  We prove local inverse-type estimates for the four non-local boundary
integral operators associated with the Laplace operator on a bounded
d-dimensional Lipschitz domain Omega for d >= 2 with piecewise smooth boundary.
For piecewise polynomial ansatz spaces and d = 2 or 3, the inverse estimates
are explicit in both the local mesh width and the approximation order. An
application to efficiency estimates in a posteriori error estimation in
boundary element methods is given.
