Description of ChallengeIn hot arid zones, a difficulty is found in combining the three functions of the ordinary window: light, ventilation, and view. If windows are used to provide for air movement indoors, they must be very small, which reduces room lighting. Increasing the size to permit sufficient lighting and an outside view lets in hot air as well as a strong glare. Therefore, it is necessary to satisfy the three functions ascribed to the window separately.
Malqaf is a part of a complete ventilation system, consisting of a large shaft rising high above the roof of a building. The system of ventilation developed depends primarily on air movement by pressure differential, but also secondarily on air movement by convection.
To satisfy the need for ventilation alone, the Malqaf or wind-catch was invented. It is a shaft rising high above the roofline, with an single large opening and a diagonally sloping top that faces the prevailing wind. It traps the wind from high above the building where it is cooler and stronger, and channels it down into the interior of the building.
The Malqaf thus dispenses with the need for ordinary windows to ensure ventilation and air movement. The Malqaf is also useful in reducing the sand and dust so prevalent in the winds of hot arid regions. The wind it captures above the building contains less solid material than the wind at lower heights, and much of the sand which does enter is dumped at the bottom of the shaft.
The value of the Malqaf is even more obvious in dense cities in warm humid climates, where thermal comfort depends mostly on air movement. It’s found especially in Egypt, Iran, and Pakistan but also in Egypt, where the Malqaf has long been a feature of Islamic architecture.