  Pulsar wind nebulae (PWNe) represent the largest class of sources that
upcoming {\gamma}-ray surveys will detect. Therefore, accurate modelling of
their global emission properties is one of the most urgent problems in
high-energy astrophysics. Correctly characterizing these dominant objects is a
needed step to allow {\gamma}-ray surveys to detect fainter sources,
investigate the signatures of cosmic-ray propagation and estimate the diffuse
emission in the Galaxy. In this paper we present an observationally motivated
construction of the Galactic PWNe population. We made use of a modified
one-zone model to evolve for a long period of time the entire population. The
model provides, for every source, at any age, a simplified description of the
dynamical and spectral evolution. The long term effects of the reverberation
phase on the spectral evolution are described, for the first time, based on
physically motivated prescriptions for the evolution of the nebular radius
supported by numerical studies. This effort tries to solve one of the most
critical aspects of one-zone modeling, namely the typical overcompression of
the nebula during the reverberation phase, resulting in a strong modification
of its spectral properties at all frequencies. We compare the emission
properties of our synthetic Pulsar Wind Nebulae population with the most
updated catalogues of TeV Galactic sources. We find that the firmly identified
and candidate PWNe sum up to about 50% of the expected objects in this class
above threshold for detection. Finally, we estimate that CTA will increase the
number of TeV detected PWNe by a factor$\geq3$.
