Make a DIY solar air heater from soda cans for next to nothing.
Pictured above is a simple small passive solar heater made from recycled aluminium drinks cans and used to heat a room.
If the building to be heated is well insultated, a solar heater such as this can lift the temperature by a significant number of degrees. A larger heater or a number of similar heaters can be used to heat larger spaces, or to heat smaller spaces to a higher temperature.Offcuts of 2 x 4 and a sheet of plywood were used to build a box to tightly hold 5 rows of 10 black-painted aluminium drinks cans.
The inside of the box was then sealed using silicone to prevent hot air from escaping.
Cold air is drawn in from a hole at the bottom of the box, and the heated air emerges from the top passing through a pipe into the room to be heated. A perspex sheet was glued to the box to let sunlight in but not let the hot air escape.