The building façade is no longer seen as just a static barrier that separates the interior building environment from the external one. In contrast, the façade becomes a dynamic playground to optimise between energy objectives and occupants' wishes. Clever and creative thinking and designing allow to realise beautiful pieces of architecture that contribute to the lowering of the total energy use of the building.
Multi-functional and adaptive facades have the potential to significantly improve energy efficiency and economic value of new and refurbished buildings, whilst providing a healthy and comfortable indoor environment to the building occupants. An adaptive façade has the ability to adapt, in real-time, some of its functions, features and behaviour in response to changing environmental conditions, performance requirements, occupants' wishes or other boundary conditions (e.g. space efficiency). The adaption has the purpose to obtain improved overall building performance related to primary energy use (heating, cooling, ventilation and lighting) while maintaining or enhancing the comfort and increasing the flexibility during the life phase of the building.
Adaptive façades provide an adequate response to changes in the internal and external environments to ensure or improve the functional requirements of the building envelopes in terms of heat, air and water vapour, rain penetration, solar radiation, noise, ?re, strength and stability, and aesthetics. They respond repeatedly and reversibly over time to changes in performance requirements and changing boundary conditions. In other words, adaptive façades provide controllable insulation and thermal mass, radiant heat exchange, ventilation, energy harvesting, daylighting, solar shading, or humidity control.
adaptive façade systems are notable for the presence of one or more of the following technological features:
• High-performance innovative materials and systems for absorbing and storing solar energy (e.g. smart, biomimetic, or bio-inspired façades, etc.);
• Devices for managing natural ventilation in combination with mechanical ventilation systems (e.g. adaptable, advanced, responsive façades, etc.);
• Mobile screens for controlling solar radiation (e.g., smart, adaptable, responsive, and switchable façades, etc.);
• Technological solutions designed to increase and/or control comfort inside the building (e.g. adaptable, active, kinetic, intelligent, interactive, and switchable façades, etc.);
• Building automation systems for the management of plants and elements of the building skin (e.g. intelligent, responsive façades, etc.).
Dynamic façades
A dynamic façade, also known as a responsive façade, is a building exterior that can change in response to its surrounding environment to maximise its performance. This can help control the interior environment within the building, and so minimise the energy consumption of building services systems. In this way, the 'skin' of the building is not static, but dynamic and can transform according to requirements.
The responsiveness of the façade can be at the macro scale, which involves changes in its configuration using moving parts, or at the micro-scale which involves changes affecting a material's structure.
Macro responsiveness might include adjustable ventilation or moveable solar shading, used to optimise the amount of solar heat gain and visible light that is admitted into a building or daylight lighting systems which can help to maximise natural daylight. Micro responsiveness refers to a movement that is controlled by the material properties. Microscale changes are related to changes in thermophysical properties, the transformation of energy or changes in opaque optical properties. In general, the response can be of different types: responding to surface temperature, light, incident radiation, external control signals.
Some dynamic facades also include methods for generating energy, such as solar photovoltaic panels. Dynamic systems can reduce a building's reliance on heating, cooling and ventilation systems as well as artificial lighting and energy requirements.
Adaptive systems that have a movement principle that is mechanic based offer a lot of opportunities for efficient control of energy use. Future systems could combine mechanic and material-based principles to create new concepts. The most applications that currently exist in the category of mechanical deformation are based on an off-plane rotation principle or hybrid deformation. Hybrid movement is most interesting because it offers a wide range of possibilities.
A recent, very promising approach for the domain of adaptive architecture is 4D-printing. This principle adds the extra dimension of time to 3D-printed structures, which turns into printed structures that can adapt themselves. Moreover, the behaviour can be controlled in a predictable way by subjecting the structure to thermal and mechanical forces. The next future step is to make hybrid materials by the union of different materials with different features, resulting in multi-material printing that can support multiple functionalities
