The elevation profiles of the ascents are measured with a bike computer,
which collects data on the distance covered and on elevation.
The profiles are then divided into sections with a length
of 250 meters along the road (dL).
From the initial and final elevation of each segment the slope (s) is determined
and from that the climb effort (dI):
dI = 0.001 s² dL
where dI is in climb effort points (cep), s in % and dL in meters.
The total climb effort of the ascent is the sum
of the effort points of all sections.
This quantity represents only that part of the effort
that is spent in addition to the effort spent on a horizontal road.
So, the profile is divided into intervals,
the climb effort for each interval equals to the number of elevation meters
times the slope
and the total effort is the sum of the efforts of all intervals.
Finally, the result is multiplied by a constant (0.001)
so that each elevation meter gained on a slope of 10%
results in 1.0 cep.
Another elevation meter gained on a slope of 5% adds only 0.5 cep
and on a slope of 1% merely 0.1 cep
For details I refer to
the Dutch version of this webpage