Case Study: External Wall Panel
External Wall Panel
The External Wall Panel (EWP) represents an opaque, self-supporting, vertical element that spans one or more floors. The panel could include a window. It is prefabricated in the workshop and installed on site. The BioBuild EWP can be defined as a wall element incorporating an external architectural finish. The general function of the EWP is to act as part of the building envelope, separating the interior from the exterior climate.
The External Wall Panel (EWP) will be prefabricated in the workshop and installed on site. The BioBuild EWP can be defined as a wall element with no internal finish and an external architectural finish. The general function of the External Wall Panel is to act as part of the building envelope, separating the interior from the exterior climate. The panel includes a window. A key feature of the design is that the window does not lie in a vertical plane. This is a design aspect which is more easily achieved using composites than conventional building materials.
Current ideas for the EWP are that it will be a facetted shape which can be tessellated across the façade of the building. It will be a single storey panel. Bespoke segments may be needed at corners. A number of concepts have been drawn up. Finite element analysis carried out on some of the designs showed the effect of wind load on the deflection of the panels. It can be seen that in the centre of the top facet there is a high deflection, so the shape of this panel will be changed to introduce extra stiffness without any penalty on weight.
The BioBuild EWP will consist of an outer skin of biopolyester resin reinforced with flax fabric. This will be self-supporting. Pultrusions of hybrid glass/flax in a polyester resin matrix will be used to provide additional stiffness and strength and to enable the panel to be fixed to the structural elements of the building. Metallic fasteners will be used for convenience and because the development of bio-based composite fasteners is beyond the scope of the project.
Design drivers and technical requirements
- Impact resistance Class E4: 343 J
- Vertical modules 2.6m wide, total height 6.0m.
- Installation using crane
- Include thermal and acoustic insulation within the thickness of the panel
- Rectangular windows may be incorporated
- Reduced number of nodes
- Internal/external surface finishes
- Self-shading structure
Image courtesy GXN.