  Global gradient driven GENE gyrokinetic simulations are used to investigate
TCV plasmas with negative triangularity. Considering a limited L-mode plasma,
corresponding to an experimental triangularity scan, numerical results are able
to reproduce the actual transport level over a major fraction of the plasma
minor radius for a plasma with $\delta_{\rm LCFS}=-0.3$ and its equivalent with
standard positive triangularity $\delta$. For the same heat flux, a larger
electron temperature gradient is sustained by $\delta<0$, in turn resulting in
an improved electron energy confinement. Consistently with the experiments, a
reduction of the electron density fluctuations is also seen. Local flux-tube
simulations are used to gauge the magnitude of nonlocal effects. Surprisingly,
very little differences are found between local and global approaches for
$\delta>0$, while local results yield a strong overestimation of the heat
fluxes when $\delta<0$. Despite the high sensitivity of the turbulence level
with respect to the input parameters, global effects appear to play a crucial
role in the negative triangularity plasma and must be retained to reconcile
simulations and experiments. Finally, a general stabilizing effect of negative
triangularity, reducing fluxes and fluctuations by a factor dependent on the
actual profiles, is recovered.
