In rooms which don't have the original decorative ceiling cornices, we are installing suspended ceilings (plasterboard and timber studwork) below the original ceilings. This creates a free route for pipe and cable runs, which both speeds installation and reduces the amount of notching/drilling of load-bearing elements.
Bathroom areas will be ventilated using single-room MVHR units (see this article for a more detailed explanation), mounted within the suspended ceiling voids...