Open-spaces Museum consumes a significant amount of energy to provide stable indoor climate for valuable exhibited items. This paper evaluates the energy saving potential of using a local air-conditioning system in open-space museum using simulation-based hygrothermal microclimates analysis. The new Viking Age Museum in Norway is taken as a case study. IDA-ICE building simulation tool was used to evaluate the thermal performance and energy consumption. ANSYS-FLUENT software was employed to assess the indoor (thermo-hygrometric parameters) Tair and relative humidity (RH) distribution, in compliance with ASHRAE requirements for exhibition objects. The simulations were conducted by dividing the large-scale museum into two separate zones and investigating different HVAC systems. Case-1 was the base case, where the open exhibition room including the exhibition object (i.e., Viking ship), is conditioned by a single constant-air-volume air handling unit (CAV-AHU). Two separate CAV-AHUs served the ship as a microclimatic zone and the exhibition room in case-2. Cases-3 and 4 had CAV-AHU for the microclimate zone. Besides, a variable-air-volume air handling unit (VAV-AHU) and a radiant floor system are used to exhibition room in case-3 and 4, respectively. Each simulation was performed during two separate weeks in winter and summer. The results showed that case-4 achieves 48.2% and 55.9% total energy saving from the base system for the winter and summer seasons, respectively. CFD modelling showed that case-4 provides a good uniformity of the Tair and RH around the ship with Tair and RH variation of 1.4 °C and 3.7%RH in winter and 3 °C and 6.5%RH in summer.