Double-skin facade

A double-skin facade builds the outer envelope from two separate layers. The inner one is usually an insulated glazed facade and the outer one a single layer of glass, with an air cavity between them that ranges from a modest gap to a walkable corridor. Solar blinds are often placed inside the cavity, where wind and rain cannot reach them. The Turkish term is çift cidarlı cephe.

How it works

The cavity is designed to behave differently through the year. In winter it stays closed, warms up and acts as a buffer that cuts heat loss. In summer openings at the top and bottom are opened, and warm air rises and escapes through the stack effect. The outer pane also lets windows be opened for natural ventilation even on high floors, and it adds another barrier against traffic noise.

Points to watch

• A poorly designed cavity can overheat in summer, so airflow has to be calculated, not assumed.
• The cavity can be divided floor by floor to stop smoke and sound travelling between storeys.
• Two layers of glass mean more cleaning and maintenance, so access needs planning from the start.

Double-skin facades are rich subjects for visualisation, full of depth and layered reflections. Balancing the reflections of two glass skins, the shadows of the blinds between them and how much of the interior shows through takes the right glass material and careful lighting.