Which material heats up the quickest under radiant flux: Oak Boards, Concrete Wall, Gypsum Plaster, or Rigid Polystyrene Panels?

Which material heats up the quickest under radiant flux: Oak Boards, Concrete Wall, Gypsum Plaster, or Rigid Polystyrene Panels?

• A. Oak Boards
• B. Rigid Polystyrene Panels
• C. Gypsum Plaster
• D. Concrete Wall

Answer: (B)

When radiant heat is applied, how fast a material warms depends on how quickly heat can diffuse through it—its thermal diffusivity. A material with low density and low heat capacity (low thermal mass) will heat up more quickly because there’s less energy stored to raise its temperature and heat can penetrate more readily. Rigid polystyrene panels are lightweight insulation foam and have very low density and low heat capacity, so they respond rapidly to radiant energy and temperatures rise faster than the denser, higher-mass materials. Oak boards, gypsum plaster, and concrete all contain more mass and store more energy, so their temperatures climb more slowly under the same radiant exposure. Hence, rigid polystyrene panels heat up quickest.

When radiant heat is applied, how fast a material warms depends on how quickly heat can diffuse through it—its thermal diffusivity. A material with low density and low heat capacity (low thermal mass) will heat up more quickly because there’s less energy stored to raise its temperature and heat can penetrate more readily. Rigid polystyrene panels are lightweight insulation foam and have very low density and low heat capacity, so they respond rapidly to radiant energy and temperatures rise faster than the denser, higher-mass materials. Oak boards, gypsum plaster, and concrete all contain more mass and store more energy, so their temperatures climb more slowly under the same radiant exposure. Hence, rigid polystyrene panels heat up quickest.