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since they possess only two facades. Projections and recesses in a serrated layout can make the row seem visually unbalanced and have a negative effect in terms of energy, since the area of the outer skin will be greater. The terraced house type can be found throughout history, but the wide range of modern variations on this form would be inconceivable without the development of experimental prototypes in the model estates of the early Modern Movement. In planning owner-occupied terraced houses, the individual wishes of clients can push their way into the foreground in an unwelcome manner and conflict with the proposed design form. On the other hand, in terraced houses erected for rented occupation, similar pitfalls can occur to those encountered in multi-storey housing. The overall form should not be watered down; at the same time, a pleasant domestic environment must be created. Developments where there is no scope to build a home with which one can identify will later be subject to vandalism or wild building-market assemblage.
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Bedroom and living areas are commonly located on different floors. The width, form and topography of the site determine the parameters for access and circulation. Longitudinal staircases are generally favoured for narrow plots of land. The wider the site, the freer the choice of vertical circulation will be. Terraced houses on a sloping site can be developed as split-level types with a series of spatial hierarchies between street and garden level. With the migration of homeowners from the country back to the city centre, urban forms of the narrow terraced house type have increasingly manifested themselves since about the 1980s – so-called town houses with up to four full storeys and a small garden. The housing types described up to now have been distinguished by their orientation to the outside in order to gain light and enjoy views. Austrian architect Roland Rainer remarked that “a withdrawal from the outer world can be achieved only through a constructional separation of public and private open spaces”.
The arrangement of a number of structures about an open central space could be understood under the general heading of “housing with courtyards”. A distinct characteristic of such developments is their introverted nature: there are few openings to the outside; and the courtyard also forms the central access route. As a rule, structures of this kind are single-storey buildings. The layout of the courtyards depends on the macroclimate and especially insolation. Courtyards in hot desert regions are usually dimensioned to prevent excessive heating of the outer walls by the sun and to allow cooling streams of convective air to be created – sometimes with the aid of pools of water. In northern latitudes, courtyards have to be designed so that the south face receives sunlight for as long as possible. The west and east faces should be generously glazed to benefit all year round from the microclimatic thermal buffer formed by the open space. The main courtyard house types are described below. The origins of the atrium house extend far back in history. In all cases, the underlying idea was to secure protection against enemies and inclement weather. Today, the atrium house is scarcely encountered in its original form, with rooms laid out on all sides of a central courtyard, since the weather conditions in northern latitudes restrict a comfortable line of access exclusively via this open space. In the “honeycomb” estates planned by the architects Neidhardt, Mittel and Ruff around 1930, a corridor zone was therefore laid out around the courtyard. In variations of this kind, proper daylighting of the adjoining rooms can be effected solely via the outer walls or via roof lights. A glazed roof over the courtyard that can be opened for ventilation purposes allows the access function of this space to be maintained, but the orientation of the private rooms must inevitably be to the outside because of the hall-like climatic conditions in the internal circulation zone. Scope for extending atrium types of this kind over a larger area is therefore limited. Single-storey atrium houses surrounded on three sides by neighbouring buildings need an almost square site at least 15 ≈ 15 metres in