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SESAC Site Växjö


Project status



Växjö, a city with 64,200 inhabitants in the south of Sweden wants to free itself from fossil fuels by the year 2030. It has already taken big steps in the right direction, reducing its CO2 emissions from fossil fuels by 34 % from 1993-2009. Another objective is to reduce the energy use per capita by 15% between 2008 and 2015.


Site facts and figures

  • Estimated population involved: 2,500
  • Approx. geographical area coverage: 200 ha
  • Approx. energy saving: 31% in ecobuildings
  • Approx. energy from RES: 95% heating



At Växjö an existing anaerobic digestion plant (Picture 1) has been rebuilt and extended to reach increased methane gas production and provide polygeneration (heat, power and purified biogas). It uses energy-rich biological waste such as sewage and food waste. The plant is self-sufficient in heating, produces 60 % of its own electricity demand and the extracted biogas is refined to serve as fuel for technical service vehicles (Picture 2) in the CONCERTO area.

Three absorption chillers are built to make use of the heat that is produced by a biomass-fired CHP also in summer (Picture 3). The first one was commissioned in 2007 and is a small demonstration object with 300 kW for testing and evaluation. The large scale district cooling system supplies the university and the hospital with cooling; it consists of 2 absorption chillers of 2 MW, a 2,000 m³ storage for 10 to 20 MWh of energy, heat exchangers for free cooling production during the winter period and about 10 km of distribution pipes to supply the university and the hospital with cooling. The system will be extended in the future to more customers and provide cooling for commercial buildings and the future office building in the town centre.

At the Teleborg School a photovoltaic plant of 528 m² has been installed on the roof (read more in “More detailed”). The Araby School has been refurbished (20% less energy demand than national average) and also a photovoltaic system has been installed.

For demand side management purposes at 400 dwellings, 5 offices and 4 stores individual meters for heating, cooling and electrical energy as well as for water consumption are installed. For a more sustainable usage of energy on the communal level Växjö is improving its application of an environmental management system.

At four different districts new eco-buildings have been constructed. In the garden district at Biskopshagen 88 dwellings in 18 buildings and a pre-school with high energy standards have been built. In Portvakten North (Picture 4) and South, the municipal housing company „Hyresbostäder i Växjö AB“ built 133 dwellings, of which 64 are located in passive houses. The municipal housing company „Växjöhem“ has built an eight storey high low-energy building containing 46 dwellings. Växjö’s first small-scale urban windmill has been installed on top of it. At Limnologen Sweden’s largest new-constructed wooden houses (134 dwellings at four buildings) have been realized. Find further information at „More detailed“.


Photovoltaics at Teleborg School

Växjöhem has installed polycrystalline PV panels on the flat roof of Teleborg School (Picture 1). The PV system has a capacity of 69 kWp and represents 532 cells with a total area of 528 m². In order to make the installation and its effects more visible, displays have been installed inside and outside in order to show the current production, as well as the total production and CO2 savings.

Along with the PV plant, six education modules have been designed so that the students can use the solar cells for educational purposes in Mathematics, Physics and English; students present the installation to foreign visitors and journalists.

The installation was completed in January 2008. In two years the plant has been able to produce around 60 MWh of electricity per year, which is equivalent to 1/8 of the school’s annual electricity need (see Table 1 for facts). Thanks to the installation, students have a great opportunity to learn more about RES, and see how it is working in reality. The PV plant has been visited by many foreign guests and media, for example NBC.

The PV installation at Teleborg School was the first one in Växjö, but the good experiences paved the way for further installations, among them one of the biggest in Sweden.


Table 1 – Facts on the PV plant

Table 1 – Facts on the PV plant


Absorption Cooling

The demand for cooling in Växjö is driven by increased indoor temperatures due to several factors: the climate, powerful lighting, the flow of people and widespread use of electronic equipment and excessive solar exposure of glass areas in modern buildings. Electrical systems were commonly used to solve this until now. Växjö Energy Ltd. (VEAB) demonstrated that electricity can be saved through absorption cooling, which is driven by district heating produced in the CHP plant. The additional heat production for cooling allows electricity production during the summer period, previously impossible due to too low heat demand in the summer.

