In-room air quality sensing apparatus and air quality control system

Abstract

An in-room air quality sensing apparatus 10 comprises a housing (12, fig 2) having an air flow path between an inlet (14, fig 1) and outlet (16) through which air generated by a fan 32 flows. A first

Description

The present invention relates to an air quality control system which utilises an in-room air quality sensing apparatus in conjunction with one or more airflow control devices. Airflow control within a building is controlled by one or more airflow control devices, 5 typically ventilation fans, positioned around the building. Some ventilation systems may be activated in response to sensing of unexpected changes to the gas composition of the air in order to flush the building of contaminants. This has several problems: firstly, air quality sensing is difficult, and therefore existing sensors will be calibrated to a specific gas to be sensed, such as carbon monoxide. If 10 more than one gas is desirable to be monitored, then the installer must create multiple gas sensing systems. This is extremely unwieldy. Secondly, the need to provide a wide variety of sensor systems means that there is no consistency of measurement. The sensing of the gas occurs at the location of the sensor, and therefore it is preferred that the expected type of gas sensor be provided in locations 15 of likely contamination, for example, nitrogen dioxide near windows by high vehicular traffic locations, carbon monoxide near fossil fuel burning sources, and so on. The gas being sampled is not the same in each case, so there is no capacity for building a true picture of the gas composition within a building. Thirdly, the systems are extremely non-portable, and must be installed bespoke to a 20 building. This is time-consuming and prohibitively expensive. It is an object of the present invention to provide an air quality control system which is highly modularised, and thus suitable for use in a wide variety of contexts, whilst also providing much more detailed information about the gas composition within a building. According to a first aspect of the invention, there is provided an air quality control system 25 comprising: an in-room air quality sensing apparatus including: a housing having an air inlet and an air outlet; an electrically-energisable fan which is configured to create an airflow path from the air inlet to the air outlet; a plurality of air quality sensors mounted on the airflow path; a first processor in communication with the air quality sensors to receive sensor output signals therefrom, the first processor being configured to generate 30 a command signal based on the sensor output signals, and being configured to calculate 26 01 26 gas concentrations for a plurality of different gases on the airflow path based on crosssensitivities of the plurality of different air quality sensors; a first wireless communication element in communication with the processor; and a plurality of airflow control devices, each device including: a housing having an air inlet and an air outlet; an electrically-5 energisable fan which is configured to create an airflow path from the air inlet to the air outlet; a second wireless communication element communicable with the wireless communication element of the in-room air quality sensing apparatus to receive the command signal therefrom; a second processor in communication with the second wireless communication element, the second processor being configured to control the 10 electrically-energisable fan of the airflow control device in response to the command signal. The in-room air quality sensing apparatus provides a large amount of information about the air quality within a building. It can thus be used as the brain of the air quality control system by providing control signals to many other air control devices within the building. 15 This eliminates the need to provide any localised sensing capability for each of the individual air quality control devices, allowing them to act as slave units to the master in-room air quality sensing apparatus. Processing requirements are thus drastically reduced across the system as a whole. The use of multiple different sensors within a single package, coupled by an onboard 20 processor, makes use of a phenomenon known as cross-sensitivity, in which the air quality sensor provides an output which is based on a composite measurement from different gas components. Most gas sensors deem this to be problematic for accuracy of measurement; however, in the present invention, the cross-sensitivities provide sufficient date to allow for the determination of multiple different gas concentrations based on a 25 few individual sensor readings. By doing so, the air within the in-room air quality sensing device can be analysed quickly and continuously, so that changes in gas composition can be promptly detected. This in turn allows for much improved control of airflow within a building to be realised. Optionally, the processor may be configured to calculate the gas concentrations based 30 on any or all of: a plurality of linear equations; a plurality of non-linear equations; and machine learning. The cross-sensitivity information may be determinable by the solution of linear equations, which can be calculated very quickly to provide live gas concentration information for a 26 01 26 large number of different gases. Other suitable solutions may be mathematically feasible, including machine learning techniques. Preferably, the in-room air quality sensing apparatus may comprise a housing having a base, gripping members being provided on the base. 5 Optionally, the plurality of air quality sensors may include a first air quality sensor having a primary