Some more architecture?
One of the most sustainable and cheapest ways to construct a building, is using the material which is available right on the spot. So in the mountains, you use stone, in the woods you use logs, but what do you do in the desert ? It is quite obvious: you use the soil.
A technique used is called rammed-earth and is simple: all you need is some wood to make a framework - let’s say 40 x 80 x 160 cm - you fill it up with a damp mixture of sand, gravel and clay, and you compress it to 50% of its original volume. Traditionally this was done by hand with a long ramming-pole. When your frame is full, you remove it, and start on the next section. Needless to say, this involves some hard labour.
The advantages of the earth walls are plentiful: they are cheap to build, they are strong, they have a high thermal mass, they are fireproof … There is but one disadvantage: they don’t cope very well with humidity, so all the exterior walls have to be sealed, a process that has to be repeated regularly to prevent the walls from decaying. Floors are made of wooden beams. The roofs are flat and consist of wooden beams too, covered with branches and sealed off with more mud.
A great place to see some of this “soil” architecture is the southern part of Morocco, more particularly the Draa valley. This river/oasis runs through the Moroccan desert and is dotted with kasbah’s, some are still inhabited, most are decaying. Luckily an effort is made to restore several of the kasbah’s, so future generations can still admire this marvelous construction technique.