Ready to measure in five minutes by following these steps

1. Connect the data logger to your computer via the USB cable provided.
2. Allow all drivers to be installed.
3. The necessary read-out software can be downloaded from https://www.greenteg.com/Download-Software/ (use the password provided to you by greenTEG). Follow the instructions to install the software on your computer. You need to have admin rights to follow all necessary steps (right click on option "Execute as Administrator"). Currently the software is compatible with Windows® only. If you use a different operating system, e.g. Mac OS®, UBUNTU® etc., please have a look at our FAQ for some hints and additional information: https://www.greenteg.com/faq-heat-flux-sensing/.
4. When you open the software, the home screen will appear (See Figure 2). Under “File” > “Language” you can change the language settings from English to German or vice versa.
5. Mount the heat flux sensor onto the surface

Short guideline on how to mount the sensors:

I. Heat flux sensor placement

1. Install the heat flux sensor on the indoor surface with the side showing the gSKIN logo facing towards you. Use the adhesive roll tape. Mount the sensor on the exposed side of the tape. Completely cover the sensor with tape and cut an additional 2cm length of tape extending beyond the edge of the sensor (tip: when cutting tape, keep the exposed side of tape facing up). Fold back the additional length of tape onto itself to create a removal tab. Peel off the yellow protective film and mount the sensor onto desired surface. Firmly and evenly apply pressure on the sensor using your fingers for 4-5 seconds to ensure good adhesion. Do not apply uneven pressure on the sensor with any hard objects. Ensure that the sensor is protected from direct heating, convection, and solar radiation.

Figure 3. How to mount the sensor correctly

b. Optional: If the wall is wet or rough, use another adhesive (consult our online shop)

c. Optional: Use thermographic imaging to help identifying representative/interesting spots for the heat flux sensor placement on your building element.

d. Optional: Cover the heat flux sensor with the same material as its surrounding material.

e. Optional: Use several sensors to obtain an average value for highly inhomogeneous building elements.

II. Temperature sensor placement

1. Place the two temperature sensors at roughly opposite sides of the building element (i.e. wall or window) at the position where the heat flux sensor is placed. Use the provided double sided tape or another tape to mount the temperature sensors
2. For U-value measurements, make sure that the ambient air temperature is measured (i.e. by measuring the temperature more than 5 cm away from the building element and avoid direct solar radiation).

Note: The cables are typically used in aerospace and therefore meet highest requirements

1. Please verify that all sensors (temperature and heat flux) are displayed correctly by reviewing their graphs under “Real-time measurement”. Here you can also directly review the approximate U-value (the U-value will still fluctuate).

2. On the home screen, push the “Start logging“ button and then do the following steps:

   • Check the sensitivity
   • Select the frequency for data logging (under ”Sampling rate”, e.g. 10 min or 30 min2)
   • Select start time (under “Start mode“, e.g. “immediately“)
   • Add a comment e.g. specifications about measurement location After you push the “Start measurement” button, your data logging process begins. In the lower part of your screen, you will see the text switch from “save settings..” to “Measurement running..”. While logging, the LED of the logger flashes in blue (when charging it flashes in yellow; when it is fully charged the logger stops flashing yellow light while having a connection to the computer). NOTE: If the LED of the logger is red, no connection with your computer is established. In this case, please make sure that all cables are connected correctly and that there is no problem with the USB port you use.
   1. After logging data for 72 hours, you should receive an exact U-value according to ISO 9869. You can stop the measurement process by selecting the “Logger” tab and there the “Stop measurement“ function. We recommend that you first review your current measurement process (as indicated in step 9) before you stop your ongoing measurement. The following box outlines the conditions, which should be fulfilled for a successful measurement according to ISO 98692:

   Short outline of the measurement conditions regarding ISO9869: I. Duration of the measurement > 72h (+ an integer multiple of 24). The software automatically calculates the appropriate time frame (see Appendix A)

   II. U-value obtained at the end of the test does not deviate more than 5% from the value obtained 24h before (dR24)

   III. The U-value obtained during the first 2/3 of the overall measurement period does not deviate more than 5% from the values obtained during the last 2/3 of the overall measurement period.

   IV. The change in heat stored in the wall is <= 5% of the heat passing through the wall.

   While test conditions I. – III. are validated by the software, condition IV. is not tested. greenTEGs measurement system does not allow measurement of heat storage changes of the wall.

   Appendix A explains the test conditions in detail.

   1. To analyse your logged data and to verify if you really should stop the logging, please select “Read record” (on home screen). In the next window, you need to select the data set you want to be displayed and analysed (the latest data set will be preselected, all data sets are ordered by the measurement start time).

   2. By selecting the latest logging file, you can review the logged data set. In the newly opened window named “Analysis“, you will find the last measured data points (see Figure 4). The values stated in the header of the window are explained in detail in Appendix A. A graphical review of the measured data is given in the chart:

      • Blue line: Heat flux (corresponding to primary y-axis)
      • Read line: Indoor temperature T1 (corresponding to primary y-axis)
      • Yellow line: Outdoor temperature T2 (corresponding to primary y-axis)
      • Green line: Calculated U-value (corresponding to secondary y-axis)
      • Dotted vertical line: Start of analysis period

      The section “comments” shows the comments made regarding your latest measurement activity (see step 7); comments can be changed afterwards.

      

      Figure 4: Analysis window showing U-value output and sensor data graphs.

      

      Figure 5: Software screen for saving data as a PDF file.

      1. On the “Read record” > “Analysis” window, you can select under the “File” menu-button “Export data…” to save the raw data as a CSV file to your laptop (note: If you need further advise in exporting data please have a look in our FAQ: https://www.greenteg.com/faq-heat-flux-sensing.
      2. To review other data logger files stored on your laptop, you can select these files via your home screen by using the “Analyse record” button (see Figure 2)
      3. For erasing stored data on your data logger, you can ONLY erase/delete all data saved on the data logger by selecting in the top menu “Logger” and then “Delete all stored data!”. There is no option to retrieve deleted data, unless you have stored it before as a CSV/msr file on your pc (see step 12).
      4. To close the U-value software, you can select the “Exit” button on your home screen or the tab “File” and “Exit” function. In case you have already started a U-value measuring process, this activity will not be stopped. Only by selecting the “Logger” function on your home screen and there selecting “Stop measurement” one can end a U-value measuring process (see step 7).
      5. To demount the heat flux sensors a few important things should be considered (also see figure 6):
         • Only pull at the strips of the adhesive tape in direction of the tape itself.
         • DO NOT pull at the cable.
         • Do NOT pull at the strips perpendicular to the wall. Be careful when removing the tape, since the tape can damage the wall when removing it too fast or wrong.

      

      

      

      Figure 6: How to demount the sensor correctly