This　research　aims　to　facilitate　informed　decision-making　to　enhance　building　energy　simulation,　reduce　costs,　and　minimize　CO2　emissions　through　building　insulation　enhancements　employing　BIM-based　simulation.　Architectural　models　of　an　apartment,　a　prevalent　residential　structure　in　Japan,　were　developed　and　examined　under　diverse　insulation　scenarios　utilizing　ArchiCAD　28.　Five　insulation　substances　were　chosen　based　on　existing　guidelines　to　ensure　conformity　with　local　standards　and　were　evaluated　for　their　thermal　and　environmental　properties:　Cellulose　Fiber,　Glass　Wool,　Urethane　Foam,　Phenolic　Board,　and　Rock　Wool　for　evaluation　based　on　thermal　and　environmental　properties.　The　simulation　parameters　were　aligned　with　Japan＇s　energy　efficiency　standards　and　climate　conditions.　The　factors　addressed　encompass　energy　performance　evaluation,　economic　viability,　and　CO2　emissions.　Simulation　findings　highlight　Urethane　Foam　as　the　most　effective　and　environmentally　friendly　building　insulation　material.　This　study　provides　valuable　perspectives　for　property　owners,　building　designers,　and　contractors,　offering　a　framework　for　insulation　enhancement　choices　that　optimizes　sustainable　construction,　reduces　environmental　impact,　and　enhances　cost-effectiveness　through　the　implementation　of　BIM-based　simulation.