Designing mainly refers to specific objects. In the field of designing furniture, it will always be a technical artefact of usable character: a chair, a table, a wardrobe, a bed, etc. Like science, designing is an intellectual plan, realised using tools suitable for a particular discipline, within the framework of which this designing is done. According to Lopaczewska (2003), the following types of design are distinguished:
• technical design—usually associated with the manufacturer, it is sometimes treated as a fragment of so-called technical preparation of production (cf. Chap. 4),
• ergonomic design—also known as humanist design—is designing objects in accordance with the requirements of ergonomics.
The term ergonomic design appeared in the early 1970s, when a new type of technical design was clearly emphasised, oriented at the so-called human factor. In literature, ergonomic design was called designing control systems and it constitutes an important part of comprehensive technical design, which in this particular way ensures compliance of the designed object with ergonomic requirements. According to Slowikowski (2000): The specificity of ergonomic design consists in the dualism of subject of designing. This is the biotechnical system (specifically, anthropo- technic), the parts of which have extremely different characteristics. One of the parts—the human being, constitutes an invariant, which features have been determined by nature, which is why the designer is left with adjusting the second: the machine, to the features of the first. This is a pragmatic interpretation of the anthropocentric principle, referred to the process of designing technical objects creating the system human-technical object.
Therefore, ergonomic designing leads to defining the system human-technical object from the point of view of the principles of ergonomics (Kroemer et al. 1994). The systematics of the validity of aims in ergonomic works can be considered at three levels:
• developing acceptable conditions, which expose the user of furniture to the loss of health or life,
• creating widely endorsed (due to the current state of knowledge) social, technical and organisational conditions,
• defining and developing conditions of physical, mental and social comfort, adaptable by future users in the scope of personal qualities, abilities and expectations.
In accordance with current trends, the designer designs the system human- technical object, but not the technical structure of the object—the piece of furniture. Ergonomics, therefore, fulfils a dual role (Slowikowski 2000):
• It sets goals of design, demanding from the designer an anthropocentric approach, i. e. shifting the characteristics and needs of the user over constructional and technical requirements,
• enriches methodological design, since it is an integral component of the art of
engineering or broader, the art of design.
The engineering technical design procedure constitutes the basis for ergonomic design. The mutual relation of technical and ergonomic design is based on the principle resulting from the characteristic for anthropocentric ergonomics recognition of the priority of features and needs of the human being in shaping the technical structure (Lopaczewska 2003). Technical structure is, of course, furniture, while their most demanding representative is directly the group of usable furniture, that is those that during use are in direct contact with the human body (furniture for lying down, sitting, resting). A person who has direct contact with a piece of furniture becomes part of a system, called the anthropotechnic system, consisting of an animate part (the human body) and inanimate part (technical element—the furniture piece) (Winkler 2005).
Therefore, in the design process, the priority is to increase the certainty of the product’s functioning by taking into account all interactions together that occur between the object and the user in terms of vision, hearing and tactile stimuli. Therefore, when designing a new piece of furniture, the form, construction, technology of implementation, functionality and ergonomics of similar products must be critically assessed, because the object of ergonomic design is precisely the system human-technical object.