HOT|COOL NO. 1/2018 "Global District Energy Climate Awards"

After having been for many years a well-kept secret – hidden under the surface of the earth – district heating and cooling has now swept onto the agenda not only in a few countries, but in large parts of the world, including EU and the Middle East. The EU Commission’s “Winter Package” is a considerable milestone, which has a lot of initiatives that will have an impact on the entire European energy sector. The Winter Package is part of the implementation of the Energy Union, and is expected to partly lead to a revision of the RE directive and to lead to concrete recommendations for how the EU Commission will fulfill the union’s joint goal of 27 % renewable energy in 2030. Why has district heating and cooling finally made it to the agenda? Because district heating and cooling is a simple and cost-effective concept to solve the large climate challenges that we face. Challenges we are facing not the next week, the next month or the next year – no, challenges that we are facing here and now. DBDH publishes Hot Cool, but the main business is helping cities or regions in their green transition. We will help you find specific answers for a sustainable district heating solution or integrate green technology into an existing district heating system in your region – for free! Any city, or utility in the world, can call DBDH and find help for a green district heating solution suitable for their city. A similar system is often operating in Denmark, being the most advanced district heating country globally. DBDH then organizes visits to Danish reference utilities or expert delegations from Denmark to your city. For real or virtually in webinars or web meetings. DBDH is a non-profit organization - so guidance by DBDH is free of charge. Just call us. We'd love to help you district energize your city!

N0.1 / 2018



SALASPILS SILTUMS - From post-Soviet boiler station to a modern enterprise

DBDH - direct access to district heating and cooling technology




4 6 7




10 13 16 20 24 27 28 30









HOT|COOL is published four times a year by:

DBDH Stæhr Johansens Vej 38 DK-2000 Frederiksberg Phone +45 8893 9150

Total circulation: 5,000 copies in 50 countries

ISSN 0904 9681 Layout: DBDH/

Editor-in-Chief: Lars Gullev, VEKS

Pre-press and printing: Kailow Graphic A/S

Coordinating Editor: Kathrine Windahl, DBDH


THE COLUMN By Lars Gullev, Managing Director, VEKS


After having been for many years a well-kept secret – hidden under the surface of the earth – district heating and cooling has now swept onto the agenda not only in a few countries, but in large parts of the world, including EU and the Middle East.

The EU Commission’s “Winter Package” is a considerable milestone, which has a lot of initiatives that will have an impact on the entire European energy sector.

The Winter Package is part of the implementation of the Energy Union, and is expected to partly lead to a revision of the RE directive and to lead to concrete recommendations for how the EU Commission will fulfill the union’s joint goal of 27 % renewable energy in 2030.

Why has district heating and cooling finally made it to the agenda?

Because district heating and cooling is a simple and cost-effective concept to solve the large climate challenges that we face. Challenges we are facing not the next week, the next month or the next year – no, challenges that we are facing here and now. The heat supply of the future is based on renewable energy, for example solar panels, geothermal, electricity from wind turbines and solar cells, district heating based on biomass, and utilization of surplus heat – whereas utilization of coal, oil and natural gas will belong to the past in few years. But it is not just the production of district heating that is facing huge changes. The pipe systems will also have to go through a renewal process where the efficiency must be increased by for example reducing the temperature level. For new district heating systems, it does not impose a big problem to design these for 4G DH – i.e. systems with flow-temperature down to 40-50 o C. Within the next ten years, we will also see many district heating systems being redesigned from 3G DH to 4G DH. In this edition of Hot Cool, we have chosen to put focus on some of the award winners from the Global District Energy Climate Awards 2017 – an award, which was set up back in 2009 by DBDH and which has since then been awarded every other year. The articles include “Lusail city district cooling system, Qatar”, ”Efficient district heating and cooling system in Tartu, Estonia”, and “Salaspils Siltums - from post-Soviet boiler station to a modern enterprise, Latvia”.

The articles all offer an insight into how efficient district heating and cooling systems are the backbone of the future energy supply.


J O U R N A L N 0 . 1 / 2 0 1 8


By Dr. Brian Vad Mathiesen, Professor, Aalborg University

The efforts have traditionally focused on building codes and technical standards, while the initiatives reducing demands in existing buildings and on the supply side have been rather scattered and less successful. Globally, there is an increasing awareness from the buildings and energy sectors, civil servants, policy makers and in the public debate, that seeing savings, heating, cooling, electricity, transport and gas as separate parts of energy system is part of the past. Three intertwined perspectives have been identified as key for the building sector and heating moving towards a renewable energy system: Firstly, higher energy efficiency in the building stock is crucial to enable a renewable, flexible energy system, especially in existing buildings. Secondly, the operation and user‐behaviour of people in buildings is a crucial element to achieve savings over time. The third is the supply mix of energy, where buildings and district heating have an important role in opening up possibilities for a more efficient use of renewable energy and more flexible energy sources in infrastructure and thermal storages. In many cases, parallel developments are required in order to unlock the potential contribution that buildings and district heating can have in a renewable energy future.

