Sint Antoniuspleintje is an environmentally sustainable housing project developed by Zonnige Kempen (ZK), a pioneering social housing provider in Belgium. The project is located in the village of Zoerle Parwijs where 13 highly energy efficient social rented homes have been constructed, increasing the supply of locally available affordable housing in the rural area and helping to reduce the fuel poverty experienced by those on low incomes. One of the pioneering approaches used in this project is a solar asphalt collector, which harnesses the heat of the road surface in summer and stores it for use in the colder parts of the year.


Project Description

Aims and Objectives

The purpose of the project is to provide state-of-the-art, environmentally sustainable social housing to address all aspects of sustainability and to improve the urban and social infrastructure of the village of Zoerle Parwijs. This housing project also serves a demonstration role in highlighting the possibility of various energy-saving methods being integrated within one project and the synergies that can be derived from them.

Programme Context

There is an increasing need for social housing in rural villages in Flanders, as well as for low energy housing since the recent increase in energy costs makes housing less and less affordable for those on low incomes. Situated in Greater Westerbro, Belgium, the large village of Zoerle Parwijs was divided by a busy provincial road making the village centre almost uninhabitable. This had led to dereliction and abandonment of property and a diminished sense of community. The area where the project was developed was a derelict area, where the houses had previously been owned by a slum landlord and had long stood vacant.

Key features

Sint Antoniuspleintje is an environmentally sustainable housing project which consists of 13 new social rented homes on a brownfield site in the village of Zoerle Parwijs in the municipality of Westerlo in Belgium. The dwellings are arranged around a square near the town centre with three detached houses, a terrace of four houses, one four-bed family house and a block containing three one-bed apartments with disabled access. The buildings are oriented as much as possible to the south and some storage areas are communal (bicycles, recycling containers). All the houses have gardens and the apartments have balconies. The 13 dwellings have a maximum capacity of 48 persons.

The buildings have a high environmental specification to save both water and energy and the energy specification of the housing is twice the Belgian average. The energy-saving features include extensive insulation, sun-oriented architecture, passive solar energy concepts (glass-fronted façades), mechanical ventilation with heat recovery (rates of 90 per cent are achieved) and energy control systems. A vertical underground heat exchanger consisting of earth probes over a depth of 50m provides an energy store.

Renewable energy sources in the project include a solar asphalt collector, flat panel solar collectors (for domestic hot water use) and photovoltaic solar energy. The asphalt collector works by water being run through pipes under the asphalt and being heated from the warmth of the road surface in summer. This heated water is then pumped underground and stays warm at 20°C. The warm water can be sent to nearby houses (where it is heated further) and it can be pumped up nearer to the road surface during winter months to prevent ice from building up on the road. The pump can also call on the water to cool the buildings on hot summer days.

Synergies are obtained through surplus solar energy in summer being stored in ground, the heat pump being used in winter for preheating domestic hot water and the glazed sun spaces preheating ventilation air. The ventilation air below the photovoltaic cells means that fresh air is heated at the same time as the panels are cooled and the location of the distribution channels through strongly insulated dwellings means that there are almost no heat losses.

Construction of a ring road has kept traffic out of the village and this project has helped to form a renewed village centre and an inhabitable space for the local community.

Residents are involved in monitoring their energy consumption and are well informed about the best way to live in their homes to maximise their energy-saving potential. The local community living in the neighbouring area were involved in developing the concept and detailed design of the public space.Other stakeholders involved were TemaS architects and Carlier bvba who carried out the architectural design and the environmental works respectively and a local construction company was responsible for the construction.

Covering costs

Funding was provided by VMSW, the umbrella organisation for social housing companies in Flanders that finances local social housing companies with funds provided by the government. Additional grant funding from the Flemish Energy Agency was made available for some of the renewable energy aspects of the project.

The capital costs of the project were US$1,910,000 for construction, US$711,000 for engineering and US$313,000 for environmental works, giving a total cost of US$2,930,400 and a total cost per unit of US$225,692. The asphalt collector and photovoltaic system were financed by the Flemish Energy Agency. ZK also raised part of the funding itself through loans from the bank. The construction costs at US$1,580/m2 are similar to the average for all Flemish housing companies.

The Flemish government covered 60 per cent of the construction cost and the remaining 40 per cent was obtained by ZK through a loan raised on the market. An additional subsidy of US$660,000 was obtained to cover the environmentally sustainable features.


  • The tenants benefit from living in good quality homes which are more affordable to heat. High quality materials of construction and the increased affordability of warmth lead to improvements in people’s health.
  • The tenants are very appreciative of the reduced energy costs and have developed a sense of pride in living in the houses, evidenced by creation of private gardens and care taken of the area.
  • The wider village community benefits from improvements to their village with the creation of the village square as a focal point for their community.
  • Wider sustainability issues are addressed through densification of the urban site, creation of shared urban space and the regeneration of the local neighbourhood
  • There is evidence of a knock-on effect when nearby developers or private individuals chose to create similar solutions.
  • There is increased interest from communities, institutions and housing organisations in the approach to sustainable housing provision. The principles of sustainable housing and the lessons learned from this project (and two others) are now incorporated into the VMSW design directives and recommendations (published November 2008), which are mandatory for social housing providers in Belgium.
  • Wider global benefits from reduced carbon emissions and the use of the project as an exemplar for other social housing providers in Europe.


