Recent technical progress allows for the thermal analysis of glass forming materials to be performed in a broad frequency range, comparable with that covered by rheology and dielectric spectroscopy. With respect to its differential scanning (DSC) variant, AC calorimetry allows for measurements at scanning rates up to 10 kHz and it is able to provide model independently the rate and the spectral shape of thermodynamic fluctuations. Moreover, as calorimetry measures a heating power which is proportional to the heating/cooling rate, the higher rates employed in the AC measurements provide a higher signal-to-noise ratio with respect to standard DSC.