Adaptive Façades Systems made from Thin Glass

Motion

Bi-wood

Various parameters, such as thickness, type of wood and content of moisture can be used to control and design the behaviour of wood. The reaction of wood to humidity is invertible, meaning that the initial state of wood is achieved after drying out. Using humidity to change wood is based on three major parameters: dimensional ratio, grain orientation and lamination. [7]

The hygroscopic properties of a cone - which is in a closed state during wet conditions and in an opened state in dry times, when the seeds can be spread by winds - can therefore be functionally reproduced by wooden bi-layer constructions composed of a resistant and of an actuation layer. [8]

Adaptive façades made from thin glass can be regulated by bi-wood constructions. The dependence of wood on humidity and its return to its original state after drying and moistening in combination with lamination of the bilayers, are an attractive option to power autonomous systems.

Bi-metal

Actuators made of bi-metal are thermally active elements which continuously deform owing to thermal variation. Bi-metal in form of stripes, ribbons or rolls are common examples of use. More specific applications are thermal snap discs and elements that work discontinuously owing to their geometry. A coating process, galvanic or chemical, further improves the corrosion resistance of the elements. [10]

Bi-metal ribbons fixed to thin glass might be used as an autonomous temperature control system for façades. A rise in temperature due to solarisation, the shade or air ventilation systems work due to deformation of the façade application.

Shape memory alloy

Shape memory alloy actuators take up the original position using temperature variation. Disposable elements change their form when heated. In contrast, two-way components take on a high temperature form when heated and a low temperature shape when cooled.

Another specific model is a shape memory alloy system which works with a disposable element and a counteracting force. It is an economic, self-sufficient solution enabled by reversible deformation, as displayed in figure 10. [10]

For thin glass applications in façades, shape memory alloys are another way of generating motion. If solarisation activates thin wires, the contraction due to the shape memory alloy enables the deformation of thin glass. [12] Especially the advantage of several positions that can be perceived are of particular interest for energy generation – PV elements.