v8.2.6

Release

EnergyPlus-8.2.6 is an iteration release, with a focus on performance enhancements. Several parts of the code went through overhauls since the release of 8.2.0 and as a result, the code is now faster than 8.1.0 in all of our test cases.

Numbers

We selected a set of input files that were provided by LBNL from an EnergyPlus performance study several years ago. After transition them from version 2.2 to 8.1, then 8.2.0, then 8.2.6, they were run against each package. The results were great for these files:

• Linux
  • 8.1.0: 1053.5581 [s]
  • 8.2.0: 999.3255 [s]
  • 8.2.6: 857.5618 [s]
• Windows
  • 8.1.0: 1028.5840 [s]
  • 8.2.0: 997.1380 [s]
  • 8.2.6: 876.652 [s]

As you can see, these files didn't show a regression from 8.1.0 to 8.2.0. Yet the enhancements made from 8.2.0 to 8.2.6 still showed a very nice speed improvement.

In addition, our set of regression test files, which is comprised primarily of the example files we package with each release, was run on Windows with full annual simulations. The results are:

• 8.1.0: 5:28:33
• 8.2.0: 6:36:59
• 8.2.6: 4:53:50

As you can see on these, the example file set did show a runtime regression with 8.2.0. This has now been addressed to the point where it is now faster than 8.1.0, by about 35 minutes. There is an improvement from 8.2.0 to 8.2.6 of about 103 minutes.

Enhancements

• Link time optimization utilized during release builds
• Solar-shading and interior radiant exchange performance tuning
• Finite difference wall-conduction model tuning
• Array allocation/dimensioning (heap) tuning

Tuning work is now being done continuously by the development team to ensure that EnergyPlus continues to be a more runtime friendly simulation engine.

Caution

This release package is intended for testing/evaluation only!! Because it is an iteration build, it includes some as-yet undocumented features, including input changes. While the transition program that is packaged with this release will transition your 8.2.0 files up to the latest syntax, you will be left with input files that are a mixed-bag between 8.2.0 and the upcoming 8.3.0 release. This will cause issues later, so please don't use this 8.2.6 build for general deployment.

User Notes

We invite you to try out your input files to check whether they are seeing the same speed increases that we have seen in our testing. Input files differ drastically, and can lead to very different hot spots within the code. Most of the enhancements made recently were because a select file (or set of files) were shown to have regressed in runtime. Once these files were identified, it was generally not too difficult to isolate the hot spot and address it.

If you are seeing a regression still from 8.1.0, we invite you to submit a ticket on the EnergyPlus Helpdesk so we can use this file in our tuning work.

Thanks,

EnergyPlus Development Team