gas sensitivity for a first gas and a secondary gas sensitivity for a second gas, the first air quality sensor producing a first sensor output, and a second air quality sensor mounted on the airflow path having a primary gas sensitivity for a third gas and a secondary gas sensitivity for the said second gas, the second air quality sensor 10 producing a second sensor output; and wherein the first processor is in communication with the first and second air quality sensors to receive the first and second sensor output signal therefrom, the processor being configured to calculate gas concentrations for each of the first, second, and third gases. Preferably, the first and second air quality sensors may be adjacent to one another within 15 the housing on the airflow path. The co-Iocation of the air quality sensors together ensures that the same air on the airflow path is being sensed, thus resulting in an accurate live overview of the gas composition at the in-room air sensing apparatus. In one preferable embodiment, the first and second air quality sensors may be mounted 20 to the same circuit substrate within the housing. Mounting of the sensors onto the same circuit substrate further improves the accuracy of the gas measurement, whilst also allowing for a more compact structure to be created. A more compact structure limits the propensity for gas recirculation within the apparatus, which could lead to inaccurate readings. 25 There may be at least three, and more preferably at least six, different air quality sensors mounted on the airflow path. The greater the number of air quality sensors, the better. At least three provides sufficient data for the main gases which should be monitored within a building, whereas six or more sensors will typically provide complete and accurate coverage of the full spectrum 30 of gases which can be detected using commercially available gas sensors. 26 01 26 In one preferred embodiment, the first and second wireless communication elements may have a communication frequency of less than 1GHz. Sub-GHz communications protocols advantageously can communicate through otherwise communications-disrupting structures, such as steel beams, concrete, or stone walls. 5 Preferably, the plurality of airflow control devices may comprise at least one of: an in-room air filter; an extractor fan; and a positive input ventilation unit. There are lots of different airflow control devices which could be controlled by a centralised in-room air quality sensing apparatus. Optionally, each of the plurality of airflow control devices may be provided in a different 10 location and the first processor may be configured to generate an airflow-control-device- specific command signal based on the gas concentrations, depending on a location of each of the plurality of airflow control devices. The wireless communication between the in-room air quality sensing apparatus and the airflow control devices allows for a widespread control system to be provided across a 15 building or site, without the need to provide localised sensing capability. Changes in gas concentration detected at the in-room air quality sensing apparatus may be indicative of problems in different locations. Methane, for instance, may be indicative of a gas leak. The in-room air quality sensing apparatus may be provided with control software which is able to provide specific command signals to different airflow control 20 devices, depending on which gases are detected. The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1A shows a top perspective representation of one embodiment of an in-room air quality sensing apparatus; 25 Figure 1B shows a bottom perspective representation of the in-room air quality sensing apparatus of Figure 1A; Figure 2 shows an exploded perspective representation of the in-room air quality sensing apparatus of Figure 1A; 26 01 26 Figure 3 shows a partial cross-section through the in-room air quality sensing apparatus of Figure 1A; and Figure 4 shows a perspective representation of a building having an air quality control system in accordance with the invention. 5 Referring to Figures 1A and 1B, there is indicated an in-room air quality sensing apparatus, referenced globally at 10, which is configured to draw air into the housing 12 thereof for the purpose of sensing the gas composition, and, accordingly, provide command signals to other airflow control devices within a building or site. The in-room air quality sensing apparatus 10 here comprises the housing 12, formed as 10 a triangular prism, with an air inlet 14 and an air outlet 16. An airflow path is defined through the housing 12 between the air inlet 14 and the air outlet 16. The in-room air quality sensing apparatus 10 is provided so as to be freestanding within a room, and is typically dimensioned to be table-top mountable. Gripping members, such as rubberised feet 18 may be provided on a base of the housing 12 to assist with this. A power inlet 20 15 may be provided on the exterior of the housing 12, so as to allow the in-room air quality sensing apparatus 10 to be plugged in. First and second end caps 22, 24 are provided at either end of the housing 14, thereby defining a perimetric air inlet 14 and air outlet 16, respectively. The internal componentry of the in-room air quality sensing apparatus 10 is shown in 20 Figure 2. The triangular prismatic shape is held in place by an internal casing 26 having first and second end cap locators 28, 30, into which the triangular end caps 22, 24 are receivable. An electrically energisable fan 32 is provided inside the housing 12, here engagable with the first end cap locator 28, for driving the air through the in-room air quality sensing apparatus 10. The first and second end cap locators 28, 30 preferably 25 create a baffle system within the housing 12, which ensures that the airflow path within the housing 12 between the air inlet 14 and the air outlet 16 follows an expected and predetermined route. The electrically energisable fan 32 is here formed as part of a particulate sensor, which provides one form of sensing capability for the in-room air quality sensing apparatus 10. 30 This is mounted to a circuit substrate 34, which is here formed as a multi-part, foldable circuit substrate. The circuit substrate 34 in this embodiment is provided having three 26 01 26 substrate portions 34a, 34b, 34c, allowing it to be folded into a configuration so as to abut the inside of the internal casing 26. A plurality of air quality sensors 36 is provided on one of the substrate portions 34a, thereby forming a dedicated air quality sensing region on the airflow path within the 5 housing 12. This can be best visualised from Figure 3. The plurality of air quality sensors 36 comprises at least first and second different air quality sensors 36a, 36b, designed to primarily monitor different gases within the air. Additional different air quality sensors 36c, 36d, 36e, 36f, 36g, 36h, 36i, for sensing different primary gases, are also provided, for a total of nine different gas sensor packages in the depicted embodiment. 10 Sensor packages which form air quality sensors 36 are not, however, gas specific. Each air quality sensor 36 has a primary sensing function, which may or may not be indicative of the gas to which it is most responsive. For example, ozone sensors are known, as are carbon dioxide sensors, carbon monoxide sensors, nitrogen oxide sensors, and so on. Each of these sensors exhibits sensitivity towards at least one other gas. This 15 characteristic is known as cross-sensitivity. Sensor packages output a sensor output in the form of a readable current, based on the gas measured at the sensor. An ozone sensor will be primarily designed for the purpose of sensing ozone in the atmosphere, but will also exhibit a strong response to hydrogen sulphide and chlorine in 20 the atmosphere, as well as more moderate responses to methane, nitrogen dioxide, carbon monoxide, and n-heptane. The expected sensor output from the ozone sensor can thus be defined as follows: sO3 = a.[O3] + b.[CH4] + c.[NO2] + d.[H2S] + e.[CO] + f.[CI2] + g.[C7Hi6] On the other hand, a hydrogen sulphide sensor will be primarily designed for the purpose 25 of sensing hydrogen sulphide. It experiences moderate responses to methane, ammonia, nitrogen dioxide, carbon monoxide, ozone, sulphur dioxide, nitric oxide, chlorine, and n-heptane. sH2S = h.[CH4] + i.[NH3] + j.[NO2] + k.[CO] + l.[O3] + m.[S02] + n.[NO] + o.[CI2] + p.[C7Hi6] The cross-sensitivity parameters a to p in these simultaneous equations are typically 30 provided within the manufacturer’s instructions, and thus can be programmed readily into 26 01 26 a processor 38 of the in-room air quality sensing apparatus 10. Linear equations, nonlinear equations, or machine learning techniques could all be used to resolve the mathematical issues here. Using only values sOa and SH2S as sensor outputs, it is not possible to completely and 5 accurately identify which gases are contributing to signal changes; however, educated inferences can be made. For example, chlorine is not typically found in the air in appreciable concentrations, and therefore may be treated as a baseline reading. By limiting the simultaneous equations in this manner, changes in the signal outputs of two air quality sensors 36 may provide an indication of atmospheric gas changes for more 10 than two gases. Of course, the more simultaneous equations that can be generated, the more accurate the determination of any changes to gas concentration over a wide variety of different gases, by solving the simultaneous equations for each air quality sensor 36. This may allow for the determination of the concentrations, and more critically, changes to the 15 concentrations, of the gas components of the air passed along the airflow path. Nine air quality sensors 36 are provided in the depicted embodiment in Figure 3, all of which are communicable with the onboard processor 38 to allow onboard determination of the gas concentrations on the airflow path for a plurality of different gases. The air quality sensors 36 are well-packed onto a single circuit substrate portion 34a, 20 which is important, though not absolutely critical, for sampling the same gas at the same time on the airflow path. Temperature and / or pressure sensors 40, 42 may be provided inside the housing 12 for the purpose of calibrating the air quality sensors 36. The manufacturer’s datasheets provide detailed information as to how the signal output for each air quality sensor 36 25 may change in response to the environmental conditions. The air quality sensors 36 are preferably gas sensors, but particulate sensors or water sensors could be utilised as well. The gas sensors will typically be electrochemical sensors. Whilst the manufacturer’s datasheets may provide detailed information about the sensor 30 packages, there will be some tolerances. As such, it may be preferable to calibrate the in-room air quality sensing apparatus 10 to determine the device-specific cross- 26 01 26 sensitivity parameters for each air quality sensor 36. This can be achieved by altering the concentrations of gas components within a gas sample provided to the in-room air quality sensing apparatus 10 during calibration; with known gas concentrations, the device-specific cross-sensitivity parameters can be calculated by solving the 5 simultaneous equations. Processing of the data from the air quality sensors 36 can therefore be performed in realtime