Adaptive façades are designed to actively regulate the exchange of material and energy flows and thus improve the balance between comfort and energy consumption. However, their technical complexity leads to higher development efforts, maintenance and costs, and ultimately fewer implementations.
Embedded adaptive functions could be an opportunity to reduce these drawbacks. If embedded adaptivity is to work within a design, the particularities of geometry and material arrangements must be considered. Nature offers fascinating models for this approach, which frames the objectives of this doctoral dissertation. The dissertation examines both adaptive façades and biology criteria that support a function-oriented transfer of thermo-adaptive principles in the early design stage. The research work discusses whether the technical complexity can be reduced by biomimetic designs and which role geometric design strategies play for thermo-adaptive processes.

The research work is divided into three phases, following the top-down process in the discipline biomimetics, supplemented by methods from product design and semantic databases. The first phase is dedicated to the analysis of the contextual framework and criteria of façades aiming at thermal adaptation.
Further, transfer systematics are developed that guide the analysis and selection process. In the second phase, analogies in biology are collected that appear suitable. Selected examples are examined to identify and systematically describe their functional principle. Two exemplary descriptions herald the third phase, in which functional façade models are created and evaluated.

The result of this research work provides a conceptual approach to generate function-imitating biomimetic façade designs, so-called physio-mimetic façade designs.

Dynamic shading systems represent the majority of realised adaptive façades. It seems that geometrically complex kinetic solutions have increased in recent years, mainly due to the use of parametric design tools and digital production. In most shading systems, however, geometry rarely plays a guiding role in the design. The kinetic mechanisms are confined to linear or planar geometries. Geometry plays an important role in biological organisms, because it is the decisive factor for efficiency and growth. Their growth patterns could provide new insights for dynamic shading designs. For this, spatial morphology criteria for shading systems were identified to obtain criteria directly related to geometry. These were supplemented by criteria on kinetic mechanisms. Then, biological analogies that correlate geometrical structures with adaptability were sought. Using biomimetic methods, particularly from functional morphology, principles in growth patterns were analysed and compared to shading systems. It revealed that the restriction to space, location, and material-inherent properties does not affect the solution diversity, but follows an evolutionary objective: Plants, for example, use ingenious geometrical structures to allow adaptation, mainly over lifetime but also dynamically. Whether these principles can be applied to the design of dynamic shading systems is then discussed. The aim of the paper is to provide impulses for further studies on adaptive shading systems that focus on the innovative use of space with greater flexibility in motion. The overall premise of the paper is to demonstrate the applicability of biomimetic methods for architectural engineering.

In order to meet the Swedish energy efficiency objectives for the built environment until 2050, a particular building stock has to be addressed: the houses of the Million Homes Programme, an ambitious housing programme of the 1960s and 70s that resulted in a large number of standardized multi-family houses all over Sweden. These are in need of upgrading the energy and comfort quality to current standards, which provides an excellent opportunity to investigate the potentials of ‘prefabricated multi-active’ façades for refurbishments on large scale. While ‘prefabrication’ is linked to cost-effectiveness and high replicability, ‘multi-active’ addresses the potential of embedded active and passive measures for improved energy efficiency and energy regulation out of the façade. Integrated building services technologies, solar technologies or moveable components, such as shading systems, are considered active measures. Passive measures include physical and constructive measures, such as e.g. thermal insulation or selective coatings of glazing’s, and provide a “passive” energy flow control to improve the thermal quality of the building envelope. Many of these strategies are well-known, traditional solutions. Although they do not provide an energy-generating or -supplying function, they dynamically interact with environmental changes; preheating of supply air through the air cavity of a façade construction or adaptive thermal buffer zones are just few of many examples. The question is how traditional passive strategies can be used to contribute most effectively to the demanded energy efficiency. The paper presents first results from an assessment dealing with this question: Two traditional ‘passive’ façade strategies, a curtain wall system and closed balconies, have been analysed in regards to their impact on energy balance and their thermal behaviour in a defined renovation scenario. The assessment is aims to support the development of a multi-active facade concept suitable for large-scale refurbishments of the multi-family houses in Sweden, which is part of the initial phase in the pre-study “Multi-active façade”. The pre-study considers architectural, technological and constructive aspects, energy performance and indoor comfort optimization, but also economic feasibility and constraints to get replicable on large scale. So-called added values that concern the upgrade to modern living standards and expectations by inhabitants and the market value of the building are also touched. The paper discusses, based on a technology screening to identify suitable key measures, the energy saving potential and impact on thermal indoor comfort of two passive renovation strategies for facades.