Traditionally, renewable energy in the electricity sector has attracted most attention. This is curious, as heating and cooling account for approximately 50% of the final energy consumption in Europe and a significant part globally. Climate change, competitiveness, energy security and dependency on imports of e.g. natural gas have meant that the heating sector attracts more and more attention in Europe. Globally, the UNFCCC COP 21 Paris Agreement and the following focus on renewable energy as well as major health effects due to local emissions from burning fossil fuels or bioenergy have meant that many countries now have a major focus on district heating and energy efficiency in buildings. Cities worldwide are growing and countries not previously leading the pathway towards a sustainable energy system such as e.g. China, Turkey, Chile, India, Morocco, Malaysia and India are now paving the way together with UN Environment (formerly UNEP) to improve building standards and utilize district heating or cooling to address these challenges. Cities may house up to 85% of the global population in 2050, which means people live closer and closer and that the solutions of tomorrow require joint local and national efforts on a policy level as well as on a technological level. In renewable energy systems, sectors need to be integrated, preferably using a smart energy system approach. The understanding of the roles of the individual technologies such as buildings, energy storage and district heating is crucial if a cost efficient transition to a renewable energy system is wanted: How far should we go with savings? What is the role of flexible demand or storage at the building level? To what extent should on‐site renewable energy production be the solution? Do we need district heating in the future and, if so, how does it need to change? What is the role of bioenergy and heat pumps? How can we use low-value heat for low value purposes? What are the policies and planning methods that can facilitate this? These questions and more are at the heart of our research in the Strategic Research Centre for 4th Generation District Heating Technologies and Systems ( The results have documented that there are vast opportunities for savings and energy efficiency in Europe and the world. The research carried out has served as inspiration for Danish and European Commission initiatives on heating and cooling as well as for global initiatives taken by UN Environment.

Bygningers energimæssige ydeevne

Bygningsdrift og brugeradfærd

Nye energikilder - nye lagrings muligheder

Three perspectives key to the role of buildings in future cost-effective sustainable energy systems



A very drastic change of direction in the European and global heating sector is needed within the near future if a cost-effective transition towards renewable energy is wanted. Calculations indicate that currently, the amount of heat wasted in Europe is enough to supply the heat demand of all buildings.


Connolly, David; Mathiesen, Brian Vad; Østergaard, Poul Alberg; Møller, Bernd; Nielsen, Steffen; Lund, Henrik; Persson, Urban; Werner, Sven; Grözinger, Jan; Boermans, Thomas;

Bosquet, Michelle; Trier, Daniel (2013). Heat Roadmap Europe 2: Second Pre-Study for the EU27. Department of Development and Planning, Aalborg University. - Mathiesen, Brian Vad; Drysdale, David William; Lund, Henrik; Paardekooper, Susana; Ridjan, Iva; Connolly, David; Thellufsen, Jakob Zinck; Jensen, Jens Stissing (2016). Future Green Buildings: A Key to Cost-Effective Sustainable Energy Systems. Department of Development and Planning, Aalborg University. - Publications available at, ,

Heat Roadmap Europe is a series of four studies initiated by the 4DH Research Centre in collaboration with industrial partners ( The studies combined energy system analyses with geographical information systems (GIS) and provide strategies and methods that can be replicated globally. The studies reveal large cost-reductions providing heat with an ambitious refurbishment of existing houses and district heating, as well as a potential for increasing the amount of renewable energy in the heating sector. A pan- European Thermal Atlas (Peta4) is publicly available and being developed down to a 100 by 100-meter resolution. The studies suggest that 30-50% heat savings are feasible and that the share of district heating should increase, on average, to 30 % by 2030 and to 50% by 2050 in urban areas. These estimates for district heating in Europe may prove conservative as we get more and more localized knowledge. In rural areas, high levels of refurbishment are needed in combination with individual heating technologies, such as heat pumps.

For further information please contact:

Aalborg University Att.: Brian Vad Mathiesen Department of Development and Planning A.C. Meyers Vænge 15 DK-2450 Copenhagen SV

Phone: +45 9940 7218

Proven Technology! Renewable Energy vs. District Heating


Austria Bulgaria Cyprus Denmark

Belgium Croatia


Czech Republic

Estonia France Greece Ireland



Germany Hungary






Luxembourg Netherlands


Malta Poland



Romania Slovenia Sweden

Slovak Republic







United Kingdom

District Heating Share (%)

J O U R N A L N 0 . 1 / 2 0 1 8


By Robin Wiltshire, Chairman of the Evaluation Panel and Chairman of the IEA Executive Committee for District Heating and Cooling