by an onboard processor 38, leading to rapid determination of air quality. The in-room air quality sensing apparatus 10 preferably includes a wireless communications element 44 which is in communication with the processor 38, and 10 preferably which has an operational frequency of less than 1 GHz. This allows the in-room air quality sensing apparatus 10 to communicate with and provide command and control signals to other air control devices which create airflow within a location. The communications frequency is suitable for transmission through communications-disrupting structures at a site, such as steel beams or thick stone walls, which allows the 15 in-room air quality sensing apparatus 10 to be used on such sites for the purposes of centralised airflow control. The provision of wireless communications of course allows for the option of decentralised processing, in which the data from the air quality sensors 36 is performed externally to the in-room air quality sensing apparatus 10. 20 The in-room air quality sensing apparatus 10 thus provides a means of improving the control of an air quality control system for a building 46, such as that shown in Figure 4. The in-room air quality sensing apparatus 10 is the control unit for all of the airflow control devices around the building 46. Each airflow control device includes a housing having an air inlet and an air outlet, an 25 electrically-energisable fan which is configured to create an airflow path from the air inlet to the air outlet, a wireless communication element communicable with the wireless communication element of the in-room air quality sensing apparatus 10 to receive a command signal therefrom, and a processor in communication with the wireless communication element. The processor is configured to control the electrically-30 energisable fan of each airflow control device in response to the command signal from the in-room air quality sensing apparatus 10. Each airflow control device may be tagged in some way which is indicative of its location within the building 46, and thus provides 26 01 26 the in-room air quality sensing apparatus 10 with additional context when providing said command signal. Examples of airflow control devices include freestanding in-room air filters 48, 50, positive input ventilation units 52, ceiling or wall-mounted air filters 54, and extractor fans 5 56. These may be positioned in different rooms in the building 46, controlling the airflow separately. The in-room air quality sensing apparatus 10 thus allows for statistical or holistic ventilation control, in that a centralised sensing apparatus 10 can command the airflow created by airflow control devices in a building 46 based on highly accurate gas 10 concentration measurements. Crucially, the identification of which gas components are changing may provide an indication of where in the building 46 the ventilation must be improved. Ammonia readings will be larger in bathrooms or lavatories, and if the in-room air quality sensing apparatus 10 senses ammonia spikes, then bathroom-located airflow control devices 15 may be activated in preference to other airflow control devices. Equally, carbon monoxide may be a more prevalent gas released from heating sources, such as stoves or boilers, and therefore ventilation in the appropriate area could be controlled as a result. The in-room air quality sensing apparatus 10 need not necessarily only be the controller for other airflow control devices, but could equally be provided with control over, for 20 instance, windows and doors within the building 46 for airflow manipulation. Similarly, the in-room air quality sensing apparatus 10 could link into existing airflow directing architecture of a building, such as ventilation ducting, to provide more powerful airflow control. The system could also be linked to a heating system of the building, to thereby allow for mutual control. 25 It will also be clear that sensing need not necessarily be confined to a single device, and cross-sensitivity measurements could be conducted based on readings from several different discrete sensor locations. This leads to an in-room air quality sensing system having a plurality of discrete in-room air quality sensing apparatuses which are communicatively coupled to one another. 30 This could thus be configured such that the system as a whole is linked to a server via wired or wireless broadband or cellular connections, or via a radio mesh network, for 26 01 26 instance. Individual devices could act as wireless bridges connecting the local radio network to the domestic or building Wi-Fi (RTM) network. It is therefore possible to provide an in-room air quality sensing apparatus which is capable of utilising the natural cross-sensitivities of commercially available air quality 5 sensors in a compact arrangement, so that detailed, real-time gas concentration information can be easily obtained for a wide range of different potential gases in the local atmosphere. This apparatus then allows for the creation of a holistic or statistical gas sensing regime to be achieved, enabling more powerful ventilation control systems to be considered within domestic, commercial, and industrial buildings and sites. 10 The words ‘comprises / comprising’ and the words ‘having / including’ when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps, or components, but do not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. It is appreciated that certain features of the invention, which are, for clarity, described in 15 the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The embodiments described above are provided by way of examples only, and various 20 other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein. 26 01 26

