European directive on the energy performance of buildings (EPBD-Energy Performance of Building Directive - 2002/91/EC, EPBD II – 2010/31/EU), mechanisms encouraged by market to improve energy efficiency in buildings, categorization of buildings according to their energy properties and methods of calculating thermal properties, heat comfort and heat parameters of the environment, power consumption for the establishment of a satisfactory comfort, energy classes for residential buildings, state of the housing stock of Serbia, national typology of residential buildings in Serbia, measures of energy
recovery etc.

Theoretical basics of heat transfer, thermal characteristics of material characteristics, soil temperature, heat losses of the pipeline, etc.

Generations of district heating system, designed temperatures in the district heating system, the influence of the temperature change in the DH system on the heat capacity, COP - Coefficient Of Performance, impact of temperature on pump operation, influence of temperatures on heat losses, energy balance of the network;
What are the consequences of changing the temperature on the delivery and distribution of heat energy? How do the end user's heating systems affect the district heating system? both existing and future ways of optimizing the temperature in the district heating system were considered, methods for reducing and estimating temperatures in the district heating system, etc.

Generations of district heating system, designed temperatures in the district heating system, the influence of the temperature change in the DH system on the heat capacity, COP - Coefficient Of Performance, impact of temperature on pump operation, influence of temperatures on heat losses, energy balance of the network;
What are the consequences of changing the temperature on the delivery and distribution of heat energy? How do the end user's heating systems affect the district heating system? both existing and future ways of optimizing the temperature in the district heating system were considered, methods for reducing and estimating temperatures in the district heating system, etc.

Operation of the heat buffer i.e. heat accumulator or heat storage including the basic principle that water in the HA is at different temperatures in height - stratification, and there is no mixing, working conditions in HA with stratification are better for the same amount of energy than in HA with water mixing, HA in the district heating network is considered as a consumer when heat comes to it, and when the heat is discharged, as the heat production unit etc.

Situation of Republic of Serbia: operation of the heating plant is at the level of 6 months per year with an average capacity utilization under 45% of the designed (installed) power, the average operating time during the heating season is below 18h/day; if the heating plants could be able to deliver the heat produced out of the heating season, the viability of their work would be higher, and the repayment periods of the investment in them would be substantially shortened; guidlines and recommendations to achieving longer/ whole year work