ASHRAE Standard 140,"Method of Test for Evaluating Building Performance Simulation Software," provides test suites that allow software developers and users to evaluate the capabilities of a Building Performance Software (BPS) program versus analytical standards and/or other software programs. The standard has proven through the years to be a good tool for identifying weaknesses in BPS both in individual programs and in the software programs in general. Up to this point, it was assumed in the test cases that the programs could properly read standard weather files and process this information for the simulations. A new test suite is being developed to test this assumption. In this test suite, BPS programs are run with different weather files and the outputs are compared to the values in the files and against the output from the other programs. Statistical analyses are performed on the results to determine the level of agreement between the programs and the data file and between each other.