An economic sustainability comparison between the natural building technique; cob and the conventional technique; concrete for residential buildings in Matagalpa, Nicaragua

Sammanfattning: Cob can serve as an alternative building material to concrete in Nicaragua. Cob is an unbaked earth-based building technique with low global warming potential that suits the humid climate in Nicaragua. It can be constructed by hand by inexperienced people using materials such as; clay, straw, sand and water. The cob technique is relatively little studied and the exact cost of cob is unclear. The purpose of this thesis was thus to provide new information that will help assessing the economic sustainability and the environmental impact of the natural building technique cob in comparison to the conventional technique concrete. The thesis was carried out by a case study of two houses in Matagalpa, Nicaragua. The results are showing that the cob technique has cheap materials that support the Nicaraguan economy of Nicaragua but takes a lot of labour force and time in comparison to concrete. The cob technique also allows the builder to make the house personal adapted, with furniture and details, fitted to the owners need. The cob has also a great potential of a long lifespan with low needs of maintenance in comparison with concrete. Concrete also has a higher local environmental impact, more CO2-emissions and higher external costs. The conclusion is thus that cob is a more sustainable technique for building residential houses in Matagalpa.