From the origonal paper www.cs.wisc.edu/vertical/papers/2013/hpca13-isa-power-struggles.pdf (which ExtremeTech does not link to):
Technology scaling and projections:
Since the i7 processor is 32nm and the Cortex-A8 is 65nm, we use technology node characteristics from the 2007 ITRS tables to normalize to the 45nm technology node in two results where we factor out tech-
nology; we do not account for device type (LOP, HP, LSTP).
For our 45nm projections, the A8â(TM)s power is scaled by 0.8Ã-- and
the i7â(TM)s power by 1.3Ã--. In some results, we scale frequency
to 1 GHz, accounting for DVFS impact on voltage using the
mappings disclosed for Intel SCC . When frequency scal-
ing, we assume that 20% of the i7â(TM)s power is static and does
not scale with frequency; all other cores are assumed to have
negligible static power. When frequency scaling, A8â(TM)s power is
scaled by 1.2Ã--, Atomâ(TM)s power by 0.8Ã--, and i7â(TM)s power by 0.6Ã--.
We acknowledge that this scaling introduces some error to our
technology-scaled power comparison, but feel it is a reasonable
strategy and doesnâ(TM)t affect our primary findings (see Table 4).