The Rise of 'Facadism' in London
I wonder how much the difficulty in bringing these building up to modern standards plays into these decisions. Over the years these building would have been fitted with a variety of different heating systems; perhaps starting with open hearth fires when they were built with large brick chimney stacks to provide thermal mass.  Over the years they probably got coal gas put in, or perhaps a back boiler hot water system operating on a thermal syphon, eventually being replaced by an early gas or oil boiler central boiler.<p>Each of these steps leaves another complex layer of hacks, fixes and dead pipes behind making it a long and challenging job to strip out and replace.<p>Similarly, when built it probably had no electrical supply at all, eventually being attached to the grid and wired with mineral insulated cable and re-wirable fuses. Over the years electricians have probably updated bits of this leaving old wires in place behind walls and ceilings.<p>Then you have the walls which would initially be lath and lime based plasters, with horse hair for strength and arsenic to stop the rats eating it. As these buildings got more sealed up, windows improved and fireplaces boarded up the condition of the plaster deteriorated. In places the plaster is patched with modern gypsum based plasters which aren&#x27;t really compatible with the naturally porous building materials.<p>Even if all that is fixed and updated there is little or no insulation in the construction of the building. Adding it internally can cause issues with condensation buildup in the fabric of the building and is all but impossible to achieve without fairly large cold bridges due to the existing construction. Adding it externally can&#x27;t be done without significantly altering the appearance of the building.<p>If that is all dealt with you probably have accessibility issues with steps and narrow door ways. Possibly fire safety issues etc.