One of the first duties of the panel, to take forward the idea of the Global Awards, was to devise an entry procedure. In order to comprehensively analyse the performance and efficacy of systems, submissions must include data that enables system efficiency and carbon emissions to be understood, together with descriptive details including the fuel mix, technology and customers served. A number of different categories for entries were also agreed upon by the panel. This is intended to reflect the diversity of scheme size, age, and innovative actions to initiate modernise or expand systems. Consequently, entries can be submitted both from long-established systems and recently installed systems, providing they have at least two years of operational data to draw upon. This also reflects the flexibility of this technology in aggregating heat demands for a networked supply of heat which allows the integration of heat from a huge variety of sources according to local availability. The Global Awards process itself evolves, in order to try to offer an effective and comprehensive method to allow any district energy system to apply. The aim is also to enable entries to be properly analysed, while not making the process too onerous. After each round, the panel still discusses issues like this: do the existing categories fully cater for the range of circumstances within which effective systems can emerge? Expect further developments for the next round, perhaps in particular to reach out more effectively globally. For now, I believe the most recent awards reflect a great new group of projects and approaches, as you will see from the proceeding articles. The 2017 Global District Energy Climate Awards were revealed on 24 October 2017, during the International District Cooling and Heating Conference in Doha, Qatar. You can also find descriptions of the inspiring schemes that have won in each of the rounds of these Awards, and those who have participated at

It has been my privilege to Chair the Evaluation Panel for the Global District Energy Climate Awards, with the help of a distinguished panel drawn from organisations across the world. Coordinated by Euroheat & Power, the panel benefits from the experience and knowledge of the International Energy Agency (IEA), the United Nations environment (UNEP), and other organisations from USA, Canada and Korea. Since the Awards were established in 2009 by DBDH (Danish Board of District Heating), there have been 5 editions with over 30 winning entries from different continents.

The reason for establishing the Awards was the knowledge that this technology is a key part of realising a sustainable energy future; it is fuel flexible and is in particular capable of using heat from renewable and secondary heat sources as well as the more established technologies like combined heat and power. Yet, it has remained underdeveloped and somewhat hidden from view. Major studies such as Heat Roadmap Europe have revealed the extent of the potential for this technology, and as a result of this, it has in recent years gained much more traction with decision-makers. We believe another important aspect lies in the recognition of individual systems. In this way, excellent systems are highlighted, and we build up a great portfolio of case studies for all to peruse. And of course, while every successful system has its own particular characteristics arising from local circumstances, nevertheless we believe that such success stories will inspire others to replicate, adapt, apply to their own towns and cities. Or perhaps also to realise that they too already have a great story to tell, that they can share by applying in the next round.

Robin Wiltshire For further information please contact:




By Margo Külaots, Chairman of the Board, Fortum Tartu

to local and renewable sources, namely peat and biomass. In the year 2000, the system went through a privatization process and became part of the Finnish company Kotka Energy Holding SA, which sold its shares in 2004 to Fortum Heat and Power OY (60 %) and AS Giga (40 %) with the name AS Fortum Tartu (current situation). SUPPORTIVE DEPLOYMENT OF DISTRICT HEATING Tartu’s City Council has strongly supported the deployment of district heating in the city, mainly through a comprehensive city planning and district heating zoning. The first urban development master plan of Tartu was established in 1999 and focused on sustainable development. It included a district heating zoning, aiming at improving the air quality in the city and avoiding district heating disconnections. Indeed, the air quality was very low at the time due to the extensive use of stoves in households -burning not only wood but also waste - and the lack of investments in the district heating system, which had seriously affected the quality of the service and resulted in increasing disconnections. The City Council published a report and organized public campaigns to raise awareness about the risk of these stoves and to justify the district heating zoning.

Over the years, Tartu’s district heating and cooling system has undergone several changes and technology upgrades, from a Soviet time district heating network to becoming a well-functioning and efficient district heating and cooling system. Nowadays, the Tartu district heating and cooling system is one of the best functioning in the country and it has been achieved in the alignment of interests between the municipality, customers, end-users and the district heating and cooling company. CITY OF TARTU AND ITS DISTRICT ENERGY SYSTEM Tartu is the second largest city with approx. 97,000 inhabitants in Estonia located in the southern part of the country. The city lies on the Emajõgi ("Mother river"), which connects the two largest lakes of Estonia - Peipsi and Võrtsjärv. The city is often considered the intellectual center of Estonia as the oldest and most known Estonian university, 386 years old, the University of Tartu, is situated there. The Supreme Court of Estonia, the Ministry of Education and Research, and Estonian National Museum are also situated in Tartu. The food industry has traditionally been important for the town's economy and some big companies in the field are A. Le Coq, Tartu Mill and Salvest. The leading printing press company in the Baltic States, Kroonpress, is also situated in Tartu. Over the years, the city’s district energy system has undergone several changes in ownership and technology upgrades. The district heating system was established in Tartu in 1967 and was first owned by the state and later by the municipality. In 1995, the system participated in a renovation program financed by the World Bank and the European Bank for Reconstruction and Development, consisting of switching its fuel from gas and oil

J O U R N A L N 0 . 1 / 2 0 1 8


The City Council does not have a direct influence in the district heating and cooling business, neither in the company’s ownership nor in its operation. However, it takes into account air quality in different parts of the city, energy efficiency improvement and district heating needs when organizing its urban planning (e.g. trying to densify the city and defining district heating zones in energy dense areas close to the existing network). INVESTMENTS FOR A SUSTAINABLE TARTU Fortum Tartu has made several investments for Tartu’s energy system to be sustainable and green:

In the areas defined as district heating zones, all new buildings and those undergoing a major renovation must be connected to the network. These areas are readjusted when the master plan is updated. The current district heating areas were defined in 2017, following a negotiation process between Fortum Tartu and the city. Around 70% of Fortum Tartu's clients are established in a DH zone. Houses can choose alternative heating solution in appointed DH zones when they meet the conditions having an energy demand below 40 kWh/m2 or being supplied with environmentally cleaner heating, e.g geothermal heating or solar thermal panels.

