INSULATING OUR SHELTERS
The belief that walls and roofs should be solid for long lasting strength is a myth.
Come summer and many of us pull out our old mud water pots and tell the kids its better to drink pot water than fridge water. Why? The mud insulates it from heat and the porous nature of its wall around permits micro ventilation, letting the water seep through. Termites could be enemies of our homes, but they are master architects building ant hills that maintain steady internal temperature. Once again, it is the principle of insulation and ventilation that play a role there, besides it being subterranean. Nature can showcase many more examples like bird nests. .
Traditional dwellings in rural areas were built with plain mud walls which insulates and local thatch roof which ventilates. Later on as materials changed, yet burnt brick walls and roof tiles continued to shelter the houses from heat and cold, though at a lesser degree compared to the vernacular style. This approach avoided non-local materials, structures were not monolithic and construction was not rock solid.
Of late, our buildings are being designed differently. We appear to believe in solid walls with thick cement plastering to make it durable, layer of impervious paint in the name of protection, hard concrete roof to make the building strong and terrace finished with dense layers for water proofing. The high density materials all around let out heat conductivity warming up the inside, and sealed off interiors result in warm air trapped inside. Naturally, we blame the house for being a hot box and buy an air conditioner or ceiling fan. Imagine the days when neither of these existed.
The belief that rock solid materials last long is a misnomer. Construction timber lasts for centuries and so too a wall with lime finish. We often say they ‘breathe’, which is a principle behind their longevity.
Seal them off, their life will reduce. The belief that walls and roofs should be solid for long lasting strength is another myth. The domes and vaults of century old monuments were neither monolith nor solid and they may last longer than all our modern buildings.
Majority of materials that we use today are machine made, with much higher density and lesser porosity than the natural or hand made materials that were used in the past. No wonder, they perform rather badly during the seasons.
Imagine designing with hollow materials like hollow clay blocks – they provide insulation thanks to the void inside, yet allow ventilation when built reverse with the openings connecting inside and outside.
In case solid bricks have to used, they can be arranged as a cavity wall, either with full cavity or as in rat trap bond. Porous materials can be replaced by hollow core options, not only in the walls but also in the roof.
Filler roofs and slabs with light weight cement blocks as inserts are two easy-to-do examples, besides ventilated hollow roofs. Beyond the passive methods, only where need arises, one may consider mechanical methods towards indoor comforts.
We have re-discovered ways of designing for climate – now need to apply them.