Skip to main content
Smart Cities Marketplace

SORCER Site Hillerød


Project status



In Hillerød, the regional capital of Denmark's North Seeland region, is showing that a zero CO2 community can become reality, with a development of more than 78,000 m² eco-houses that will exceed by at least a quarter of current energy efficiency standards.


Site facts and figures

  • Estimated population involved: 6,000
  • Approx. geographical area coverage: Information will follow
  • Approx. energy saving: 633 MWh/y electricity and 2,185 MWh/y heating
  • Approx. energy from RES: 1,924 MWh/y electricity and 8,889 MWh/y heating



Demand, electricity


Eco-building, Class I 236
Eco-building, Class II 2533
Total – electricity 2769



Supply, heat


Two stage gasifier 3,234
Biomass boiler 2,352
Solar Thermal 1,200
Heat Pumps in Class 1 275
Total – heat 7,061


Supply Electricity


Two stage gasifier 1,525
Wind 143
PV 7
Total – helectricity 1675



The demonstration activities in Hillerod focus on the “Ullerød” district and include new construction of 86 Energy Class 1 dwellings (41% savings in heat consumption and 100% usage of RES compared to normal Danish practice) and 670 “Eco dwellings” (33% and 100% respectively). Furthermore a city college (5,580 m², low energy class 2 building) is being built in a new Campus area near the train station, a conference centre (consisting of new and refurbished parts) has a total floor area of 3,000 m² and an office building of 5,000 m² has been built according to BR08 low energy class 2.

The northern part of Ullerød is supplied with heat and electricity produced in a biomass based energy central. A two-stage gasification plant (Picture 1) produces the base-load heat demand (about 1,000 kW heat power). A biomass boiler (7.2 MW) supplements the heat production and works as backup system in summer period (Picture 2). A low temperature district heating net has been established in the southern part of Ullerødbyen.  The pipe network has been constructed and consumers are connected to the net, which has the temperatures 60/30 °C. The operation of the connected biomass boiler started in May 2011. The plant has a total capacity of 8 MWtherm.
In the southern part of Ullerød a central solar system 3,000 m² (Picture 3+4) has been installed to supply the local low temperature district heating system, which is connected to the existing CHP plant. This plant will be increased by another 500 m² soon. Another smaller plant (788 m²) has also been installed during CONCERTO and started to produce energy in late 2012 (Picture 5).

Altogether 497 kWpeak of small-scale photovoltaics have been installed. One of the larger systems (30 kWpeak) was implemented at the concert venue “Klaverfabrikken” making it the world's first CO2-neutral concert venue (Picture 6). Another large system (25 kWpeak) is installed on the roof of the retrofitted town hall (Administrative Centre).

In the field of electricity consumption there is another demonstration project planned. Setting up a new LED lighting system around the castle in central Hillerød is in process.

At Hillerod (SORCER) a low temperature district heating network was installed within CONCERTO and connected to the existing district heating network. The existing CHP plant, which supplies heat to the network, was supplemented by a large solar thermal plant of 3,000 m². The size of the solar plant was chosen to cover the total demand of domestic hot water of South Ullerød during the summer period. As further funding money could be shifted to the task of increasing renewable energies, it is planned to add an additional area of 525 m² of solar collectors, located right beside the existing plant. The project responsibles give a short technical description of the existing plant: “The solar system consists of 240 solar panels, each having an effective area of 12.58 m². The heated fluid from all solar panels is grouped in a single district heating, providing heat to the plant room. Here the heat from the collectors heats up the water for district heating in a large heat exchanger, and the heat is pumped from the district heating network to the consumer. In the building there are pumps respectively. […] The solar panels are placed on a noise protection embankment, which is inclined by 10° and oriented to the south. In order to obtain the optimum orientation to the sun, the solar panels are mounted at an angle of 27° from the surface of the embankment, so that the total angle is 37°. This slope provides a high production in the three summer months when the sun is high in the sky.”. The calculated annual energy production from the existing plant (3,019.2 m² net effective area) is 1,500,000 kWh and the annual CO2 emission reduction was figured at 309 t/a (7,725 tons over a life-time of 25 years) according to the project responsibles.

Lessons learnt

The following information has been gathered as part of the CONCERTO Premium policy research.

Benefits of CONCERTO:

Key benefits:

Development of low temperature district heating areas is a prerequisite for the future supply of low energy houses. This is used by consulting engineering companies, city planners and utility companies in making the energy supply for the cities of the future. Much increased awareness in the municipality concerning low energy measures in both their own buildings and in terms of the municipal planning (where it is now a requirement to build low energy buildings). Ullerødbyen is seen as a green area where it is possible to get in touch with nature and still be close to the city. Klaverfabrikken which is a local music venue has received enormous attention for becoming the first CO2-neutral music venue in Europe (or the world). This has resulted in very positive awareness of what it means to be CO2-neutral.

Skill development:

In the municipality the administrative staff working with energy in terms of both building permits and operation of municipal buildings improved their skills. As an example the team that issues building permits have been through extensive teaching concerning low energy buildings. In the utility company they have improved their business cases concerning low temperature district heating systems. The utility company has also started using biomass, which they did not do before.

In COWI the low temperature district heating system was used as basis for further development of new solutions for district heating supply. Also the monitoring principles used in the project resulted in new skills for persons in COWI

In Klaverfabrikken a large number of staff and volunteers are now aware of the advantages of PV. An unknown number of citizens in Hillerød have learned about the advantages of low energy buildings and PV. The project partners Weiss and DTU (Technical University of Denmark) developed the two-stage gasifier.

Local economic effects: For planning and project work 7 full-time equivalent (FTE) person-years were required for the planning and construction of the CONCERTO project.


