Background: Ground heat exchangers installed in boreholes are an expensive component of a ground-coupled heat pump system, where minimizing the borehole length with appropriate materials and configuration can reduce the overall cost of the system. Methods: Design calculations performed analytically indicate that the coaxial pipe configuration can be more advantageous than the single U-pipe configuration to reduce the total borehole length of a system. Results: A decrease of the borehole thermal resistance and an increase of the thermal mass of water contained in the coaxial exchanger helped to reduce borehole length by up to 23% for a synthetic building load profile dominated by cooling. The decrease of the borehole thermal resistance was achieved with an outer pipe made of thermally enhanced high-density polyethylene, where the thermal conductivity is 0.7 W m -1 K -1 .

Les auteurs ont répertorié et analysé 260 cas de pourridiés en France sur vigne, arbres fruitiers et plantes florales, ornementales et à parfums.Vigne, L'armillaire est l'agent de pourridié le plus répandu et le plus grave sur la vigne, le pêcher, l'abricotier et Arbres fruitiers, l'amandier. Le pourridié laineux à Rosellinia est au contraire plus fréquent sur pommier, jasmin, lavande, Plantes florales, ainsi que sur les cultures florales non ligneuses. Le rosier, le cerisier, le figuier et l'olivier hébergent l'un et Pourridiés, l'autre parasite avec des fréquences comparables. Armillariella,Les symptômes des deux agents de pourridié sur divers hôtes font l'objet d'une description. Les deux R osell i n i a .champignons sont indiscernables par les symptômes qu'ils entraînent sur la partie aérienne des plantes parasitées. Par contre, l'aspect du mycélium agrégé souterrain permet généralement une distinction aisée entre les deux espèces. SUMMARYRoot-rot caused by Armillariella and Roseliinia in France on vine, orchard trees and flower crops. L Etiology and symptoms Vine,Orchard trees, About 260 cases of root-rot were observed and analyzed on vine, orchard-trees and flower crops in central and Flower crops, southern France. Root-rots, 'Apart from a single attack of Roesleria hypogea on vine, only two parasites were encountered : the honey Armillaria (ella) , fungus (Armillariella mellea sensu stricto = species « D » according to Korhonen) and the white root-rot Rosellinia.' fungus (Rosellinia necatrix (Hart.) Berl.). 'Armillariella is by far the more common on vine, peach, almond and apricots. It is a serious problem in the « Côtes-du-Rhône » vineyards and in the peach and apricots crops of Southern France. On the contrary, Rosellinia is the more frequent on apple, lavender, jasmine, carnation and all the fleshy flower plants. It sometimes causes important damage in apple orchards. On rose, cherry, fig and olive, both fungi are encountered. In two cases (on a fig-tree and on an olive-tree), Armillariella and Rosellinia were found together, attacking the same plant.The symptoms due to both fungi on several hosts are described. The symptoms on the foliage do not differ but the two parasites are generally easily distinguished by the appearance of aggregated mycelium inside the roots and collar.