Heat flux plate

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heat flux sensor

HFP01 is the world’s most popular sensor for heat flux measurement 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. The sensor is very robust and stable. It is suitable for long term use on one location as well as repeated installation when a measuring system is used at multiple locations. If measuring in soil, in case a more accurate measurement is needed the model HFP01SC should be considered.


HFP01 measures heat flux through the object in which it is incorporated or on which it is mounted, in W/m2. The sensor in HFP01 is a thermopile. This thermopile measures the temperature difference across the ceramics-plastic composite body of HFP01. A thermopile is a passive sensor; it does not require power. Using HFP01 is easy. It can be connected directly to commonly used data logging systems. The heat flux in W/m2 is calculated by dividing the HFP01 output, a small voltage, by the sensitivity. The sensitivity is provided with HFP01 on its calibration certificate. A typical measurement location is equipped with 2 or more sensors. HFP01 is the world’s most popular sensor for heat flux measurement in the soil as well as through walls and building envelopes.

HFP01 unique features and benefits

  • low thermal resistance (essential for use on walls and windows)
  • large guard area (required by the ISO 9869 standard)
  • low electrical resistance (low pickup of electrical noise)
  • high sensitivity (good signal to noise ratio in low-flux environments such as buildings)
  • robustness, including a strong cable
  • IP protection class: IP67 (essential for outdoor application)

Click on drawing in Gallery for HFP01 heat flux plate dimensions: (1) sensor area, (2) guard of ceramics-plastic composite, (3) cable, standard length is 5 m. All dimensions are in mm.


HFP01 calibration is traceable to international standards. The factory calibration method follows the recommended practice of ASTM C1130.


HFP01 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.

Suggested use

  • building heat flux
  • U-value and R-value measurements
  • soil heat flux

Working with heat flux sensors

A typical measurement location is equipped with 2 heat flux sensors for good spatial averaging. If the sensitivity of a single sensor is too low, two or more sensors can electrically be put in series, creating an amplified single output signal. The user should analyse his own experiment and make his own uncertainty evaluation. More information can be found in the HFP01 manual.


  • longer cable, in multiples of 5 m, cable lengths above 20 m in multiples of 10 m
  • LI19 hand held readout unit

See also

  • if measuring in soil, in case a high level of quality assurance and accuracy of the measurement is needed, consider use of model HFP01SC
  • model HFP03 for increased sensitivity (also consider putting two or more HFP01’s electrically in series)
  • view our complete  range of heat flux sensors
  • view the TRSYS01 building thermal resistance measuring system which includes 2 x HFP01 and 4 x matched thermocouple type K
  • Campbell Scientific dataloggers


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