Naked Science Forum

General Science => General Science => Topic started by: Andrew Norton on 17/04/2009 01:30:02

Title: What are the prism-shaped rotating objects seen on roofs?
Post by: Andrew Norton on 17/04/2009 01:30:02

Andrew Norton  asked the Naked Scientists:
   
Hi Chris
     
What are the shiny prism shaped things found on some buildings and which rotate? Is this to deter the birds from defecating on the roof
tiles?

Kind regards

ANDREW NORTON  

What do you think?

Title: What are the prism-shaped rotating objects seen on roofs?
Post by: Chemistry4me on 17/04/2009 01:32:26

What's this? I have never seen such a thing.

Title: What are the prism-shaped rotating objects seen on roofs?
Post by: lyner on 17/04/2009 11:06:13

If they are on chimneys, they could be rotating cowls - to stop back draft down the flue. New ones can look shiny for a few months / years.

Title: What are the prism-shaped rotating objects seen on roofs?
Post by: cedar_tree on 18/04/2009 03:26:59

they are wind turbine vents, or its an 3D space observatory

Title: What are the prism-shaped rotating objects seen on roofs?
Post by: chris on 18/04/2009 12:36:30

Yes, they are rotating cowls that point into the wind such that the open (vent) side is always facing downwind. This prevents the wind from blowing back down the chimney, stopping smoke or flue-gas build-up in the house or building.

They are quite popular in South Africa. Our next door neighbour (who is from South Africa originally) has one, and when I was in Grahamstown for SciFest I noticed quite a few houses using them. I presume there are quite a few windy days there?


Chris