A	area of heat transfer, m2
D	dimension of structure closure, m
H	multilayer insulation thickness, m
K	thermal conductivity, W/(m·K)
L	wall length, m
R	thermal resistance, m2·K/W
T	temperature, K
q	heat flux, W/m2
Greek symbols
δ	plastic wall thickness, m
ε	emissivity of plastic material
σ	Stefan–Boltzmann constant
Subscripts
a	air
C	cooled side
c	convection
H	heated side
HB	heated at the bottom
HT	heated at the top
i	insulation
L	related to walls that have length L
n	number of layers
p	plastic
r	radiation
w	wall