Heating energy consumptions are compared when impinging jet ventilation (IJV) and mixing ventilation (MV) systems are used in heating modes in large-height spaces. The indoor thermal environments with different outdoor temperatures are simulated by employing CFD techniques for both the constant volume (CAV) and variable volume (VAV) systems. The results show that IJV can distributes the warm supply air into the occupied zone more easily than MV with a Top-Top configuration. The energy consumptions in IJV for heating fresh air and re-circulated air are much less than those in MV because IJV can overcome the disadvantage of thermal stratification that exists in MV rooms, but the power consumed by the fans for IJV is slightly higher than that for MV due to the lower temperature difference between supply and indoor air in the former, resulting in higher total heating energy consumption for MV when compared with IJV. Moreover, the results also show that with MV being replaced by IJV, the heating load index can be reduced and the lower the outdoor air temperature or the higher the required fresh air flow rate is, the more obvious reducing effect for IJV on heating load index. (C) 2016 Elsevier B.V. All rights reserved.