  We use a real-space renormalization group (RSRG) to study the low temperature
dynamics of kinetically constrained Ising chains (KCICs). We consider the cases
of the Fredrickson-Andersen (FA) model, the East model, and the partially
asymmetric KCIC. We show that the RSRG allows one to obtain in a unified manner
the dynamical properties of these models near their zero-temperature critical
points. These properties include the dynamic exponent, the growth of dynamical
lengthscales, and the behaviour of the excitation density near criticality. For
the partially asymmetric chain the RG predicts a crossover, on sufficiently
large length and time scales, from East-like to FA-like behaviour. Our results
agree with the known results for KCICs obtained by other methods.