The project has been carried out in close cooperation with the Royal Institute of Technology (KTH). The operation started in June 2007 and the performance was evaluated in order to obtain design criteria for larger chillers. The hospital and the university were then connected with plans to extend the district cooling system to more customers later on. Two full scale chillers in the CHP plant, each of 2 MW, produce cooling that is being distributed in pipes to the hospital and the university area. In the district-heating system are also installed 2 MW of free cooling and an accumulator that increases the peak capacity. The result is that the electric driven compressor machines, still in the university and the hospital, are only used for peak loads and as an emergency backup.

The cooling demand from the hospital and the university is estimated to 8,000 MWh per year, of which 6,400 MWh can be supplied by absorption and free cooling. The previous use of electricity for cooling purposes can be reduced by nearly 2,000 MWh per year. At the same time, the use of district cooling makes the production of about 2,000 MWh of electricity from biomass in the CHP plant possible. All in all, this is equivalent to reducing CO2 emissions by 4,000 tonnes on the European electricity market. During the coming years more customers will be connected to the system, such as shopping malls, industries and offices. The fully developed system is estimated to have a capacity of 25 MW.

(text taken from SESAC case study)


Wooden Eco-Buildings at Limnologen

The private party “Midroc Property Development” has constructed 134 apartments in four 8-storey buildings with a wooden frame. The construction of the houses has been studied by many researchers and universities and they are the largest newly constructed wooden houses in Sweden. In order to avoid moist in the building process, large tents were covering the houses during construction (Picture 3). This procedure turned out to be very efficient and has been used also in Portvakten South. High insulation with good airtightness and heat recovery cause low-energy consumption in these buildings. An individual feedback system to the tenants contributes to a low energy use.

The construction of the houses ended in 2008 and 2009. The energy statistics available in autumn 2010 showed that the use of district heating in the buildings was 69 kWh/m² and the use of electricity was 9 kWh/m² - the energy targets were achieved.

Lessons learnt

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

Benefits of CONCERTO:

Key benefits:

The participation of Växjö in the CONCERTO Initiative raised the level of innovation in the local project. The SESAC-project has further increased Växjö’s attraction as a destination for those interested in “green” issues (at least 100 visiting delegations per year). International media exposure was achieved. The “Fossil Fuel Free Växjö” has become a CONCERTO model for other cities all over the world. CONCERTO thus significantly contributes to the achievement of such ambitious climate protection targets. New technological solutions could be explored: district cooling and vertical axis wind turbines, high rise wooden houses, which are built without heating systems but with heat recovery and bio-energy district heating supply for the domestic hot water, a world unique project that minimizes the environmental impact. Besides being CO2 efficient in the production process and the standing period, the buildings themselves serve as a carbon sink. As part of SESAC Växjö produced guidelines for efficient energy management. Due to the SESAC-project, housing companies realized they could do so much more, develop better buildings and they have consequently raised their construction standards. The knowledge gained from the SESAC project fed also into the new local energy plan and helped getting it approved. The council learned about running an EU-project. In Växjö the SESAC buildings, especially the houses, paved the way for a new type of Public tendering and negotiation process, leaving the City and its Public Housing Companies with less risk and the private building contractors more incentive-based in their fulfillment of the energy and technological performance requirements.

Skill development:

In the SESAC communites Grenoble, Delft and Växjö training sessions on the environmental management system ecoBUDGET were organized. A lot of training was undertaken as part of SESAC - construction workers have learned a lot. The learning effect increased from one building to the next. Energy efficiency standards were increased on those buildings that had not initially been planned as passive houses.

Local economic effects:

New green companies were established. A large local company developed heat exchangers to recover heat from waste water for the passive houses.


Barriers encountered:

Administrative barriers:

Risks posed by an innovation-averse administration had to be anticipated and The Public Procurement Act had to be complied with by the Eco-Building demonstration project, which comprised public and private developers. In order to anticipate these, early support regarding how to combine Innovation and Risk-Mitigation in relation to The Public Procurement Act was done, through extensive cooperation with external consultants and the technical coordination. A lesson learnt is that innovative tendering alone doesn’t attract enough attention from the still somewhat conservative building industry. It was not until the housing companies actually invited potential building companies into face to face meeting, and also provided information and training, that the real dialogue started and a new type of project tendering and procurement could be put in place.

