Greetings.

Would this contraption have some use; or is it somehow already done ?

A plain single wall metal (black, aluminium?) chimney exposed to a sunny location and preferably shielded from wind direction; heats up the air inside.

The air heated by the metal chimney rises and vents at the top end, pulling air trough the room at the bottom end of the pipe creating a flow as a fan does.

Humble yes, not exactly air conditioning, but hey, it is a fan with its corresponding effect on skin. Does such thing exist ? The sunnier and hotter it is, the faster the ventilation flow. No increase in humidity as evaporative coolers do. No energy consumption, moving parts or motors, noise nor maintenance. The pipe could pass trough a helly hot attic space (like mine) too to extract/soak more heat before venting. Bigger pipe diameter = better results ? Just block in winter or manage to reverse flow ?

Do you believe would work ? What would you polish/improve to this idea ? Does it have merit ? Thanks.

3 hours ago, Externet said:

Greetings.

Would this contraption have some use; or is it somehow already done ?

A plain single wall metal (black, aluminium?) chimney exposed to a sunny location and preferably shielded from wind direction; heats up the air inside.

The air heated by the metal chimney rises and vents at the top end, pulling air trough the room at the bottom end of the pipe creating a flow as a fan does.

Humble yes, not exactly air conditioning, but hey, it is a fan with its corresponding effect on skin. Does such thing exist ? The sunnier and hotter it is, the faster the ventilation flow. No increase in humidity as evaporative coolers do. No energy consumption, moving parts or motors, noise nor maintenance. The pipe could pass trough a helly hot attic space (like mine) too to extract/soak more heat before venting. Bigger pipe diameter = better results ? Just block in winter or manage to reverse flow ?

Do you believe would work ? What would you polish/improve to this idea ? Does it have merit ? Thanks.

In principle yes, especially if painted matt black. This is known at the Stack Effect: https://en.wikipedia.org/wiki/Stack_effect

You can also get help from any ambient breeze by mean of the venturi effect, with a suitably shaped cowl on top, to create a slight pressure drop at the top when the breeze blows. And then there are these rotating cowls that spin in the wind and create suction by means of the design of their blades. My neighbour has those at the top of his 3 storey house.

Obviously, with all these options, you need to provide for air ingress close to ground level (perhaps from above a patch of grass in shade, i.e. not from just above a piece of concrete exposed to full sun!) , to replace the air drawn out at the top. You might want to give thought to where to site that, to get a cooling draught from it at the spot where it would be most beneficial.

Edited July 22, 2025Jul 22 by exchemist

Architecturally this is called passive cooling.

Here are some links.

https://en.wikipedia.org/wiki/Passive_cooling

How India's lattice buildings co...

How India's lattice buildings cool without air con

For centuries, India’s architecture featured intricate lattice structures. Now, as modern architects search for better ways to keep buildings cool, it’s making a comeback.

1 hour ago, studiot said:

Architecturally this is called passive cooling.

Here are some links.

https://en.wikipedia.org/wiki/Passive_cooling

How India's lattice buildings co...

How India's lattice buildings cool without air con

For centuries, India’s architecture featured intricate lattice structures. Now, as modern architects search for better ways to keep buildings cool, it’s making a comeback.

A nice architectural example, but the explanation the article gives of the venturi effect makes no sense. It says the air is compressed as it passes through small holes in the jaali screen and cools when it expands on the other side. That is not a venturi effect, it's just adiabatic compression and expansion and I am not convinced it is either significant or would have the effect described. The towers on the other hand would provide cooling by the stack effect and possibly some venturi suction with a breeze blowing across the top.

Bernoulli's principle does seem to work with the lattice windows mentioned. The point is that the air stream accelerates in the interior space, giving the cooler feeling as air moves across the skin more rapidly than it would have coming through a standard large aperture window. I mean, no, the lattice doesn't actually extract heat or anything fancy, it just makes the air move faster.

BTW, I would think that sizeable attic vents would help overall house cooling more than the stack shown on OP. Attic air can get up to 150 F in hot climates, so it's useful to ventilate the space thoroughly. Then block vents in winter.

Some more links

An interesting american discussion site about the subject

https://permies.com/t/208521/tech/Venturi-effect-air-flow-buildings

A technical paper on Hawa Mahal

https://www.irjet.net/archives/V9/i3/IRJET-V9I3386.pdf