TRSYS01 heat flux measuring system

High-accuracy heat flux measuring system with 2 measurement locations

TRSYS01 is a high-accuracy system for on-site measurement of thermal resistance, R, thermal conductance, the Λ-value, and thermal transmittance, the U-value, of building envelopes. TRSYS01 is mostly used for measurements according to standard practices of ISO 9869 and ASTM C1155 / C1046. The system is equipped with high-accuracy electronics, two heat flux sensors of model HFP01 as well as two pairs of matched thermocouples. The two measurement locations provide redundancy, leading to a high level of confidence in the measurement result. The high accuracy of the heat flux sensors and temperature difference measurements ensures that TRSYS01 continues measuring when other systems no longer perform; in particular at very low-temperature differences across the wall.

  • Temperature difference sensors: tested for 0.1 °C accuracy requirements
  • Superior heat flux sensor, stable: waterproof (IP67), corrosion-proof
  • Continues measuring when others give up: high sensitivity amplifier + high sensitivity sensors


Building Physics

On-site measurements of thermal resistance, R, are often applied in studies of buildings. Alternatives are to measure its inverse value, the thermal conductance which is called the Λ-value, or the thermal transmittance which includes ambient air boundary layer thermal resistance, the U-value. The measurements of R are based on simultaneous time-averaged measurements of heat flux Φ and differential temperature, ΔT, (using two temperature sensors each on a different side of the wall).

R = ΔT / Φ

High Accuracy
The ISO and ASTM standards give detailed directions concerning the measurement method, sensor installation, and data analysis. The TRSYS01 system employs dedicated sensors and electronics. Their high accuracy and sensitivity ensure that TRSYS01 will still measure under circumstances where competing systems no longer perform reliable measurements; i.e. down to very low heat fluxes and low-temperature differences across the wall. The matched thermocouple pairs in TRSYS01, model TC, measure temperature differences with an uncertainty of better than 0.1 °C over the entire rated temperature range. TRSYS01 includes 2 x HFP01heat flux plates. HFP01 is the world’s most popular sensor for heat flux measurement in studies of buildings.

Robust and Stable
Equipped with heavy-duty components, TRSYS01 has proven to be very robust and stable. It survives repeated installation necessary in this application where measuring systems are typically used at multiple locations.

Suggested Use

  • Building U-value and R-value measurement

Areas of Application

Building physics / insulation, thermal comfort and energy budget measurement



-heat flux (2 x)
-temperature (2 x)
-temperature difference (2 x)

Required data analysis to determine building R-value and U-value

to be performed by the user according
to ISO and ASTM standard practices

Standards governing use of measuring system

ISO 9869 and ASTM C1155 / C1046

Number of measurement locations

2 (can be increased on request)

Cable length per location

location 1: 10 m
location 2: 20 m

Rated operating temperature HFP01 and TC

-30 to +70 °C range

Uncertainty of calibration heat flux sensors

± 3 % (k = 2)

Guard width to thickness ratio

5 m/m (as required by ISO 9869 D.3.1)

Acceptance interval temperature difference measurement

± 0.1 °C (required by ISO 9869, paragraph 5.2)

Measurement duration range

> 3 days

Data storage capacity

> 30 days

Adapter rated power supply

110-220 VAC, 50 / 60 Hz

Temperature difference measurement resolution

0.02 °C

Heat flux measurement resolution

0.02 W/m²

Connection to PC

via USB or RS232


• Rechargeable battery pack for autonomous use
• LP02 pyranometer
• More measurement locations


Download Product Brochure

Download Product Manual

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