• In 2006, the company started its own local fuel production (for biomass sourcing peat production), to have secure market based fuel supply in changing market situations. In 2007, Fortum Tartu began the development of a new combined heat and power plant fueled by biomass (75%) and peat (25%). The plant with a heat capacity of 50 MW and electricity capacity of 25 MW was commissioned in 2009. • Between 2009 and 2014, the system continued expanding, mainly through the acquisition of another local district heating system in 2013 in the “Tamme” area (90 GWh of sales, 3 production units, 34 km pipeline) and the installation of new peak capacity. • With the restructuring of the whole district heating system, in 2013 an old fossil fuel based boiler house in city center was closed. • In 2014, the development of district cooling projects started and the first district cooling plant, based on free cooling from the river Emajõgi, was commissioned in May 2016, becoming the first district cooling system in the Baltics and Eastern-Europe. • In 2016, after long negotiations and discussions with customer Lõunakeskus (Southern Estonia’s biggest shopping mall/entertainment center), the next district cooling project started. Fortum Tartu offered the customer a ful l solution of district heating and cooling. Lõunakeskus was connected to the district heating network in October 2016. The district cooling system for Lõunakeskus started its operations in the beginning of June 2017. • Automatic smart meter readers are installed to 75% of the customers, and the plan is to cover 100% of customers with smart metering by 2020.



Some years ago Fortum Tartu identified four areas for district cooling development in the city. The first cooling customer for Fortum Tartu was the Estonian National Museum. Fortum Tartu made a tailor made local cooling and DH solution for this nationally very important building. First DC customers in Tartu downtown were the new shopping centre Kvartal and the hotel Lydia. The third DC plant and network was built for the area in town where southern Estonian’s biggest shopping mall Lõunakeskus lies. The future plan is to connect downtown and Lõunakeskus DC networks. The fourth DC project in one part of the city is also under construction. DC is on the free market and the price depends on the customer and its features.

Investments to new technology and systems have helped to reduce CO2 emissions by almost 40% (from 2008 to 2017). District cooling itself will be environmentally beneficial by reducing CO2 emissions by 52 % (2700 ton/year) compared to the customers own alternative, 71% of decrease will be in primary resources and 70% of decrease in electricity demand.


Both district heating and cooling networks are expected to continue growing. They are one of the main enablers of Tartu’s environmental strategy. Fortum Tartu will continue with the investments to new solutions and technologies to make Tartu an even more green and sustainable place to live.

Today Tartu’s district heating and cooling system is a medium- size system with approximately 80,000 end-users. Tartu’s district heating network supplies around 50 % of the buildings in the city and 75% of its citizens. The main customers are from residential and service sectors. The typical heat consumption (heat for heating and hot water) for old buildings is 150-180 kWh/ m2/y and 80-110 kWh/m2/y for new and renovated buildings (theoretical assumption). The weather conditions in Tartu are quite favorable for district heating: 3894 heating degree days (with reference temperature of 18 °C) and a rather long heating season (7 months). The district heating market in Estonia is regulated by the Competition Authority. Tartu’s district heating price from the beginning of this year is EUR 48.90/MWh (ex. taxes), which is lower than the average national price for district heating (approximately EUR 60/MWh). The main competitors for district heating are individual natural gas boilers and in some cases wood-burning stoves (mainly in one-family houses) or direct electrical heating. The district heating network in Tartu is approx. 175 km long with losses in production being only 10.8%. The heat is produced by 10 production units (mainly CHP and one boiler house; the overall heating capacity is 313 MW) and waste heat from local printing industry Kroonpress, as well waste heat from the district cooling network, which is used to heat up the buildings in Tartu.

For further information please contact:

AS Fortum Tartu Att.: Karita Kivi, +372 5565 8961 Turu 18, 51014 Tartu Estonia

Phone: +372 5565 8961

J O U R N A L N 0 . 1 / 2 0 1 8


By SIA "Salaspils Siltums", Latvia

Heating is an important component of quality of life for the residents of Latvia as the average outdoor air temperature is 2.1 o C during the heating season from October to April while in the summer months, there is a demand for hot water. District heating is used in approximately 80% of Latvian households, as well as in most public and industrial buildings. The fundamental mission of the district heating company is to ensure a reliable supply of heat at the lowest possible price, without harming the beautiful and green nature of Latvia.

