The Kondo effect is a strong correlation non-perturbative emergent phenomenon. It was first discovered in the bulk by analyzing magnetic impurities embedded in normal metal. With the progress of nanodevice fabrication a renewed interest in Kondo physics has been rekindled. To obtain reliable quantitative predictions for such experiments, unbiased numerical simulations such as various variants of quantum Monte Carlo (QMC), or numerical renormalization group (NRG) are widely used. In this talk, I will give a brief introduction into the applications of Renormalization group techniques to continuous phase transitions. Later, a solution of a magnetically tunable Kondo effect by using numerical Renormalization group is shown. The obtained results are carefully compared to the experimental data obtained in a corresponding nanodevice investigated in the group of prof. Van der Zant at TU Delft.