My son has a few heart problems and his room is freezing?

my son has a few heart problems ( a murmur, a hole in the heart, had a closure of a pda and his valve dont pump enough blood thro) i have been told by the hospital that if his lips go blue to get him in asap, but his room is freezing as the windows let so much cold air in (my landlord wont sort it) and ive rung the council and they can only insulate the loft and walls, and i havent got enough money to lave the heating on as im a single parent, how am i supposed to tell if he is cold because of the weather and his lips are going blue or because of his heart and can the cold put strains on his heart. ive tried contactin my landlords as there are many problems but im on a 6 month lease and dont want to be kicked out because of the ongoing list of problems that he dont want to sort, thanks