I'd just kiss goodbye to your security deposit, and move on. The landlord could theoretically take action against you for breach of contract, but s/he would be mad to..... The judge would expect the landlord to have "mitigated the losses" of the contract termination (i.e. found a new tenant asap). Also, the judge would take into account your ability to pay etc etc... and you could probably argue a breach of contract on the landlord's side because the heating/insulation in the house wasn't up to scratch. The forfeiture of the deposit would probably be enough to satisfy any judge, as well as the PRTB (who would have to be the landlord's first port of call anyway).
The potential costs for the landlord in pursuing the case (should s/he lose it) mean that only a fool would take legal action against an unemployed tenant over breaking a lease and expect to recoup any money, regardless of whether he or she is entitled to sue.
If you genuinely can't afford to stay there, then I'd just move out as planned and call the landlord's bluff. S/he will give up soon enough.