THE ROAD TO ENERGY INDEPENDENCE One of the key energy goals of the company is the diversification of fuel. Using woodchips, a local renewable resource, has resulted in greater energy independence from the fossil fuel natural gas. To achieve this, a number of highly important production development projects were implemented with the support of EU funds. As a result of the upgrades, the CO2 emissions decreased by 80% compared to 2011.

Salaspils Region is located 20 kilometres from the capital Riga. The population of the region is approximately 23,000. The producer, distributor and transmission operator of district heating is the municipal enterprise Salaspils Siltums. The company was founded in 1996, based on a Soviet-era boiler station. Changes in the management board took place in 2011. With the focus on sustainable development of district heating, an ambitious modernisation project and process optimisation was launched. In record time, thanks to the support from local government and smart management, Salaspils Siltums has grown into a world-class district heating company, offering customers district heating that is significantly greener, safer, more reliable and costs less. The peak load of district heating consumer in Salaspils is approximately 27 MW. Salaspils Siltums supplies approximately 60,000 MWh of heat to consumers annually, supplying 85% of the households of the region, as well as government institutions and other consumers. The company uses two heat sources. The largest of them is located in Salaspils; it is equipped with three gas-water boilers and a woodchip boiler with condenser. The total length of district heating pipelines in Salaspils is approximately 21 km. The other heat source supplies the nearby village of Saulkalne. It runs on two gas-water boilers. The length of the pipeline network is short: approximately 1 km.

CO2 emissions in 2010-2016

More efficient use of fuel, workforce optimisation and other cost reduction measures enabled the implementation of one of the main objectives of the company – to gradually reduce the district heating price rates by 23% from 2010 to 2016.



In order to ensure efficient production and reduce gas consumption, three high-efficiency gas-water boilers were installed replacing the outdated Soviet-era equipment.

The gas boiler station before and after the upgrade

Fuel diversification

The boiler station was converted to full automation. The company has established a single heat measuring system that can provide the instantaneous load for each consumer, the heat carrier flow data, the heat source and heat transport energy efficiency indicators online. These measures make it possible to optimise the heat load, preventing heat losses in sections of the pipelines, and also encourage the consumers to save energy. Since 2016, the company has an LVS EN ISO 50001:2011 certified energy management system; the company monitors and analyses its energy efficiency performance. The company buildings have been renovated, greatly reducing the heating energy consumption. To partially cover own electric power consumption, 86 solar panels with a total capacity of 25 kW have been fitted on the roof of the building.

From 2008, the company was purchasing heat from the adjacent CHP plant running on natural gas, while the rest of the energy was produced using natural gas. To partially switch to renewable energy sources, a 7 MW woodchip boiler was commissioned in 2012. In order to increase energy efficiency and the effectiveness of the overall system, in 2015 it was decided to supplement the woodchip boiler with a 1.68 MW flue gas condenser. The company purchases woodchips with a 40-50% moisture level. Since the woodchips are so moist, the flue gas condenser recovers latent heat from the hot flue gas. The flue gas temperature before the condenser is an average of 160-170 o C, while after the condenser it is 45 o C. For example, in 2017, 32,438 MWh of energy was produced in 2017 and an additional 6,991 MWh recovered from the flue gas. Currently, 61% of the heat is produced using renewable energy resources – 50% from the woodchip boiler and 11% from the flue gas condenser. Until August 2017, 21% for the total amount of energy was purchased from the adjacent CHP plant, which is now closed.

Solar panels for electricity generation

Site of Salaspils Siltums before and after the construction of the woodchip boilers

J O U R N A L N 0 . 1 / 2 0 1 8


The customer service levels are worth a special mention. Customers of Salaspils Siltums can choose when to start the heating season. Using a remote data reading system, an employee of the company continuously monitors the heating energy consumption and advises the consumers on more efficient use of the heat energy. The employee ensures that the temperature schedule is strictly respected. A low return temperature ensures less heat losses and increases the efficiency of all production facilities, especially the flue gas condenser.

Operator control panel before and after upgrade

One of the main problems of post-Soviet boiler stations was the high amount of losses in heat transport. The company has been working hard to reduce the relative heat losses by replacing all heat pipelines with pre-insulated pipes, as well as ensuring the compliance of the heat carrier flow with the outdoor temperature and also monitoring the return temperature.

Temperature schedule

Salaspils Siltums also participates in the process of energy efficiency improvement for apartment buildings by offering renovation project management.


The company has ambitious plans for the future. Work is already underway on another new upgrade project – Salaspils Siltums is planning to install a solar collector with accumulation tank to use solar energy for producing heat. In addition, a 3 MW woodchip boiler is to be installed, replacing the fossil fuel with woodchips.

