Courtyards used to be an essential feature of traditional Indian houses. We need to readopt them as a key strategy for truly green architecture, argues Himanshu Burte
Buildings in India can be truly green and reasonably comfortable using the simplest of design principles and ideas. Some of these, like internal courtyards, are an intrinsic part of Indian traditions.
Courtyards have been important in traditional architecture for two reasons.
First, they are often comfortable spaces with fresh air and natural light for large parts of the day, and can be used for many different functions. Second, they also make indoor spaces around them more comfortable, by bringing daylight into the house and by enabling better ventilation. They remain valid even today as a way of achieving natural and healthy comfort inside a house without additional cost in terms of money or electrical energy. They are a key strategy for truly green architecture.
Resolving a paradox
In India, light and ventilation can be (but are not necessarily) contradictory desires. Heat accompanies daylight, so large windows directly opening to the wide outdoors can light up rooms while also making them too hot for comfort. Make the windows too small and you don’t have enough ventilation to reduce indoor temperatures, bring in fresh air, or carry away our sweat. The courtyard can be seen as a way of resolving the paradox.
Firstly, it traps a small expanse of open-to-sky space within the walls of a house. The enclosed open space of the courtyard is different from the completely open space of the street or garden. In hot dry places and seasons which abound in most of inland India, the swirling hot (or cold) wind and dust are kept out of the courtyard by the rest of the house.
Moreover, the enclosing walls of the courtyard also tame the glare of daylight. Sunlight bounces off the walls and floor of the courtyard before it enters adjacent indoor spaces. Ultraviolet rays are absorbed by these surfaces and the intensity of light is also reduced in the process of reflection.
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The house is opened to the courtyard by placing verandas, doors and windows to open into it. Reflected sunlight, cooler and less sharper than the direct sun, enters the verandas and indoor spaces and lights them up. At the same time, the courtyard also helps ventilate the indoor spaces, being a source of fresh air and also a device to exhaust the hot indoor air.
All about ventilation
Ventilation refers to the movement of air between indoor and outdoor space. This movement is important on three counts — reducing indoor temperatures during the hot period, replacing stale air with fresh, and evaporating the sweat off our skins.
Many factors influence the ventilation that a courtyard enables — wind direction, size and distribution of windows to the streets or fields, whether the ground storey is packed with rooms or is a stilted area. However, courtyards also use what is called the ‘stack effect’ to induce ventilation .
It works something like this. The sun makes the air of the courtyard hot by day. Hot air rises, and cooler air from adjacent indoor spaces replaces it (since air always moves from higher pressure to lower pressure areas). This cooler air is then warmed by the sun till it too rises and the cycle continues At night, instead of hot air leaving the courtyard, cold air enters the house through it. This kind of ventilation works best when the difference between indoor and outdoor temperature is significant, which is more likely in the very hot and dry parts of India than along the coasts.
More than one courtyard
Larger buildings can extend this stack effect by having more than one courtyard, provided air can move from one to the other.
Vinod Gupta, a New Delhi-based architect with a specialisation in energy studies, has written about a large haveli in Jaisalmer which has two courtyards of unequal size. The width of the smaller courtyard around which the family spaces are arranged, is approximately half the height of the adjacent three storeys opening into it. This ensures that the courtyard is shaded from the direct sun by the walls of the rooms around it.
The other courtyard at the back of the house is much bigger and is used for tethering animals. Because it is bigger and therefore less shaded by its walls, this courtyard gets directly heated by the sun. Hot air in it rises and cooler air from the family courtyard nearby rushes into it, setting up a stream of ventilation that ensures ventilation through the entire building.
Understanding their eco-logic
Many contemporary buildings use courtyards. However, users are not always aware of the logic behind their working. For instance, in a building not using other induced ventilation systems, a courtyard may be rendered useless (or even cause discomfort) if it is covered by a polycarbonate sheet with no ventilators.
It may be equally useless if all the windows on the outer periphery of the building are kept closed, which would shut off the supply of fresh air into the building to keep the stack effect in operation. If however, design and use are properly matched, the courtyard can provide great benefits in terms of thermal comfort, as well as a unique spatial experience.
[Himanshu Burte is a Goa-based architect]