Passive Solar Energy

     Passive solar energy is good way to achieve a free heat source for your home.  One of the simplest ways is to install a sun room that can be opened and closed.  Use dark colored carpets and furnishings to absorb as much of the hear as possible.  Using this in the winter can save money on heating bills.
     There are those who take this a step further actually installing a green house on the southern side of their home.  This not only gets the heat but also can feed you many fine vegetables even in the winter.  There is one man referred to as the "Garbage Warrior" who builds totally energy sustaining homes that require no utility payments.http://www.garbagewarrior.com/press  

     There are many designs to consider when designing for passive solar heating.  https://www.google.com/search?q=passive+solar+heating&hl=en&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=8s_UT4vLLYnK9gTNwqm1Aw&ved=0CI4BELAE&biw=1024&bih=602

  




      Another way of using solar energy passively is creating a solar hot water heater.  http://en.wikipedia.org/wiki/Solar_water_heating  There are many systems currently available on the market. 
     I have seen systems so simple they involved no more than an inclosed case, painted black on the bottom with a pipe making twists on top of it.  This water heater works very well.  And can save you a lot on energy bills.  sources.