LESS IS BONE

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The books that provided the basis for the development of a theory in this research include, among others, Reyner Banham’s The Architecture of the Well-Tempered Environment (1969) and The Selective Environment by Dean Hawkes et al. (2002). This research owes many concepts to these books; however, it also aims to explore their limitations.

Banham introduces a significant distinction between environmental typologies of control, categorizing them into three types: conservative, selective, and regenerative. As Hawkes underlines in The Environmental Tradition (1996), Banham is not critical of the adoption of one mode over another; rather, he describes the relationship between modes of control and architecture, though not in terms of active or passive user control. Banham examines the relationship between exposed controls (power, selective, conservative) and the architectural language generated by them. In his analysis, there is no qualitative difference between Piano’s Centre Pompidou and St. George’s School by Emslie A. Morgan. However, from a user control perspective, these two buildings are very different. Piano’s building employs mechanical air conditioning, and the design is not related to environmental considerations. Users have no control, and in terms of user-facade interaction, their role is highly passive.

On the other hand, St. George’s School uses manual control for ventilation and solar radiation. The south facade includes a ‘solar wall’ consisting of two layers of glass separated by a space to diffuse light into the teaching areas (Banham, 1969, p. 281). Users can control ventilation through openable windows that include opaque panels, painted black on one side and polished aluminum on the other. Depending on the season, users reverse these panels to reflect or collect solar radiation. What can be criticized is Banham’s assertion that full control can only be achieved through mechanical means, where users have minimal control. This is not necessarily the case. Selective buildings with high user control of the facade demonstrate that “full control” can be achieved through active user-facade interaction. Banham’s vision of technological progress leans more toward a Positivist perspective than a precise analysis of user-machine interaction.

Dean Hawkes reinterprets Banham’s concept of selectivity and focuses on selective design. For Hawkes, selective design refers to buildings whose form is justified by climatic considerations. He defines selective design as a system of interacting elements—form, fabric, materials, mechanical systems, and the controls that operate upon them (Hawkes, 2002, p. 31).

According to Hawkes, selective buildings respond to seasonal and diurnal variations in solar radiation, temperature, humidity, wind speed and direction, and daylight variation. However, Hawkes does not clearly define the relationship between user control and selective design. This research does not analyze the interaction of all these elements but focuses specifically on the interactive aspects related to user control of the facade. This aspect is crucial in the design of selective buildings.

It is important to underline that in this research, the term selective facade differs from interactive facade. While Hawkes uses these terms synonymously to refer to the interaction between form and climatic responsiveness, this research defines interactive facade specifically as user-facade interaction. Therefore, not all interactive facades are necessarily selective facades, and vice versa. For example, Le Corbusier’s buildings in Chandigarh employ fixed brise-soleil and natural ventilation to regulate solar radiation and humidity. Here, users have a passive interaction, but the facade effectively responds to climatic variations. Dean Hawkes states that in selective design, control is managed by occupants, and environmental control may be a combination of automatic and manual means, whereas exclusive design is predominantly artificial and automatically controlled (Hawkes et al., 2001, p. 7). It is possible to demonstrate that self-learning (artificially intelligent) facades operate autonomously using climatic sensors without user intervention. Although these facades are automatically controlled, they are still selective facades. The facade of the Secretariat in Chandigarh regulates solar radiation without manual or automatic user control. Users have only a passive interaction with the facade, while the facade itself passively interacts with climatic variations.

The concepts of active and passive control in relation to environmental regulation have been only marginally explored by Hawkes in The Selective Environment. He emphasizes that occupants play a crucial role in achieving comfort standards, leading to an inherent interaction between the building and its users.

“The idea of selective design rests upon the understanding of a building as a system of interrelated and interacting elements. The form, fabric, materials, mechanical systems of a building, and the controls that operate upon them are located within naturally occurring climate with all of its seasonal and diurnal variations of solar radiation, temperature, humidity, wind speed and direction, variations of ambient light, so forth.” (Hawkes et al., 2002, p. 31)

In Hawkes’s view, selective buildings are interactive buildings, where materials, fabric, mechanical systems, and control mechanisms function as interactive elements. He contrasts selective buildings with exclusive buildings, distinguishing them as follows: selective buildings utilize ambient energy sources to create natural environments, whereas exclusive buildings predominantly rely on mechanical systems to create controlled, artificial environments (Hawkes, 1996, pp. 14-15).

What is particularly interesting is Hawkes’ idea of selective interaction between buildings and environmental control. While the concept of selective design originates in the pioneering work of Olgyay and Banham’s seminal The Architecture of the Well-Tempered Environment, Hawkes’ interpretation differs significantly from Banham’s. According to Banham:

“Selective mode employs structure not just to retain desirable environmental conditions, but to admit desirable conditions from outside. Thus a glazed window admits light but not rain, an overhanging roof admits reflected sunlight but excludes the direct sun, a louvered grille admits ventilating air but excludes visual intrusions.” (Banham, 1969)

Hawkes, however, introduces the question of occupant control. For him, not only is the building employed in a selective mode, but the occupant cooperates with the building to filter the natural environment as a first step in the process of adaptation (Hawkes et al., 2002, p. vii). As he notes, many selective buildings use some mechanical systems to achieve comfort standards. However, in exclusive buildings, the relationship between the building and mechanical systems is fundamentally different:

“One of the fundamental conceptual shifts in the development of the exclusive mode was the assumption that the plant was a primary agent of control. In selective design, auxiliary systems should be regarded as secondary to the environmental function of the fabric.” (Hawkes et al., 2002, p. 13)

For Hawkes, a defining characteristic of selective buildings is occupant intervention—adjusting the fabric by opening windows, drawing blinds, and operating mechanical systems such as heating controls and lighting. Unlike Hawkes, this research does not focus on the distinction between selective and exclusive modes but rather on how they interact with occupants. Specifically, it aims to understand the relationship between different user control modalities and varying degrees of facade responsiveness.

