Solar Morphing Kinetic Envelope

from BT Bundle 2021

Green Roof Tile: Improving local biodiversity

By Christina Koukelli

Kinetic responsive systems are gaining attention in architectural applications, to help reduce the building’s energy consumption and environmental impact, while improving the indoor comfort conditions. The thesis explores the potentials of Shape Memory Alloys (SMAs) for the design of autoreactive facade systems without using additional energy. The exploration is conducted and assessed through the design of a facade concept for the city of Athens in Greece, aiming to improve both the indoor and outdoor environment by means of a kinetic autoreactive system, with a focus on the building’s direct and indirect impact on the Urban Heat Island (UHI) effect. The main research question is: “How can thermo-responsive Shape Memory Materials be integrated in an autoreactive facade system to reduce the building’s impact on the Urban Heat Island effect in the Mediterranean climate, with a focus on the case study of Athens, Greece?”

The methodology follows a feedback-loop logic informed by environmental and energy performance evaluation studies conducted in the Grasshopper environment to optimize the geometry and movement of the proposed shading component. Throughout the facade design development, a comprehensive and systematic computational toolset is being developed, targeted on the abovementioned performance evaluation studies. The proposed facade system, as a case study application and outcome of this iterative process, features a dynamic seasonal response, triggered by the temperature changes and exhibits a dual function. During the coolingdominated periods, the aim is to reduce the cooling demands, by increasing the reflective surfaces directing the incoming solar radiation to the atmosphere, while also increasing the shading and self-shading effect through undulated geometries. In the contrary, during the heating-dominated periods, the system adapts a double facade function with multiple-cavity zones for heat amplification, with a higher solar absorption enabled through larger sun exposure.

The system’s mechanism composed of two SMA wires, operates in coordination with a pivot axle and rotating mechanism, in combination with elastic steel threads and membranes that can accommodate the dynamic deformations. The activation of the SMAs, due to the environmental temperature changes, causes their linear deformation and initiates with a single movement the linear and rotational movement of the components involved, in a cause-effect internal system, while also controlling the cavity aperture. The design aims to minimize the need for actuators and mechanical parts with no additional energy, while the study evaluates in parallel the energy and environmental performance in the urban microclimate and the potential for passive operation. Through the development and assessment of the facade concept, the objective is to explore the potentials and limitations for the application of autoreactive envelopes in the facade design and development. At the same time, the aim is to exploit the possibilities and optimization potentials offered through the developed iterative computational workflows and to propose a digital toolset to be used in a broader range of applications.