WO2022248884A1

WO2022248884A1 - Sterilisation apparatus

Info

Publication number: WO2022248884A1
Application number: PCT/GB2022/051364
Authority: WO
Inventors: David Paul Campbell; Michael Gormley; David Kelly
Original assignee: Heriot-Watt University
Priority date: 2021-05-28
Filing date: 2022-05-27
Publication date: 2022-12-01
Also published as: GB202107667D0; GB2607098A

Abstract

A sterilisation apparatus (10) for an air handling system is described. The air handling system comprises an air outlet (30) having an air outlet cross-sectional area. The sterilisation apparatus (10) comprises a housing (20) having a housing inlet (22) and a housing outlet (24), wherein the housing inlet (22) is configured for fluid communication with the air outlet (30) of the air handling system; an apparatus flow path (40) defined between the housing inlet (22) and the housing outlet (24) and having a path length, and a sterilisation light source (26) arranged to sterilise air within the apparatus flow path (40). The housing inlet (22) comprises a housing inlet cross-sectional area transverse to the apparatus flow path (40), and the housing inlet cross-sectional area is equal to or greater than the air outlet cross-sectional area. Also described is a method of sterilising a flow of outlet air from an air handling system (10) and a building drainage waste and ventilation system (610).

Description

STERILISATION APPARATUS

FIELD

The present disclosure relates to a sterilisation apparatus for an air handling system, a method of sterilising output air from an air handling system and an air handling system comprising a sterilisation apparatus. In particular, the present disclosure relates to apparatus and methods for use with a building ventilation system, such as a building drainage waste and ventilation system.

BACKGROUND

Air handling systems are used extensively to allow for air circulation and/or movement. For example, an air conditioning system may be considered an active air handling system whereby air is drawn into an air conditioning unit and outputted at a desired condition at a specific location. Air handling systems also comprise passive systems, for example building ventilation systems comprising air vents and ducts provided within buildings. Building drainage, waste and ventilation systems are also passive air handling systems. A building drainage system is an arrangement of waste pipes provided from building sanitary fittings and appliances that are connected to the mains sewers to allow for effective drainage of waste produced by these fittings and appliances. Typically, building drainage systems are provided with drainage, waste and ventilation pipes that have an outlet to the atmosphere to provide for ventilation of air from the building drainage system.

Drainage, waste and ventilation (DWV) pipes in large buildings are typically open to atmosphere at the top. The outlet of the pipe is arranged to protrude from the top of the building, for example at roof level. This is a functional requirement for a building’s DWV system to ensure the integrity of water traps inside the building. DWV systems can generate large volumes of airflow (for example, up to ten times the water flow) and can be subject to short sharp air pressure spikes. Additionally, there is typically a gentle positive (upward) pressure within the system caused by the attached sewers and the wind or ‘stack’ effect due to height. Together, or in isolation, these factors result in a predominantly slow upward drift of air out of DWV pipes. Drainage, waste and ventilation (DWV) pipes may therefore be considered a passive air handling system within a building. There are some solutions to mitigate against the effects of air pressure spikes within drainage, waste and ventilation systems. However, there is currently nothing to prevent the positive-pressure-induced upwards drift of air and as such, the DWV stack tops are typically left open at roof level. In some cases, particularly in small buildings such as houses, one-way (i.e. in-flow) air admittance valves are provided at the outlet of the pipe. In larger buildings, for example healthcare buildings and high-rise, the DWV stack tops remain open to specifically to stop positive pressure build up and the associated risk to all the water traps in the building.

DWV systems can act as incubators for pathogens such as, for example, MERS, SARS and Covid-19. This can be problematic, particularly if a fault in the DWV system occurs. For example, the loss of trap seals was implicated in an outbreak of SARS at Amoy Gardens in Hong Kong.

Existing technology has targeted reducing the effects of air pressure spikes or by providing means by which to prevent the loss of trap seals in water traps. However, while these may prevent the flow of noxious gases from sewers, possibly containing pathogens, from entering the building, there is currently no consideration given to the presence of the pathogens within the system themselves.

