On light: designing for the Kerala monsoon

Most of the houses we admire in Kerala were built before air conditioning, and they are comfortable in a way that newer ones often are not. The reasons are simple and old: deep overhangs, a roof that breathes, rooms arranged so the breeze has somewhere to go.

We try to design for the monsoon first and the summer second. If a house is dry, shaded and ventilated in August, it will be pleasant in April. The reverse is not true.

Overhangs and thresholds

Our roofs overhang by at least a metre and a half on every side. That protects the walls, keeps the driving rain off the glazing, and means a window can stay open through a downpour. The veranda becomes the room you live in for four months of the year.

Light without heat

North light is the easy one. The harder problem is the west, where the sun comes low and hot in the evening and where, in Kochi, the best breeze also comes from. Louvred timber shutters on the west elevation let the air through and take the sun out. They are the single most useful detail we draw.

Perumbavoor tested that thinking hardest. An hour inland, without the sea breeze the city gets, a building has to make its own air movement or the rooms never cool down after dark. Both blocks there are single-banked, so every apartment has windows on opposite walls, and the stair halls are open to the sky and work as chimneys.

The veranda is not an extra. In this climate it is the most important room in the house.