Design Series II: Defining Spatial Expression - The Sunshade

Architecture Dated:  May 9, 2016
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The Brise- Soleil as a sun breaker

In the Design series, Defining Spatial Expression, Prof. Ar. Rajini Itham Mahajan, Senior Architect, VBT Consortium and HOD, Aakar Academy of Architecture, Bengaluru discusses various elements that define Architecture in terms of their evolution, significance- aesthetic and functional and construction possibilities. In the second of the series, we will explore the evolution of the SUNSHADE as an element of passive climate control and form accentuation.

 

Traditionally called the ‘Chajja’, the sunshade refers to any horizontal or partially inclined built component to protect from climatic elements. Apart from playing a pivotal role in Micro Climate Control, the sunshade has also been one of the form defining or accentuating elements in architectural facades.

Evolution:

History says ancient architects had to reconsider their building design due to scarcity of wood, the then primary building material, which was in high demand for ship building. The chief source of heat, charcoal was also becoming expensive. Hence, the master builders started to integrate passive climate control into the design process.

In India, prominent examples include the ‘Jharokhas’ of Rajasthan, designed to provide privacy to the women, while considerably offsetting the extreme climates of the desert region. Here, the ‘Jharokha’ extends from the building as a sunshade and balcony seat combined with stone trellis screens to keep away dust. This feature is also visible in Indo Islamic Architecture.

Sunshade ArchitectureFig 1. The Jharokha in Indian Architecture                                               Fig 2. The ornate overhang and perforated screen in Indo Islamic Architecture

Functional Significance:

Over the years, the sunshade gained prominence in tropical and temperate climates to protect from the sun and keep out precipitation. It aids in diffusing natural illumination thereby reducing glare and heat gain in tropical zones while admitting sunlight in temperate climates to reduce mechanical heating. It transformed from a simple projection to an elaborately ornate element to complement the style, especially in residential architecture.

To protect from angular precipitation, vertical elements called fins were also introduced on either side of the windows. Some buildings combined the sunshade and fins to form Egg crate devices. Variations of the same began to define elevations of Modern Architecture in the early and mid-20th century. Eminent architects experimented with the design of sun protecting devices. One such innovation is the ‘Brise – Soleil’, the sun breaker seen in the architecture of Chandigarh, as visualized by Le Corbusier. 

The Brise- Soleil as a sun breakerFig 3. The Brise- Soleil as a sun breaker

The introduction of air conditioning did impact sunshade design. As climate controlled glass and steel buildings gained prominence, the visual impact of the sunshade as a conspicuous façade element was losing significance. In response to current day challenges to sustainability and energy efficient building solutions, Architecture is revisiting concepts of passive climate control. The sunshade is making a comeback and being reinvented to adapt to a contemporary design language. 

Structural Sub Elements: 

The sunshade, by itself is rarely a structural element, unless it is part of a roof projection. The sunshade is typically a cantilevered extension of the structural lintel, which spans the window opening. It is either cast in RCC monolithic with the lintel or fixed later through metal rivets. 

The sunshade is typically 600mm wide, extends 150mm beyond the window opening on both sides and is maintained at minimum thickness to reduce dead load. The sunshade could be precast or cast in situ. In some cases, such as architecture with sloping roofs, the roof overhang doubles as the sunshade. 

Material:

The most common sunshade material is RCC. But young contemporary designers are exploring alternate materials such as metal, wood, bamboo, glass and even fabric. Tensile structures are also gaining popularity as a modern day shading devices.

Sunshade integrated as a roof canopy and space frame with the structural glazingFig 4. Sunshade integrated as a roof canopy and space frame with the structural glazing

Style:

Traditional architecture incorporates sun shading devices, in tune with the defining elements of style. Now the sunshade is fused to be part of the overall form. In residential high rise, the sunshade is usually provided as a 100mm wide Plaster band. The sunshade forms an interesting pattern on the façade either as a physical element or as a play of light and shade.

Jharokha ArchitectureFig 5. Perforated Sunshade forming shadow patterns                                     Fig 6. Plaster bands in High Risea

Sunshades may also be motorized as awnings, drop down or even angular rotation as per building orientation. They may also be retractable. With curtain wall and structural glazing facades incorporating special types of glass details, the function of the sunshade has also been redefined. 

Conclusion: 

As one of the primitive needs to protect from adverse climate conditions, the sunshade evolved and later progressed as an essential exterior form component. Over the years, building perforations were modified as per style or design sensibilities, sometimes inset to completely obliterate the sunshade or merged as the roof projection instead of a attaining a separate identity. Current responsible design practices promote reinstating the importance of the sunshade, irrespective of the nature of the building to make architecture more climate and site responsive, encouraging young designers to integrate function, structure and aesthetics.

You May be Interested in Reading Design Series I: Defining Spatial Expression - The Staircase

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