Heating buildings causes ~10% of global CO2 emissions. The electrification of heating using renewable energy can reduce emissions, although the intermittent nature of renewables presents a challenge. Heat pumps integrated with thermal energy storage is a promising way to match heating load demands and renewable power generation profiles. In this work an adsorbent-based thermal energy storage system comprising silica gel is built within a duct branch such that it can be directly integrated with heating, ventilation, and air conditioning systems in buildings. The effects of varying the airflow velocity from 0.4 to 0.8 m/s on the outlet air temperature of the TES unit is investigated. Results show the maximum temperature of heated air coming from the outlet of the TES unit does not significantly depend on the airflow velocity. However, lower airflow velocities prolong the time taken for the outlet air to reach the maximum temperature during the discharging phase. Furthermore, energy storage densities greater than 1000 kJ/kg are achieved. These results bode well for the further development of customized heating, ventilation, and air conditioning-integrated thermal energy storage systems that operate with heat pumps to facilitate the electrification of heating.