FHF05 Series

Foil heat flux sensor with thermal spreaders, flexible, with temperature sensor

FHF05 is the product range to start looking if you consider measuring heat flux. Models are available in five different dimensions and sensitivities. All FHF05’s are flexible, have an integrated temperature sensor and have thermal spreaders to reduce thermal conductivity dependence. Rated temperature range is from –70 to +120 °C. FHF05 measures heat flux from conduction, radiation and convection. Optionally, black BLK and gold GLD stickers are available for all five models to separately determine heat transport by radiation and convection. In case the FHF05 series does not match your needs, have a look at other heat flux sensor models for special applications.

  • flexible (bending radius ≥ 7.5 x 10-3 m)
  • low thermal resistance
  • wide temperature range
  • fast response time
  • large guard area
  • integrated type T thermocouple
  • robustness, including connection block, for strain relief
  • IP protection class: IP67 (essential for outdoor application)
  • integrated thermal spreaders for low thermal conductivity dependence


Sensors of the FHF05 series are suitable for general-purpose heat flux measurement. The range is available in five different dimensions. Larger dimensions mean a higher sensitivity and a larger area over which the heat flux is averaged. They are thin, flexible and versatile. FHF05 measures heat flux through the object in which it is incorporated or on which it is mounted, in W/m2. The sensor in FHF05 is a thermopile. This thermopile measures the temperature difference across FHF05’s flexible body. A type T thermocouple is integrated as well. The thermopile and thermocouple are passive sensors; they do not require power.

Multiple small thermal spreaders, which form a conductive layer covering the sensor, help reduce the thermal conductivity dependence of the measurement. With its incorporated spreaders, the sensitivity of FHF05 is independent of its environment. Many competing sensors do not have thermal spreaders. The passive guard area around the sensor reduces measurement errors due to edge effects and is also used for mounting.

Using FHF05 is easy. It can be connected directly to commonly used data logging systems. The heat flux in W/m2 is calculated by dividing the FHF05 output, a small voltage, by the sensitivity. The sensitivity is provided with FHF05 on its certificate.

Equipped with a connection block, which may serve as strain relief, and with potted protective covers on both sides so that moisture does not penetrate, FHF05 has proven to be very robust and stable.

FHF05 calibration is traceable to international standards. The factory calibration method follows the recommended practice of ASTM C1130 – 21.

Would you like to to study energy transport / heat flux in detail? Hukseflux helps taking your measurement to the next level: order FHF05 with radiation-absorbing black and radiation-reflecting gold stickers. You can then measure convective + radiative flux with one, and convective flux only with the other. Subtract the 2 measurements and you have radiative flux. BLK – GLD stickers can be applied by the user to the sensor. There are stickers for every sensor dimension. Optionally, they can be ordered pre-applied. See the BLK – GLD sticker series user manual and installation video for instructions.

Suggested Use

FHF05 series have sensors for general-purpose heat flux measurement, often applied as part of a larger test – or measuring system. FHF05SC series (soon available) on the other hand, is a self-calibrating version of the standard model FHF05, combined with a HTR02 series heater (soon available). FHF05SC series is used when the highest level of quality assurance is required and for long-term heat flux measurement. The self-calibrating sensor is available in a 50X50 and 85X85 model.


Building physics / insulation, thermal comfort and energy budget measurement
Heat flux measurement to validate CFD thermal simulations
Industrial monitoring and control / heat flux and heat transfer measurement
Meteorology / surface energy flux measurement
Scientific research / heat and heat transfer measurement


BLK – GLD stickers
Black and gold stickers for measuring convective and radiative heat flux separately
convective and / or radiative heat flux



heat flux, temperature

Outer dimensions foil with guard

(10 x 10, 15 x 30, 50 x 50, 15 x 85, 85 x 85) x 10⁻³ m

Sensitivity (nominal)



1 x 10⁻⁶ V/(W/m2)


3 x 10⁻⁶ V/(W/m2)


13 x 10⁻⁶ V/(W/m2)


7 x 10⁻⁶ V/(W/m2)


50 x 10⁻⁶ V/(W/m2)

Temperature sensor

type T thermocouple*

Thermal spreaders


Rated bending radius

≥ 7.5 x 10⁻³ m

Rated load on cable

≤ 1.6 kg

Sensor thermal resistance

11 x 10⁻⁴ K/(W/m²)

Sensor thickness

0.4 x 10⁻³ m

Uncertainty of calibration

± 5 % (k = 2)

Rated temperature range - continuous use

-70 to +120 °C

Rated temperature range - short intervals

-160 to +150 °C**

IP protection class


Standard wire length

2 m


without wiring, without connection block; with 5 m wire length; with 10 m wire length; with BLK-black and/or GLD-gold stickers for every dimension

* temperature measurement uncertainty: 2 % of value in ˚C. For details, refer to user manual

** when measuring at temperatures of -160 °C , contact Hukseflux.

*** sensor is not suitable for continuous exposure to water

• with 5 or 10 metres cable length
• separate cable in 2, 5 or 10 metres length
• without wiring, without connection block
• LI19 hand-held read-out unit / datalogger
NOTE: LI19 measures heat flux only
• BLK sticker for all models (to measure radiative as well as convective heat flux)
• GLD sticker for all models (to measure convective heat flux only)
• BLK – GLD sticker series can also be ordered pre-applied at the factory


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Download Product Manual

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