In this talk we show that the Dirichlet Laplacian on a periodically perforated domain (compact or not) converges to a homogenised limit when the period lengths tends to 0. Classically, only strong resolvent convergence has been shown. Using abstract methods for convergence of operators acting in varying Hilbert spaces, we can also show norm resolvent convergence. This is a joint work with Andrii Khrabustovskyi (KIT)