Relative heat losses, 2010-2017

For further information please contact:

SIA "Salaspils Siltums" Att.: Ilze Polikarpova, Energoefektivitates specialiste Miera iela 31a Salaspils, LV-2169, Latvia

Phone: 67944930

Replacing the heating pipelines with pre-insulated pipes



By Vinod Kesavannair, Engineering Manager, Marafeq Qatar LLC

cooling load of around 500,000 tons of refrigeration (TR) or 1,760 MW, by using multiple chiller plants with a total capacity of approx. 360,000 TR. The ultimate district cooling system will serve over 800 buildings through 170 km (supply and return) underground piping from four production plants. Plants are built in phases to meet the phasing of the development and to reduce the capex spending upfront. Chilled water will be delivered at interface in buildings between the district cooling system and the customer buildings (Energy Transfer Stations or ETS). To maintain adequate cooling to the buildings, the district cooling system is designed to deliver 5°C chilled water to customer buildings. The system is also designed to operate distribution pumps to supply the necessary differential pressure at the hydraulically most remote point(s) in the distribution system. For the system to operate properly and efficiently, the buildings must be designed and operated to deliver an aggregate return water of 14°C from the ETS to the plant. As buildings come online, Marafeq Qatar will continuously monitor building performance and work with customers to solve problems that might arise related to lower delta T. To help the building owner meet design delta T and reduce his operating cost while maintaining building comfort, Marafeq Qatar guides them in basic principles needed to make a building “district cooling ready”. Marafeq Qatar’s planning made sure all four district cooling elements would work integrally so that availability, comfort, and energy performance objectives can be met.

One of the largest district cooling systems in the world when completed, Lusail City District Cooling System, being developed to the north of Doha, Qatar, will have around 500,000 TR (1,760 MW) connected load. Through many design innovations it aims to provide extremely reliable, flexible and efficient cooling service to end-users. When fully completed, the system will save around 500,000 tons of CO2 emissions compared to traditional air-cooled systems used in the region. INTRODUCTION Lusail City is being developed to the north of Doha by Qatari Diar and Lusail Real Estate Development Company (LREDC). More than 200,000 residents will live in Lusail City, with 170,000 people expected to work in the city’s different districts, and 80,000 expected to visit its entertainment, recreation and retail and hospitality facilities. Lusail City’s 19 districts will encompass not only new residential, commercial, hospitality, and retail opportunities, but a full array of community needs, complete with schools, mosques, medical facilities, sport, entertainment and shopping centers. From the beginning, the visionaries expected a utility company would provide district cooling services, and in 2009, Marafeq Qatar was officially created. Marafeq, which in Arabic means utility, was tasked with providing district cooling, gas, pneumatic waste, and traditional waste management. Of these business classes, district cooling is by far the largest in terms of capitalization and revenue. DISTRICT COOLING SYSTEM OVERVIEW The Lusail City district cooling system will be the largest district cooling system for a development, which will supply chilled water to end-users through an integrated network with a connected

J O U R N A L N 0 . 1 / 2 0 1 8


NETWORK DESIGN Marafeq Qatar designed the distribution network of approx. 170 kmwith strategically placed loops and isolation valves. To assure high quality, Marafeq Qatar selected an all welded pre-insulated steel piping system with integrated leak detection system; all certified in accordance with the EN 253 family of standards. The key to EN 253 is that the pipe is fixed in place by transmitting strain energy from thermal expansion / contraction to the ground through the insulation. If the bond between the insulation and the pipe or casing fails then the pipe slips and strain energy is transferred to pipe bends or valve bodies. Marafeq Qatar also discouraged flanged connections except in special cases. Extensive industry practice in Europe has demonstrated flanged valves installed in chambers are weak links in the distribution system, and the European trend is to use an all welded system.

In line with the local codes to save precious potable water, make up water in cooling towers is designed with Treated Sewerage Effluent (TSE) water supplied by the local utility company. Chiller plants are designed with Ultra Filtration and Reverse Osmosis systems to filter and polish the TSE water to protect the major equipment from potential fluctuation in TSE water quality. TECHNICAL CHALLENGES Lusail City is developing across large areas (both north and south) which meant Marafeq Qatar had to closely communicate with the master developer about the changes in master plan and phasing. Changes in the master plan and phasing schedules required modifying the District Cooling System phasing strategy. Plants’ capacity phasings were continuously monitored and updated along with the main utilities required—power, water and drainage.

Coordinating the various segments of the distribution network also proved challenging since the network was divided into multiple construction packages, and these were in various stages of development. Interconnection of these sub packages into one network and preserving the earlier completed networks proved to be challenging. Since plot locations for distribution plants were somewhat limited, Marafeq Qatar had to carefully analyze network design and pumping to make sure all customers could be served and with some margins to allow for the inevitable changes that come with such an immense effort as Lusail City.

PLANT PRODUCTION DESIGN When planning the plant production, Marafeq Qatar assured the design was well thought, incorporated with redundant elements in order to maintain chilled water availability, and with design lives of 25 years for electrical and mechanical equipment and 50 to 60 years for civil works and pipelines. To minimize the impact on the electrical system grid, the Lusail City district cooling system will use stratified chilled water Thermal Energy Storage (TES) to shift demand from the peak period to off-peak periods. Although the primary benefit of TES is peak shaving, using TES benefits efficiency because chillers can operate more often near maximum efficiency region and can operate more often in the evening (off-peak period) when wet bulb temperatures may be lower, which makes the entering condenser water temperature lower and the chiller efficiency higher.



