Nearly 10 years ago I wrote a blog post looking at one of the most often quoted statements in earth building literature. The post got lost in the midst of website changes, so I trawled the Wayback Machine, picked it out and have updated it to 2022.
Almost every book and presentation about earth buildings begin with the phrase
“Around one third of the world’s population lives in buildings constructed from earth”
This is really quite a statement, and is often cited without much thought about where it came from, and how relevant it really is.
I would like to examine this statement, and perhaps to challenge it!
I believe the statement first originated at the 1982 exhibition organised by CRATerre at the Pompidou centre in Paris.
This statement was then repeated in Earth Construction: A comprehensive Guide, published by Hugo Houben and Hubert Guillaud in 1994, a book which has gone on to be the bible of earth building in Europe.
I don’t know where the information is from, but have a feeling that in 1982, one third of the world’s population was about right.
In 1982 the world population was 4.6 billion and and was around 37% urbanised, ie 2.75 billion people living in rural areas. So if one third of the world’s population live in earth buildings, this makes 1.5 billion people living in earth buildings, about 55% of the world’s rural population.
I assume here that 100% of the urban population lives in non-earthen built homes (comprising say concrete block, timber frame, or fired brick) and that 45% of the world’s rural population live in non-earthen built homes.
This seems a reasonable set of assumptions, though analysis of Paul Oliver’s Atlas of Vernacular Architecture would be a great help to this study.
Lets look at the statistics now (2022). The world’s population is 7.9 billion, with the rural population continuing to reduce. In 2006 the world’s urban population surpassed the rural population, now at 44% (3.4 billion)
I contend that the increase in urban population has not built new earth houses, and that possibly some of the rural population have moved from earthen homes to concrete block homes.
One third of the world’s current population is 2.6 billion – are this many people really living in earth buildings?
If we assume the same percentage split of rural earthen (55%) to non-earthen (45%) houses in 2022 as in 1982, then we arrive at 1.9 billion people living in earth buildings in 2022. This is 24% or around one quarter of the world’s population, not one third, and assumes that new earthen homes have been built for the increase of 400 million (1.5 to 1.9 billion people). This is a very large number of new mud brick buildings, and is also potentially too high.
I have made some very broad assumptions in the above analysis, so perhaps the one-third figure is perhaps now an overestimate. If we assume that 1.5 billion people (still a great number) continue to live in earthen homes, this equates to 18% of the world population, and that many, but perhaps not 400 million of those born since 1982 live in new earth buildings:
Those living in earthen houses in 2022 is around one-fifth or 20% of the world’s population.
1982 Terre Exhibition Poster at the Pompidou Centre, Paris
Urban Kathmandu, Nepal
Rural Burkes Pass, New Zealand