Why is it innovative?

  • The project is based on Zonnige Kempen’s six-stage energy concept philosophy, the first three elements of which are increasingly accepted practice, but the latter three of which are rarely used:
    1.Limit the energy consumption as much as possible
    2.Use renewable energy sources 3.Use energy resources as efficiently as possible
    4.Measure and check the consumption
    5.Give proper information to the tenants
    6.Communicate your findings
  • Use of renewable energy systems, including a solar asphalt collection system, which stores heat generated by the sun shining on the tarmac road surface and uses it locally.


What is the environmental impact?

  • The project ensured a more appropriate use of energy and water resources. The six-step approach used ensured reduction in consumption, increased user awareness and involvement and the use of renewable energy systems, as well as passive solar design.
  • The dwellings have been built on a brownfield site where possible waste construction materials from demolition were utilised. For example, recovered bricks were used for the façades. Only FSC labelled wood or native wood is used. Certain construction materials were not used, such as PVC and some types of insulation materials, as the raw materials are not recyclable. Construction waste was thus minimised with good building site practices.
  • Renewable energy systems used include ground source heat pumps, photovoltaics and use of the public square area of asphalt to act as a solar collector and collect/store heat. The asphalt temperature can rise to 60ºC in the summer and absorbed heat is held in store in an underground storage system consisting of vertical heat exchangers. At the end of the summer an average storage temperature of 20ºC is achieved and this is used throughout the winter to feed a heat pump which supplies heat to a low-temperature heating network, consisting of floor heating and oversized radiators. By the end of the winter the storage temperature has reduced to 8ºC.
  • Positive feedback loops and synergies are encouraged, with surplus heat stored in the underground heat store for use later in the year and the pre-heating of ventilating air by moving it through the glazed sun spaces. By sucking in the ventilating air below the photovoltaic panels, the fresh air is pre-heated at the same time as the panels are cooled.
  • It is not anticipated that any gas will be used for space heating and that only a limited amount will be used for water heating. Surplus energy produced in the summer by the photovoltaic cells is sent to the national grid.
  • Awareness raising is carried out through the public viewing of the energy installation in the project (through the glazed wall) and the data being made publicly available on the ZK website (currently under construction).


Is it financially sustainable?

  • The project is largely grant funded as it is part of the Belgian social housing provision system, together with extra funds received in respect of some of the more innovative energy systems. Construction costs are similar to those of other Flemish social housing schemes.
  • The rent paid by the tenants is mainly determined by the income level of the tenant. Energy costs have to be met by the resident, however, and fuel poverty is a major factor for those on low incomes, particularly in an era of significantly rising energy prices. Living in very low energy houses means that the households do not have to spend such a large proportion of their disposable income on energy. Although there is a collective heating installation the tenants have individual meters and are responsible for meeting their own energy costs.


What is the social impact?

  • The creation of an urban square as a community focus and densification of the area has helped to restore a sense of place and community in a large village that was bisected by a major road. Creation of a small by-pass as part of the project has also meant that the former division of the village by the major road no longer exists and this has been a major contributory factor to the improved sense of community.
  • The project resulted in increased social integration. The design of the housing ensures that a range of tenants can live in them, including older and disabled people, as well as families and single persons.
  • The residents are involved in monitoring their energy consumption as it is recognised that it is very important that they are involved if the energy savings are to be maximised. Meetings are held with the tenants to explain how they can live in their accommodation to maximise the energy savings and ‘smart’ meters are provided to enable consumption to be monitored. The boiler room is conceived as an educational room; the public can view the installation at all times and the data is shown on a viewing screen. There are plans to create a website where the energy consumption data can be constantly shown and monitored.


  • Financing problems for the experimental parts of the project was an initial barrier but the project was selected to receive regional funding to support these parts of the project.
  • The technical installation was a learning process as this was the first time it had actually been tested in reality.
  • There were problems with the local planning authority that had planned to use the square with the asphalt collector for car parking, not understanding that it was important that it should not be permanently shaded. This was overcome by explaining the mechanics of the asphalt collector system in simple language to the municipal officers.

Lessons Learned

  • It is very important to plan together and work as a team. Each partner (designer, technical engineer, environmental designer etc.) needs to be involved in the design stage to ensure that the necessary synergies between the different parts of the project can be developed.
  • Monitoring the technical installation is critical, not just as part of the learning process but also to ensure that the maintenance process is optimised.



A thorough evaluation process has taken place in cooperation with the Flemish Institute for Technological Research (completed at the end of 2008). This involved monitoring the technological performance of the entire project, but also included discussions with the residents to understand how they are using the dwellings and any problems that they might be experiencing. Early results show an excellent performance from the asphalt collector.



There is evidence of local transfer of the good practice by both social housing and private house builders. The umbrella organisation VMSW has used the experiences of ZK to convince other social housing companies to develop more environmentally sustainable social housing. Indirectly the project has influenced a range of other stakeholders and working groups, for example the proposal from the Flemish Administration to the government on the transition management process for sustainable building and housing and the development of sustainable housing indicators by the province of Limberg.