Technical Field of the Invention

The present invention relates to a heat flux sensing device and in particular to a heat flux sensing device adapted for monitoring the thermal performance of a building. Background to the Invention

In order to study energy efficiency in buildings, it is necessary to gain an understanding of energy losses within said buildings. One such energy loss is from the heat flux through the walls of a building. This can be assessed by affixing a heat flux sensor to the wall being monitored. In order to generate accurate measurements, the heat flux sensor must be closely and securely fitted to the wall.

Some accurate heat flux sensors are rather fragile. In particular, the connection between the sensor and the power/data wires is prone to breakage under mechanical stress. Accordingly, whilst it is relatively straight forward to fit sensors securely in position, for instance using adhesive, it is difficult to subsequently remove the heat flux sensor without damage. This limits the prospects of the reusability of the senor. Accordingly, it is typical to provide a measurement rig adapted to securely affix the heat flux sensor to the wall. Conventional measurement rigs are very expensive and somewhat bulky. Furthermore, these rigs are difficult to set up and require a wired power and data connection in order to operate. Whilst it is possible to use rather more robust heavy duty heat flux sensors, these can be less suitable. In addition, they typically require secure mounting using tape. Tape mounting can have an influence on local heat flows. More pertinently, in order to ensure that the sensor is held in secure contact with a surface, the tape must be relatively ineleactic and be backed with strong adhesive. If not, the sensor will gradually move out of position as the tape stenches or as it peels away from the wall surface. Use of such strong tape typically causes damage to the wall upon removal. This can be a disincentive to a building owner in terms of conducting tests and/or the cost of making good such damage negatively impacts on the desirability of carrying out testing.

To obtain detailed overall measurements of the heat flux within a room, it is typically necessary to utilise separate dedicated sensors to measure other relevant quantities such as the air temperature and/or the wall temperature. Measuring such quantities spaced apart from the heat flux sensor reduces the accuracy of the energy flow model. Additionally, a relatively bulky mounting rig for the heat flux sensor can also impact on the local heat flux. Furthermore, if the sensors are tape mounted, this can create significant dame, particularly where each is separately tape mounted.

It is therefore an object of the present invention to provide a heat flux sensing device that at least partially overcomes or alleviates at least some of the above problems.

Summary of the Invention

According to a first aspect of the present invention there is provided a heat flux sensing device comprising: a heat flux sensor; a support frame upon which the heat flux sensor is mounted; a housing provided around the support frame, the housing comprising a heat flux opening corresponding to the dimensions of the support frame; and biasing means operable to urge the support frame to project out of the heat flux opening. By urging the support frame to project out of the housing, the biasing means hence urge the heat flux sensor to project out of the housing. When the housing is affixed to a wall or other surface, this therefore ensures that the heat flux sensor remains in good contact with the wall or surface, without putting excess stress on the heat flux sensor during operation or installation or removal. Furthermore, enables good contact between the sensor and surface even when held in position using relatively weak adhesive means, tape or mounting rigs.

The support frame is preferably mounted to the rear of the heat flux sensor. The support frame preferably corresponds to the shape of the heat flux sensor. In a preferred embodiment, the support frame comprises an extended duct having a cross-section corresponding to the shape of the heat flux sensor.

The heat flux opening may be provided in a front face of the housing. In some embodiments, a rear opening may be provided in a rear face of the housing. The rear opening may also correspond to the support frame. This provides additional freedom of movement for the frame within the housing. Beneficially, it also allows an external force to be applied to the frame against the bias provided by the biasing means. This can enable the heat flux sensor to be withdrawn behind the front face of the housing whilst the external force is applied. This can prevent the heat flux sensor being damaged during installation or removal of the device. In some embodiments, the support frame may be provided with one or more projecting ribs. In such embodiments, the heat flux opening and rear opening may comprise corresponding notches. The notches and ribs help locate the frame in position relative to the housing and limit undesired motion of the support frame relative to the housing.

The ribs may be spaced to enable a connection wire for the heat flux sensor to lie there between. The ribs thereby provide additional protection to the connection wire for the heat flux sensor. The ribs may be provided with an end bar connecting them at the front of the frame. The end bar can provide additional protection for the connection wire of the heat flux sensor.

The biasing means may comprise one or more springs. The support frame may comprise one or more spring anchors for retaining the springs. The or each spring may be mounted between spring anchors. The spring anchors may be provided upon the rear face of the housing and side arms projecting from the supporting frame.

The housing may be provided with fixing means operable for affixing the housing to a surface. Typically, the surface is a wall. The surface may alternatively be a floor or ceiling. The fixing means may be temporary fixing means or permanent fixing means. In one embodiment, the fixing means comprise adhesive or one or more adhesive strips or pads. Preferably, the adhesive strips or pads are removable adhesive strips or pads. Since the biasing means acts to urge the heat flux sensor into contact with the surface, removable adhesive strips or pads are sufficient to hold the device in position. Accordingly, if the device is removed, these strips or pads can be removed without damaging the surface. The heat flux sensor may be a heat flux sensor of any suitable form, including but not limited to thermoelectrice heat flux sensors. Suitable heat flux sensors include, but are not limited to those supplied by Hukseflux, greenTEG and Omega.

The device may incorporate one or more additional sensors. In one embodiment, the device further comprises a surface temperature sensor. The surface temperature sensor may be a contactless temperature sensor. Preferably said sensor comprises an infra red sensor. The surface temperature sensor may be mounted within the housing and aligned with a surface temperature opening provided in the front face of the housing. Most preferably, the surface temperature opening is provided adjacent to the heat flux opening.

Additionally or alternatively, the device may comprise an air temperature sensor. The air temperature sensor may be an air temperature sensor of any suitable form. The air temperature sensor may be provided within the housing. The air temperature sensor m provided adjacent to one or more airflow openings. The airflow opening may be provided to enable a flow of ambient air through the housing.

Where the device is provided with both a surface temperature sensor and an air temperature sensor, the device can readily provide measurements of heat flux through a surface, the temperature of the surface and the temperature of the ambient air. This can enable measurement and/or monitoring of the surface heat resistance. The device may be provided with a power supply. The power supply may comprise a battery. The battery may be mounted within the housing.

The device may be provided with a communication unit. The communication unit may be operable to communicate data from the device to external devices. The communication unit may also be able to receive data or control instructions from external devices. Preferably, the communication unit is a wireless communication unit operable to utilise a wireless data link. Suitable data links may include but are not limited to Wifi, Zigbeee or similar links such as those using the ISM band. The device may comprise a processing unit. The processing unit may be operable to control operation of the device. The processing unit may comprise a microcontroller. The device may comprise a data storage unit. The data storage unit may be operable to store data generated by the sensor. The data storage unit is preferably a solid state data storage unit. In some embodiments, the solid state data storage unit may be a removable data storage unit such as a flash memory device.

According to a second aspect of the invention there is provided a heat flux sensing device comprising: a housing, a heat flux sensor provided within an opening in a front face of the housing, the heat flux sensor operable to measure heat flux from a surface to which the housing is fixed; a surface temperature sensor operable to measure the surface temperature of a surface to which the housing is fixed, the surface temperature sensor mounted within the housing and aligned with a surface temperature opening in the front face of the housing; and an air temperature sensor mounted adjacent to one or more airflow openings and operable to measure the temperature of air within the housing. The heat flux sensing device of the second aspect of the present invention may incorporate any or all features of the first aspect of the present invention as desired or required. A heat flux sensing device of the second aspect of the invention can readily provide measurements of heat flux through a surface, the temperature of the surface and the temperature of the ambient air. This can enable measurement and/or monitoring of the surface heat resistance.

A method of monitoring heat flux comprising the steps of affixing a heat flux sensing device according to the first aspect or the second aspect of the present invention to a surface; and monitoring the output of the heat flux sensing device.

The method of the third aspect of the present invention may incorporate any or all features of the first or second aspects of the present invention as desired or required. Detailed Description of the Invention

In order that the invention may be more clearly understood an embodiment thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

Figure 1 is a schematic block diagram of an embodiment of the heat flux sensing device of the invention;

Figure 2 is a view of the front face of the housing of the heat flux sensing device of the invention;

Figure 3 is a view of the rear face of the housing of the heat flux sensing device of the invention;

Figure 4 is a partial cutaway view illustrating the mounting of the heat flux sensor and support frame relative to the rear face of the housing; Figure 5 is a partial cutaway view illustrating the mounting of the heat flux sensor and support frame relative to the rear face of the housing and other components of the device; and

Figure 6 is a partial cutaway view illustrating the mounting of the heat flux sensor and support frame relative to the front face of the housing and other components of the device;

