Diagnose Your BPIP Input File — Are Your AERMOD Inputs Accurate?
Building inputs are vital in dispersion modeling since these values are used to estimate downwash effects in AERMOD. Building downwash is created by air flow over and around structures. This effect can greatly increase predicted concentrations by factors of three to five.
Typically, the building dimension inputs generated from EPA’s Building Profile Input Program (BPIP) will produce unrealistically high concentrations. This is because BPIP, the standard tool for determining building dimension inputs, handles many situations poorly. BPIP could incorrectly:
- Merge nearby buildings into one single building
- Ignore or misrepresent lattice structures
- Mishandle buildings with a low, large footprint or complex geometry
What Does The BPIP Diagnostic Tool Do?
Using your BPIP output file, the BPIP Diagnostic Tool evaluates all wind directions for each stack to identify building dimensions that are outside of the tested theory in the model. The tool then generates a report indicating areas that may be problematic, which gives you the information to decide whether standard BPIP methods accurately represent downwash effects, or if you need to consider other methods that will be more accurate.