Ultra sensitive heat flux plate

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HFP03 is an ultra sensitive sensor for measurement of small heat fluxes in the soil as well as through walls and building envelopes. The total thermal resistance is kept small by using a ceramics-plastic composite body. See also model HFP01: putting several HFP01 sensors electrically in series is an alternative for using HFP03.


HFP03 measures heat flux through the object in which it is incorporated or on which it is mounted, in W/m2. HFP03 is specifically suitable for measurement of small flux levels, in the order of less than 1 W/m2, for instance in geothermal applications. The sensor in HFP03 is a thermopile. This thermopile measures the temperature difference across the ceramics-plastic composite body of HFP03. A thermopile is a passive sensor; it does not require power. Using HFP03 is easy. It can be connected directly to commonly used data logging systems. The heat flux in W/m2 is calculated by dividing the HFP03 output, a small voltage, by the sensitivity. The sensitivity is provided with HFP03 on its calibration certificate.

Click on drawing in Gallery for HFP03 dimensions: (1) sensor area, (2) guard of ceramics-plastic composite, (3) cable, standard length 5 m. All dimensions are in mm.


HFP03 calibration is traceable to international standards. The factory calibration method follows the recommended practice of ASTM C1130.


HFP03 can be used for on-site measurement of building envelope thermal resistance per unit area (R-value) and thermal transmittance (U-value) according to the standardised practices of ISO 9869, ASTM C1046 and ASTM 1155.
The user should analyse his own experiment and make his own uncertainty evaluation. More information can be found in the HFP03 manual.

Suggested use

  • extremely small heat fluxes
  • geothermal heat flux


  • longer cable, in multiples of 5 m, cable lengths above 20 m in multiples of 10

See also

  • putting multiple HFP01’s in series creates a  high-sensitivity measurement at a lower cost than when using HFP03. It also has the advantage of spatial averaging over a larger area.
  • if measuring in soil, in case a high level of quality assurance and accuracy of the measurement is needed, consider use of model HFP01SC.
  • view our complete range of heat flux sensors.


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