10-02-2014, 05:08 PM
This is a long awaited release, because the code base of EnergyPlus has changed from Fortran to C++ from this version. Personally I think this is a right move, as the number of Fortran programmers has been declining for years. C++ will feel more familiar to many, including those C, Java and Objective-C programmers, who represent the largest three communities according to some statistics.
There has been quite some speculations and lively debates about the pros and the cons of this transition (see here, for example) before the release. One of the concerns was that performance of the program will suffer, since C++ is not as geared towards scientific computing as FORTRAN is. Well, we were eager to see the impact for ourselves; so we ran the jEPlus benchmark set as soon as the new E+ was installed. The chart below shows the results. Basically, the simulation speed for v8.2 is slower than v8.1 in almost all test cases. On average the simulation time is 15% longer, with a few cases reaching 60+%...
![[Image: fetch.php?media=download:simulation_time_increase.png]](http://www.jeplus.org/wiki/lib/exe/fetch.php?media=download:simulation_time_increase.png)
There has been quite some speculations and lively debates about the pros and the cons of this transition (see here, for example) before the release. One of the concerns was that performance of the program will suffer, since C++ is not as geared towards scientific computing as FORTRAN is. Well, we were eager to see the impact for ourselves; so we ran the jEPlus benchmark set as soon as the new E+ was installed. The chart below shows the results. Basically, the simulation speed for v8.2 is slower than v8.1 in almost all test cases. On average the simulation time is 15% longer, with a few cases reaching 60+%...
