This heritage renovation is that of a small building located at the entrance of the town of Rivarennes and marquantfortement it in front of the town hall. This building, which is composed of an island at the entrance to the city, has very ancient origins evidenced by some architectural elements still in place that the project is committed to preserving.

The "angles" of wall without chaining, rounded (one outside and one found inside housing 3) may have belonged to a medieval square dwelling . This hypothesis is supported by the joist crossing of housing 3 and a XVIth or XVIIth century framework. This first building was then enlarged and is inserted today in a two-storey house, probably completed in the nineteenth century and having undergone changes in the twentieth with several concrete openings, and the cementing of soil and partially walls. oven with a small home on the floor extends this set.

The choice of rehabilitation studied by the PACT of the Indreavec the community of communes has determined the realization of 4 housing including 3 (R + 1) in the building and a PRM (person with reduced mobility) occupying the ground floor of this extension ; the floor here has not been reused. All the walls of these buildings are built of limestone rubble assembled on two facings, mounted on the ground with possibly a little lime on the level of framing and chaining, composed of cut limestone blocks. All the joists and beams are in oak as well as the carpentry. The exterior woodwork dating back to the twentieth century are in oak. They have been redone identically (shutters, windows and shutters) to preserve the character of this immovable borough.

Sustainable development approach of the project owner

The choice of materials allows the good conservation of the structures of the old building by the maintenance of the transfers of water vapor of the envelope and the grounds, as far as possible compared to the regulatory standards (it is very difficult for example to create a lime concrete slab in a public building facing a control office). This makes it a particularly effective demonstrator project in the framework of PCET of the Parc. Conservation of a building that is almost entirely recyclable and consumes little gray energy, also saves the gray energy of a construction and the space consumption that this represents.

In the framework of the experiment described, several technical orientations were chosen with three priority axes: performance, respect for the existing structure and use of biosourced materials.

In order to respect the problems related to hygrothermal walls, two technical solutions have been realized.

• In three dwellings, the walls were lined with hemp wool interior on a timber frame with a vapor brake membrane installed to manage the migration of water vapor. Insulation performance meets the criteria found in new construction. The whole of the walls was also the object of a treatment with the realization of a coating lime sand outside and a gobetis of lime inside.

• In the housing 4, was implemented a thermal correction by coating lime-hemp. This solution, in theory, thermally less efficient aims to enhance the hygrothermal exchanges of the wall and thus measure the actual performance and no longer theoretical of this type of insulation.

• In this same housing and for the same purpose was implemented a breathable slab type pozzolan lime. We then find two types of thermal insulation of low floors. Traditional insulation under polyurethane type to meet the constraints of height sub-ceiling (abandonment of the cork panel in draft phase because too thick), and insulation cellulose wadding instilled at the level of the cellar of housing three.

The attic is all insulated with hemp wool.

Architectural description

The "angles" of a wall without chaining, rounded (one outside and one inside the dwelling 3) may have belonged to a medieval square dwelling. This hypothesis is supported by the crossing joist of housing 3 and a XVIth or XVIIth century framework. This first building was then enlarged and is inserted today in a two-storey town house, probably completed in the nineteenth century and undergoing changes in the twentieth century. with several concrete openings, and the cementing of the floors and partially of the walls. A room of oven with a small home on the floor prolongs this set.