EnergyBase: The Merger of BLAST and DOE

For the past several decades, the US government has maintained and supported two hourly building energy simulation programs, DOE–2 and BLAST. DOE–2 has been supported by the Department of Energy (DOE), and has its origins in the Post Office program written in the late 1960s for the US Post Office. BLAST has been supported by the Department of Defense (DOD), and has its origins in the NBSLD program developed at the US National Bureau of Standards (now NIST) in the same time period. For the loads calculation DOE–2 uses a room weighting factor approach and BLAST uses a heat balance approach. The need for two separate government supported programs has been questioned for many years, and discussions of the possible merger of the two programs began in May 1994 with a DOD sponsored conference in Illinois. The project began in earnest in 1995 with a two-phase plan. The goal of the first phase is to combine the best features and capabilities of BLAST and DOE–2 into a new program. The new program will have a modular structure making it more amenable to accepting modifications and additions. The first phase is being done by a joint team with members from the University of Illinois, the Lawrence Berkeley National Laboratory, and the US Army Construction Engineering Research Laboratories. The goal of the second phase, which will begin in 1998, is to produce a new generation energy analysis tool using the lessons learned from not only the current programs, but the combined program as well. The phase 1 combined program, called EnergyBase, incorporates several innovative features including variable time steps of less than an hour, built-in template and external modular systems simulation modules that are integrated with a heat balance based zone simulation, and generalized input and output data structures tailored to third party interface development. This paper presents an overview of the organization and capabilities of EnergyBase, describes the restructuring process that was necessary to build an easily extensible collection of modules, and explains the rationale behind the overall program organization.