The transfer of heat from the source of energy to consumer's installations - or a house substation respectively requires pipelines through which hot water or steam is transferred. In Ljubljana, 156 km of hot-water network and 9 km of steam network were built in the previous years.
The major part of network is built in the ground in ducts, a smaller part above ground on pillars, in joint communal collectors or in cellars of various buildings. In the last few years, the system of direct installation of pre-insulated pipelines to the ground is mainly used. This kind of installation is generally acknowledged in the world and is cheaper than the traditional construction using ducts. The building of the steam network has somehow stopped in the last years. The reason can be searched in the decrease of the erection of new industrial plants on those locations where technological steam supply would be possible.