IMPRESS developed three prefabricated panel options for building renovation:
- a polyurethane based insulated panel with improved thermal performance and light radiation,
- a thin, lightweight pre-cast concrete sandwich panel with optimum thermal and weathering resistance, and
- a lightweight pre-cast concrete sandwich panel incorporating Phase Change Materials (PCM) to adapt the thermo-physical properties of the building envelope and enable optimum passive heating and cooling benefits.
The first two options are suitable for over-cladding while the third option is suitable for re-cladding. The addition of embedded sensors to all panels was analysed, that are used for the assessment of the final product performance, integrated with the building in-use.
Polyurethane Based Insulated Panel
The hybrid polyurethane (HPU) materials are a new type of lightweight hybrid material based on PU foam and hydrated cement in which both the inorganic and the organic phases are co-continuous throughout the material and the phases are finely and intimately dispersed within each other.
The closed-cell foam structure gives the material properties typical of porous materials: in particular, the hybrid foam evidences thermal insulation, sound absorption and acoustic insulation, high impact energy and low density typical of polymeric foams. At the same time, the hybrid foam exhibits water vapour permeability, improvement of thermal stability, high compressive mechanical behaviour, and adhesion to concrete and mortars typical of inorganic binders such as cement.
Pre-cast concrete sandwich panel (with and without PCM)
IMPRESS developed a lightweight precast concrete sandwich panel with integrated Phase Change Materials (PCM) which will be used as a re-cladding option and a variation of this panel without the PCM which will be used as an over-cladding option.
Textile reinforcement and high-performance concrete enable a reduction in panel thickness and weight. Using the production methods both layers of concrete can be reduced to as little as 20mm, for the development of the over-cladding panel.
Through the use of novel integration methods of PCM, the thermo-storage properties of the sandwich panel is further enhanced. The internal layer of the precast+PCM panel acts as a heat store, absorbing heat due to solar gain, thereby reducing the internal space temperatures during the warm part of the day and enhancing the environment during cold periods.
Key to the technology development is the microencapsulation of the PCM material, which changes state from solid to liquid. IMPRESS uses microencapsulated PCM and optimises current incorporation techniques such as immersion and direct mixing.