Shared walls, cool interiors

Beat the heat in Bengaluru with shading walls - a simple, sustainable solution for cooling interiors naturally.

Bengaluru recorded 35°C on March 15, 2025. Can’t Bear the Heat? Try Shading Your Walls!

For a modern urban dweller, it may be unusual to see houses clustered closely together, like a herd of sheep, in older villages, hillside settlements, or medieval heritage towns. Similarly, take children to a zoo, and they may notice how several animal species sleep one over the other in a single mass. Any connection between these two phenomena — one human-made, the other an instinctive animal behaviour?

Yes, there is. Closely built structures mutually shade each other’s walls, keeping interiors cool. The shared walls act as thermal mass, further insulating the spaces inside. Similarly, animals that huddle together share body heat in colder climates while also gaining psychological comfort year-round. Ultimately, it’s all about walls and skins.

Walls form the largest surface area of a building, more than floors, roofs, or support structures. They define the visible elevation, accommodate windows, and house storage units, and invite varied decorations. With our frontal vision, humans tend to focus on walls more than any other building element, even though we also perceive entire interiors and external views.

What remains invisible to us is how much direct and diffused solar heat walls absorb — primarily through light but also via contact with hot air. The combined effects of convection and conduction gradually heat the building’s interiors, especially today, when setback rules prevent structures from being shaded by neighbouring buildings or trees.

Modern architecture has replaced small wooden windows, or even the tiny apertures of historic buildings, with large glass windows. While they provide expansive views, they are often covered with curtains, another modern trend! Glass, a high conductor of heat and light, turns our interiors into brightly lit, overheated spaces, akin to microwaves.

The problem itself suggests the solution: prevent direct sunlight from reaching the outer surface of walls. Planting trees near walls is one option, but they require space, may not provide dense foliage, could obstruct views, and might damage structures with their roots.