a ball of light

I heard a cool story on the radio yesterday about a simple way to improve the lighting in poor housing.

In the Philippines they fill a plastic soda bottle with water and a bit of bleach, and poke it through a hole in the roof. The water acts as a lens and vastly increases the light in the room.

It is used in places where they can't afford power and are so tightly packed in that they have no windows so the place is dark all day... until now!

As they have monsoons, the waterproofing was all sorted out using some kind of flashing, which also prevents the bottle falling down with the expansion and contraction of the roof in the sun.

Practically free... and brilliant!