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Good practice examples > Serbia > Energy efficiency measures carried out in the district heating system of the Public District Heating Plant “SUBOTIČKA TOPLANA”
Energy efficiency measures carried out in the district heating system of the Public District Heating Plant “SUBOTIČKA TOPLANA”
February 10, 2015
Name of GP initiative

Energy efficiency measures carried out in the district heating system of the Public District Heating Plant “SUBOTIČKA TOPLANA”

Number of GP initiative SRB 2
Region/country

Belgrade / Serbia

Author/Email Dušana Todorović /dtodorovic@mas.bg.ac.rs
Aleksandar Jovović /ajovovic@mas.bg.ac.rs
Institution University of Belgrade Faculty of Mechanical Engineering
Year of implementation: 2007
Time horizon of initiative/map/etc.:

General description:

The main objective of the project was to reduce heat and electricity consumption via demand-side energy efficiency improvements in district heating system, but without affecting the comfort level of the end-users. Improving energy efficiency in district heating systems, but without sacrificing the quality of heat supply, is deemed to be specially important since it affects reliable operation of the entire power generation and distribution system in the country, primarily by diminishing the need of consumers to use additional, electricity based energy sources for space heating.

The project has been carried out in the Public District Heating Plant SUBOTIČKA TOPLANA in Subotica. The company “SUBOTIČKA TOPLANA” provides services related to the heat production and distribution, heat distribution system control and heat trade. Within the scope of the project, the following energy efficiency measures have been carried out in the district heating system of the Public District Heating Plant SUBOTIČKA TOPLANA:

  • heat substation reconstruction,
  • heat meter installation in heat substations,
  • introduction of consumption-based billing in the residential sector.

The municipality of Subotica is spread over the area of 1008 km2, inhabited by a population of approximately 148,000. Production capacities of Subotica Public Heating Plant “SUBOTIČKA TOPLANA” equals 141 MW and include two hot water distribution lines and three steam boilers placed at the same location. Fuel combusted for the purpose of heat production include natural gas and heavy oil.

The active length of hot water distribution line is 5 km. Heat substations are of the direct and indirect type. Total number of heat substations equals 300. Nominal water temperature mode is 130/70°C for direct i.e. 130/75°C for indirect type heat substations. Consumer heating systems are based on radiator heating, where both two-pipe (80%) and one-pipe (20%) distribution systems are present. Total number of heat connections equals 1140, while the annual heat production equals about 11,965 MWh.

Number of housing units connected to the district heating system equals 9500, representing 25% of all city households. About 500 family houses and 400 public and office buildings are connected to the district heating system as well. The overall household heated area equals 500,000 m2, while heated public and office space area equals 300.000 m2. Total heat capacity of the heating system installed equals 124 MW.

A detail analysis of the reductions and savings achieved in heat and electricity consumption through implementation of the above specified measures as well as resulting financial effects and CO2 emission reduction have been carried out.

Steps in creating the initiative/roadmap/strategy:

Analysis conducted over several heating seasons had indicated that some of the consumers were being supplied with significantly larger amount of heat than needed. On the other hand, other consumers were being supplied with insufficient amount of heat, causing them to use additional energy sources for space heating, mainly electricity. The following activities were identified as a solution to the problems specified:

  • reconstruction of heat substations through introduction of ambient temperature-based regulation and frequency control mode of pump regulation,
  • allation of heat meters in heat substations,
  • installation of thermostatic valves and heat allocators on all radiators.

For the above specified reasons, project have been carried out in two phase, both aimed at determining energy efficiency increase and CO2 emission reduction achieved:

Phase 1: Heat substation reconstruction and installation of instrumentation and control equipment

Prior to heat substation reconstruction and installation of instrumentation and control equipment, system regulation was performed manually, with measurements carried out in larger time intervals. In this mode of operation, it was not possible to continuously regulate the water flow rate and temperature depending on the ambient temperature. Therefore, it was not possible to continuously regulate the heat demand. For this reason, heat supply was not able to follow the actual consumer needs, resulting in excess heat being delivered. Excess heat delivered to the consumers represented an unnecessary energy loss.

Within the scope of the Phase 1 of Project activities, heat substations were equipped with modern instrumentation and control equipment, enabling continuous measurement of ambient conditions and parameters of heat supply. Flow regulators installed in heat substations regulate the flow of hot water to the consumers via control valves installed in the primary water return line. Regulation of hot water temperature is carried out in boiler houses, as a function of the ambient air temperature.

Effects of heat substation reconstruction and installation of instrumentation and control equipment were analysed based on data recorded during two heating seasons i.e. heating season 2005/2006 (prior to reconstruction) and 2007/2008 (after the reconstruction). The effects were monitored based on data recorded in 9 heat substations.

Phase 2: heat substation reconstruction, installation of instrumentation and control equipment and a shift to the consumption-based billing in the residential sector

Based on the experience gathered during the Phase 1, another phase was carried out in the district heating system of the Public District Heating Company “SUBOTIČKA TOPLANA”. Phase 2 was initiated with an aim to obtain more detail analysis of various energy efficiency measures implemented. Within the scope of the Phase 2, the following energy efficiency measures were implemented:

  • reconstruction of heat substations through introduction of ambient temperature-based regulation and frequency control mode of pump regulation,
  • installation of heat meters in heat substations,
  • installation of thermostatic valves and heat allocators on all radiators.

