 Then stacked the containers horizontally behind an Equator-facing double glazing with the blackened bottoms facing outside.This water wall involves the same principles as the Trombe walls but employs a different storage material and different methods of containing that material.Like the dark colored thermal mass of the Trombe walls, the containers that store the water are also frequently painted with dark colors to increase their absorptivity, but it is also common to leave them transparent or translucent to allow some daylight to pass through.