More generally, other air handling systems such as air conditioning systems, building air vent ducts and the like, may also have pathogenicity by providing a breeding ground for pathogens within enclosed spaces of the system, thereby allowing the spread of pathogens by the redistribution of air throughout the system.

SUMMARY

Aspects of the present disclosure relate to a sterilisation apparatus for an air handling system, a method of sterilising output air from an air handling system and an air handling system comprising a sterilisation apparatus.

According to a first aspect of the present disclosure, there is provided a sterilisation apparatus for an air handling system, wherein the air handling system comprises an air outlet having an air outlet cross-sectional area, the apparatus comprising: a housing having a housing inlet and a housing outlet, wherein the housing inlet is configured for fluid communication with the air outlet of the air handling system; an apparatus flow path defined between the housing inlet and the housing outlet and having a path length, a sterilisation light source arranged to sterilise air within the apparatus flow path; wherein the housing inlet comprises a housing inlet cross-sectional area transverse to the apparatus flow path, and the housing inlet cross-sectional area is equal to or greater than the air outlet cross-sectional area.

In use, the sterilisation apparatus can be fitted to an outlet of any air handling system to sterilise the flow of air exiting the system, without impeding the pneumatic operation of the system. Accordingly, the sterilisation apparatus may be considered to be an inexpensive, stand-alone apparatus that may be retrofitted to different air handling systems, particularly building air handling systems.

Beneficially, the sterilisation apparatus can manage, reduce or prevent the spread of pathogens arising within air handling systems. The sterilisation apparatus can sterilise the exiting gases to neutralise any pathogens which may be present. Air handling systems, for example, building waste, drainage and ventilation systems, air conditioning systems and the like, can be breeding grounds for harmful pathogens. These pathogens are then free to exit the system via the air outlet due to normally present flow of air from the system. This could present a transmission risk. Similarly, where the inlet to an air handling system is located within a pathogenic environment, for example on an infectious hospital ward, the input air can also represent a transmission risk. Therefore, the apparatus may be configured to be in fluid communication with an air inlet of the air handling system in addition to or as an alternative to the air outlet.

However, care must be taken to ensure that any modifications to an existing air handling system does not impede the flow of air entering or exiting the system as this could have implications on the functioning of the system as a whole particularly in the case of a naturally ventilated system such as a DWV system.. The present disclosure provides a means to effectively sterilise the flow of outlet air whilst not impeding the operation of the air handling system itself. The disclosed sterilisation apparatus for an air handling system does not present any additional air flow resistance which would in turn result in a resistive pressure rise and therefore affect system ventilation

It will be appreciated that other gases may be present within the air flow of output air from an air handling system and that the sterilisation apparatus should not be limited to the sterilisation of pure air. For example, where the air handling system is a drainage, waste and ventilation system, the outlet air may comprise a mixture of air and other gaseous components typically found in drainage waste and ventilation systems, for example, but not limited to, methane, carbon dioxide, sulphur dioxide, hydrogen sulphide, ammonia.

The air handling system may be a passive air handling system. For example, a building air vent and duct system. In a building air vent and duct system, an air inlet may be located internally, for example inside a room. An air outlet may be located internally or externally to the building. For example, on an external wall, or inside a room within the building. Alternatively, the air inlet may be located externally to the building and the air outlet may be located internally, for example within an internal room.

The air handling system may be a building drainage, waste and ventilation system. The air outlet may comprise an outlet pipe that is open to the atmosphere, for example, located on an external wall or located on the roof of the building.

The air handling system may be an active air handling system. For example, a building air conditioning and ventilation system. The air outlet may comprise any outlet from the air conditioning and ventilation system intended to deliver cooled or ventilated air into an internal location. The air outlet may comprise an external air outlet intended to deliver air from the building to the outside environment. The system may comprise an air inlet. The air inlet may comprise any inlet where air is provided to the air conditioning and ventilation system, for example an air inlet located internally within the building or externally to the building.

