BS 8233 facade level difference calculator
Predicts the internal sound level Leq,2 in habitable rooms from a facade free-field level Leq,ff, using the BS 8233:2014 Annex G “more rigorous” method (equations G.1 and G.2). Octave bands 63 Hz to 8 kHz, with libraries for glazing, trickle vents, external walls and (for top-floor rooms) roof or ceiling build-ups.