Objectives
CRAterre's task is to develop building materials using soil and a plant fiber derived from the Typha australis plant, then to start distributing them with a view to contributing to greater energy efficiency in Senegal's buildings, and reducing CO2 emissions.
The objectives of CRAterre's mission are fourfold:
- An identification of the Senegalese context and a state of the art on the use of plant fibers in construction.
- An experimental component based on the identification results, with several seminars to present the results;
- A demonstration component, including the training of future material producers and the construction of an eco-pavilion to showcase the various Terre-Typha materials developed;
- An application section, providing for the implementation of various actions to disseminate the results more widely.
All over the world, the scientific community and builders are showing increasing interest in the use of natural fibers to reduce the energy impact of the construction and use of buildings. Typha australis reed is one such resource, with its very fine internal honeycomb structure offering particularly interesting potential. In Senegal, this reed is tending to invade the Senegal River and Lac de Guiers (Dakar's main source of fresh water). It has even become a major ecological problem. As a result, a great deal of research has been launched to try and transform this nuisance into a sustainable resource. Among other things, this is the aim of the PNEEB/Typha program, in which CRAterre is actively involved, which aims to produce insulating materials in and for Senegal using Typha soil and fibers.
PNEEB is Senegal's national program to reduce greenhouse gas emissions through energy efficiency in the building sector.
The activities that have been carried out include :
- An initial mission to identify the Senegalese context, during which a team of four CRAterre experts was deployed to analyze the different housing typologies in the Dakar and July 2014 Saint-Louis regions. This study focused on the various building materials available, local raw materials (we were able to identify
examples of clays that could be used for materials), local techniques and know-how, and to make contact with a number of economic players working in the field of earth construction, energy efficiency or Typha harvesting (Economic Interest Groups).
- Research and development on different types of products based on Typha alone and Typha-earth mixes. For the latter, the process ranges from research into possible formulations (choice of soils, preparation of different Typha shreds, proportions of soil and Typha) to methods and tools for the production of building elements.
- A feedback seminar in Dakar, bringing together a majority of stakeholders in the development of these materials in Senegal, which was held in Dakar on February 17 and 18, 2015 in the presence of more than 80 participants.
- A workshop with economic, technical, scientific and civil society players to carry out an initial technology transfer and check the feasibility of the materials we've developed in Grenoble.
At a later stage, once we are satisfied that they meet local demand and various technical, social and cultural requirements, the materials will undergo physical characterization, including thermal, mechanical and acoustic characterization, as well as fire resistance testing.
A training course for professionals will soon be held in Diamniadio. The eco-pavilion demonstrator for Terre-Typha products is also being designed as part of the research program. Construction is due to start at the end of 2015.
Results
To date, different types of materials have been developed for different construction systems.
For partitions and wall lining, blocks, Terre-Typha panels and Typha-only panels are currently being developed. During the feedback seminar, it was also suggested that the question of alternative blocks to cement blocks (especially for new buildings) for non-load-bearing walls should be explored in greater depth.
For floors, Terre-Typha or Typha-only hourdis and lining solutions such as Terre-Typha blocks and panels are also being considered.
For roofs, this would involve Typha-only panels inspired by traditional Typha mats (and techniques used in Romania) or Terre-Typha panels. Several variations are then possible: either a treatment on the underside (such as panels under corrugated sheeting; hourdis under a flat roof), or a treatment directly on the roof (tiles and/or Typha panels alone; or Typha thatch).
The gain in grey energy (the amount of energy required to extract, produce, process, transport, install, use, maintain and recycle the material) should be considerable for substitute materials (blocks, panels or hoardings), as raw earth requires little energy to produce the materials and so does the processing of Typha.
Particular attention will be paid to aesthetics, with different types of finish being proposed: other local resources may also be used. The question of insulation and acoustic performance is still under study. Earth has the advantage of providing thermal inertia and regulating humidity, and Typha leaves have good insulating properties, as well as hygrothermal regulation. With such properties, the results in terms of improving thermal comfort, and in particular limiting the use of air conditioners, are bound to be highly satisfactory, compared with the current situation where too many buildings and materials used are not very energy-efficient.
Partners
To achieve this, CRAterre is working in close collaboration with the amàco project led by Les Grands Ateliers and the Labex AE&CC of the Ecole Nationale Supérieure d'Architecture de Grenoble, as well as with those responsible for the project in Senegal (Unité de gestion PNEEB/TYPHA, Ministère de l'Environnement et du Développement Durable, Direction des Etablissements Classés, UNDP and GEF), and plans to involve representatives of the construction sector in order to best meet the needs, wishes and capacities for valorizing the results.