The sterilising apparatus may configured to be retrofitted to existing air handling systems. Accordingly, there would be no requirement to redesign the existing air handling systems to accommodate the sterilising apparatus. The sterilisation apparatus may be considered a stand-alone apparatus that would have no impact on the pneumatic operation of the air handling system and any linked services. The present disclosure therefore provides a simple and economical solution.

For example, where the air handling system is a building drainage, waste and ventilation system, the housing inlet may be configured to be fluidly connected to an air outlet pipe of the drainage, waste and ventilation system. The cross-sectional area of the air outlet pipe will be defined by the pipe diameter. For example, where the air handling system is an air conditioning system, the housing inlet may be configured to be fluidly connected to an air outlet pipe or duct, or an air inlet pipe or duct. The duct may be any appropriate shape. The cross-sectional area of the air inlet or the air outlet will be defined by the pipe diameter or the geometry of the duct.

The housing may comprise a base, wherein the housing inlet is provided in the base. The housing inlet may be configured so as to not form a flow restriction on air entering the housing via the housing inlet from the air outlet of the air handling system.

The housing inlet comprises a housing inlet cross-sectional area transverse to the flow path that may be at least equal to the air outlet cross-sectional area. In such a way, the housing inlet may be fluidly connected to the air outlet of the air handling system without affecting the velocity of the air as a flow of air passes through the housing inlet from the air outlet of the air handling system. The housing inlet may take the form of an opening within the base of the housing, for example an orifice. The opening may be sized according to the dimensions of the air outlet of the air handling system. This may allow the apparatus to be directly fitted to the air outlet of the air handling system. Alternatively, an intermediate fitting may be provided to fluidly connect the housing inlet to the air outlet. For example, where the air outlet is a pipe, the intermediate fitting may comprise any suitable pipe fitting or adapter. The housing inlet may be configured for sealing engagement with the air outlet. The apparatus may further comprise a seal. The seal may be provided to provide sealing engagement between the housing inlet and the air outlet.

The housing cross-sectional area may be greater than the air outlet cross- sectional area. In such a way, the housing may be configured to slow the velocity of the air entering the housing via the inlet. Reducing the velocity of the air may ensure that the housing does not have any effect on the pneumatics of the air handling system. Reducing the velocity of the air may provide for improved sterilisation by increasing the time for the air within the housing to travel along the apparatus flow path to the housing outlet.

The housing may be sized to reduce the velocity of the air flowing into the housing via the housing inlet to about, for example, 15 %, 10 % or 5 %, preferably 5 % of the velocity of air within the air inlet or air outlet of the air handling system. In a DWV system, the velocity of air flowing into the housing may typically be dependent upon the height of the building and the diameter of the drainage stack. In a DWV system, the typical upward air velocities (outward drift) may be in the range of about 0.1 m/s to about 0.5 m/s, while typical inward air velocities when the stack is in use may be in the range of about 0.5 m/s to about 2 m/s.

The housing may comprise a housing volume. The housing volume may be dependent upon the operational requirements of the air handling system. For example, the size of the air handling system (such as number of pipes) and/or the height of the air handling system (such as stack height). For example, where the air handling system is a drainage, waste and ventilation system, the housing may comprise a volume of between 0.1 to 2 m³, depending on the height of the air outlet pipe. The height of the air outlet pipe may depend upon the building height. For example, a building which is 50 m tall may require a housing having a volume of at least 0.4 m³. For example, a building which is 100 m tall may require a housing having a volume of at least 0.75 m³. For example, a building which is 200 m tall may require a housing having a volume of at least 1.5 m³. The volume of housing required for a DWV system may be determined based on at least one of stack diameter, air velocity and required sterilisation time.

