventilation.

The control hub 50,150 may be integrated into an air supply unit 2,102,202,222 or an air extraction unit 3,103,203,223 and may include a wireless transmitter-receiver, wireless transceiver or wireless router. The wireless network may be a wireless local area network (WLAN), and a cellular network, the internet, an intranet, a long range wireless area network (LoRaWAN), a low power wireless area network (LPWAN), GSM, NFC, Bluetooth or WiFi. The control hub 50,150 may be in wireless communication with the air extraction unit 2,102,202,222 and/or air supply unit 3,103,203,223 via a wireless local area network (WLAN), and a cellular network, the internet, an intranet, a long range wireless area network (LoRaWAN), a low power wireless area network (LPWAN), GSM, NFC, Bluetooth or WiFi.

The control hub 50,150 may interact with a mobile computing device such as a smart phone running a mobile app or may be in wireless communication with such a mobile computing device or one or more healthcare devices. Connection from the control hub 50,150 to a mobile computing device can enable remote access to the system 1 ,201 and to the user interface 54 of the system. The mobile computing device may be used to adjust the settings of the ventilation system in accordance with user preferences.

In alternatives, signals may be sent to and between the components of the ventilation system 1 ,201 by using the mains electricity system or wiring as signal carriers.

Additionally or alternatively to the sensing units 27,41, standalone sensors may be used anywhere within or outside the interior space.

The sensing units 27,41 may include any type of sensor, for example RH sensor(s), absolute humidity sensor(s), temperature sensor(s), carbon dioxide sensor(s), carbon monoxide sensor(s), total volatile organic compounds (TVOCs) sensor(s), nitrogen dioxide sensor(s), sulphur dioxide sensor(s), ozone sensor(s), formaldehyde sensor(s), methane sensor(s), radon sensor(s), particulate matter sensor(s) or pressure sensor(s). The list if sensors is not exhaustive and the skilled person will appreciate that any suitable sensors may be used with the present ventilation system 1 ,201.

The skilled person will appreciate that the ventilation system 1,201 can be used to ventilate the interior space for any number of reasons and based on any measured properties of the interior space. The control hub 50,150 can use any sensor data to select the most suitable air for ventilation. For example, where the ventilation system is to be used to remove buildup of radon from anywhere within the interior space, e.g. when elevated levels of radon are detected within a wet room 4,204,224, the ventilation system 1 will create a balanced flow of air from a region where the measured concentration of radon is low (e.g. in the air intake space 8,208) to the wet room 4,204,224 and will exhaust the high-radon-concentration air from the wet room 4,204,224 into an exhaust space 7,207,227.

The sensing units 27,41 may be adapted or the control hub 50, 150 may be adapted to receive external instructions via WiFi or a smart device to detect the use of a nebulizer in the interior space. When a rise in a level of airborne antibiotics from the nebulizer is detected in e.g. a wet room 4,204,224, the control unit 50,150 may transmit signals to the appropriate air extraction unit 2,102,202,222 and air supply unit 3,103,203,223 to ventilate the wet room 4,204,224 with air from an adjacent space (e.g. a habitable room 6,206,226). The supply and extraction of air is balanced. This reduces the flow of airborne nebuliser antibiotics into the neighboring space(s), reducing the risk of antimicrobial resistance (AMR) for other occupants and animals of the spaces.

The ventilation system 1 ,201 may be controlled according to any suitable operation mode which can be set and/or adjusted by the user. Several example operation modes are described below, but the skilled person will understand that other operation modes are possible, including combinations of one or more aspects of each example operation mode. Furthermore, the control hub 50,150 can be set to operate the ventilation system 1,201 according to a first operation mode during certain times (e.g. on certain days or during certain seasons) and according to a second operation mode at other times.

In an optional continuous mode, the control hub 50,150 causes air supply unit(s) 3,103,203,223 and air extraction unit(s) 2,102,202,222 to be continuously active and can increase or decrease the speed of the fans according to sensor measurements, time of day and/or occupancy within the interior space.

In an optional periodic mode, the control hub 50,150 activates air extraction unit(s) 2,102,202,222 and air supply unit(s) 3,103,203,223 during regular time intervals.

In an optional duty cycle mode, the control hub 50,150 activates and deactivates air supply unit(s) 3,103,203,223 and air extraction unit(s) 2,102,202,222 according to a duty cycle.

In an optional sensor-driven mode the control hub 50,150 activates and deactivates the air extraction unit 2,102,202,222 and air supply unit 3,103,203,223 based on sensor measurement(s).

The ventilation system 1 ,201 of the invention provides a dynamically-controlled balanced ventilation system 1 ,201. The algorithm of the system processor of the ventilation system 1 ,201 can use a control strategy which provides demand-controlled ventilation and/or uses the 'equivalent ventilation' principle as a resource for utility grid demand response to provide an energy or air quality advantage and/or a resource to the utility grid.

The control hub 50,150 is operable to minimise energy consumption, utility bills and other non-IAQ costs (such as thermal discomfort or noise) of the ventilation system 1,201. The ventilation system 1 ,201 can adjust ventilation rates in time or by location in a building to be responsive to electricity grid needs and/or operation of other air moving and air cleaning systems. The control hub 50,150 may receive direct signals from utilities such that the ventilation system 1 ,201 can respond to electricity grid needs, electricity demand and/or electric grid control strategies. The ventilation system 1,201 may be responsive to occupancy meaning that the ventilation system 1,201 can adjust ventilation depending on demand such as reducing ventilation if the building is unoccupied. The ventilation system 1,201 of the invention works automatically requiring little or no user intervention.