Turning now to figure 1, a heat flux sensing device 1 comprises a heat flux sensor 11 operable to measure heat flux from a surface, in this example a wall, to which the device 1 is fixed. A surface temperature sensor 16, typically an IR sensor, is operable to measure the surface temperature of the surface to which the device 1 is fixed. An air temperature sensor 17 is operable to measure the temperature of ambient air local to the device 1. The device 1 further comprises a microcontroller 12 operable to monitor the operation of the sensors 11, 16, 17. The microcontroller 12 is connected to a data store 14 for storing details of the outputs of sensors 11, 16, 17. The microcontroller 12 is also connected to a communication unit 13 for wirelessly communicating details of the outputs of sensors 11, 16, 17 to external devices. The sensors 11, 16, 17, microcontroller 12, data store 14 and communications unit 15 are powered by a battery 15.

Turning to figures 2&3, the device 1 is provided within a housing 20. The housing 20 has a front face 21, intended in use to be fixed to the wall, and a rear face 22. A heat flux opening 23 is provided in the front face 21 for the heat flux sensor 11. The heat flux opening 23 allows the heat flux sensor 11 to be positioned in contact with the wall. A surface temperature opening 24 is provided for the surface temperature sensor 16. The opening 24 allows the surface temperature sensor 16 to view the wall and thereby detect the surface temperature of the wall.

Airflow openings 25 are provided to enable ambient air to circulate through the housing 20. The air temperature sensor 17 is provided adjacent to the airflow openings such that the temperature of the ambient air can be measured.

As can be seen in figure 3, the rear face 22 has an opening 23 a corresponding to the heat flux opening 23.

In order to achieve optimum performance, the heat flux sensor 11 must be closely and securely fitted to the wall. To this end, the heat flux sensor 11 is mounted on a support frame 30. The support frame 30 has the form of a duct with a cross-section corresponding to the shape of the heat flux sensor 11 and the heat flux opening 23.

The support frame 30 is provided with side arms 31 upon which are provided spring anchors 39. Corresponding spring anchors 29 are provided on the interior of the rear face 22. Springs 32 are mounted between the corresponding spring anchors 29, 39. The springs 32 are operable to urge the support frame 30 away from the rear face 22. As a consequence, the support frame 30 is urged to project out of the heat flux opening 23 and thus, in the absence of any other forces, the heat flux sensor 11 projects proud of the front face 21, as illustrated in figure 2. When front face 21 is affixed to the wall, the springs 32 act to urge the heat flux sensor into a close and secure fitting with the wall. As there is provision for relative movement between the heat flux sensor 11 and the housing 20 and it is the housing 20 that is directly affixed to the wall, minimal stress is applied to the heat flux sensor 11 during installation or removal of the device 1 or from unexpected impacts during monitoring operation.

The support frame 30 is also provided with a pair of ribs 37, the ribs connected by an end bar 38 at the front of the frame 30. Between the ribs 37 is provided a passage for a serial connection cable 11a connecting the heat flux sensor 11 to the microcontroller 12. The cable 1 la is protected by the ribs 37 and end bar 38. The cable 11a gradually transitions to a non-serial cable l ib before connection to the microcontroller 12. The openings 23a, 23 are provided with notches 27, 28 to accommodate the ribs 37 and end bar 38 respectively. An additional benefit of the ribs 37, end bar 38 and notches 27, 28 is to help confine the relative motion of the support frame 30 and the housing 20.

Turing now to figures 5 & 6, the relative positions of the remaining components within the housing 20 is illustrated. The battery 15 is provided at the opposite end of housing 20 to the heat flux sensor 11. Between the battery 15 and heat flux sensor 11 is provided a circuit board 10 upon which is provided the microcontroller 12, data store 14 and air temperature sensor 17.

The communications unit 13 is mounted separately to the circuit board 10 on an antenna means 18 to enable transmission and receipt of wireless communication signals. The communications unit 13 typically comprises an RF (radio frequency) transceiver operable according to a standard data transfer protocol such as Bluetooth, Zigbee or the like.

Whilst the above embodiments relate to a combined device incorporating both a surface temperature sensor 16 and an air temperature sensor 17, the skilled man will appreciate that either or both sensors 16, 17 can be omitted if a pure heat flux sensing device 1 is desired.

The above embodiment is described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.