The housing may have any appropriate shape. For example, the housing may be cylindrical, cuboidal, cubic, or an irregular shape. The housing may take the form of a drum or box.

The housing may be constructed of any suitable material. For example, the housing may be constructed at least partially from plastic. For example, the housing may be constructed from uPVC or the like. The housing may be constructed at least partially from metal, for example aluminium, steel or the like.

The housing may comprise a reflective coating. The reflective coating may be provided on at least one internal surface of the housing. The reflective coating may be provided to increase the intensity of the light emitted from the sterilisation light source. Accordingly, the reflective coating may comprise a material which is configured to reflect the light emitted from the sterilisation light source. For example, the reflective coating may comprise at least one of aluminium, stainless steel, mylar, glass, or e PTFE.

The apparatus may be configured to be weatherproof. The apparatus may further comprise weatherproof mounting brackets. For example, the housing and/or the brackets may be coated with a weatherproof coating. This may provide for increasing the longevity of the sterilisation apparatus, particularly if the sterilisation apparatus is to be located outside.

The apparatus flow path is defined between the housing inlet and the housing outlet and has a path length. The path length may be selected to ensure sterilisation of the air within the apparatus flow path. For example, the path length may be selected to provide for a minimum sterilisation time for the air within the apparatus flow path. For example, the sterilisation time may be at least 15s. The flow path may be configured such that there is no significant induced air flow resistance in either direction in the air velocity ranges typically encountered during normal operation of the air handling system to which the apparatus is in fluid communication with. The apparatus flow path may be unobstructed between the housing inlet and the housing outlet. Accordingly, the path length may be defined by the dimensions and geometry of the housing.

The housing may be provided with a baffle arrangement. The baffle arrangement may increase the path length of the apparatus flow path. The baffle arrangement may be disposed in the housing between the housing inlet and the housing outlet. The baffle arrangement may be coupled to the housing. For example, the baffle arrangement may affixed by a securing means such a screw or screws, an adhesive, or the like. The baffle arrangement may be integrally formed with the housing.

The baffle arrangement may comprise one of more baffles. The baffle or baffles may comprise, for example, a disc shape, a cylindrical shape, rectangular or square shape. The baffle or baffles may take the form of a spiral within the housing.

The provision of a baffle arrangement may increase the path length and as such, the time air spends inside the housing. Accordingly, the provision of a baffle arrangement may allow for more effective sterilisation. The provision of a baffle arrangement may reduce the volume requirement of the housing, for example, to provide for the sterilisation of the air passing through the housing.

The sterilisation light source may be configured to sterilise pathogens. The light source may comprise a wavelength suitable for sterilising pathogens present with air passing through the housing in the apparatus flow path. For example, the light source may comprise at least one of visible light, ultra violet light, or infra-red light. For example, the light source may comprise UV(C) light having a wavelength range of 100 to 280 nm.

The sterilisation light source may comprise a minimum intensity to allow for sterilisation of pathogens present with air passing through the housing in the apparatus flow path.

The sterilisation light source may comprise one or more light sources. For example, the sterilisation light source may comprise at least one light emitting diode (LEDs). The light emitting diodes may be provided for example, as single, discrete LEDs or in the form of strips of LEDs. The use of LEDs as a sterilising light source may provide for a low power and inexpensive sterilisation apparatus.

The light source may be arranged to sterilise the air within the apparatus flow path. The light source may be affixed to an internal surface of the housing. For example, the light source may be screwed to the internal surface of the housing. For example, the light source may be affixed to the internal surface of the housing using a suitable adhesive. Where multiple light sources are provided, they may be distributed throughout the housing to provide effective sterilisation within the length of the flow path.

Where the housing comprises baffles, the light source or light sources may be affixed to the baffles and/or an internal surface of the housing.

The light source may comprise a power supply. The power supply may be configured to be connected to mains electricity. The power supply may comprise a battery or battery pack. The power supply may be solar powered. For example, solar panels may be provided on an external surface of the housing to power the sterilisation light source.