From data produced by the ventilation system 1 ,201 , the heat loss of each room of a building and the thermal time constant of the building can be calculated. This enables current heat loss and insulation levels to be assessed and future energy efficiency retrofit measures mapped out. The ventilation system 1 ,201 can provide information to building owners, occupants, and managers on operational energy consumption and indoor air quality as well as signal when systems need maintenance or repair. For example, the ventilation system 1 ,201 can include sensors to detect when system components need maintenance, such as filter replacement. The ventilation system 1,201 can include sensors to detect air flow, system pressures or fan energy use in such a way that system failures can be detected and repaired. Air extraction unit(s) 2,102,202,222 and/or air supply unit(s) 3,103,203,223 can include airflow sensors, air pressure sensors and/or energy consumption detectors.

The control hub 50,150 is operable to continually adjust the ventilation system 1,201 in time and by location to provide desired IAQ benefits to occupants within a building. The ventilation system 1 ,201 can time-shift ventilation to periods when indoor-outdoor temperature differences are smaller, or away from periods where outdoor temperatures and humidity are at their minimum or peak.

In some of the embodiments discussed above, air flow is balanced in the sense that the total rate of intake through the air intake arrangements 3 is equal to the total rate of air extraction through the air extraction arrangements 2. This approach is appropriate for many installations. However, the embodiment to be described below refines this approach by additionally estimating a rate of air infiltration to the building through other routes, and by allowing for this rate of air infiltration in balancing the air flow.

For brevity, in what follows, the term “air infiltration” will be used to refer to passage of air into/out of the building through routes other than the air intake arrangements 3 and the air extraction arrangements 2. It is to be understood that air infiltration may be negative (i.e. the total flow by these routes may be in a direction form the building toward the exterior). Air infiltration takes place through a number of routes in a typical building including, without limitation, porous walls, air vents, windows and doors when open, unintentional openings in ceilings and roofs, gaps between floor boards, and so on. It contributes to the total flow of air into (or out of) the building.

The so-called “stack effect” has a bearing on the rate of air infiltration. When the building’s interior is warmer than the exterior, warm air rises within the building and escapes from its upper levels. Pressure is consequently reduced lower down the building, causing external air to be drawn in. When the temperature difference is reversed - the exterior being warmer than the interior - the stack effect can likewise be reversed, although its magnitude is typically smaller.

Pressure difference between the interior and the exterior of the building also has an influence on the rate of infiltration. One factor affecting the pressure difference is the effect of wind impinging on the building’s outer face(s). The present embodiment of the invention may be implemented in the type of physical system already described. It differs from previously described embodiments in regard to the programming of the control hub 50, 150.

The estimation of air infiltration by the control hub 50, 150 may be carried out by a machine-learning type process. In the present embodiment it comprises the following steps:

-A sensor, which may be a proximity sensor, detects occupancy in a room and the number of occupants.

-The expected CO2 concentration from metabolic generation of CO2 is determined from the number of occupants.

-From the determined expected CO2 concentration, a 'natural' ventilation time constant (airflow through gaps in the building fabric) is determined from the CO2 decay curve. This provides the airtightness level of the room and potentially the complete house/building.

-From 3 the natural ventilation time constant, the influence of airflow through gaps in the building fabric ('natural’ ventilation) is determined. Fans in the room will be off until the CO2 reaches a target level which allows time for the decay curve to develop.

-The pressure is known for the room and for the outside of the building (i.e. a combination of the stack effect and facade wind pressure), so Delta P, the difference between external pressure and internal pressure, is known.

-The temperature is known inside the room and at the exterior so Delta T, the difference between the internal and external temperature, which has a bearing on the magnitude of the stack effect, is known.

-Based on the above parameters, the machine-learning system is configured to learn over a period of time the expected infiltration rate for each room in relation to Delta P and Delta T.

-From the above, the system can determine the expected influence of airflow through gaps in the building fabric on the room ventilation rate.

-When the CO2 threshold level is reached, the fan of the air intake arrangement 3/air extraction arrangement 2 is activated. Its flow rate is known. CO2 concentration can be expected to decay and by measurement of this concentration over time a decay curve can be obtained, providing a “total” decay constant, resulting from both infiltration and forced air flow. Using the resultant data, an air change efficiency is determined for the room. --The fan of the air intake arrangement 3/ air extraction arrangement 2 can then be set by the control hub 50, 150 to provide the pressure required to generate the required ventilation rate, that is the volume of air flowing through the a room, i.e. the fan flow rate plus the infiltration rate. -The sensors determine Delta P and Delta T in each room.

-By comparing the air intake fan flow rate and room pressure in a habitable room vs air extraction fan flow rate and room pressure in a wet room, the system can determine the true ventilation rate and if it is in balance. If the airflow rate is out of balance, the system controls fan unit speeds to adjust the volume flow rate and pressure. In the preceding discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of the values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of the parameter, lying between the more preferred and the less preferred of the alternatives, is itself preferred to the less preferred value and also to each value lying between the less preferred value and the intermediate value.

The features disclosed in the foregoing description or the following drawings, expressed in their specific forms or in terms of a means for performing a disclosed function, or a method or a process of attaining the disclosed result, as appropriate, may separately, or in any combination of such features be utilised for realising the invention in diverse forms thereof.