IMPACT ON THE COMMUNITY AND ENVIRONMENT For building owners, the initial capital expense is lower because there is no need for oversized/redundant chillers, cooling towers, and ancillary equipment. With district cooling, building owners will see lower operational and energy expenses with stable and predictable prices. Building owners do not require highly skilled O&M teams, which reduces their O&M costs. The building design will have greater architectural freedom, and spaces that otherwise would be used for air conditioning equipment will be freed up for better uses. The tenant will enjoy better ambiance, greater comfort, more uniform temperature, and less noise. Society will see lower power demand with less stress on the electrical infrastructure, and emissions will be lower. Marafeq provided guidelines for the building owners to follow when they design and construct their energy transfer stations. To date, Marafeq Qatar has reviewed and inspected nearly 400 customer submittals and installations and regularly meets with them to discuss ETS issues. The community won’t notice this, but architects are free to be creative without being encumbered with locating local chillers and associated cooling towers, pumps and to handle the issues of space, noise, vibration etc. However, the community will notice the quiet ambiance because of the absence of local cooling plants. The community won’t see the 500,000 tons of CO2 not emitted, but the world environment will notice. The community will notice the reliability and comfort provided by district cooling even though they will forget it as district cooling becomes the new “business as usual”.

INNOVATION AND APPROACH The Lusail City project is so huge that each of the 19 districts or each of the four district cooling plants is like a project in itself. And within the overall scheme, Marafeq Qatar prepared plans for temporary, modular, and permanent chiller plants to serve the various districts. Marafeq Qatar understands the need to integrate the four system elements—building side, ETS, distribution network, and chilled water production. All four elements must function properly if the system is to meet customer expectations for reliability, comfort, and efficiency. We were aware of the past problems that district cooling providers suffered when capacity was built ahead of customer commitment. Based on gross floor area and building occupancy type, Marafeq Qatar estimated customer demand using key figures time-tested in the region. From the beginning, we constantly communicated with the master developer and validated construction progress through site inspections and discussions with sub-developers. Customer needs must be met but without building too much capacity ahead of demand. For this reason chiller plants will have the capability of expanding in phases to more closely follow growth in the development. Marafeq Qatar tracks changes in the development progress and adjusts how and where chiller production capacity should be added. Marafeq Qatar wi l l careful ly expand the system using efficient equipment, thermal energy storage to reduce power consumption and the demand put on the electric grid, recycled treated sewage effluent to reduce potable water consumption, and environmentally friendly refrigerants. Using the EN 253 piping system might cost more initially, but in the long run it will save money and thus benefit the district cooling customers. Employing welded isolation valves and Pressure Independent Control Valves (PICV) in the ETS ensures a robust and better controlled customer interface. In the end, the district cooling services offered by Marafeq Qatar will reduce CO2 emissions by reducing power consumption, reduce power demand on the electric grid, reduce potable water consumption and all the while providing extremely reliable, flexible, and efficient service from multiple plants connected to a single integrated distribution network.

Marafeq Qatar LLC Att.: Vinod Kesavannair P.O. Box 5651, Doha,Qatar Phone: +974-40120146; +974-55465198 For further information please contact:

J O U R N A L N 0 . 1 / 2 0 1 8


By Mag. Gerald Schweiger MA, researcher at AEE INTEC in Gleisdorf/Austria and lector at Technical University Graz in Graz/Austria. PhD Stéphane Velut, PhD, Modelon AB

To enable the transition towards a low carbon energy system, we need to increase the efficiency of existing systems and to assess and design completely new energy systems that may differ fundamentally from those of today. Both require computational tools and methods that allow detailed investigations, depicting and mapping real systems as precisely as possible. This article presents a novel framework that allows for fully dynamic simulations and optimizations of 4th Generation District Heating (4GDH) Systems. Two cases show the applicability of the framework. An existing district heating network is adopted to test the simulation requirements for 4GDH systems. The second case presents the dynamic optimization of a district heating system in a planned city district based on physical models of the entire system.


language Modelica and a high-level, large-scale continuous dynamic optimization method implemented in and Optimica Compiler Toolkit (OCT). Out-of-the box models for simulation and optimization are available in Modelon’s Thermal Power Library. THE FRAMEWORK The framework consists of a library for fully dynamic investigations of district heating systems and an automated workflow which is shown in Figure 2. We developed a comprehensive library with out-of-the box models for simulation and optimization. Engineers are used to such models for simulation; out-of-the box models for optimization are rare but offer novel and intuitive possibilities for engineers. The district heating library consists of models for production, distribution, storage and consumption as well as different control schemes. Models can be connected intuitively while no programming skills are required. Advanced users can further utilize the advantages of Modelica and adopt existing models or develop new ones.