In some circumstances, more than one housing may be provided. For example, the sterilisation apparatus may comprise two or more housings, each housing having a sterilisation light source. This may provide the sterilisation apparatus with a degree of modularity which may allow for the number of housings to be selected depending on the requirements of the air handling system.

Each housing may comprise a housing inlet and a housing outlet. At least one of the housing inlets may be configured for fluid communication with an air outlet of the air handling system. The apparatus flow path may be defined between each of the housing inlets and housing outlets, respectively.

The housings may be coupled together by a fitting, for example a duct, pipe or conduit. Alternatively, the housings may be integrally formed. The two or more housings may be arranged in series. When arranged in series the apparatus flow path may be defined between the housing inlet of a first housing and the housing outlet of a second, or third, or n-number housing.

Alternatively, the two or more housings may be arranged in parallel. When arranged in parallel, the apparatus flow path may comprise multiple flow paths defined between each of the housing inlets and outlets, respectively.

According to a second aspect, there is provided a method of sterilising a flow of outlet air from an air handling system using the sterilisation apparatus according to the first aspect, wherein the method comprises: providing an apparatus comprising a housing having a housing inlet and a housing outlet, wherein the housing inlet is configured for fluid communication with an air outlet of the air handling system; wherein the apparatus comprises an apparatus flow path defined between the housing inlet and the housing outlet and having a path length, and a sterilisation light source arranged to sterilise air within the apparatus flow path; wherein the housing inlet comprises a housing inlet cross-sectional area transverse to the apparatus flow path, and the housing inlet cross-sectional area is equal to or greater than the air outlet cross-sectional area; and the method comprises sterilising air within the apparatus flow path.

According to a third aspect of the disclosure, there is provided an air handling system comprising a sterilisation apparatus according to the first aspect.

The air handling system may comprise a building drainage, waste and ventilation system. The air handling system may comprise a building ventilation system. The air handling system may comprise an air conditioning and ventilation system.

For the purposes of the present disclosure, it should be understood that the features defined above or described below may be utilised, either alone or in combination with any other defined feature, in any other aspect, embodiment, or example or to form a further aspect, embodiment or example of the disclosure. BRIEF DESCRIPTION OF DRAWINGS

These and other aspects of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a schematic view of a sterilisation apparatus;

Figure 2 is a further schematic view of a sterilisation apparatus comprising a baffle arrangement;

Figure 3 is a further schematic view of a sterilisation apparatus comprising a baffle arrangement;

Figure 4 is a further schematic view of a sterilisation apparatus comprising a baffle arrangement;

Figure 5 is a schematic view of an example sterilisation apparatus having two housings; and

Figure 6 is a schematic of a sterilisation apparatus in use with a building drainage waste and ventilation system.

DETAILED DESCRIPTION OF THE DRAWINGS

A sterilisation apparatus 10 is shown in Figure 1. The sterilisation apparatus 10 comprises a housing 20 with a housing inlet 22 and housing outlet 24. In figure 1, the sterilisation apparatus 10 is shown in fluid communication with an outlet pipe 30 of a drainage waste and ventilation system. It will be appreciated that the housing 20 is configured to be connected to any outlet pipe of an air handling system, for example an air conditioning system. The housing inlet 22 of the housing 20 is configured to be connected to the outlet pipe 30 by any appropriate means, for example a bracket or fitting. One or more seals 21 may be provided to seal the connection between the housing inlet 22 and the outlet pipe 30.

The housing 20 comprises sterilisation light sources 26 in the form of UV sterilising light emitting diodes (LEDs). The LEDs are positioned on the inner surface of the housing 20. The LEDs are fixed to the inner surface using any suitable fixing method. For example, the LEDs may be fixed using a suitable adhesive, or a mechanical fastening, such as screws, nails or the like. The number of LEDs may be determined by operational requirements to ensure effective sterilisation of the air within the housing. The flow path of air entering the housing 20 is shown illustratively by arrows 40. Air will enter the housing 20 from the outlet pipe via housing inlet 22. As the flow of air passes through the housing 20, it will be subjected to UV light sterilisation from the UV LEDs 26. Thus, the flow of air 40 exiting from the housing outlet 24 of the housing will be free from harmful pathogens.