Technical barriers:

One site had problems with retrieving energy data from the metering system.

Economic barriers:

There were difficulties in calculating the housing costs. The usual situation in Sweden is that tenants do not pay for their consumption of district heating energy nor domestic hot water. Heating is often included in the rent (not declared as a separate sum). The housing provider guarantees to supply a minimum temperature e.g. 18°C or 21°C with the option for residents to increase the temperature above that. Therefore, they lack financial incentive for saving energy. In CONCERTO, individual heat meters were therefore used.

Further economic barrier was posed by short sighted national incentives, which result in an unclear investment situation. After elections in Sweden in 2006, subsidies for rental properties were removed, just before SESAC. This caused problems for the project part dealing with the construction of passive houses, as building new apartments for renting became more expensive. So higher rents would be required in order to recoup the investment, which in turn would make it more difficult to find tenants. Hence housing companies were hesitant. However, Växjö is constantly growing, meaning that there is a housing shortage in Växjö. Through this, construction of the passive houses went ahead. Now all dwellings are rented out, but it took longer, and required extensive marketing.

Furthermore, the biogas project got more expensive than expected. Amendments could be made every year, budgets could be moved, budget shifts between countries.

Social barriers:

The project objective of saving 5% of electricity consumption in households throughout Växjö could not be achieved, as a change of behavior takes longer than expected and electricity is to cheap (so people feel it is not worth the effort) and the campaign was not extensive enough. It is expected that the objective will be reached eventually, but will take longer than expected.


Success factors identified:

Technical Success Factors:

In order to help the tenants keeping an energy saving routine, displays showing the energy use are installed in each apartment, also using the internet Platform “EnergiKollen“.

Social Success factors:

Development of the campaign SAMS that aims at a 5% reduction of electricity among all households in Växjö was important. Also, competitions were organized using a smart metering box and the internet platform “EnergiKollen“, through which the municipal utility informs end users about their energy consumption (for both electricity and district heating). This interface is available online and can be accessed by every end-user. Additionally, 123 households in two different buildings participated in testing different kinds of smart metering appliances. Citizens could compare their energy consumptions, get together in teams and enter competitions on which team could reduce their energy consumption the most. Competitions were held for the household with the lowest energy consumption in a given month with a restaurant meal as price. The underlying rationale for it is the belief that as soon as people understand their energy consumption, they will be encouraged to behave in a more energy efficient way. In the first building, 29 households received a smart metering appliance with a display on which they could see their consumption (electricity, hot and cold water) and costs and receive feedback on their energy consumption behaviour and savings. The other 40 households in this building had the same appliances with a display, but did not receive feedback. In the second building (54 dwellings), householders received information on their electricity, space heating, hot and cold water consumption on a display. Their system included also a feedback. An accompanying study comparing electricity consumption in the two different types of buildings evaluating the effect of the feedback system and comparing them with the reference apartments not involved in the SESAC project revealed the effectiveness of the display feedback system and demand side management. Results show 34% savings of annual electricity when compared to reference apartments in Växjö.

Institutional success factors:

The municipality of Växjö had set up an advisory committee in 2007 composed of the university and industry representatives advising how to achieve goals and considering the measures assuring regional economic growth. This played an important role in setting up a strategy. The committee is now no longer active local energy company is owned by the municipality. In Växjö, questions related to CONCERTO and the SESAC project have been integrated in the local census, which mainly involved questions on the perception of the municipal services. There is strong support across the local population and across all political parties for retaining the status of “greenest city in Europe”. Close dialogue between environmental office at the council + planning department + housing company. Great commitment of all involved.

Economic success factors:

Regarding project delivery, the SESAC buildings, especially the passive houses, paved the way for a new type of public tendering and negotiation process, meaning that the city and its public housing companies are exposed to fewer risks and the private building contractors have greater incentives, based on their fulfillment of the energy and technological performance requirements. The innovation and demonstration project with distributed bio-fuelled absorption cooling for the local energy utility VEAB’s office, has opened technical and financial possibilities for a substantial extension of this environmentally friendly and electricity saving cooling solution to several of the City’s new and existing buildings. It used an innovative cross-financing model, including green certificates from VEAB’s CHP production. Altogether, the presence of a national CO2-tax has influences at local level. Having this tax (since 1994) on oil and other fossil fuels acts as a strong incentive for emissions savings.


