If air has so low conductivity why does putting insulation b

If air has so low conductivity, why does putting insulation between the studs lower the heat transfer so much?

Solution

firstly , conductivity is a measure of heat transfer , that is how good a material can conduct heat. Conductivity depends on material compositioin , density , the temperature between the surfaces .

Insulation is resistance to heat transfer , that is opposite to thermal conductivity .

A low thermal conductivity body transfers the heat loss , indeed can be said as a good insulator since it allows minimal heat transfer. Similarly a high thermal conductivity body is a bad insulator.

Heat transfer by air is a convection phenomenon and with insulators is a conduction phenomenon and conduction is more familiar one

Though air is the cheap insulator available , Insulation materials are low density materials and are manufactured from low thermal conductivity materials and are made to ensure that they contain good number of voids for air flow . Convection from air can be steady state process or transient state process .