Name: Cesar Baquerizo Arosemena
What I meant was that if I design a house for example and I want it to be
insulated from sound and heat, so that I don't need to have my AC on, and
the external walls, are made of bricks, but these bricks, have holes in them,
Is it better to leave the holes empty, or is it better to fill them with
Filling the holes in the bricks with sand might make the walls more
bulletproof, but it probably won't help insulate against sound or heat.
Air is a very good insulator for heat, as long as it cannot circulate. The
air locked in the holes in a brick can't circulate much.
Pockets of air also make good soundproofing. Sound travels through solids
well, but putting holes in the solids causes the sound to break up as it
goes from solid to air and back again, and the sound will interfere with
itself and lose energy.
I think the real reason that some bricks have holes in them, though, is to
make them hold their mortar more strongly.
Richard Barrans Jr., Ph.D.
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Update: June 2012