The overall goal was to develop numerical methods and tools for the simulation and optimization of (future) district heating and cooling systems. As fluctuating energy sources have an increased share in the overall energy mix, other parts of the energy systems must become more flexible to match the available renewable supply with the demand in terms of location, time, quantity and quality. Previous research has underpinned the potential of district heating to provide flexibility for the overall energy system. District heating provides multiple options for the integration of renewable energies, short & long- term storage technologies, Power-to-Heat (P2H), (industrial) waste heat utilization and smart integration of other urban infrastructures such as wastewater treatment plants. To address the challenges of this emerging paradigm in district heating design and operation, new requirements arise for simulation and optimization tools such as dynamic and multi-domain analysis. The author was lucky to get intense support from university and industry in the field of modelling, and applied math as well as from applied research and industry to tackle real world problems and to look two steps ahead, where we find various ideas, concepts and even more uncertainties.

Unified network representation

Network plan

Modelica model

Here, we present a novel framework to represent and simplify on-grid energy systems as well as to perform fully dynamic, thermo-hydraulic simulation and optimization of district heating and cooling systems. This article is partially based on our scientific publications, where more details including a precise mathematical formulation of the proposed methods can be found. This framework combines the engineering need for high-level description format including readily available and validated component libraries and sophisticated numerical optimization methods which are often cumbersome to use. The framework is based on the modelling

Dynamic optimization

 Fully dynamic investigations  Automated workflow  Real-time applicable

Solving the problem using / OCT

Dynamic optimization problem

Figure 1: The framework: from the network plan to dynamic optimization results




Ramp 1

Inertia 2

Inertia 1

Torque 1

The optimization of district heating networks (normal l y refer red to as production planning) can be formulated as an optimization problem, involving both discrete („Is my unit on or off?“) and continuous decision variables („How much heat should be produced? At what temperature level? “), transport delays, nonlinear and dynamical behavior. The resulting optimization problem is known as a mixed-integer-optimal control problem for which no general, robust and scalable method exists. We propose a novel method that enables a precise solution, while the solution time is sufficiently low for

Spring 1

Modelica model

Causal model (Simulink)

Figure 2: A simple mechanic model; the Modelica model is much more simple to interpret compared to the Matlab Simulink model.

real-time applications. Generally, sophisticated optimization methods are written in low level languages and they are difficult to use for engineers. The Modelica language extension Optimica was introduced to allow the formulation of optimization problems based on Modelica models. This extension enables a flexible and easily understandable formulation of the optimization problem including an objective (“What is the goal of the optimization (€, CO2, etc.)?”) and constraints (min/max temperatures, pressures, mass flows, etc.). The major advantages of including model coherences based on physical laws into the optimization formulation are high accuracy and the possibility to impose constraints on physically and operational relevant variables such as temperature, pressure or mass flow, based on limitations of the real system. A NEW MODELING PARADIGM FOR ENERGY SYSTEM MODELLING: ADVANTAGES AND POSSIBILITIES Modelica is an open, equation-based modeling language for multi-physic systems. Modelica has clear advantages over other languages mainly for the following reasons: (i) It can represent the physical structure of systems. Compared to causal languages, it is simple to interpret the graphical representation of models (see Figure 1). Models representing physical entities can be easily connected together using a graphical editor. This makes Modelica particularly suitable for application engineers. (ii) It is simple to code and to read the code. Model knowledge is stored in books (and human minds) in the form of equations. This knowledge usually cannot be transferred directly to computers, since conventional modelling languages do not allow equations. Modelica enables the modeler to model a system directly by the means of equations. This significantly increases the reusability, extensibility and adoptability of models and it enables faster developments compared to conventional modelling languages. (iii) Models described by equation- based languages can be integrated easily into optimization problems. Previous work has shown that the use of computer algebra in combination with equation based languages can speed up the solution significantly compared to conventional optimization methods. (iv) Modelica is particularly suitable for cross disciplinary developments.

Modelica has a lot of validated and well documented libraries in many physical domains including libraries for different subsystems of energy systems. A large variety of free and commercial libraries and modelling environments are available for modeling, simulation, optimization, model-based design and product life cycle management. These libraries consist of so-called “out of the box” models, which can be used via drag and drop. Modelica is a well-established modelling language in industry (7% of German power production is based on Modelica models. Furthermore, Modelica supports Functional Mock-up Interface (FMI). FMI is a tool independent, industrial standard for co- simulation of dynamic models and it is supported by more than 90 tools. Complex models are usually decomposed into subsystems (power – heat – buildings). Classically, such systems are modelled in a single tool, but very often there are more suitable tools available for different subsystems. In the context of energy systems, this offers novel possibilities. The model of an entire urban energy system could be decomposed into different subsystems, and these subsystems can be linked together via FMI. WHO BENEFITS FROM THE PROPOSED FRAMEWORK? Precise, physics-based models and a framework that is easy to use for engineers allow energy suppliers to increase the efficiency of existing systems as well as to design novel systems that may differ fundamentally from those of today. Furthermore, this framework can be used by the scientific community to work on concepts for future urban energy systems; the framework can be extended to other domains.

J O U R N A L N 0 . 1 / 2 0 1 8

Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32

Made with FlippingBook - professional solution for displaying marketing and sales documents online