Indoor heating Answered

Hi,
I hope this is the correct place to ask some rocket minded guys how we can solve our fridged home problem.

Our 30yr old cottage built with 2 layer perimeter brick and covered with heavy clay tiled roof becomes a freezer in winter.
With restricted use of power as a result of our Govt's poor planning it gets cut at anytime and gas heaters not being safe, is there a simple way to get natural heat other than installing a fireplace at great cost that could heat all rooms?
 B'lieve me guys it's ccold here even with a winter's sun outside, so solar panels or similar would need to absorb heat to distribute it all round and be very costly -  Sunny South Africa not so warm. 

Muscpro