Renovating without altering: meeting an energy and architectural challenge
Located in the Droixhe district of Liège, currently undergoing major transformation with the arrival of the tramway and the Liège Expo project, the Libération Complex is benefiting from a comprehensive energy renovation.
Built in the 1970s, the complex accommodates a school, a daycare centre, a large events hall, a boxing gym and a police station. Designed according to modernist principles – clean lines, exposed structures and durable materials such as concrete, brick and glass – it has retained remarkable architectural quality over the decades.
After more than fifty years of use, a global energy renovation became essential, carried out with full respect for the original identity. Led by the City of Liège, the project brings together Canevas and engineering firm greisch for structural and building services design.
Renovating with respect for modernist heritage
The intervention aims to reconcile energy performance, comfort and preservation of the original aesthetics. The open, light-filled buildings continue to meet contemporary user needs; the challenge was therefore to improve performance without altering their character.
Building envelope and materials
The opaque external walls are clad with thin glazed brick tiles bonded to insulation, replicating the colours, patterns and dimensions of the existing façade. This mixed insulation approach – combining internal and external insulation – was carefully designed to eliminate any risk of thermal bridging. Dew point analyses were carried out to ensure the long-term durability of the buildings.
Aluminium window frames with double glazing retain the original glazed proportions and subdivisions, featuring natural anodising inspired by modernist frames. Exposed concrete structures (frames, columns, beams and walls) are cleaned and repainted, preserving the legibility of volumes and the visual lightness that define the complex’s architecture.
Efficient and understated technical systems
Ventilation and indoor comfort
A high-efficiency double-flow ventilation system with heat recovery ensures fresh air supply and occupant comfort while limiting energy losses.
Open-loop geothermal energy and photovoltaics
Heating and cooling rely on open-loop geothermal energy, a technology that extracts thermal energy from the groundwater of the Meuse gravel aquifer and returns it to the ground after use. Water drawn from a depth of approximately 12 metres passes through a heat exchanger, providing heat in winter and cooling in summer. This energy feeds a state-of-the-art water-to-water heat pump, whose electricity consumption is partially offset by a rooftop photovoltaic installation.
The system’s performance is based on two key parameters: a temperature differential of 5 °C between water intake and discharge, and a flow rate of 90 m³/h, ensured by two pumping/reinjection doublets and a backup borehole.
The Liège basin offers particularly favourable geological conditions for this technology. Compared with an air-to-water heat pump, open-loop geothermal systems provide stable year-round efficiency thanks to a constant water temperature between 12 and 15 °C, while also reducing the urban heat island effect by avoiding hot air discharge.
By way of illustration, the energy savings achieved are equivalent to the annual heating consumption of nearly 100 households.
Exemplary environmental monitoring
Sensors installed in the aquifer monitor water levels and temperatures, both during the design phase and throughout the first five years of operation.
The pumping and reinjection wells, drilled within the school playgrounds, comply with strict environmental specifications, eliminating any risk of pollution.
The project benefits from support from the European Recovery Plan, which promotes diversification of energy sources and reduction of the carbon footprint of public buildings.
Long-term expertise
For several years, engineering firm greisch has developed extensive expertise in open-loop geothermal systems and integrated energy renovation.
This multidisciplinary approach – combining engineering, architecture and sustainability – has already been applied to several landmark projects, including the NSI headquarters in Liège and the PLAWA project in Namur (renovation of SPW ARNE).
The firm’s working methodology, specifically developed and refined through numerous energy renovation projects and rooted in the multidisciplinary approach that defines our practice, made it possible in this case to adapt more easily to budgetary variations inherent to the allocation of subsidies.
Project partners
- Client: City of Liège – Department of Public Works – Municipal Buildings
- Architect: Canevas
- Structural and building services engineering: Bureau greisch
- Hydrogeology consulting office: Phreatis
- Acoustic engineering consultants: ATS
