It would be up to the tribunal members based on the facts of each case to make a judgement on what is necessary to bring it up to the required standards.
“the installations in the house for the supply of water, gas and electricity and for sanitation, space heating and heating water are in a reasonable state of repair and in proper working order”
and also case law on
Habitability (Mcarthy v GCC 1988) “a house suffering from cold and damp which can only be made habitable by incurring huge heating bills cannot be said to be habitable”
It may be useful for those residents to get in touch with our helpline (or alternatively can contact me directly) to discuss further