Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

India's lattice buildings cool without air con

bbc.com

Post reply on HN
Print view View original

31–40 of 87 posts

Re: India's lattice buildings cool without air con

#31

Post by phyzome »

trabant00 wrote: post #17

I don't think this is correct at all: > Jaali’s cooling feature relies on the Venturi effect in a similar way to an air conditioning unit. "When air passes through holes, it picks up velocity and penetrates afar. Due to the small apertures, air gets compressed and when released it gets cooler," says Pandya. When the air passes through the holes, yes, it picks up velocity, but that velocity is lost immediately upon ex…

Another quote:

« One notable feature of the building is its application of a physics principle called the "stack effect", whereby the rotation angles of each brick in the jaali are designed to minimise solar radiation. »

...that's not what the stack effect is.

Re: India's lattice buildings cool without air con

#32

Post by galangalalgol »

trabant00 wrote: post #26
galangalalgol wrote: post #22

Earlier quoted context omitted.

As the air shrinks in volume (and as you say, speeds up) it goes up in temp. It dumps sone of that heat into the marble. So when it opens back up, it slows down and cools down. The material choice would seem to be very important. Marble and sandstone both have high thermal mass but low thermal conductivity.

> As the air shrinks in volume (and as you say, speeds up) it goes up in temp. It does not shrink in volume, it does not compress, it only speeds up so the debit remains the same. If anything it would expand as an effect of the Venturi, because the pressure drops.

I was looking at a picture from the venturi in an AC loop where one side is higher because of the compressor and over restriction Yeah, venturi would seem to be a non-effect here.

Re: India's lattice buildings cool without air con

#33

Post by culturestate »

smcl wrote: post #20
gattilorenz wrote: post #18

Earlier quoted context omitted.

I think they're popular all across the Mediterranean, I've certainly seen them in Italy and Croatia. Shutters are noticeably missing in areas in Northern Europe due to "never being hot enough", except... now they would be welcome.

I remember seeing them a fair amount in the old quarter in Hanoi, quick search shows my memory isn't failing me: https://www.indochinavoyages.com/travel-blog/hanoi-old-quart...

For what are probably obvious reasons, this style of shutter is everywhere in the post-colonial tropics. Look at any heritage building in Hong Kong, Singapore, Hanoi, Nassau, Martinique…

Re: India's lattice buildings cool without air con

#34

Post by samarthr1 »

refactor_master wrote: post #7
vivegi wrote: post #5

Earlier quoted context omitted.

Using an airconditioner and lattice structures/jaali are not mutually exclusive. As an example, if you consider large buildings like hotels that have an open central courtyard, the open spaces could use the lattice structures for cooling/circulation while the rooms, banquet/conference halls and other closed spaces can use airconditioners. Since the lattices offer passive cooling, they can lower the overall energy bil…

Given the amount of traffic, street level noise, and air pollution in many Asian countries I don’t see this being implemented any time soon, in places where it matters. Ceiling fans would also work really well, but similarly require openings in buildings. Now you only see them in traditional buildings (read: museums most often) because they were made with airflow in mind, before the age of AC. People will prefer a he…

Have you lived in a residential area in a city like Hyderabad or Bengaluru before?

The smaller side streets are usually peaceful, unless you have the misfortune of living next to a building under construction.

Re: India's lattice buildings cool without air con

#35

Post by smusamashah »

trabant00 wrote: post #17

I don't think this is correct at all: > Jaali’s cooling feature relies on the Venturi effect in a similar way to an air conditioning unit. "When air passes through holes, it picks up velocity and penetrates afar. Due to the small apertures, air gets compressed and when released it gets cooler," says Pandya. When the air passes through the holes, yes, it picks up velocity, but that velocity is lost immediately upon ex…

Jaali probably just acts like an air shield (i.e. the air thrower above doors in shopping stores). This way you still get fresh air except lower rate of heat transfer.

We have this in our family home. Was not a fan of them because they collect all the dust but after reading this article they seem to have a very good use we never think about.

Re: India's lattice buildings cool without air con

#36

Post by ajmurmann »

guywithahat wrote: post #2

They also make it impossible to add air conditioning if I'm reading this right and can only really cool things down to the surrounding temperature (basically attempts to keep buildings from turning into greenhouses). Very cool but I don't see this being implemented anywhere where someone can afford AC

If I understood the article correctly, the temperature could be slightly lower than surrounding air sure to the venturi effect. At least that's what the article claimed, even though it provided no concrete numbers on its effectiveness

Re: India's lattice buildings cool without air con

#37

Post by ajmurmann »

Retric wrote: post #11
refactor_master wrote: post #7

Earlier quoted context omitted.

Given the amount of traffic, street level noise, and air pollution in many Asian countries I don’t see this being implemented any time soon, in places where it matters. Ceiling fans would also work really well, but similarly require openings in buildings. Now you only see them in traditional buildings (read: museums most often) because they were made with airflow in mind, before the age of AC. People will prefer a he…

A shell within a shell also works. It’s common for tall building to have air gapped external cladding to reduce the need for cooling. There are significant trade offs around construction costs, views, and the need for cooling. However, the savings can be very significant for more extreme designs.

You are spotty on. That's also what the article described some modern buildings are doing with these jaali screens

Re: India's lattice buildings cool without air con

#40

Post by SanjayMehta »

nisegami wrote: post #30
pembrook wrote: post #19

Earlier quoted context omitted.

In the example you give, there’s no way of knowing if it’s been properly designed for Indian climate per given budget constraints. There appears to be windows on only 2 sides of the building, 1 of which is far enough inset to create significant shade. Depending on what direction the building faces, this could in fact be optimal design for staying cool while still having windows. Now, of course, the best design for st…

>Now, of course, the best design for staying cool would be an underground cave carved out of rock with no windows—-but is that really how we want to live? Adding light and some ventilation is a lot less energy intensive than cooling

Caves can get unbearably hot and humid here too.
Post reply on HN