Aerogel glazing system is an advanced energy-efficient glazing system designed to reduce the building energy consumption. However, there is no study focused on the energy performances of aerogel glazing systems filled with different aerogels. To analyse the energy performance, the solar extinction coefficient is an indispensable parameter, which is unknown yet. In this research, the solar extinction coefficient is calculated by Mie scattering and Monte Carlo method. The spectral distribution of solar irradiance is taken into account. The influences of porosity and nano-particle’s size are discussed. Then, the solar heat gain coefficients of different aerogel glazing systems versus incidence angle are calculated. Finally, a dynamic heat transfer model is used to simulate the energy performances of different aerogel glazing systems. A case study is carried out for Hong Kong. The results indicated that the porosity of monolithic aerogel has greater influence than the diameter, and the reciprocal effect between the porosity and the diameter is negligible. It is also figured that aerogel with small nano-particle and low porosity will lead to a better energy conservation performance in cooling dominated region.