Plea2004 - The 21th Conference on Passive and Low Energy Architecture. Eindhoven, The Netherlands, 19 - 22 September 2004 Page 1 of 5 An Overview of the Balcony’s Contribution to the Environmental Behaviour of Buildings N. Papamanolis Dept. of Architecture, Faculty of Engineering, Aristotle University of Thessaloniki, Greece ABSTRACT: Balconies constitute an important element of the architecture of buildings in a broad spectrum of geographical areas. Especially in areas with a mild climate, they represent an inseparable and characteristic component of the local architecture. The main purpose of a balcony is to offer the inhabitants quick and easy access to the environment. Nevertheless, in parallel with their functional role, their presence on a building’s façade influences several mechanisms that determine the interaction between the building and its environment. Such mechanisms and the resulting influences concern numerous aspects of building physics, like sun-control, daylighting, heat transfer, damp protection, sound insulation, wind-loading, natural ventilation, etc. Accordingly, the building’s energy behaviour is also affected. This paper examines the role of balconies in the environmental and energy behaviour of the buildings to which they belong. In particular, it determines the environmental factors whose interaction with buildings in which balconies appear is altered by the presence of those balconies, it investigates the mechanisms which cause these changes and assesses their results. Conference Topic: 5 Materials, building techniques and sustainability Keywords: balcony, sun-control, daylighting, thermal insulation, sound insulation, wind-loading, natural ventilation INTRODUCTION to the presence of balconies on their façades. It also investigates the conditions which determine whether Balconies are extensions of the roofed areas of balconies play a positive or negative role in the apartments above ground level that are intended to environmental and energy behaviour of the buildings offer the residents quick and easy access to the to which they belong, with a view to drawing external environment. Although they may be found in conclusions about the usefulness of, and the buildings at all latitudes, their presence is more preconditions for, including them in the design of pronounced in buildings situated in areas where the buildings in areas in which such conditions prevail. environmental and particularly the climatic conditions are mild for long periods of the year. In conditions such as these, the role of balconies is enhanced to 2. THE STRUCTURE AND ELEMENTS OF A the extent that the external environment is attractive BALCONY for long periods of time and they possess properties which are more conducive to a feeling of comfort than As structural elements of buildings, balconies take those which exist in the interior of buildings. In these the form of projections. Their structure varies in areas balconies represent an important factor in the accordance with the supporting structure of the functional organisation of apartments situated above building to which they belong, but generally they are ground level, and a conspicuous morphological formed by constructing an extension of the slab feature in the faces of the buildings to which they between two successive levels (floors). A belong. They also play a decisive role in the conventional concrete balcony consists of a slab environmental and, by extension, the energy approx. 15 cm thick whose reinforcement forms an behaviour of the buildings that have them inasmuch extension of the reinforcement of the adjacent firmly as they intervene in and influence almost all of the fixed slab of the supporting structure. As for balconies mechanisms which determine how buildings interact constructed on a metal supporting structure, these with the environment. Finally, in these areas consist of a series of horizontal metal girders approx. balconies represent an important factor in building 10 to 15 cm wide which also form an extension of the architecture, particularly the architecture of residential horizontal girders in the adjacent floor-level, and the buildings. intervening gaps are filled with small slabs of ceramic This paper identifies and examines the material or concrete. Similarly, in the case of a mechanisms and processes that determine the wooden supporting structure, the balcony rests on environmental behaviour of buildings and are related wooden beams whose intervening gaps are covered Plea2004 - The 21th Conference on Passive and Low Energy Architecture. Eindhoven, The Netherlands, 19 - 22 September 2004 Page 2 of 5 by planks. The length of these projections is subject each other and perhaps with different orientations, yet to considerable limitations due to the moments the overall impression that the building creates is of a produced by the loads they bear and, in any case, is prismatic structure. The presence of balconies on its dependent on the nature of the supporting structure. façade certainly breaks up this prismatic appearance. In