This phase of Project represented an extension of the previous phase, including more parameters to be monitored in fewer buildings.

Three similar type buildings were selected with their heat delivery regulation and metering system subjected to gradual energy efficiency improvements. Building A was adopted as the reference facility and used for comparison with the effects of the energy efficiency measures implemented in other two buildings. Measures implemented in building B included heat substation improvements while the measures carried out in the building C additionally included improvements on the end-user side.

Measurements carried out in heat substations and analysis of the results obtained have undeniably showed that significant savings could be accomplished through introduction of individual metering and individual billing, when the end users were expected to pay only for the heat actually consumed, as seen in building C.

Targets and target determination:

The Project was implemented with a goal to reduce heat and electricity consumption on a supply-side of district heating system, but without affecting the comfort level of the final consumers.

In addition, the Project was aimed to prove that implementation of heat metering and consumption-based billing was economically justified i.e. that, when compared to the lump-sum billing based on the total surface area of the space heated, consumption-based billing more effectively motivated consumers to use heat more rationally.

The overall aim of the Project is to plainly present that with implementation of appropriate energy efficiency measures in district heating systems is possible to achieved significantly reduction in heat and electricity consumption as well as CO2 emissions, and as final aim improvement of living and working condition. As clearly shown by the results achieved in this project:

hase 1:

Heat substation reconstruction resulted in energy savings of 185.47 MWh i.e. reductions in the quantity of heat delivered to the heat substations. It was determined that during the specified heating season 2005/2006 heat substations were being provided with insufficient amount of heat i.e. heat being delivered to the substations was lower than the heat demand. Following the reconstruction of hot water distribution system, the heat substations were started to being supplied with sufficient amount of heat that was, for the reasons specified above, higher than the values measured during the reference heating season 2005/2006.

Phase 2:

Based on the results obtained the following is concluded:

  • savings in heat and electricity consumption have been achieved,
  • reduction in heat consumption achieved through implementation of energy efficiency measures varied from 10.43 to 20.59%, calculated on a cumulative basis for the heating seasons 2006/08, depending on the measures implemented,
  • significant savings in heat consumption were achieved only after the old radiator valves had been replaced with thermostatic valves and consumption based billing system, based on the readings of the heat allocators installed, had been introduced (building C),
  • reduction achieved in electricity consumption equaled about 30%, resulting from the installation of new variable speed pumps,
  • ant savings in electricity consumption were achieved only after the old radiator valves had been replaced with thermostatic valves and consumption based billing system, based on the readings of the heat allocators installed, had been introduced (building C),
  • trend of reduced electricity consumption was recorded in buildings B and C where new pumps had been installed; when compared to the electricity consumption recorded in the building A, savings in electricity consumption recorded in heat substation of the building C equaled 44.3%.
  • having in mind different heat billing methods and reductions in heat consumption achieved, tenants of the building C had received a 20.59% lower heating bill compared to the bill received by the tenants of the building A i.e. 11.34% lower compared to the bill received by the tenants of the building B.
  • based on the results obtained, it is concluded that, compared to the building A, CO2 emissions reduction achieved in building C is two times higher that the reduction achieved in the building B. If the calculated savings were to be applied to the entire heating area serviced by the Public District Heating Plant “SUBOTIČKA TOPLANA” (500000+300000 m2), but taking aside all differences with respect to size, position, age, quality of construction and thermal insulation of individual buildings, as well as number and habits of the occupants, the overall CO2 emissions reduction could be estimated. And it gives that buildings type B would result in the overall CO2 emissions reduction of 2000 t per heating season, while measures implemented in buildings type C would result in 4000 t less CO2 emitted per heating season.

Success factors/barriers:

This Case Study illustrates the importance of the energy and energy efficiency related reforms implemented up to date as well as those planned to be carried out in the future. In addition, the Case Study indicates a requirement for energy managers to be more involved in the activities carried out in the construction sector, contributing to the construction quality improvements and monitoring the effects of projects similar to the ones described herein.

In addition, it is necessary to increase awareness of the population and distribute information on the results achieved in this type of projects, especially in the field of financing, in order to provide appropriate financial subsidies to heat consumers and providers, but to the equipment manufactures as well.

Responsibility for application:

  • Ministry of Mining and Energy:
    Professor Milos Banjac, PhD, Assistant Minister, milos.banjac@mre.gov.rs
  • University of Belgrade Faculty of Mechanical Engineering:
    Professor Aleksandar Jovovic, PhD, ajovovic@mas.bg.ac.rs
    Professor Dragoslava Stojiljkovic, PhD, dstojiljkovic@mas.bg.ac.rs

Implementation costs:

The total cost of project actions amounts to 775,822.51 EUR of which:

  • Phase 1: 700,000.00 EUR, realized with financial support of European Agency for Reconstruction;
  • Phase 2: 75,822.51 EUR, out of which:
    • 53,989.32 EUR (71.2%) - donation amount by the European Agency for Reconstruction (EAR),
    • 21,833.19 EUR (28.8%) - participation of the Beneficiary.

Economic effects (GDP, employment):

Not evaluated.

Links:

Acknowledgment:

A Project has been presented as a National Case Study of Republic of Serbia within the scope of United Nation Economic Commission for Europe (UN/ECE) the project titled Financing Energy Efficiency Investments for Climate Change Mitigation.

This document was developed in the framework of the LOCSEE project.

European Union SEE Regional Policy Network collaboration area (members only) Regional Policy Network