We are living in a world where the underground resources are growing scarcer and scarcer, and this is especially challenging as the global population rises; in order to adapt to this problem, the best decision, by far, is to go for renewable energy. 

As the name clearly states is, renewable energy is energy that doesn't end (at least in non-astronomic time), and it refers to using resources such as solar energy, wind power, water, etc. Among these, solar energy plays a crucial role in this system.

Solar renewable energy, in general terms, refers to the use of energy from solar radiation for water heating, space heating, electricity, or other related purposes. However, a relatively unknown solar thermal technology is solar air heating; the fact that it is so shadowed by other technologies is a real surprise if you ask me, because it is the most cost effective solar technology.

Basically it is used to heat or condition air for buildings, and it has a high applicability, from common houses or even flats to industrial buildings. Actually, it works best for industrial buildings, and it addresses buildings from almost all climates and areas.

There are two types of solar air heating: glazed and unglazed. Basically, unglazed collectors are air heating systems that consist only of metal absorbers, without any glazing on top; these systems heat ambient (outside) air instead of recirculated building air and are usually mounted on walls. They are usually cheap, but not extremely effective, and have a lifespan of about 30 years. Glazed heaters function in a somewhat similar matter, but they can also be mounted on roofs, when there is some regional or architectural requirement.  The simplest such device works in a fashion similar to a conventional forced air furnace; it absorbs the sun's energy and it ducts any air it comes in contact with, in a simple yet effective manner.

Generally, these devices are classified into one of these categories:

  •  through-pass collectors,
  •  front-pass,
  •  back pass,
  •  combination front and back pass collectors

I'm not going to go into technicalities here, if you want more information regarding these categories you can find it on http://en.wikipedia.org/wiki/Solar_air_heat.

However, solar air heating is growing in popularity, especially since some quite efficient devices can be built with limited resources and skill, and still receive good results. Hopefully, the world will use this technology, and integrate it with other types of renewable energy, so we can build a better, cleaner, and more effective future for generations to come.