Claims

1. An air quality control system comprising:an in-room air quality sensing apparatus including:a housing having an air inlet and an air outlet;5 an electrically-energisable fan which is configured to create anairflow path from the air inlet to the air outlet;a plurality of air quality sensors mounted on the airflow path;a first processor in communication with the air quality sensors to receive sensor output signals therefrom, the first processor being10 configured to generate a command signal based on the sensor outputsignals, and being configured to calculate gas concentrations for a plurality of different gases on the airflow path based on cross-sensitivities of the plurality of different air quality sensors;a first wireless communication element in communication with the15 processor; anda plurality of airflow control devices, each device including: a housing having an air inlet and an air outlet;an electrically-energisable fan which is configured to create an airflow path from the air inlet to the air outlet;20 a second wireless communication element communicable with thewireless communication element of the in-room air quality sensing apparatus to receive the command signal therefrom;a second processor in communication with the second wireless communication element, the second processor being configured to25 control the electrically-energisable fan of the airflow control device inresponse to the command signal.

2. An air quality control system as claimed in claim 1, wherein the in-room air quality sensing apparatus comprises a housing having a base, gripping members being 30 provided on the base.

3. An air quality control system as claimed in claim 1 or claim 2, wherein the plurality of air quality sensors includes26 01 26a first air quality sensor having a primary gas sensitivity for a first gas and a secondary gas sensitivity for a second gas, the first air quality sensor producing a first sensor output, anda second air quality sensor mounted on the airflow path having a primary gas 5 sensitivity for a third gas and a secondary gas sensitivity for the said second gas, the second air quality sensor producing a second sensor output; andwherein the first processor is in communication with the first and second air quality sensors to receive the first and second sensor output signal therefrom, the processor being configured to calculate gas concentrations for each of the first, second, and third 10 gases.

4. An air quality control system as claimed in any one of the preceding claims, wherein the first and second wireless communication elements have a communication frequency of less than 1GHz.

155. An air quality control system as claimed in any one of the preceding claims, wherein the plurality of airflow control devices comprises at least one of: an in-room air filter; an extractor fan; and a positive input ventilation unit.20 6. An air quality control system as claimed in any one of the preceding claims, wherein each of the plurality of airflow control devices is provided in a different location, and wherein the first processor is configured to generate an airflow-control-device-specific command signal based on the gas concentrations, depending on the location of each of the plurality of airflow control devices.25

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