Method for filling a trench comprising a pair of conduits and such a filled trench

A method for filling a trench comprising a pair of conduits of one or more thermal energy distribution systems, the pair of conduits being configured to deliver fluid with a different temperature in each conduit, the method comprising:

• filling the trench with particulate filling material such that the pair of conduits are circumferentially surrounded by the particulate filling material on all sides thereof as seen in the vertical cross sectional side view of the filled trench;
• wherein the act of filling comprises:
• filling the trench with particulate filling material of a first type such that a first filled section of the trench is formed, wherein the first filled section of the trench is occupying a space in between the pair of conduits;
• and
• filling the trench with particulate filling material of a second type such that a second filled section of the trench is formed, wherein both of the pair of conduits are surrounded by the second section;
• wherein the first section separates the second section into two spaced apart portions;
• wherein the filling material of the first type has a first thermal conduction coefficient and the filling material of the second type has a second thermal conduction coefficient, wherein the first thermal conduction coefficient is smaller than the second thermal conduction coefficient;
• and
• wherein the first section and the second section are horizontally separated from each other, as seen in a vertical cross sectional side view of the filled trench.