Driving forces are the willingness to take responsibility, regional growth and development and public relations while environmental and energy legislation plays a secondary role. The main driving force for private sector has been the possibility to get media exposure at the EU level. There was massive political support across all parties.


Business models used:

In Växjö, the Växjö Energi AB (VEAB), an energy company created by the municipality of Växjö and owned by the local residents, was involved in the demonstration activities of the SESAC project. This company is in charge of the provision of district heating and electricity (Sandvik bio-fuel based combined heat and power plant) and with the implementation of energy saving measures. Within the SESAC project, VEAB has been involved in demand side management demonstration activities, involving the introduction of different smart metering solutions in a sample of households and in measuring the effects. They developed the internet platform (EnergiKollen) mentioned above. VEAB is also involved in a demonstration activity on heat driven cooling combined with the biomass fired CHP plant. A demo chiller at Sandviksverket provided valuable input for feasibility studies and planning of a full-scale solution, which however is not yet completed. An innovative cross-financing model, including green certificates from VEAB’s CHP production was developed. This meant that the work regarding biomass fuelled absorption cooling for the local energy utility VEAB’s office, has opened technical and financial possibilities for a substantial extension of this environmentally friendly and electricity saving cooling solution to several of the City’s new and existing buildings.


diagramm vaexjoe

diagramm vaexjoe

Legacy – follow-on projects:

In the SESAC communities (Växjö, Delft and Grenoble), stakeholder meetings were organized and involved stakeholders of the local service sector (e.g. builders, architects, housing companies, etc.). During these meetings it was discussed how the results reached in the demonstration activities could be used in the day-to-day work of these stakeholders. In this way, it was tried to create a spill-over from the demonstration activities and to motivate companies to replicate construction techniques developed within the SESAC project (e.g. wooden constructions, passive houses). In order to continue CONCERTO-like endeavors an application for Smart Cities had been submitted. Initially this was turned down, but a new application will be made. Furthermore, the city hall is supposed to be refurbished to CONCERTO-Standard and the municipal energy company has moved on to develop an energy-plus building.


Legacy - Policy Developments:

The local energy plan for Växjö had been rather old – SESAC provided the opportunity to revise and improve it and make it more ambitions (this formed part of the project activities).

The CONCERTO approach

Absorption cooling, based on biomass, has been introduced in Växjö. As a first step, cooling is distributed to the hospital and the university. The system replaces electric cooling and is at the same time a basis to increase a local electricity production using Renewable Energy Sources. In the sewage treatment plant, food waste and sludge are sources for biogas that is used for polygeneration of heat, electricity and vehicle fuel.

About 400 energy efficient apartments and one pre-school with a photovoltaic plant have been erected. Many of the buildings have a wooden construction, including the eight storey passive houses. The target was to reach 30% less energy use than applicable regulations. Displays in the apartments as well as web-based tools have helped tenants to reduce their energy use.

In Biskopshagen, a garden district in Växjö, the municipal housing company Växjöhem has built 88 dwellings in 18 buildings and one pre-school with the purpose of having a low energy use. All of them are connected to the district heating system.

An eight storey high low-energy building containing 46 apartments has been built. The house has high insulation standard with good air tightness and heat recovery. In order to help the tenants keeping a low energy routine, displays showing the energy use are installed in each apartment.

134 dwellings in four wooden buildings at the building site have been realised. They are Sweden’s largest newly constructed wooden houses. The energy statistics showed that the use of district heating in the buildings was 69 kWh/m² and the use of electricity was 9 kWh/m². In Portvakten North and South in Växjö, 133 apartments have been constructed, of which 64 are located in passive houses.


A test house for training purpose was built on the construction site of the neighbourhood “Biskopshagen”. Builders and other professionals can train their skills in applying new technologies just before applying them on the real project.



Julia Ahlrot

Thematic Field

  • New Building(s)
  • Refurbished Building(s)

Dwellings type 1

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