Buffer calculation example: unfired perforated brick

lower case letters represent the columns in the excel spreadsheet
[...] square brackets enclose dimension check

Constant: grams water in 1 m3 space at 18C and 10%RH = 1.529

Data:
d = thickness of specimen m
e = exposed area m^2
f,g,h = measured water movement for 10% RH cycle 24hr, 96hr, long
l = specimen density in kg/m^3
m = water sorption for 10% RH change around 50%, g/kg (measured in sorption exp.)

Calculation of experimental B-value:
Calculate water exchanged for 1 m^2:
H = (water exchanged)/(exposed surface area) [unit = g.m^-2]
Calculate equivalent volume of space:
B = H/1.529 [unit = g.m^-2.g^-1.m^3 = m ]

Calculation of theoretical B-value for infinitely long cycle:
Weight of specimen:
W = (surface area) x (thickness) x density [unit = m^2.m.kg.m^-3 = kg]
Total exchangeable water:
E = W x sorption [unit = kg.g.kg^-1 = g]
Normalise to 1 m^2 exchanging surface:
H = E/area [unit = g.m^-2]
Convert to equivalent volume of space:
B = H/1.529 [unit = g.m^-2.g^-1.m^3 = m]