F33d M3: The impo$$ible ING-esti0n of wØrds

Buildings in earlier periods usually had some basic structures: foundation, wall, roof, door and win-dow. Windows were part of the wall and their form, size and framing had an impact on architec-tural design. In modern times windows underwent major technological changes. Their material could be wood, but also metal, concrete or plastic. At the same time performance requirements became more sophisticated. Finally, designers integrated windows into window walls: curtain walls, window structural glass façades or wall claddings. The vari-ous types of window wall, curtain wall and cladding have been discussed together with their basic material in Chapter 2.

Windows fulfil a number of functions, such as:

• provide daylight to premises

• provide solar energy

• produce a therapeutically positive effect

• insulate sound

• provide heat insulation and ventilation (Muneer et al., 2000).

The basic parts of a window are the frame, glass, shading and sun directing construction, and ventila-tion device. Each has its funcventila-tion and also its impact on architectural design. The properties of glass and their performance have been discussed earlier in Chapter 2. Heat and sound and reaction to sunshine depend on the number of glass layers, their sealing, the property of the glass panes, coat-ing on the glass and the type of fillcoat-ing in the air space between panes.

Daylight has an impact on the design of windows and buildings. This includes study of glare, which is

the excessive brightness contrast within the field of view. The frame also has an influence on these properties. In new architecture designers try to keep the frame sections as narrow as possible. An extreme result in this respect is structural glazing without any external visible frame sections.

Windows being part of the external envelope, a number of computer-based window and window wall design programs have been worked out and are in use.

Window frames may be produced from two differ-ent materials, for example, wood and plastics, steel or aluminium. In recent time plastics have gained considerable headway and developed into the most common material for window frames.

Today windows also impact on the aesthetic appearance of buildings through their form, struc-ture and colour. A colour may be imparted to steel windows by coating or painting them. Aluminium window sections may be treated by various meth-ods of coloration thereby obtaining brown, red, gold, or other colours. The most frequently applied plastic for manufacturing windows is the impact-resistant PVC and the colour most in use is white or grey although now other colours also can be applied.

The window walls were designed with a stick sys-tem, with a spandrel system or with individual pan-els made from steel or aluminium (coated or cast).

The window wall itself progressed to the curtain wall and various cladding systems. Claddings were assembled either from lightweight metal panels or multi-layer panels or from pre-cast reinforced con-crete panels.

During the period of the International Style the ‘cur-tain walls’ were developed. The earliest cur‘cur-tain walls in tall buildings had a ‘stick’ system, vertical mullions, and transoms, frames and insulated pan-els. From 1950 onwards, panel systems with pres-sure equalization were applied and later, steel or aluminium panels were pressed like a car body.

The Japanese Kubota and the Swiss Alusuisse companies developed the manufacture of cast alu-minium panels. The post-modern period saw the appearance of structural glass façades, which were discussed previously in Chapter 2.

Figure 3.6 Curtain wall frame, insulating double glazing (Alusuisse, Switzerland). © Sebestyen:

Lightweight Building Construction, Akadémiai Kiadó.

3.1.6 Roofing

Traditionally the selection of roofing material and detailing of roofs was a consequence of the avail-ability of natural materials and local tradition. Roof-ing materials were shRoof-ingle, reed, clay and concrete tile, stone slab (these were used for rain-shedding systems), copper, lead, and zinc sheet. In modern times metal (primarily aluminium) has been used in long strips joined with ingenious clips and mechan-ically assembled. Under the top layer frequently an additional weatherproofing layer was applied.

These old materials are actually still in use but new materials have been added: stainless steel and alu-minium sheet, asphalt, bituminous felt, plastics,

Figure 3.7 Façade with cast aluminium panels, Kubota, Japan. © Sebestyen: Lightweight Building Construction, Akadémiai Kiadó.

Figure 3.8 Façade from vacuum-formed hard PVC cladding panels, Hoechst, Germany. © Sebestyen:

Lightweight Building Construction, Akadémiai Kiadó.

Figure 3.9 Barrel vault with semi-spherical domical ends.

Figure 3.10 A type of a Schwedler dome.

Figure 3.11 Prefabricated three-pinned arch-ribbed dome.

composites, and built-up structures. High-pitched roofs with hard roofing are still to be found but low-pitched and flat roofs are increasingly coming to be used.

The range of plastic (elasto/plastic systems) has been considerably expanded; they may now be

‘single-ply’ or elasto-plastic systems, modified bitu-minous systems, or ‘multi-ply’ but ‘single-layer’

systems. Tent roofs are making an appearance with new forms and are treated as part of mem-branes and tensegrity structures.

Among the technical solutions a new principle has been introduced with the inverted roofs in which the heat insulation is laid on top of the load-bearing structure and is protected against wind uplift and sunshine effect by gravel or concrete paving.

The selection of the type of roofing has become pri-marily a consequence of architectural and structural form: technical roofing solutions have been devised for all kinds of roof forms. This means that modern technology no longer restricts the architectural design of the building and specifically the design of roofs.

Figure 3.12 Basic forms of braced timber dome and vault.

Figure 3.13 Stadium with timber roof structure, Hamar, Norway.

Figure 3.14 Timber structure dome, Izuma, Japan, designers: Kajima; Masao Saitoh.