The two key measurements are:
(also known as thermal mass for buildings)
The energy to raise 1kg of a substance by 1°C
c = J kg¯¹ °C¯¹
A high value has a low temperature rise for a given amount of heat input, or requires a greater heat input to get a given temperature rise.
The ability of a substance to conduct heat.
k = -q/𝛻T in W m¯¹ °C¯¹ where:
q is the heat flux, the flow of energy per m² cross sectional area per second, in W/m²
𝛻T is the temperature gradient, i.e. change in temperature / thickness, in °C m¯¹
An insulator has low thermal conductivity
From these are derived:
Rate of transfer of heat energy from the hot to the cold end
𝛼 = k 𝜏¯¹ c¯¹ in m²/s where:
c, k as defined here
𝜏 is the density in kg/m³
A measure of how readily a body will exchange heat with its surroundings
𝑒= √(𝑘.𝜌.𝑐) in J/(m² °C √𝑠 )
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