Brief History¶

EnergyPlus has been under development since 1997 and was first released in 2001. EnergyPlus has its roots in both the BLAST and DOE--2 programs. BLAST (Building Loads Analysis and System Thermodynamics) and DOE--2 were both developed and released in the late 1970s and early 1980s as energy and load simulation tools. BLAST was developed by the Construction Engineering Research Laboratory (CERL) and the University of Illinois while DOE-2 was developed by Berkeley Lab and many others. Their intended audience is a design engineer or architect that wishes to size appropriate HVAC equipment, develop retrofit studies for life cycling cost analyses, optimize energy performance, etc. Born out of concerns driven by the energy crisis of the early 1970s and recognition that building energy consumption is a major component of the American energy usage statistics, the two programs attempted to solve the same problem from two slightly different perspectives. In the late 1990s, concern about limitations of both BLAST and DOE-2 as well as difficulty in maintaining the old code bases prompted combining the development efforts for a new program called EnergyPlus. EnergyPlus was originally written in Fortran, in 2014 it was converted to C++. It was developed as a simulation engine, and many graphical user interfaces utilize it.