window-to-wall ratio
The percentage of a building's facade occupied by transparent or translucent glazing that admits light.
The window-to-wall ratio of a building is the percentage of its facade taken up by light-transmitting glazing surfaces, including windows and translucent surfaces such as glass bricks. It does not include glass surfaces used ornamentally or as cladding, which do not provide transparency to the interior. Only facade surfaces are counted in the ratio, and not roof surfaces.
This figure affects heat transfer and daylight through the facade. Windows usually provide less thermal resistance than insulated opaque walls, but the ratio alone does not establish a building's energy efficiency.
Translucent glass bricks contribute even though they do not give a clear view outside. Opaque glass cladding and roof glazing remain outside this facade-window calculation.
Related definitions
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GIF rental area
The rental floor area measured according to the standards of Gesellschaft für Immobilienwirtschaftliche Forschung. -
area
The total land and water surface belonging to and occupied by an object or geographic entity. -
construction area
The total amount of built floor space occupied by solid structural elements like columns, walls, and doors. -
footprint area
The total surface area occupied, covered, or overhung by a built object, including its projecting elements. -
gross floor area
The total area of all interior spaces within an object, including occupied, common, and utility areas. -
lot area
The total area of the land property associated with a built object, including the area occupied by its footprint. -
minimum rentable area
The smallest division of floor space available for rent or lease within a structure. -
photovoltaic area
The total surface area of the photovoltaic panels installed on a structure. -
rental area
The cumulative built floor area available for rental or lease, including vacant space and excluding shared common areas. -
total available space
The floor space available to prospective users, including vacant space and occupied space to be vacated. -
total facade area
The total area of all parts of a structure's facade, not counting minor indentations. -
total roof area
The total area of all parts of a structure's roof, including flat and sloping sections. -
usable floor area
The enclosed interior floor area of a built object, excluding the space occupied by fixed walls, columns, and other structural elements.