Sometimes, you need to Lose little Battles, inorder to Win the final War!Is that from the school of human wave attacks?
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Petro, I have seen that precise manoeuvre being performed by a cat. It is an indication of worm infestation and the cat does it due to anal irritation from the worms- administer anthelmintics pronto.Fair enough. Maybe it is less prevalent in cats, after all dogs are coprophacics.
I have never seen a cat drag its anus across the parlour carpet alan.Cats tend to be cleaner than dogs.Depends on your definition of clean. They certainly spend more time licking themselves, and in more places, than dogs, but anyone allergic to cat saliva (and a surprisingly large number of people are) wouldn't agree with the proposition.
If you are going to fill the cavity with stuff that doesn't collapse, etc., then the stuff currently used for cavity insulation seems ideal. Why invent anything more expensive or less easy to install?It is far cheaper, as i said. It doesnt collapse under long term deformation, it doesnt hold water, my super air pocket insulation is cheaper lighter and can be inflated on site to mean transport is now far easier. It is full of air that does not undergo convection. But i digress.
Bubble wrap works pretty well (ask any rough sleeper) but tends to collapse under its own weight and is a fire or toxic smoke hazard, so it isn't used in buildings.Very helpful, but unfortunatley in this senario the cubes are made from fire resistant non smoke highly durable super resiliant uber duber kevlar stuff that poses no threat to the building, thermal losses or the cost.
DON'T PUT WORDS IN MY MOUTH, IT'S DISHONEST.. I CANNOT PUT WORDS IN YOUR MOUTH. THE ARGUMENT HAS DEFEATED YOUR POINT. THAT IS THE ODD SENSATION YOU ARE AWARE OF IN THE CHASM IN YOUR HEAD. Stop attempting to stifle the conversation.
. With convection the air molecules are quickly moved from one wall to the other wall.At 1 molecule thick it would require a flow rate of considerable velocity, something we know is not present. The mixing of particles in a stream would mean the turbulence as mentioned by @evan_au, and ruled as destructive by @alancalverd, if however these stream are undergoing conduction it would rule the advantage nil and void.
However, how thick are the bricks that form these partitions?I was thinking more along the lines of cubes of air in thin plastic containers, such as you find in giant bubble wrap packaging just placed within the cavity. It would be many many times cheaper than filling the wall with expensive glass fibre.
Where convection is possible, the rate of transfer of heat from the left side to the right side can be very high. However, if you can prevent convection then the air can only use conduction to transfer heat from left to right which is slower. As the earlier posts have suggested, in small spaces, Convection is prevented. Any attempy to establish an organised flow of air is quickly disrupted and just becomes a chaotic flow of molecules in random directions.So a line of molecules 1 thick in a circulation that is based on conduction from on one side and conduction to the other seems scientifically more transmissive than a column containing many particles each conducting heat from one side to the other? It is all based on conduction. The temperature difference in the air is one factor, if you heat for longer it will achieve a faster cooling, but the heating likewise will take longer, ea molecule with ten times the temperature will take >10 times to heat. The heat conduction of air remains the same and central whether transmitting in a circulatory manner or a conduction manner.
Would a cavity wall with 10cm high partitions in a 10cm cavity or even 10cm cubes really perform better than a 10cm open cavity?
Convection means driving down one side of the street to collect stuff from n houses, then driving back up the other side, depositing rubbish as you go, so you shift all the stuff in a distance 2l where l is the length of the road.Yes but in the case of conduction you have more dust carts working all at the same time doing one bin, where as with convection they are all queued up doing an entire side of the street one after another. I would expect the working all at the same time to win to be honest.
For conduction, you shuttle between the sides of the road, taking one bin at a time so you have to drive 2nw to shift the same amount of stuff across the road, where w is the width of the road. Replace the dustcart with a molecule and n becomes very large.
And turbulence occurs more in small spaces, while laminar flow is possible in large spacesBut what is the difference between air convecting and air transmitting, it all has to "pick up" heat one side and deposit it the other, whether it is replaced in a flow, or is static, all of the air has to perform this task.
If the gap is too narrow, you can't get laminar flow down one side and up the other - turbulent mixing interrupts the convection pattern. That's how gas-filled double glazing works, regardless of the belief system of the observer.But what difference does it make if the air undergoes heating, convects and then cools to air that under goes heating and cooling between pockets in a linear fashion? I cannot see the difference
Not sure how air is "drawn in" to a cavity wall acting as a chimney. Mine are supposed to be wind- and water-proof all the way to the ground.Building standards are still not what they should be, 20 years ago you could have a cavity open to the loft space, as well as the plasterboard dot and dab being open. Walls today have exterior ventilation placements in the brickwork as well as an airgap infront of the insulation to guard from condensation. Years ago air would go into the open hollow cavity at the eves and would eventually exit at the ridge, not warm but no condensation.
As for the density and conductivity of the filler, polystyrene or polyurethane foam is about 96% air by volume - you can pretty much ignore the plastic contentI wondered whether the change of density, (gas to solid) would limit transmission, it takes much more air to raise a solid by the same temperature. Hence slowed transmission, or insulation?