The BESTEST method for evaluating and diagnosing building energy software.

The increasing power of personal computers has e:ncouraged a proliferation of building energy simulation software packages. The prospective user has no way to quantitatively judge the appropriateness of a given software package for a given design problem. To address this issue, the Building Energy Simulation Test (BESTEST) procedure was developed for systematically testing whole building energy simulation programs and diagnosing sources of predictive disagreement. The BES TEST procedure takes a "comparative testing" approach where a program is compared to itself or to other programs. It focuses on testing a software package's ability to model thermal processes associated with the building envelope. Field trials of its approach were conducted with a number of detailed state-of-the-art programs by researchers from nations participating in International Energy Agency (IEA) Solar Heating and Cooling (SHC) Programme Task 12 and Annex 21. The approach consists of a number of carefully specified test case buildings that progress systematically from extremely simple to relatively realistic. The outputs from tested programs are evaluated according to diagnostic logi,c to determine the algorithms responsible for predictive differences. The procedure has proven very effeetive at revealing bugs, faulty algorithms, and input errors in a variety of detailed and simplified software for commercial and residential buildings. Since it was first published in 1995, BESTEST has been used and/or adopted by a number of nations, states, certifying bodies, and universities. Recently BESTEST was augmented to better accommodate simplified software and software for buildings in hot humid climates. Current work conducted in collaboration with IEA Solar Heating and Cooling Programme Task 22, and the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) Standards Project Committee 140 includes development of tests for heating, ventilation, and air-conditioning (HV AC) algorithms. This paper describes the BESTEST procedure, recent additions to the procedure, and results obtained by those who have used it to evaluate software.