The state of the built environment makes one inclined to ponder how ethics affects the space that is designed and its aesthetic quality. As a consequence, there arise questions concerning the provisions of ethical codes of professional conduct that architects must adhere to on the one hand, while on the other, the practical guidelines for architectural design and planning. In a period when matters of durability (firmitas) and utility (utilitas) have been largely dominated by other branches of design, including the matters of ecology, beauty (venustas) has come to be considered as the most essential constituent attribute of architecture. Selected interpretations of Beauty and its relationship with Good (Vitruvius, 1954; Tatarkiewicz, 1962, 1982) have been presented, including in light of the latest findings of neurobiology and neuroaesthetics (Zeki, 2011, 2019; Qiuling et al., 2018; Ishizu, Tsukiura, Cabeza, 2011). The term appropriateness (Krakowski, 1989) is herein accepted, understood as a notion of intentional, socially conditioned beauty and considered proper to describe the aesthetic standard of the built environment under design. This paper is an attempt at finding practical methods of ensuring aesthetic quality (beauty) in newly designed and redesigned spatial situations. It identifies the field of professional law (the ethical code of conduct for architects), wherein aesthetic matters are largely ignored on the one hand, while on the other it points to the necessity to teach and implement a design process that is tender (Tokarczuk, 2019) and mindful (Dominiczak, 2016) dialogue in a specific understanding of encounters with the Other (the Second), whether it’s an architect, a user or a structure. It notes the proposal of creative aesthetics (Sławińska, 1973) as a potentially possible integral branch of design. Contrary to the professional ethics of architects, which pertains to individuals who practice design and are ethically responsible for their professional conduct (design), the ethic of architecture refers to aesthetic relationships that emerge in architectural situations (Dominiczak, 2016). In this understanding, built structures are personified and seen as entities with their own identities (if the designer wills it) that engage in dialogue with Other entities (Levinas, 1998), which both create and define a given space.

The paper presents the investigation of the optimum design parameters of a solar air heater (SAH) having wire ribs as artificial roughness by using the Taguchi method. The solar air heater has arc shape roughness geometry with apex upstream flow on the absorber plate. The objective of this paper is to obtain a set of parameters that deliver maximum thermo-hydraulic performance. For this objective, a new parameter the thermo-hydraulic improvement parameter ( ^ηTHIP), has been introduced. For the present analysis, the effects of Reynolds number (Re), relative roughness pitch ( P/e), angle of attack ( α), and relative roughness height ( e/Dh), denoted by A, B, C, and D, respectively, have been considered. An ( L ₁₈ = 6 ¹ · 3 ²) orthogonal array (OA) was chosen as an experimental plan for applying the Taguchi method. The set of control factors for the solar air heater SAH which delivers the maximum Nusselt number (Nu), and minimum friction factor ( fr) – are A ₆B ₂C ₂, and A ₁B ₁C ₃ respectively. To obtain the maximum THIP the experimental set-up requires only one single run using the parameter A ₆B ₂C ₂, hence there is no need to run it all 54 times.