The housing inlet 22 comprises a cross-sectional area transverse to the flow path, for example, the flow path at the housing inlet, which is at least the same as or greater than the cross-sectional area of the outlet pipe 30. The outlet pipe 30 cross- sectional area is defined by the diameter of the outlet pipe 30. Accordingly, the housing inlet 22 is configured to not form a flow restriction on the air entering or leaving the housing 20.

In Figure 1, the flow path 40 between the housing inlet 22 and housing outlet 24 is unobstructed. Accordingly, the path length of the flow path is defined by the dimensions of the housing 20 and the arrangement and number of internal baffles, where baffles are provided.

Figures 2 to 4 show alternative arrangements of the sterilisation apparatus, where like reference numbers incremented by 100, 200 and 300 respectively have been used to identify like features. These have not been described again for brevity. As shown in Figures 2, 3, and 4, the housing 120, 220, 320 is provided with a baffle arrangement 128, 228, 328 to increase the path length of the flow path of the air through the housing.

Various types of baffle arrangement are envisaged and it will be appreciated that any suitable shape or form of baffle arrangement may be used. For example, in Figure 2, a series of disc shaped baffles 128 are provided within the housing 120. In Figure 3, a spiral baffle arrangement 228 is provided. In Figure 3, the UV light sterilising LEDs 236 are positioned on the baffles 328. This could be in addition to LEDs provided on the inside surface of the housing 328.

The total volume of the housing will be dependent upon the operational requirements of the ventilation system. For example, the size of the ventilation system (number of pipes) and the height of the pipe (stack height). For typical building drainage waste and ventilation systems, the volume of housing required is between 0.1 to 2 m³. Some example housing volumes are provided below in table 1. Table 1

The housing 20 is configured such that there is a relative increase in volume of the housing 20 compared to the outlet pipe 30 immediately adjacent the exit of the outlet pipe 30. This reduces the flow rate of air within the housing 20. Sterilisation apparatus according to the present disclosure will be sized so as to reduce the velocity of the gas flowing into the housing via the inlet to about 15 %, 10 % or 5 % of the velocity of the gas within the outlet pipe 30. In a DWV system, the velocity of air flowing into the housing is typically dependent upon the height of the building and the diameter of the drainage stack. Typical upward air velocities (outward drift) may be in the range of about 0.1 m/s to about 0.5 m/s, while typical inward air velocities when the stack is in use may be in the range of about 0.5 m/s to about 2 m/s.

Figure 5 shows an alternative sterilisation apparatus 400 comprising two housings 420a, 420b stacked vertically and connected via connecting outlet pipe 432. The housings 420a, 420b can be in the form of any of those outlined above. Alternatively, the housings 420a, 420b could be directly connected. The arrangement of Figure 5 demonstrates that the sterilisation apparatus 400 can be a modular system whereby the sterilisation requirements of the ventilation system can be met by increasing the number of housings 420a, 420b in contrast to providing a single housing with a larger volume, for example.

Figure 6 illustrates a drainage waste and ventilation system 610 in a building 630. The system comprises a number of branched waste pipes 612, each waste pipe is connected to at least one sanitary appliance (e.g. a toilet, sink, washing machine). The branched pipes 612 feed into a main waste pipe 613 that is connected to a building sewer pipe 614. The building sewer pipe 614 feeds into the mains sewer. The main waste pipe 613 comprises an outlet 616 that is vented at the roof 620 of the building. DWV systems can generate large volumes of airflow (for example, up to ten times the water flow) and can be subject to short sharp air pressure spikes. Additionally, there is typically a gentle positive (upward) pressure within the system caused by the attached sewers and the wind or ‘stack’ effect due to height. Together, or in isolation, these factors result in a slow upward drift of air out of the outlet 616. A sterilisation apparatus 600 according to the present disclosure is provided and is in fluid communication with the outlet 616. The sterilisation apparatus 600 may be any of the previously described sterilisation apparatus and is sized according to the height of the building. The sterilisation apparatus 600 sterilises the air venting from the waste pipe 613 into the atmosphere, thereby helping to prevent the spread of pathogens.

