Vertical Louvered Solar Control

Exterior shading devices, when typically used, are horizontal planes that are most effective at the south face of buildings in the northern hemisphere. Horizontal devices are less effective on the eastern and western exposures of buildings due to lower solar altitude in the morning and evening. An iconic response to the limitations of horizontal shading is the brise-soleil, propelled into the lexicon of modern architecture by Le Corbusier. The vertical extrusions of the waffle like device are better suited for eastern and western exposures, especially if the vertical extrusions are not oriented directly on an east-west axis.

Less iconic is a movable vertical louver shading system, which appeared in Brazil and was introduced to the United States by Richard Neutra in the late 1940’s. Neutra’s advancement of the system culminated in an automated system that satisfied shortcomings in the brise-soleil, and provided an additional aesthetic for modern architects. A kinetic system addressed the difficult challenge of shading western and eastern exposures during the cooling season, while allowing for daylighting when heat gain is less of a liability. Neutra’s use of the system countered a horizontal emphasis in mid-century architecture and conveyed order like Mies van der Rohe’s exterior curtain wall extrusions. Neutra’s order, unlike Mies’s, integrated poetry with performance.

Use of exterior solar-breaks in the United States receded in the 1960’s, and returned with limited use after the energy crisis of the 1970’s. However, many applications are less integrated then earlier iterations. Moveable exterior vertical louvers have reappeared in Europe, and in only one recent project by a notable architect in the United States. This paper traces the development of the mechanized vertical louvers system and contextualizes its disappearance. Relatively low-tech by today’s standards, the system represents a viable contemporary solar control solution.