Brief

One of the essential design components of this application was to ensure that it saved time during the pre-design phase, particularly for domestic contractors performing the calculation by hand.

To test this, a Masters of Engineering student familiar with geothermal systems was given all of the input data required to design a geothermal system, along with all of the calculations required to compute the pipe length required.

The student was told to perform the calculation 4 times, keeping record of all variables, their units and ultimately the pipe length required. For each iteration, the student was timed as to how long it took them to complete the task and told whether the system was designed correctly or not, though they were not told what the error was if there was one. This was done to attempt to replicate a real-life scenario where the designer would only know that the system was poorly designed once it had already been installed. Therefore, for each new iteration, all the student knew was that they had made a mistake in the previous calculation.

Once the student had completed the 4 iterations, they were then asked to then repeat the process again for the same scenario, but this time using the application to compute results. Again in this scenario, errors were recorded and the student was told whether there was an error in their results or not though not specifically what the error was.

An error throughout the calculation was deemed any variable that was calculated incorrectly. Whether the calculation was deemed successful or not, was whether the max pipe length was the correct value. An example where the student made an error, though calculated the correct pipe length was in Attempt 3 (Figure 12). The student made a calculation error on the pipe length required for cooling, though calculated the heating pipe length correctly which was the larger measurement.

Result

The results of the test indicated that even with repetition of the exact same scenario, with the exact same variable, with all the equations in-hand, the quickest the student was able to do it by hand and calculate a successful pipe length was 14 minutes! In contrast, they attempted the same scenario using the application and completed it successfully every time, always in less than 2 minutes!

For interest, we filmed some of the testing and put this short video together: