This paper reports on experimental observations on TCV with a scan in upper triangularity ${\delta }{\mathrm{up}}$, including negative triangularity, focusing on the power fall-off length ${\lambda }{{\rm{q}}}$ in L-Mode. The upper triangularity is scanned from −0.28 to 0.47. Smaller ${\lambda }{{\rm{q}}}^{\mathrm{out}}$ is measured at the outer divertor target for decreasing ${\delta }{\mathrm{up}}$ together with higher edge temperature ${T}{{\rm{e}},\mathrm{edge}}$ leading to increased confinement. This effect is observed for both magnetic drift directions for discharges in deuterium and helium. In helium larger ${\lambda }{{\rm{q}}}$ values are observed compared to deuterium. The power fall-off length at the inner divertor target ${\lambda }{{\rm{q}}}^{\mathrm{in}}$ has a non-monotonic behaviour with changing triangularity. The largest values are around ${\delta }{\mathrm{up}}=0$. The ratio ${\lambda }{{\rm{q}}}^{\mathrm{in}}/{\lambda }{{\rm{q}}}^{\mathrm{out}}$ increases for decreasing ${\delta }{\mathrm{up}}$ for positive triangularity and is approximately constant for negative triangularity. ${\lambda }{{\rm{q}}}^{\mathrm{out}}$ is compared to available scaling laws. Partial agreement is only observed for a scaling law containing a proxy for ${T}{{\rm{e}},\mathrm{edge}}$ at ASDEX Upgrade (Sieglin 2016 Plasma Phys. Control. Fusion 58 055015). Extending this scaling to TCV and using ${T}{{\rm{e}},\mathrm{edge}}$ at ${\rho }{\mathrm{pol}}=0.95$ suggests that ${\lambda }{{\rm{q}}}^{\mathrm{out}}$ is independent of machine size ${\lambda }{{\rm{q}}}^{{\rm{L}} \mbox{-} \mathrm{Mode}},(\mathrm{mm}),=$ $165\cdot {B}{\mathrm{pol}}{({\rm{T}})}^{-0.66}\cdot $ $A{({\rm{u}})}^{-0.15}\cdot $ ${T}{{\rm{e}},\mathrm{edge}}{(\mathrm{eV})}^{-0.93}\cdot $ $R{({\rm{m}})}^{-0.03}$. Possible explanations for smaller ${\lambda }{{\rm{q}}}^{\mathrm{out}}$ for decreasing ${\delta }{\mathrm{up}}$ is a reduction in turbulence or a direct effect of increasing ${T}{{\rm{e}},\mathrm{edge}}$.