EnergyPlus Performance Improvements via JSON Input Refactoring

Abstract

EnergyPlus is the flagship whole-building energy simulation program developed by the U.S. Department of Energy. This paper describes the refactoring efforts around the EnergyPlus input processor to natively support JavaScript Object Notation (JSON), allow validation through use of a JSON schema validator, convert and validate typical EnergyPlus input data file (*.idf) files to JSON files, and improve related metrics such as: read time for schema and input files, parse time for processing input, and time to query/return data from EnergyPlus internal data structure. Performance improvements on sample files result in 14% and 60% reduction in schema and input file reads respectively, 36-62% reduction to process input, and 24-99+% query reduction for functions that take advantage of the new format. For the files tested, overall speedup realized as part of this JSON refactor is 1.6x to 5.4x.