ENERGY  ALTERNATIVES: RENEWABLE
ENERGY AND ENERGY CONSERVATION
TECHNOLOGIES



  (a)  Passive Thermal Systems :
  The  simplest method for the collection of solar energy is to 
  design  windows  of  buildings for  systematic  collection of 
  available  solar energy in the cold season.  Solar collectors 
  that make no use of ancillary  equipment like  fans and pumps 
  are  known  as  passive  systems.  Passive  collection is the 
  simplest and usually the most cost-effective way of gathering 
  solar energy (beam and diffuse), and many of these techniques 
  have  been  used  for  centuries.  They  became  neglected by 
  architects and builders during the period of low-energy costs.  
  Technically  speaking,  passive  heating  techniques are well 
  understood.  They  have  the  advantage  of using traditional 
  materials and building  techniques, and can be used in a wide 
  range of climates.  Since people live in the "collector", the 
  approach  is  chiefly  of  interest for heating  buildings in 
  temperate  climates and upland and mountainous areas in lower 
  latitudes.