Specific heat and thermal conductivity data for a homologous series of base‐catalyzed silica aerogels in the temperature range 0.1–20 K are analyzed in a three regime model. The three regimes, dominated by phonons, fractions and particle modes, respectively, reflect three structural regions as found by SANS measurements. The thermal properties of aerogels are compared to those of dense amorphous quartz and important differences are found.