The following diagram summarizes the differences between interactionism and Hawkes’s concept of the selective environment. It is adapted from Scott Murray’s interpretation of James Fitch’s idea of the building envelope as a selective filter (Murray, 2009) and Dean Hawkes’s concept of selective environment.

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(adpted from James Martson Fitch, Dean Hawkes and Scott Murray)

The selective facade (at the center) represents a generic climatically responsive facade. On its right is the external environment, while on the left is the user who, together with the facade, forms the user-facade interaction. The external environment, subject to seasonal and diurnal climatic variations, encompasses four key categories of variations:

1. Thermal – including winter-summer temperature and humidity, wind direction, and solar radiation.

2. Waterproofing – protection from rain.

3. Air quality – ensuring fresh air while controlling unpleasant odors, dust, and pollution.

4. Visual – providing and regulating daylight while controlling glare.

All these elements serve as points of control that either the user or the facade must manage to maintain responsiveness to climatic changes. The left side of the diagram represents user-facade interaction (interactionism), where the focus is on how the user's active or passive role influences the nature of selective facades. On the right side is the selective environment (Hawkes’ concept), where the emphasis is on the relationship between climatic variations and the facade. In this framework, users act as the ultimate judges of environmental comfort, which is shaped by the interplay between selective design and climate.

Facade and User Control: Hawkes’ Theory of Environmental Control Evolution

This research builds on Dean Hawkes’ theory of the evolution of environmental control. Hawkes illustrates this development through four schematic diagrams:

1. Minimal System (Fig.1) – This represents a simple loop system in which:

   • D denotes environmental disturbances.

   • C represents physiological variables that determine human comfort.

   • N is the channel through which disturbances affect physiological variables, encompassing both the physical environment and individual physiology.

   • P accounts for external variables such as geographical location and body posture.

   • Ro signifies human control over environmental variables.

At this stage, Hawkes does not incorporate architecture or the built environment. This model could represent a naked person in an open environment, such as a park or a street. In this scenario, the interaction between the individual and their surroundings occurs through N, a combination of the physical environment and personal physiology.

2. Environmental Control through Clothing and Building Fabric (Fig.2) – This stage introduces F (a filter), which Hawkes defines as the building fabric. The internal environment is now labeled I, and N is modified to N' to account for the effects of clothing. Additionally, P’ represents the variability introduced by both clothing and building fabric. In this model, as indicated by the absence of an arrow between C and Ro, occupants lack direct control over the environment. Instead, control is achieved solely through building materials and clothing. This stage is comparable to the primitive hut and the adoption of clothing as a means of environmental adaptation.

3. The Introduction of Mechanical Systems (Fig.3) – Hawkes explains that, over time, environmental control evolved beyond passive fabric solutions with the introduction of mechanical systems, or “plant,” denoted as M. Here, P’ is replaced by P’’, which is now subject to regulation by occupants. This marks a shift where users gain some level of control over both the building fabric and mechanical systems.

4. Automated Environmental Control (Fig.4) – In the final stage, buildings integrate both mechanical systems and building fabric into a fully automated control system. In this model, environmental regulation is no longer dependent on direct occupant interaction, as automation replaces manual adjustments.

Hawkes effectively explains the nature of building-user interaction in terms of environmental control. However, his historical model oversimplifies the evolution of environmental architecture by omitting buildings that rely solely on occupant-controlled fabric without mechanical systems. His framework jumps from the primitive hut directly to the integration of mechanical systems, overlooking an important phase in which architecture depended entirely on occupant control of building fabric (Ro). This overlooked typology is crucial in understanding the development of environmental control strategies.

Furthermore, Hawkes analyzes the relationship between occupant behavior and environmental control primarily as a means of achieving human comfort, rather than as a driving force in the evolution of environmental control strategies. This research seeks to bridge that gap by examining how different modalities of user control influence facade responsiveness and environmental adaptability.

Dean Hawkes, Environmental control, minimal system. (Hawkes, 1996, p. 29)

Dean Hawkes, Environmental control augmented by clothing and building fabric.

(Hawkes, 1996, p. 30)

Dean Hawkes, Environmental control augmented by clothing and building fabric.

(Hawkes, 1996, p. 31)

Dean Hawkes, Environmental control augmented by clothing and building fabric.

(Hawkes, 1996, p. 30)

(Drawing by the author) Diagram of Interactionism following the idea of selective environment of Hawkes. Interactive facades (IF) are the modifier but also the element around which the building-user interaction is filtered. N’ is the channel between external

and internal factors influence the human behaviour and consequently the achievement of

user comfort.