conventional buildings with a supporting structure It lightens it and adds variety. Indeed, as in most of concrete or metal, which make up the majority of cases balconies do not consist merely of their multi-storey buildings, balconies rarely exceed 2.5 structural elements but also a host of other objects metres in length, a semi-empirical limit which satisfies and accessories (e.g. chairs, tables, cupboards, their simple and relatively low-cost construction, and flowerpots, awnings), the effect they have on the also falls within the tolerable vibration level when overall appearance of the building to which they variable loads are exerted. Wooden balconies are belong is even greater. These observations reveal the usually narrower due to the fact that wood is a weaker first and most obvious consequence of the presence material [1]. of balconies on the façade of a building: the alteration Balcony floors are constructed on top of the final of its geometrical features and, ultimately, its surface of the supporting structure with materials appearance. The extent to which these things are suitable for outdoor areas (e.g. ceramic tiles, marble, altered depends, of course, upon the number and terrazzo). Their surfaces are slightly inclined for water size of the balconies in the building concerned, or drainage purposes. In addition, they are constructed alternatively the proportion of the overall surface area at a lower level than that of the indoor floors in order of its faces that the balconies occupy. However, even to prevent water flowing into the interior of the if this proportion is small, the impact of the balconies building. A relatively rare type of balcony floor is that on the overall visual effect is catalytic. In areas where in which a section of the floor close to the façade of the climatic conditions favour their existence, the building contains openings which are covered balconies form a characteristic feature of the façades over with a grating to enable the air to flow vertically of buildings. In Greece, for example, which has a over the surface of the building. Mediterranean climate, balconies are an essential Apart from its horizontal floor, every balcony has a feature of all residential buildings. All apartments parapet at least 1.10 m high along its outer edge above ground-floor level will have at least one which protects all those who use it from the danger of balcony in the form of a projection. Indeed, very falling off. The parapet, which generally forms a frequently more than one balcony will exist, or even supplementary feature of the main structure of the continuous balconies occupying most of the surface balcony, may be constructed from a variety of area of the building. The width of balconies in different materials and possess different forms. In residential buildings in Greece ranges from a cases where the construction material is wood or minimum of 0.5 m (in the case of secondary metal, they generally take the form of railings. On the balconies) to a maximum of approx. 2.5 m. other hand, in cases where they are built of concrete Sometimes the balcony width is further increased by or brick, they are usually solid. A relatively recent incorporating a section of the roofed area of the version involves the use of a metal frame to support apartment within it (Fig. 1). highly durable panes of glass, with varying degrees of transparency, as facing panels. Finally, not infrequently parapets may consist of a variety of different forms and materials, usually a mixture of solid and semi-permeable components, even on the same balcony. One structural element of buildings which is directly connected with balconies is that of balcony doors. All balconies need at least one balcony door to provide residents with access to them. Moreover, the presence of balconies in front of openings in the shell of a building favours the construction of balcony doors instead of simple windows. The fact that the opening in a balcony door has roughly twice the surface area of a window of the same width is already an indication of the type of indirect influences that balconies exert on the environmental and energy behaviour of the buildings to which they belong. 3. INFLUENCES OF BALCONIES ON THE ENVIRONMENTAL BEHAVIOUR OF BUILDINGS 3.1 Influences on appearance A building without balconies has flat, vertical Figure 1: Façades of typical multi-storey apartment faces. These may well consist of a number of flat buildings in Greece. The presence of balconies in vertical surfaces situated at different distances from them is very conspicuous. Plea2004 - The 21th Conference on Passive and Low Energy Architecture. Eindhoven, The Netherlands, 19 - 22 September 2004 Page 3 of 5 3.2 Influences on shading and natural daylighting structural elements of the shell, causing an increase An obvious influence of balconies on buildings is in their temperature and, indirectly, a change in the the way in which their presence produces a shading internal climate. These mechanisms, insomuch as effect on the buildings’ façades.