Barriers encountered:

Technical barriers:

The delivery of the gasifier which is based on new technology took  much longer than expected to finish, and therefore the production was delayed significantly. The low energy class 1 buildings (7.000 m² in the project) had problems with too high energy consumption and bad thermal indoor climate together with draught problems. Installing monitoring equipment as specified by CONCERTO Plus (and later Premium) was a very costly matter, which in some cases cost the same as the support which was paid to each house owner as a scale of unit cost. This made it very hard to justify installation of detailed meters   

Solutions: For the gasifier it has been decided to wait for the finalization of the plant. Towards the end of the project low energy buildings have been standard constructions. Two or three meters have been installed for each household, which means that some of the values must be estimated based on previous/other knowledge

Economic barriers:

Little interest in private construction from 2007 to 2010, which was the most vital period in the project in terms of getting buildings finished and entered into the project. For the gasifier it was close to not being constructed due to a high price compared to the income it is expected to generate during operation

Solutions: Two major changes to the SORCER project to change the project from mainly dwellings to also include other types of buildings. The gasifier was included after all after a careful examination and feasibility study compared to alternative solutions.

Social barriers:

There was little interest in participating in the project for the developers in Ullerødbyen in the beginning of the project. Users in the low energy class 1 buildings were disappointed in the project results, as they had problems heating their buildings and avoid draught.

Solutions: Meetings were held with the developers to get them interested in the project. This was done in 2010 and 2011 and resulted in much greater interest from the developers as low energy buildings were also much more common. Meetings, surveys and careful analysis of the situation were conducted. This improved the situation somewhat.

Administrative barriers:

In the project a large number of single-family houses were included which led to a large number of contracts and difficulties in project reporting.

Success factors identified:

Technical Success Factors:

The project basis in this project was the fact that Ullerødbyen should have low energy buildings supplied by low temperature district heating. The heat to the city should come from solar thermal, biomass boiler and CHP gasifier. This concept proved to be a success throughout the project in spite of the changes.

A "negative" success was that monitoring of the low energy class 1 buildings participated in ensuring that a ban has been introduced in Denmark on using air-to-air heatpumps as the only heat source. This is important as air-to-air heatpumps have proven to be very inefficient (and too small) when it is very cold outside.

Social success factors:

Ullerødbyen was seen as a very successful area due to the green areas surrounding the buildings. Klaverfabrikken was a huge success from a disseminative point of view with good positive stories in the media about the fact that they became carbon neutral.

Institutional success factors:

The utility company realized during the project that installing solar thermal fields in different places in the city strengthens the district heating grids to improve security of supply and lower heat losses. After the first plant which was supported by the SORCER project, three more plants have been installed where only one of these was supported by SORCER funds.

Business models used:

For EE projects no specific business model was used, except that business models helped towards reducing the cost of the low energy building.

For PV (photovoltaic) systems, these more or less sold themselves due to the so-called "nettomålerordning" (energy meter roll back scheme) which implies that the production of the PV makes the energy meter spin backwards. In other words the value of the production is the same as the cost of the production. This was a very good funding scheme for the owner of the system. However it ensured that several of the systems were installed in the CONCERTO area.

For the RES systems it was a decisive factor that the plants can produce heat cheaper than the price of the heat from the local CHP plant which was based on natural gas. It is generally speaking not allowed to claim a higher price of heat because it is based on renewable sources.

Legacy – follow-on projects:

As stated above, the utility company installed three solar thermal fields of around 500-800 m² throughout the city (one with CONCERTO-finance). A new building complex similar to the low energy class 1 houses in Ullerødbyen was planned, but based on different heat supply technology - without the air-to-air heatpumps. A second gasifier is already being built in Hillerød (based on another technology, but this would probably not have happened without SORCER). 

Legacy - Policy Developments:

As a result of the monitoring in the low energy class 1 buildings, the use of air-to-air heat pumps was banned as the only heating source in Danish buildings used for all year occupancy. The results added to similar results from other projects. The reason is that the heat pumps cannot supply sufficient heat when it is really cold outside - and at the same time the COP is extremely low.

The CONCERTO approach

A combination of a number of renewable sources will provide power for the settlement. Biomass will be burned to produce electricity and heat, with the biomass plant having 500kW heat capacity. There will also be a major investment in solar power, with the construction of the 3,000 m² solar thermal plant that will be connected to the district heating grid. A variety of other techniques will be used to complement the main renewable sources, including wind energy, PV capacity, heat pumps, and low-energy district lighting.

Around 670 houses in the new community will be Class 2 dwellings, meaning they go beyond mandated Danish standards by reducing heat energy demand by additional 25%. The Class 2 housing development will cover more than 72,000 m², and will include single family houses, row houses and high rise apartments and small industry. These will be accompanied by 6,500 m² of Class 1 apartments, meaning their heat energy demand is 50% below national standards. All housing will be well insulated, and will have other energy saving measures.

Importantly, a system for energy data collection of each house will be developed, with energy usage information collected in a central computer. In this way, the utility company can follow the individual consumption of each household and hence target energy advice.


Consumers will be able to monitor their consumption of both heat and electricity through an online graphical presentation available through the Internet, on their television, or via an energy meter. Additional data from weather forecasts and heat storage status will be available on the supply side, so that the utility can moderate its energy output accordingly.


Peter Weitzmann

Building aspects

  • Building Energy Services
  • heating and DHW
  • Building Energy Services
  • other please specify
  • Technology used to supply the buildings
  • heat pump: compression
  • Technology used to supply the buildings
  • other please specify

Energy Carriers

  • Electricity
  • Solar thermal energy
  • Wood Chips 30% moisture

Energy Systems Types

  • Sustainable Generation
  • Solar Thermal Plant

Thematic Field

  • Energy System(s) Integration
  • New Building(s)
View reported data

Project data