Considering this it can be said that if nothing is done for DHN renovation, the expenses to cover DHN heat losses will increase twice in case the fuel prices do not increase in the future.
The objective of this study is the assistance of a bundle of genetic algorithm (GA) software package to explore several possible variations of buildings and DHN renovation processes as well as their combining possibilities and to comparing them.
An increasing number of studies focus on the discussion of how the heat demand alteration in buildings may develop DHN in the future and alter to meet future thermal heat supply needs.
The implementation of residential buildings' renovation programmes leads to a decrease in the consumption of heat supply amount to buildings and is one of the factors of DHN pipeline modernisation.
The technical and economic feasibility has been investigated for twin (Basogul, Kecebas 2011) and triple (Dalla Rosa, Christensen 2011) pipe system geometries of DHN network, pipe sizes or district heating water (DHW) quantity variation.
The use of low-level parameters of heating water for DHN allows using plastic pipelines rather than a pair of single steel pipes.
Besides the DHN system's hydraulic modelling tasks, it is necessary to include network optimisation as well.
The above studies show in general that the reduction of buildings' heat demand can go in conjunction with the refurbishment of DHN and improves the efficiency of energy systems.
The multi-storey residential buildings built at different times contain the different thermal characteristics of buildings, as well as the DHN pipelines and its wearing rate.