It should be understood that the examples provided herein are merely exemplary of the present disclosure and that various modifications may be made thereto without departing from the scope defined by the claims.

Claims

1. A sterilisation apparatus for an air handling system, wherein the air handling system comprises an air outlet having an air outlet cross-sectional area, the apparatus comprising: a housing having a housing inlet and a housing outlet, wherein the housing inlet is configured for fluid communication with the air outlet of the air handling system; an apparatus flow path defined between the housing inlet and the housing outlet and having a path length, a sterilisation light source arranged to sterilise air within the apparatus flow path; wherein the housing inlet comprises a housing inlet cross-sectional area transverse to the apparatus flow path, and the housing inlet cross-sectional area is equal to or greater than the air outlet cross-sectional area.

2. The apparatus according to claim 1, wherein the housing inlet is configured to not form a flow restriction on air entering the housing via the housing inlet.

3. The apparatus according to claim 1 or 2, further comprising a seal configured to seal the housing inlet and the air outlet of the air handling system.

4. The apparatus according to any preceding claim, wherein the housing inlet comprises an orifice.

5. The apparatus according to any preceding claim, wherein the housing cross- sectional are is greater than the air outlet cross-sectional area.

6. The apparatus according to any preceding claim, wherein the housing is sized to reduce the velocity of the air entering the housing via the housing inlet.

7. The apparatus according claim 6, wherein the housing is configured to reduce the velocity of the air by 5 % to 15 % of the air velocity of air within the air outlet of the air handling system.

8. The apparatus according to any preceding claim, wherein the housing comprises a housing volume, and wherein the housing volume is between 0.1 to 2 m³.

9. The apparatus according to any preceding claim, wherein the housing is constructed at least partially from plastic.

10. The apparatus according to any preceding claim, wherein the housing is constructed at least partially from metal.

11. The apparatus according to any preceding claim, wherein the housing further comprises a reflective coating provided on at least one internal surface of the housing.

12. The apparatus according to any preceding claim, wherein the housing comprises a weatherproof coating.

13. The apparatus according to any preceding claim, wherein the apparatus flow path is defined according to the dimensions and geometry of the housing.

14. The apparatus according to any preceding claim, further comprises a baffle arrangement disposed within the housing between the housing inlet and the housing outlet.

15. The apparatus according to claim 14, wherein the baffle arrangement comprises at least one baffle, and wherein the baffle comprises at least one of a disc shape, a cylindrical shape, a rectangular shape, a square shape, or a spiral.

16. The apparatus according to any preceding claim, wherein the sterilisation light source comprises at least one of visible light, ultra violet light or infra red light.

17. The apparatus according claim 16, wherein the sterilisation light source comprises one or more light sources.

18. The apparatus according to any preceding claim, wherein the sterilisation light source comprises a light emitting diode (LED).

19. The sterilisation apparatus according any of claims 14 to 18, wherein the sterilisation light source is provided on the baffle arrangement.

20. The sterilisation apparatus according to any preceding claim, comprising two or more housings, wherein each housing comprising a housing inlet and a housing outlet and a sterilisation light source.

21. A method of sterilising a flow of outlet air from an air handling system, the method comprising: arranging a sterilisation apparatus according to any of claims 1 to 20 to be in fluid communication with an air outlet of an air handling system, and sterilising the air within the apparatus flow path.

22. A building drainage waste and ventilation system comprising a sterilisation apparatus according to any of claims 1 to 20.