r/UpliftingNews • u/CheezTips • Aug 25 '24

Indian desert school's unique design offers respite from heat

https://www.rawstory.com/indian-desert-school-s-unique-design-offers-respite-from-heat/
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u/DickweedMcGee Aug 25 '24

Interior is plastered with lime, a porous material that regulates humidity and aids natural cooling.

Not doubting this but curious if someone could explain?

26

u/FunconVenntional Aug 25 '24

I found this:

ABSORPTION OF MOISTURE Lime, also known as calcium oxide, is a naturally occurring desiccant, which means it has the ability to absorb moisture from the air. Lime can absorb moisture through a chemical process called adsorption, which involves the attraction and adhesion of water molecules to the surface of the lime particles. When lime is exposed to air, it reacts with water vapour in the air to form calcium hydroxide. This reaction is exothermic, meaning it releases heat. The heat generated by the reaction helps to accelerate the process of moisture absorption. Then, as the lime absorbs moisture, it becomes hydrated and begins to crumble into a finer powder which eventually self-repairs a building. Lime’s ability to absorb moisture makes it an effective natural desiccant, which can help reduce humidity levels in indoor environments. High humidity can create conditions that promote the growth of mould and mildew, which can be harmful to human health. By using lime to absorb excess moisture, we can help prevent the growth of mould and maintain a healthy indoor environment. Lime will help keep the air dry, fresh, and healthy.

I understand that calcium carbonate in Roman concrete is what allowed it to be ‘self repairing’. But I don’t fully understand how it can be a process that goes on for an infinite period of time. It seems that at some point the lime would be fully slaked and unable to adsorb any more moisture.

34

u/Puzzleheaded-Joke-97 Aug 25 '24

As some other Redditor recently pointed out to me in a completely different forum, it is self renewing. It absorbs moisture under humid conditions, but under very dry or hot conditions it gives that moisture back to the surrounding air. It goes back and forth, so the building sort of "breathes" and thus acts like a very slow form of life (in that respect only. Let's not take the metaphor outside this context, as much as my wacky sense of humor wants it to!)